Friday, July 31, 2009

Tri-2, Wk12, Day 118 - Friday ATP

I'll focus a little on ATP today. ATP stands for adenosine triphosphate. Notice the prefix "tri" before the word phosphate which indicates we have three phosphate atoms in ATP. When ATP is broken down it releases energy which I believe is along the order of -31 kJ/mol. Those units are kilojoules per mole. The negative sign indicates an exothermic reaction in which energy is released. There are many words we've encountered which make use of the 'ex' prefix. The most common word we all know is the word 'exit' which has the ex prefix. We also have the word exogenous which refers to something coming from outside of a system.

When ATP is broken down it loses a phosphate and goes from a tri-phosphate to a di-phosphate and is then known as ADP (adenosine diphosphate)

What I've been curious about is that ATP is kind of referred to as an energy source, the high octane fuel of the human body but, when it comes to muscle contraction, a primary role of ATP is to allow our muscles to relax after contraction. When we die, ATP production stops and muscles will stay in a contracted position which is referred to as rigamortis.

We also have the prefix endo which is used in endothermic and describes a process in which energy is consumed. Endogenous means coming from withing. In biochemistry we'll refer to taking resources in via our diet as exogenous while those things being made inside our body as endogenous. Endo is also used to describe many of the tissues in our bodies which are closest to the innermost portion of an organ.

Tri-2, Wk12, Day 117 Thursday - ACES!


Me + Neuroanatomy = A!!!!
Holy Cow! I Aced the neuroanatomy test! According to our tutors this was the hardest of the four test we take and the kid here Aced it! :)
Out of the 60 question test it looks like I missed less than 5 questions. Hmmm, there were five fill in the blank bonus questions which I think I did pretty well on. So, ...well, even better because it's still about 5.5 questions missed out of 65. I really knew this stuff - quite happy.

I need to get focused on upcoming fun which is a bit intimidating in my head. It seems like a big mountain rushing towards me.

Mon 8/3 - Gross Anatomy II Quiz & Physiology I Quiz
Tue 8/4 - Gross Anatomy II Practical & Biochemistry II Quiz
Wed 8/5 -
Thur 8/6 -
Fri 8/7 -

Mon 8/10 -
Tue 8/11 - Neuro Lab Slide Exam 2

I know we have more on some of the days I left blank but don't remember what it is. I'll find out tomorrow at school. This was an odd duck day for sleeping, I woke up at 12:30 a.m. this morning but was asleep fairly early.

Wow - it's almost 4 a.m. & I need to get moving ...I was thinking of going to the 5:30 a.m. boot camp this morning but I'll need to leave by 4:30 a.m. to make it in time ....but, I'm thinking a nice cup of coffee and organizing & studying school stuff sounds much more appealing. This should be easy to rationalize because I'm already sore from yesterdays workout.

BTW - My BluCigs finally arrived today - those suckers are strong and I'll need to be careful with them but they are also tobacco free. I have a link for the Blu Cigs on my blog since I've become an affiliate with the company but they haven't been taking any new orders due to the overwhelming demand. They stopped taking orders on July 7th and weren't going to take any new orders until after Aug 1st. I need to check if this is a publically traded company. ;)

Today's pic is of the letter A because that's the grade I got on my neuroanatomy test! :)

Wednesday, July 29, 2009

Tri-2, Wk12, Day 116 Wednesday


Well ...I had a nice little post here but my computer crashed so now it's gone.
We'll try again tomorrow. I have two days without a test!

Todays pic is Logan's logo :)

Tuesday, July 28, 2009

Tri-2, Wk12, Day 115, Tuesday - 600 billion/second


According to a video posted by a fellow chiropractor there are approximately 600 billion chemical reactions in the human body every second of our life.

Regarding blood & capillaries - capillaries are the most important site for exchanging nutrients and waste yet, only about 5% of our blood volume is in the capilaries at any one time with about 60% in our veins.
Something else I learned was that blood will sit in capillary beds for 6 to 12 seconds on average. I previously thought blood was continuously moving throughout our system and didn't realized it paused anywhere but, apparently, it does pause in our capilary beds due to precapillary sphincter muscles which help regulate blood flow.

It's 1:30 a.m. now and have been studying for neuro - I took a 3 hour nap earlier but it's not quite cutting it. I'm thinking of laying down for an hour then getting back to it.

Today's picture is of a capillary bed.

Monday, July 27, 2009

Tri-2, Wk12, Day 114 - Deja vu


Kind of a long day today - headed out at 6 a.m. and got home at 7:30 p.m.
I stayed after for some neuro and biochem tutoring - the biochem tutoring was fantastic.
I was curious about some things in neuro - we were discussing the optic tract which is among the last part of the visual pathway. The ventral or lower part of the optic tract runs from the lateral geniculate nucleus which is located rather centrally in the brain and the ventral portion of that tract actually runs a bit forward before reversing directions and heading back to the visual cortex. Since it's the lower geniculate tract (aka Meyer loop) it would be going to the cuneus gyrus. I need to brush up on some of this but - the temporal lobe of the brain is what makes sense of what we see and I'm asking the teacher how this happens -
here's my conundrum - what's being said/taught is that the transmitting neurons kind of "drop off" information in the temporal lobe which is where we make sense of what we're seeing BUT - we dont' actually see ANYTHING until the nerve impulses reach the visual cortex of the brain - is it possible to make sense of something before we actually "see" it?!?

I was given the argument about everything happening so fast that we can't notice what's going on but that was kind of a unsatisfactory answer in my opinion.

I wondered if this visual construction may play a part in Deja vu? In case there is a time lag - say a millisecond between the temporal lobes which interpret and make sense of what we're seeing and the part of our brain that actually let's us see what's out there. If there ever is a time lag then it could/would be a plausible theory behind deja vu.

Small changes can make a huge difference. Even with the Flat Earth Society - if the curvature of the earth were zero then we would be on something flat but the actual curvature is about 6 inches every mile so while not zero, it's only off by about 6 inches.
Light is another thing like that - take the time it takes light to travel a meter - not zero seconds but, pretty darned close.

So too, the time to travel from the temporal portion of the ventral optic radiation to the visual cortex may be exceedingly fast but, it still requires a time greater than zero seconds.

Heck - I need to post some more notes on our Google Group website then get to bed.

Today's picture is a drawing of the visual pathway and includes the optic radiation I mentioned previously. :)

Sunday, July 26, 2009

Sunday Studies - Neuroanatomy



I'm starting to get a little better appreciation for the basics of neuroantomy. It's very name suggest we are learning the anatomy of neurons and a neuron is just a specialized type of cell commonly referred to as a nerve cell. Now, let's start thinking in terms of plugs and extension cords to help us understand the anatomy of nerve cells and the whole concept of neuroanatomy. Readers may wish to refer to the picture in this blog labeled "Structure of a Typical Neuron". There are only 4 or 5 parts we need to concern ourselves with at this time.
OK, imagine you're holding a plug in your hand. The prongs that get stuck into an outlet are analogous to the dentrites of a cell. The little plug part you have your fingers on when you stick the prongs into an outlet are like the cell body. Then we have a cord. This cord is like the axon which sticks out of the plug and ends up terminating or ending somewhere. Let's say, we have a lamp and decide to plug the lamp into the wall. The prongs we push into the wall are the dendrites, the part of the plug we grasp to push in the prongs into the outlet is the cell body, the cord leading to the lamp is the axon and the end of the lamp where we screw in the light bulb is the axon terminal.
That's about it. Well, that's four things. You've probably noticed insulation around wires, the insulation around the wires (axons) in nerve cells is called myelin.
With our lamp plugged in, the electricity flows from the plugs in the outlet to the light bulb receptacle in the lamp the same way electricity or an action potential travels from the dendrites of a nerve cell to the axon terminals.

What if our cord isn't long enough? Then we may use an extension cord. At one end of the cord, we have prongs (dendrites) to stick into an outlet and at the other end we have slots where another set of prongs can be plugged in (the axon terminal end). And, as many of us know around Christmas time when we are stringing up lights we may have to use several extension cords to get everything the way we want it. This is much like the neuroanatomy in the human body. Hearing, for example has four sets of extension cords running from the ears to the part of the brain which perceives sound.
With our lamp, we put a light bult at the axon terminal end then, when the power is turned on, we get light.
Our nerve cells don't go to light bulbs but may may go to things like sweat glands, eye balls or even our heart.

Now, the fun thing about neuroanatomy is that all those plugs or cell bodies are given different names.

Hearing has four sets of extension cords therefore it has four plugs or cell bodies.
Plug 1 = spiral ganglion
Plug 2 = cochlear nerve
Plug 3 = inferior colliculus
Plug 4 = medial geniculate nerve

But, I need to focus on other sets of extension cords and wiring. In the last two days of class we covered to full chapters - chapter 11 the somatosensory system which pertains to touch, proprioception, pain and temperature both in the spinal cord and via cranial nerves (since each has a different pathway) and Chapter 15, The Gustatory and Olfactory Systems (taste & smell).

If nothing else, I'd like to get the pathways for all those things listed here - it will make for a good review.

Something else I forgot to mention - the actual path or way an axon or cord travels is usually given a name as well. If we run our cord to the lamp along the wall, we might call that the "wall tract" if we run it across the middle of the floor we might call it the Uncle Harry Tract because uncle harry is the crazy person who decided the cord should run across the floor.

OK - we've got 31 sets of spinal nerves which go out of and into our spinal cord. The nerves which go out are motor (efferent) nerves (they help move things and make things happen). The nerves which go into our spinal cord are sensory (or afferent) nerves which help us perceive the outside world and let us know what the heck is going on.
We also have 12 cranial nerves which may also be motor, sensory or a bit of both.
If we perceive something from our arms, legs or torso then that information is going to be transmitted to our spinal cord.

Let's start with pain & temperature nerves that get transmitted through our spinal cord. Now, instead of saying Plug 1, Plug 2 ...we will refer to these neurons in the order they appear by calling them 1st order neurons, 2nd order neurons, etc. We may also call them primary, secondary, tertiary and so forth.

You step on a nail! OUCH! A-beta fibers in effect - The action potential elicited by the pain shoots up the nerve from our foot to an area just outside our spinal cord known as the spinal ganglion which is where our first order neuron lives. From there, the cell body of our next cord lives just inside the spinal cord and it's called the Tract of Lissauer (2nd order nucleus).
Now, if you stepped on a nail with your right foot then the spinal gangion and Tract of Lissauer are both on the right side of your body but, after the nerve impulse leaves the Tract of Lissauer, the impulse will cross over to the left side of the spinal cord via an exit ramp known as the "Ventral White Commissure" then the axon continues up the spinal cord and here the axon road is called the Spinothalamic Tract. Let's look at that word, spinothalamic, and take it apart - we basically have "spine" and "thalamic" which indicates that this road travels from the spine to the thalamus. Lots of words are spliced together like that by simply adding the letter "o" and squeezing the two other words together.
For instance, that Ventral White Commissure we mentioned, it travels "ventromedially" to the central canal of the spinal cord. Take that word apart (ventromedially) and we can see that it's simply the words "ventral" and "medial" smashed together with the letter "o" between them. Ventral means front or anterior and medial means towards the middle so ventromedially means the ventral white commissure crosses the middle of the spinal cord, in front of the central canal.
Incidentally, the central canal is literally, a canal or space that runs down the middle of our spinal cord and is where cerebrospinal fluid runs ...hey - there's another one of those words with the letter "o" in the middle ...cerebrospinal = cerebrum + o + spinal. Generally speaking when a word is put together like that it can tell you where something is coming from and where it's going to.
Let's get back on track with the spinothalamic tract which runs from the spine to the thalamus.
The thalamus contains the third order neurons - these neurons can be medial (towards the middle) or lateral (towards the sides or away from the middle)
Spinal pathways meaning impulses that would come in from our arms, legs or throrax for example go to the ventral posterolateral nucleus in the thalamus which is then the 3rd order neuron.

OK - I'm having a little bit of an Ahah moment. One thing we've learned in school is that proprioception inhibits nociception which doesn't mean a darn unless you know what proprioception and nocicption are - but proprioception and touch go together and nociception refers to pain and what I've noticed is that pain/temperature nerves and touch/proprioception nerves all go into the ventral posterolateral nucleus of the thalamus. This bit of neuroanatomy starts to lend credence to the notion that touch inhibits pain or (proprioception inhibits nociception, same thing)
To help remember this concept, I've noticed some students write down "Mommy kisses boo boo" Mom's kiss is the touch or proprioception and the boo boo is pain or nociception.
Keep in mind, as mentioned in a previous blog - the nerves used for touch perception are larger and have better insulation than nerves used for pain which means nerve impulses travel faster for touch than for pain. Think of the thickness of nerve fibers like highways as compared to two lane dirt roads - the bigger and better the road, the less resistance there is to traveling fast.

Anyway - from the ventral posteriolateral nucleus of the thalamus we have a tract of cords called the posterior limb internal capsule which travels to the SI area of the cerebral cortex. The SI area is also known as the primary somatosensory area of the brain (another word with "o" in the middle!) Somato means body so primary somatosensory area refers to the part of the brain that perceives senses of the body.
I've included a brain picture to show exactly where these somatosensory areas are located in the human brain. It's an area known as the postcentral gyrus. In the brain, we have gyrus and sulcus. The gyrus are the hills and the sulcus are the little ridges or valleys between the bumps/gyrus. Looking at the side of a human brain you would be able to notice a long sulcus or groove running down the side of the brain which is called the central sulcus - the gyrus on either side of the sulcus are named according to their relative position to the central sulcus. So, we have the precentral gyrus and the postcentral gyrus - our final destination for our touch/proprioception & pain/temperature senses are in the postcentral gyrus.

btw - here is an interesting video on senses and brain development http://videos.scienceofecd.com/unisa/bd3_mustard1.htm

Let's get things summarized here -

For spinal pain/temperature, here is the path ...
  1. spinal ganglion - 1st order neuron
  2. Tract of Lissauer - 2nd order neuron
  3. ventral white commissure - where the nerve axons dessucate or cross over to the other side of the body.
  4. spinothalamic tract - name the axon is given as it ascends up the spinal cord into the thalamus
  5. ventral posterolateral nucleus - 3rd order neuron
  6. posterior limb of internal capsule
  7. Primary somatosensory area of the brain (post central gyrus)
For spinal touch/proprioception, here is the path
  1. spinal ganglion - 1st order neuron
  2. gracile/cuneate tract
  3. dorsal column nucleus - 2nd order neuron
  4. internal arcuate fibers - where the fibers decussate or cross over to the other side (this happens in the medulla which is wehre the 2nd order neurons are located.
  5. medial lemniscus - name given to axon tract that ascends to the thalamus
  6. ventral posteriolateral nucleus - 3rd order neuron
  7. posterior limb of internal capsule
  8. primary somatosensory area of the brain (post central gyrus)
Well, those are the paths if you sense something with an arm or leg since those nerves go to the spinal cord but, I'm sure we've all felt the stinging pain of a sunburn on our face or the tickle of a fly that's landed on our nose. Those are different neuron pathways and are referred to as Cranial pathways - so ....

For Cranial touch/proprioception we have
  1. trigeminal ganglion - 1st order neuron (in the pons)
  2. principal trigeminal nucleus - 2nd order neuron (still in the pons)
  3. decussation occurs in the pons
  4. ventral postereomedial nucleus of the thalamus - 3rd order neuron
  5. posterior limb of internal capsule
  6. primary somatosensory area of the brain (post central gyrus)
For Cranial pain/temperature we have
  1. trigeminal ganglion
  2. a desending tract called the spinal trigeminal tract
  3. caudal spinal trigeminal nucleus - 2nd order neuron
  4. decussation in the internal acrcuate fibers
  5. ascending tract called the trigeminal thalamic tract
  6. ventral postereomedial nucleus of the thalamus - 3rd order neuron
  7. posterior limb of internal capsule
  8. primary somatosensory area of the brain (post central gyrus)
Cool - now we have touch/proprioceptoin and pain/temperature pathways summarized ...next would be taste and smell ...

Taste is a bit interesting in that it has three primary or 1st order neurons. The anterior 2/3 of the tongue is innervated by the Facial nerve, cranial nerve (CN) number 7 or VII ...cranial nerves are most properly denoted by Roman numerals. The posterior 1/3 of the tongue is innervated by the glossopharyngeal nerve (CN IX) and the eppiglotal region is innervated by the Vagus nerve (CN X)
so ....let's try the pathway ....
  1. geniculate ganglion of the facial nerve - 1st order neuron
  2. inferior or petrosal ganglion of the glossopharyngeal nerve - 1st order neuron
  3. inferior or nodose ganglion of the bagus nerve - 1st order neuron
  4. those three 1st order neurons then meet in the solitary or gustatory nucleus - 2nd order neuron
  5. the axon then ascends up to the ventral posteromedial nucleus - 3rd order neuron
  6. then head out via the gustatory radiation to ...
  7. the primary gustatory area in the parietal operculum (another part of the "outer" brain, just below the postcentral gyrus)
Smell pathway ....I'm not entirely certain but will do my best ...
  1. mitral cells in the olfactory bulb - probably 1st order neurons
  2. olfactory tract
  3. olfactory trigone
  4. lateral olfactory striae
  5. primary olfactory cortex
  6. ends in the entorhinal area of the brain which is so deep in the brain that it's right next to the brain stem
the olfactory association area is more towards the front of the brian - I'm just not clear on this neurological pathway.

The preceeding pathways represent the two chapters we went over last week in class. I think I already mentioned the auditory pathway (chapter 12) at the beginning of this blog. Chapter 14 was the visual pathway - I think I have that one memorized - let's see ...

Ugh ...I'm already thinking I could write a better neuro book - certainly at least help clarify the darned subject matter - Things such as 1st, 2nd, 3rd ...order neurons should really be listed or shown with a picture. It's difficult when things that should be grouped together aren't.

OK - the first two order neurons are located in the retina - bipolar cells are primary and ganglion cells are secondary. Honestly, I might consider the rods and cones as two different primary nucleus but, I didn't discover this stuff so ....
the lateral geniculate nucleus is the third order neuron - recalling the medial geniculate nucleus was for hearing (4th order for hearing)
I think that's it for the visual pathway because after the lateral geniculate nucleus we have optic radiation paths which go to the visual cortex. OK - here it is -

Visual pathway -
  1. bipolar cells - 1st order neurons
  2. ganglion cells - 2nd order neurons
  3. lateral geniculate nucleus - 3rd order neurons

I better get to bed -
The one picture I haven't talked about yet shows the density of neuron connections at birth, at 7 and age 15. We hit our peak of neuronal connections in the brain about age 10 then the brain starts to destroy the weakest synapses and preserves only those that have been "magically" transformed by experience - once again ...use it or lose it. From the pictures it's clear that there is a greater density of neurons at age 7 than at age 15.

That's also true and applicable to things like cochlear implants. When a child receives a cochlear implant it works much better than say, for an adult, who has never been able to hear. The portion of our brain used for hearing - if not ever used is taken over by other areas of the brain so, when a person loses one sense and then we notice other senses becoming more acute and sharp there is a physiological reason since the areas that are sharper may now make use of the area of the brian which is no longer used for the lost sense. As a child, not as much time has elapsed for other portions of the brain to take over the lost senses area of the brain.


this link below shows how neurons can be destroyed by mercury

One final word - I'd like to thank my parents for all the help and support they give me throughout the week. When I come home from school and I see the work they've done to help me out the first words in my head - every time - are "thank you"
It really does help a lot. :)

Saturday, July 25, 2009

Tri-2, Wk11, Day 113 - Friday


It was a light day at school and about 20 people were missing from our Biochem class. We all had a pretty tough week. The big test next week is Neuroanatomy and I've got to score well on this upcoming test. It's got me debating about whether to go on Saturday's BACA (Bikers Against Child Abuse) Run. It's a great time but maybe too much time that could be better spent studying. So far, I think we've only got three test scheduled for next week which is a little bit scary because we only have about 4 weeks left and we'll be getting hit hard in the following weeks.

Today's picture is of different afferent nerve fibers. Afferent fibers are those which travel from various parts of the body back to the spinal cord. Unbenownst to me - they come in different varieties just like the different kinds of wires that can bring an Internet connection into your house to your computer. We have three different types of A fibers and one C type fiber.
Here's a pretty decent analogy pertaining to the speed of each fiber.

Fiber Type Analogous Speed
C Dial Up
A-delta DSL
A-beta Cable
A-alpha Fiber Optic

I guess that analogy will make the most sense to people who know a thing or two about the different ways of getting the internet to your computer. Hopefully, everyone knows that dial up is the slowest and a Fiber Optic light connection is the fastest.

C fibers are used for chronic (slow) pain and warmth and travel about 2.2 mph. A-delta nerve fibers conduct impulses are a little faster (maybe 20 mph) and are used to help detect acute pain and cold. A-beta fibers are faster and used in transmission of touch, pressure and vibration.
The fastest are A-alpha fibers and are used for limb position and motion - these nerves are capable of sending nerve impulses up to about 260 mph.

Of intersting note is that impulses from being touched travel faster than either kinds of pain (acute or chronic) impulses. This may be one reason why touch inhibits pain (or nociception) I'll have to take a closer look at the neural pathways of pain and touch to see if there is any neurological routing reason why touch inhibits pain. I think part of pain inhibition via touch may also have to do with different chemical releases in the body. GABA (gamma-aminobutyric acid) seems to come up a lot in various classes.

For inhibitors, at least in the basal ganglion portion of the brain, we learned about GABA and D2 (a type of dopamine). For excitatory chemicals we learned about Glutamate and D1 (another type dopamine).

There is also a concept known as DisInhibition which has the opposite effect on a target cell. Thing of it this way. To go faster in your car you can press down on the gas pedal (excitatory) or you can inhibit the acceleration by pressing on the break but you can also get the same effects by lightening up on the accelerator or by pressing harder or softer on the brake pedal.

Those previously mentioned inhibitory and excitory chemicals are the basis for grave diseases such as Parkinsons disease in which there is a dopamine deficiency which causes a decreased activation of the neurons of the cerebral cortex.

Friday, July 24, 2009

Tri-2, Wk11, Day 112 - Thursday

I went to bed yesterday at 4:16 p.m. and just woke up about 1/2 hour ago at 5 a.m.
I didn't realize I was in such need of sleep. Guess I need to head out and get to school - Friday's are my short days but I may be staying to work on neuro.

Wednesday, July 22, 2009

Tri-2, Wk11, Day 111 - Wednesday



Here we have the physiology "bible" - Textbook of Medical Physiology and another, slightly easier reading physiology book by Tortora.

Tonight is all about the physio - it's review time - crunch time. I'd say I know the material fairly well but, the test tomorrow is 60 questions over 50 minutes thus, we have 50 seconds to answer each question. So - simply knowing the material isn't quite enough for a good grade but, it's definitely a start.
btw - GRADE UPDATE - I got two quizzes back from Neuroanatomy and Aced them both - 100% on the take home and a 95% on the in class quiz. The Microbiology test went fairly well today also - I got a raw score of 34/50 which seems to have compared favorably with a few of the classmates I've chatted with. I needed it. After the curve I'm guessing that will end up being a B. The Micro grade is actually about a 50% improvement over my previous first couple test. Anyway ...I need to get to physio so ...here's all about the heart

incidentally - my brother emailed me a bit of a question earlier today and a part of the answer I gave him pertaining to the heart was this ... 40 billion beats of the heart is equivelant to the number of beats in the average lifespan of 16,000 people - I don't remember the number of times a heart beats per year but I remember that tid bit ... (it was actually a bit of an economic question but I had to put that physio spin in at the end) ;)

Let's start at the beginning - about 21 days after an egg is fertilized - that's about when the heart gets its start ...maybe that's going too far back but, while the heart is in a fetus there is an opening between the right and left atrium known as the foramen ovale. When the heart is all grown up that shunt of an openening closes and leaves a depression in the atria known then as the fossa ovalis. Let it be known throughout the land that, henceforth, holes shall be known as foramens and depressions shall be known as fossa. And ...that's pretty much how it is in the human body. There is also a hole in the skull known as the foramen ovale that a cranial nerve passes through but, back to the heart. Also, when a fetus there is a duct connecting the pulmonary trunk with the aorta known as the ductus arteriousus. Again, when the heart is grown up then that ductus is no longer used (blood HAS to go throught the lungs after birth) and like everything else in the body we once again come upon the adage - Use It Or Lose It. Since the ductus arteriousus stops being used as a blood vessel it ends up atrophying into a ligament known in the grown up heart as the Ligamentum arteriousum.

So - baby is born - butt is slapped (by the way - I believe the S5 dermatome is right on the bullseye (the anus)) and heart starts to ideally function the way it should -

Let's get to know the heart. To the North, we have Atriums - to the South, Ventricles. and each has a right and left side. The right atrium is the portion of the heart that receives blood from the rest of the body, the systemic cardiovascular system. There are three veins which return blood to the right atrium of the heart, they are, the superior vena cava, inferior vena cava and the coronary sinus. The coronary sinus doesn't get as much press as the vena cava but, the heart needs blood just like any other organ in the body and the nutrients in the blood aren't in the chambers of the heart long enough to be able to diffuse into the heart muscles (or myocardium) So - the heart has it's own network of blood vessels known as the coronary or cardiac ciculation. The coronary arteries branch out and down from the ascending aorta and cradle the heart in a network of arteries, like a life giving hand, they surround the heart and give it everything it needs to chug right along for up to a century!

The back wall of the right atrium is smooth but the anterior wall of that chamber is rough and covered with a muscle known as pectinate muscle. Between the right and left atrium is a partition (you know, the one that had the hole in it) it's called the interatrial septum. There's only one way to get out of the right atrium and that's through a valve which leads to the right ventricle. That valve is known as the Tricuspid Valve. We may also refer to it as the right atrioventricular valve. Notice, in that name (atrioventricular) the first part of the name has atrium in it and the second part of the name as ventricle in it. Just knock out a few letters and connect the two halves with an 'o' and we have atrioventricular. If we don't designate right or left we may say atrivoventricular or AV valves to generally refer to the valves which lead from the atriums to the ventricles.

Moving down into the right ventricle, we notice the heart of the wall is a bit thicker, on the order of 5-6 mm or about two tenths of an inch thick. This ventricle forms most of the anterior surface of the heart. Things get a little rough in the ventricle and the wall contains a series of ridges known as the trabeculae carneae. Emminating from a portion of the trabeculae carneae are muscles called the papillary muscles. The papillary muscles are connected to the tricuspid valve by tendon like cords known as the chordae tendineae. Now, here is one of those backwards things ....you might think that when the papillary muscles contract that those muscles would shorten and open the valves but, the reality is just the opposite - when those muscles contract - the tricuspid valves CLOSE. ...and that's pretty important. ...

The Right Ventricle pumps the old deoxygenated blood to the lungs via tha pulmonary trunk and the blood returns all fresh and clean like via four pulmonary veins - two from the right lung and two from the left lung.

OK - so that finishes up some of the anatomy for the right heart - we've sort of got two pumpers in our bodies. The right side is the pumper for the pulmonary circulatory system and the left pump is the big dog - it's the pumper for the entire rest of the body.

I need to pick up the pace here or just get back to my formal studying - I was thinking I could outline the material for our test here but I've barely scratched the surface.

Here's something interesting to think about regarding the heart sounds. Recall from a previous blog that the first heart sound (S1) we hear is when the atrioventricular valves close and the 2nd heart sound (S2).

Now, think of the sounds made when opening or closing a door. You aren't going to get much sound from opening a door but you can get a pretty good sound from closing the door. The valves are the same way - not much sound when they're opened but enough cavitation when they close that we can hear 'em! :)

Guyton's get's pretty technical, right down to the decibel when it comes to hearing sounds - murmurs and mitral valve regurge and things like that.

I need to work on the leads for an ECG. Heck - maybe I can learn a bit here by talking it out. Looks like the Tortora physiology book isn't going to cut it for this topic and we'll have to resort to the bible of physiology - GUYTONs - Ch11 - The Normal Electrocardiogram -
The basic concept is simply enough. When cardiac impulses travel through the heart a small portion of that current spreads into adjacent tissues. If electrodes are placed on the skin on opposite sides of the heart then electrical potentials generated by the current can be recorded and that recording is known as an electrocardiogram. I have to know a bit about where three main leads are placed on the body ...

OK, let's say the heart has a negative charge on the inside and there's a positive charge on the outside. When we depolarize the heart muscle, those roles change - the inside becomes positive and the outside negative ...a graph will move to the positive on a piece of paper as the heart is being depolarized and when the entire heart muscle is depolarized the line on the graph will return back to zero becaue when things are all positive on one side and all negative on the other then we have zero action potential.
When the heart goes back from being neg on the outside and pos on the inside (a depolarized state) then the graph will read negative and come back to zero once the depolarization is complete.

Let's talk about that ventricular muscle again - the left one. btw - the left ventricle is MUCH thicker and stronger than the right ventricle. It has to push blood through the entire body which offers much more resistance then simply pushing blood through the lungs like the right ventricle. While the right ventricle is only about 2/10ths of an inch - the left ventricle is about 1/2 inch on average. Meaty!

anyway ...The P wave occurs at teh beginning of contraction of the atria and the QRS complex of waves occurs at the beginning of contraction of the ventricles - the ventricles remain contracted until after repolarization, that is, until after the T wave. Repolarization of the atria is known as the atrial T wave but, as mentioned previously, it's recording tends to be obscured by the much larger QRS complex.

...3 a.m. update - physio test is a mere 5 hours & 15 minutes away - I'm probably not going to sleep since there are still a few things I need to get down. However, if I'm not going to sleep at all then I need to make sure I'm awake, alive and vibrant by test time. It's only 5 hours - no big deal.

I need to know which ions flow into and out of the heart at various stages and I still need to get a grasp on the Leads. but, i have learned about the Dicrotic wave produced during isovolumetric relaxation when the aortic semilunar valve closes and there is a slight rebound of pressure in the aorta so, I've got that going for me. :)
I tell ya - if I get anything less than a B on this test, I'll be horrified. ...3:21 a.m. ...OK - let's learn -
Flow of Current Around the Heart During the Cardiac Cycle
Recording Electrical Potentials from a Partially Depolarized Mass of Syncytial Cardiac Muscle:
OK - I understand instantaneous potentials on cardiac muscle - I recall the flow is from neg to positive. So, for a positive reading we must flow out of the negative lead, into a negative medium, over to a positive medium where a positive lead is located so the circuit can be completed back to the positive lead - electrons which flow in this direction will have a positive reading. - the converse is likewise and gives a negative reading.

before stimulation; all the exteriors of the muscle cells are positive and the interiors are negative.
As soon as an area of cardiac syncytium becomes depolarized, negative charges leak to the outside of the depolarized muscle fibers, making this part of the surface electronegative.

again - A meter connected with its negative terminal on the area of depolarization and its positive terminal on one of the still polarized areas records positively.
4:25 a.m. -
Flow of Electrical Currents in the Chest Around the Heart
...one finds the average current flow occurs with negativity toward the base of the heart and with positivity toward the apex. This is during depolarization.
depolarization spreads from the endocardial surface outward through the ventricular myocardium then, immediately before depolarization has completed its course throught the ventricles, the average direction of current flow reverses for about 0.01 second, flowing from the ventricular apex toward the base, because the last part of the heart to become depolarized is the outer walls of the ventricles near the base of the heart.

Electrocardiographic Leads
Three Bipolar Limb Leads
standard bipolar limb leads -
a lead is not a single wire connecting from the body but a combination of two wires and their electrodes to make a complete circuit between the body adn the electrocardiograph.

Lead I. ...the negative terminal of the ECG is connected to the right arm and the positive terminal to the left arm.

Lead II. ...the negative terminal of the electrocardiograph is connected to the right arm and the positive terminal to the left leg. Therefore, when the right arm is negative with respect to the left leg, the ECG records positively.

Lead III. ..the negative terminal of the ECG is connected to the left arm and the positiver terminal to the left leg. This means that the electrocardiograph records positively when the left arm is negative with respect to the left leg.

Einthoven's Triangle.

Einthoven's Law. ...states that if the electrical potentials of any two of the three bipolar limb ECG leads are known at any given instant, the third one can be determined mathematically by simply summing the first two ((but note that the positive and negative signs of the different leads must be observed when making this summation).

5 a.m. - testing in 3 hr 15 min - I WILL stay awake, vibrant, alert & happy :)
well ...I dont' quite understand all this. I need to get back to practicing my graphs which is a big thing I'll use on the test. - gotta have 'em down and be able to draw them very quickly and accurately.
Shower - maybe stop by Mc D's for an egg Mc Muffin - going for the protein - move blood sugar levels up - pound one more pot of coffee - stimulate the sympathetic nervous system - release epi and noripinephrine ...or maybe I should just inhibit the vegus nerve a little bit .... naa, too much work (and additional thinking of exactly how to do it)

signing off - wish me luck! :)

Tuesday, July 21, 2009

Tri-2, Wk11, Day 110 - Tuesday

Today's picture is of Rickettsia. What's rickettsia? Good question and one I should know for tomorrow's microbiology exam.

Rickettsias are small, Gram-negative coccobacilli which are microscopic obligate intracellular parasites.

That definition probably doesn't help anyone out so we'll take it piece by piece.

Rickettsia - the name of the thing in the picture
small - we're talking about 0.3 to 0.5 micrometers in diameter and 0.8 to 2.0 micrometers in length. A micrometer is one-millionth of a meter and a meter is kind of like a yard so, rickettsia are pretty darned small.
Gram-negative - this basically referes to the outer membrane of the organism. Gram-negative means the membrane is a thin peptidoglycan (as opposed to a thick one which would be referred to as Gram-positive)
......peptidoglycan - this is a polymer (large molecule) that consist of sugars and amito acids that form a mesh like layer.
coccobacilli - this refers to the type of organism and usually refers to it's shape. Cocco means round or spherical and bacilli generally means rod shaped. Maybe these little buggers come in both varieties
microscopic - like we said - these suckers are SMALL
obligate - basically meaning "out of necessity"
intracellular parasites - micro organisms that are capable of growing and reproducing inside the cells of a host.

Apparently, there are many different kinds of rickettsiae and they come in groups like the Thyphus group or the Spotted Fever Group - Scrub typhus used to be a group but it looks like that one has been reclasified.

Thyphus Fever is a systemic diseases caused by reckettsiae. Thyphus fever comes in a few varieties itself - one is known as Epidemic typhus caused by Rickettsiae Prowazekii. In 1812, epidemic typhus helped drive Napoleon from Russia; more recently, during World War I, it infected over 30 million Russians and killed 3 million.

Rocky Mountain Spotted Fever is another illness caused by Rickettsia Rickettsii.

I've got a list of 10 different Rickettsia diseases to get familiar with before tomorrow's test.

With regards to chiropractic and these many diseases, I would be heading to an MD to get whatever medicinal treatments are available. These diseases have some pretty high mortality rates - Scrub typhus or stustugamushi disease has a fatality rate of 50% if left untreated but, with antibiotics, fatalities are rare.

btw - tsutsugamushi is Japanese for "bad little bug"

off to bed!

Monday, July 20, 2009

Tri-2, Wk11, Day 109 - Monday

Today's picture comes from the Official website for Kuwait University Medical Students - no kidding, here's the link http://kuwaitmd.hsc.edu.kw/main/
btw, the images in these blogs can be clicked on to see them full size and you can right click on the images to open them up in a new window or tab.
Anyway - today's picture represents the cardiac cycle. Yup - we're still delving into the wonderful world of coronary carnage. If you spend a couple scant hours looking at the pic then some interesting things come to light (they did for me anyway).

At the top of this chart we have ventricular pressure in blue along with atrial and aortic pressure shown in gray. The middle part of the chart shows the electrocardiogram with our old friends, the P, QRS and T waves. The bottom portion shows the phonocardiogram and three sounds in the heart. The first two sounds are the most common that people know about, I think I read there are four sounds but the latter sounds are probably nothing that could be heard w/ a stethoscope. The first two sounds represent the familiar "lubb" "dup" sounds. The first sound comes from the closing of the atrioventricular valves and the second sound is from the semilunar valves.

When we get our blood pressure taken we're getting the pressure generated by our left ventricle. If you look at the chart of Pressure (mmHg) and follow the blue line, you'll notice on the ascending portion of the blue line that intersects with the opening of the aortic valve and follow that intersection over to the left we'll see it corresponds with a pressure of around 80mmHg. This corresponds to diastolic pressure ...it's kind of interesting to note that the diastolic pressure is obtained during systole (contraction) of the ventricle. Basically, it's the least amount of pressure needed in order for the ventricles to force open the semilunar valves. If you're a right ventricle, you'll be sending blood to the lungs to get refreshed and if you're a left ventricle, then you've got your work cut out for you because you'll be sending your blood throughout the entire body or systemic circulatory system. Once the left ventricle has squeezed out all the blood it can then the blood pressure in the aorta slams those semilunar valves shut and that's the second heart sound we hear ("dup")

When that blue line is at it's peak and we follow the peak over to the corresponding pressure we'll notice it's at about 120 mmHg. So, this graph represents a patient with a blood pressure reading of about 120/80 which is what we like to see :)

I am starting to learn a little more detail about the electrocardiogram readings. The QRS complex does involve depolarization of the ventricles but I'm thinking the sharp upward spike from Q to R is the depolarization along the interventricular septum (the part that separates the two ventricle) and the sharp downward reading from R to S is when the Purkinje fibers shoot the depolarization back up the ventricular myocardium. At least, that's how I'm seeing things for now.

I mentioned hyper (high) and hypo (low) kalemia and calcemia the other day. Those conditions can be seen on an EKG or ECG ....I've always heard EKG and learned from my readings that EKG comes from the German word - elektrocardiogram - I guess it's got a 'k' in there where us Americans put a C.
In cases with too much Potassium (K+, hyperkalemia) we can see high T-waves and Hypokalemia (low potassium) has a tendency to produce 'u' waves. I don't think U-waves are seen much under any normal circumstances.
High levels of calcium - hypercalcemia provides for a narrow QRS complex and I believe low levels of calcium widens the QRS complex.

There are abnormalities such when the conduction of the electrical impulses get stuck between the atria and ventricles - these are referred to as atrioventricular blocks or AV blocks and they come in three degrees - just like burns - and ...the severity rises with each degree.

In first degree blocks, there are simply longer intervals between the P and Q waves. This could be due to scarring of the myocardium or heart tissue. With 2nd degree blocks - you probably want to get your patient a shiny new Medtronics pacemaker and if a patient comes in with 3rd degree heart block then you want to make sure your malpractice insurance is up to date because they could die on the spot ...kind of makes you wonder how they get into the hospital in the first place?
Ventricular fibrillation is pretty bad also.
I think if I just get that chart memorized then I should be in pretty good shape for the test - at least regarding the cardiac cycle portion of the test. The chart in our (American) powerpoint is actually a bit more detailed. Regarding Systole and Diastole, there are sub-phases of each one. Systole includes a period of isovolumic contraction and a period of ejection while diastole involves a period of isovolumic relaxation, passive ventricular filling and active ventricular filling. There are other charts that go with that stuff as well.

Huh - I really wanted to talk about proprioception tonight but I guess all the cardio study caught me off guard.

Some personal interesting things I've learned about the heart ....
When pronouncing the words "systole" and "diastole" you pronounce the E at the end, it's a long e. I had always pronounced those words with a silent e.
More interesting - is that the heart has a fibrous skeleton that separates the top and the bottom of the heart. The fibrous skeleton partitions the atriums on top from the ventricles on the bottom. The fibrous skeleton even has a cool name - TRIGONES. We have a left and right fibrous trigone and the valves in the heart all have fibrous rings.

A big part of these trigones is to keep the electrical current passing throughout the heart in an orderly and coordinated manner. The sparkplug of the heart starts in the right atrium at a location called the sinoatrial node or SA node. When I see that letter S in SA I think "start" and it helps me keep straight where the spark starts. Next the impulse goes to the AV node or antrioventricular node, which is still in the atrium, then in order to get around the fibrous skeletal trigones there is a single path where the impulse gets to cross over, down into the ventricles called the Atrioventricular Bundle or AV bundle - this is also known as the Bundle of HIS - strange name but, it's pretty important so I guess it gets a special name. ....
now, we know a snake hisses and a snakes tongue is forked so, this Bundle of HIS also forks and becomes the right and left bundle branches which go down the ventricular dividing line known as the interventricular septum - those branches head all the way down the the bottom or apex of the heart where they meet the super fast and fun loving Purkinje Fibers - The SA and AV nodes are kind of slow pokes when it comes to electrical conduction - they fire away at a speed of about 2 inches per second but those darned Purkinje fibers blast away at better than 13 FEET per second! Those Purkinje fibers shoot the electrical impulse back up the outside walls of the ventricles. (recalling that the septum between the ventricles kind of runs down the middle of the heart)

Purkinje reminds me of Penske - you know, the race car people (http://www.penskeracing.com/)
So, it makes sense that Purkinje fibers are so fast ;)

I've got two more nights to study for this physio test - hoping for the best. We've also got our third microbiology exam on Wednesday along with a biochemistry quiz - I'll do what I can with each - tomorrow is a long day at school - 9 hours straight classes - no lunch break - might get out a bit early from micro lab and anatomy dissection sometimes gets out early - no worries - long days at chiro school are pretty good things to have in the big scheme of things.

btw - I brought my pocket sized Guytons physiology review book in when I went to the doctors office this past Friday and my MD doc commented that it was the same book he used way back when - and I think he graduated in '72. He mentioned that he thought Dr. Guyton was dead now but his books are still THE bible when it comes to physiology.
Thy Guytons practice quizzes will be the last thing I do in prepping for this test - it's kind of a formidable book. :)

Sunday, July 19, 2009

Weekend Studying


I did a great deal of studying but I really need to get more done. I could use the next 5 days off along with next weekend. I used some online stopwatches yesterday to track how long I was imbued with my studies and I probably got in 9 or 10 hours yesterday - another stop watch logged the time I was not studying and just cleaning, doing laundry or washing the car and that was near 4 hours.

Anyway - I have another pic for the ECG. We still have the standard P QRS T waves along with a heart. During the P wave, the right atrias depolarized and contract, during the QRS complex the ventricles depolarize and contract, during the T wave the ventricles repolarize.

I guess I'm in decent shape for the upcoming test - I need to know exactly what ions are going into and out of the heart during each phase. The main ions are Calcium, Potassium and Sodium.

If anyone is familiar with the periodic table then they might see that Ca stands for calcium which makes sense but we also have K for potassium and Na for sodium which doesn't make quite as much sense but, sodium is called Natrium in Latin and potassium is called kalium so when we have conditions such as hyper or hypo-natremia then we are talking about high or low levels of potassium.
Hypernatremia (too much sodium) decreases heart rate
Hyperkalemia (too much potassium) decreases heart rate
Hypercalcemia (too much calcium) increases heart rate.

at least ...that's what the book says - however if you have a three-chambered frogs heart hanging from a string and add any of those elements then the heart rate seems to go all over the place and never really stabilizes although I did see beats per minute get as low as in the 20s, they just never stayed.
Ringers are used to bring the heart back to normal thumping capacity. We can have Ringers at 32 degrees celcius (room temp) or warm ...I think that was around 37 degrees celsius which is also normal body temperature or cool. Warm increases heart rate, cool decreases heart rate.

We can also have things like norepinephrine which is the neurotransmitter released by the sympathetic nervous system on the heart which will increase heart rate and then we have acetylcholine which is released by the parasympathetic vagus nerve (CN X) which slows the heart rate down.

The sinoatrial (SA) node is autorhythmic and sets a pace of about 100 beats per minute and is located in the right atrium. a couple other areas of the heart can also conduct their own rate of contraction but the area which has the highest rate sets the tone for the entire heart which is why the SA node is known as the pacemaker of the heart.

The reason most people have a resting heart rate lower than 100 beats per minute is because of the hearts innervation with the vagus nerve (CN X) which, as mentioned, is parasympathetic and slows down the rate of the heart. CN X (cranial nerve #10, the vagus nerve) is the only parasympathetic nerve going to the heart and all the rest serve to increase heart rate when necessary.

This makes me think back again to the open heart surgery and reading that heart transplant surgeons are more like plumbers than electricians becuase only the plumbing is hooked up in a heart transplant patient and I still recall a life expectancy of 10-12 years for heart transplant recipients. Contrast this with a potential 80 to 100 year life expectancy with an original heart that has all it's electrical wiring in place and we might start to suspect that the nerves play a pretty important role in the lifespan of a heart.

This also leads us back into the realm of a chiropractic adjustment - I still don't have all the physiology down for the adjustment but did learn of an initial study done in 1949 where a patient had electrodes placed along the spinous processes of their back. It was interesting to note that the spinal segments which were fixated had much higher electrical activity than those which were mobil and not fixated. Also, when pressure was applied to the fixated segments, the electrical activity increased. When pressure was applied to the non-fixated vertebral segments there was no increase in electrical activity.

Basically, the muscles surrounding the vertebrae (and there are a TON of them) are closer to their stimulation threshold when they are fixated and not able to move as they should. Another study along these lines came back in the early 1970s, circa '72 or 74 by an MD.

...checking my class notes now ...

The 1949 study was done by Denslow, I believe he was a DC and the MD in the 1970s was Barry Wyke.

Adjustments to the spine reduce sensitization - there are inhibitory effects brought on by motion - loss of motion means loss of GABA (gamma-aminobutyric acid) which (per wikipedia) is a chief inhibitory neurotransmitter in hte nervous system. It plays an important role in regulating neuronal excitability throughout the nervous system. In humans, GABA is also directly responsible for the regulation of muscle tone. ...If anyone cares to read more here's the link;

I guess something I've been realizing is that the crux of chiropractic has to do with the central nervous system (CNS) moreso than the vertebrae which are always so prominetly displayed in most offices. It makes more and more sense all the time that back pain is about 2% of what chiropractic is good for. It has much to do with keeping that little cord, the spinal cord, which is about the width of two pencil erasers, functioning optimally.

The brain and the spinal cord are the command centers for the body and from an embryological point of view, you'll notice a neural groove being formed before the heart or any other organ in the body. The neural groove is the precursor of a person's nervous system.

For this week -
Mon - Gross Anatomy II Quiz
Tue - Neuroanatomy Take home quiz and Physiology Lab due
Wed - Biochem Quiz, Microbiology Exam #3
Thurs - Physiology Exam #3

I've already completed everything for Tuesday, I worked on Gross today and answered a couple hundred questions regarding physiology over the weekend.


Friday, July 17, 2009

Tri-2, Wk10 Days 107 & 108

Thursday (107), and Friday (108)

I've been wanting to learn about electrocardiograms so I could post something that I think my Mom has found interesting but, I don't have that great of a grasp on it which makes it difficult to write about.

The picture for today is a typical secion for a normal electrocardiograph and shows the standard peaks and valleys labeled P, Q, R, S and T. Loosely speaking, the P represents atrial depolarization and the flat part of the line after the P wave is atrial contraction (systole)

QRS is comonly known as the QRS Complex and represents ventricular depolarization and the flat line right after is when we have ventricular systole (contraction).

During T we have repolarization of the ventricles and the flat part of the line after the T wave represents ventricular diastole (relaxation)

You might wonder where the repolarization of the atrial takes place and that would be during the QRS complex - maybe that's why that area is called complex because so much is taking place. ;)
The QRS complex is simply much larger than the atrial repolarization so the QRS complex mask what's going on in the atria.

Wednesday, July 15, 2009

Tri-2, Wk10 Day 106 - Tuesday, July 14

Crashed early Tuesday night and am up early for my day off on Wednesday.

...this post never quite made it past the draft stage but, as I recall, I did get up around 3:30 a.m. and studied until about 9:30 a.m. then slept for another 3 hours then got back to studying. Overall, it was a very productive day in terms of studying. :)

Monday, July 13, 2009

Tri-2, Wk10 Day 105

Got my bell rung today in Gross II. Quiz didn't go very well. I didn't plan well enough to work around my birthday celebration with my family. Kind of fried & very tired.

Eric, "How do we normally get carnitine?" to which Dr. Guitweiler replied, "We make it, it's an exhaustively methylated primary amine." ...I have my television turned down low and my biochemistry DVD at regular volume and that was the last question asked on the DVD. What the heck is an exhaustively methylated primary amine? I guess it's carnitine but, I don't think I'll ever have my teacher's appreciation for what that means.

Speaking of hearing ...I was reading about the vestibulocochlear cranial nerve earlier tonight ...I keep understanding things at deeper levels but it is slow going. The cranial nerves may be sensory, motor or both. The vestibulocochlear cranial nerve is sensory which means we are dealing with "afferent" nerves or nerves that travel from the sensory organ to the brain. I'm wondering if a cranial nerve includes everything along the path from the sensory organ to the brain - I'm not exactly sure.

In the inner part of the ear concerned with hearing is called the cochlea (look at today's pic for an example of one). It kind of looks like a snail's shell. The inside of the cochlea is divided down the middle and in the middle part is something called the cochlear duct which contains tiny hair cells which help the brain to register sound. From what I've read - the hair cells interpret volume and the basilar membrane which is directly below the hair cells help interpret frequency.

When sound waves first enter the cochlea the basilar membrane is narrow and as it travels through the cochlea the membrane gets wider. The narrow part of the membrane interprets high frequency sounds and the wider part of the basilar membrane responds to low frequency's.

What's amazingly interesting, and a bit complex, are those hair cells. Those cells run along the basilar membrane and seem to come in sets of two - as in a single hair cell along with a triplet of hair cells.

This is where things get interesting. Those hair cells are capable of transduction! That's what telephones do - at least, I know that's how the older telephones used to work (not sure about cell phones). Transduction is the conversion of energy from mechanical to electrical forms - it's how the mechanical sound waves we hear are changed into an electrical action potential capable of traveling over nerves to get to the part of the brain that makes sense of that electrical input.

Now, those hair cells I was talking about come in sets of three - the single hair cell has three hair cells and the triplets of hair cells each have three distinct hair cells. ...I guess we need to be a little more specific than "hair cells" they may look like hair cells but are actually called steriocillium which ...are just little things that look like hair :)

The cells have three sets of steriocillium which come in short, medium and tall. And all three steriocillium are connected to one another. when those little steriocillium are erect and not being swayed by sound then the tips of the steriocillium have little gates which are about 15% open. Those gates are specifically designed to let in Potassium ions (K+). When the hair cells get pushed towards the taller steriocillium then those gates open up and let in greater than normal amounts of K+ which in turn, causes the base of the steriocillium to let in greater than normal amounts of Calcium ions (Ca+). The Ca+ in turn cause a greater than normal release of neurotransmitters from their synaptic vesicles. This in turn causes increased impulses along the nerves traveling to the brain (afferent neurons) and the brain interprets this as an increase in sound intensity or how loud something is. This whole process in the inner ear is referred to has depolarization.

How about when things get quiet? That is known as hyperpolarization and occurs when the hair cells ...opps - I mean steriocillium bend towards the short hairs. This has an effect of closing the potassium gates which reduces the amount of potassium let into the cells which in turn reduces the amount of calcium released which reduces the amount of neurotransmitters to the cranial nerves which go to the brain ...it's how we interpret a decrease in sound intensity.

That's *part* of the vestibulocochlear cranial nerve (CN VIII). the other part is the vestibulo part which hooks up to the semicircular canals in the inner ear. I think the vestibular part of the nerve will be a bit more complex because that nerve also has innervations with the abducens, trochlear and oculomotor nerve to help keep us balanced. :)



Sunday, July 12, 2009

Tri-2, Wk9 Days 101, 102, 103, 104

Survived - Midterms are Over! -
Last night was the first good nights sleep I've had in a while and I *really* needed it.
The only class I'm in trouble with is neuroanatomy but since I quit pledging the fraternity my studies have continued to improve and I do think I have a very good chance of pulling out of neuro and maybe even improving a few other grades and making it on to Tri-3.
I heard from a classmate tonight that she knew of three people that were dropping neuro in order to focus on their biochemistry class. If I keep up the effort like I've been doing then I should be alright. We're off school this Wednesday for a school event called Field Day. It's when all the Tri's compete against each other in various sporting events. I'll be staying home and continuing to catch up on my school work.
Currently, my highest midterm grade is in physiology. I don't want to put anything on the back burner in order to solely focus on my weaker classes.

There are a variety of things I'd like to write about. Mainly, I'm just glad midterms are over. I was getting tired of going to bed sick every night.

For today's picture I'm picking a powerpoint slide out from neuroanatomy. It shows the neural auditory pathway, the small box at the lower right is a cross section of a piece of our inner ear known as the cochlea. From the cochlea to the part of our brain that processes hearing we traverse a path involving the four auditory neruons listed below

1. Spiral ganglion
2. Cochlear nuclei
3. Inferior colliculus
4. medial geniculate nucleus

after that 4th nucleus, nerve impulses travel to a place in our brain known as the transverse temporal gyrus of Heschl.

I think I picked this picture becuase that pathway is one of the things I learned tonight and have memorized :)

Monday, July 6, 2009

Tri-2, Wk9 Day 100 - Monday


Day 100! Wow ...
just keeping with everything and doing my best. I do have until around August 21st to dig myself out of this deep, cavernous hole I've gotten myself into. I got 9/10 on my Gross II quiz today. We've got a
Microbiology Midterm on Wednesday
Philosophy Midterm on Thursday
Biochemistry II Exam 2 on Friday.

I stuck with Neuroanatomy for most of the weekend.

I did get a fantastic new TomTom GPS type navigation system for my car as an early birthday present which is really cool! I have it programed in to guide me to school tomorrow but, the neat thing is that I can also tell it what time I want to arrive. So, tomorrow I would like to be at school at 5:30 a.m. and right now I have 6 hours and 13 minutes ahead of schedule so as long as I can sleep, get up, shower, dress and get everything ready for school tomorrow and leave in 6 hours and 13 minutes then I'll be right on schedule.

I have a ton of work to do for these upcoming test. These are huge test and will wholly determine my midterm grades for Micro Lab and Philosophy. Once again, Biochem is one of my stronger classes so it will kind of have to go on the back burner whilst I pour extra energy in the classes which aren't going so great.

Right now I have 8 classes and 4 labs. I've looked ahead to the next trimester and that one consist of 10 classes and 4 labs.

Today's picture - I was looking for a nice pictoral representation of the physiology behind a chiropractic adjustment but apparently none yet exist on the internet?! I actually don't know enough to fully understand adjustment physiology but I'm starting to recognize it when I see it. :)

For now, I'll just put up the good old Meric Chart which many chiropractors, including my brother, hang in their office. It's a decent representation of efferent motor nerves which simply means those nerves which exit the spinal cord to various parts of our body. These kinds of charts tend to be the easiest for patients to understand but they are a bit light when it comes to the hard core science behind chiropractic.

Consider, for example, a heart transplant patient. All doctors do when they transplant a heart is basically, hook the plumbing back up but there aren't any nerves that are re-attached. Granted, people might be better off if nerves could be hooked back up but, that isn't the case and a transplant patient can maybe get a good 10-15 years on average (just trying to remember from a heart transplant operation I watched last month)

Anyway, there seems to be much more benefit due to the effect an adjustment has on the afferent nerves. That has been the focus of research over the last 10-15 years.

Friday, July 3, 2009

Friday Studies - NBN

NBN - Nothing But Neuro -
Today's pic is of visual field defects. So, if we have a lesion of the lower part of the geniculocalcarine tract then we have a condition known as left homonymous superior quadratic anopsia.
piece of cake :)

After spending all day on this chapter that stuff does kind of make sense.
homonymous means the same visual field in both eyes
superior means the defect in vision is towards the top
quadratic means just 1/4 of the field is affected
anopsia refers to a defect in the visual field.

I'm still getting used to the geniculocalcarine tract ...gotta find exactly where that spot is in the brain and what it looks like from all different angles and levels. It can all be a bit tedious.
Dr. Jan Clifford did send out an email today stating her office hours today but I didn't really want to spend the two hours driving to get out and back to school.

I am dead tired. I'm glad today is still Friday and I've got the weekend left to keep studying.
We've only got four test next week :)
Monday - Gross Quiz
Tuesday - My Birthday!
Wednesday - Microbiology Midterm
Thursday - Philosophy Midterm
Friday - Biochemistry

Biochemistry is pretty huge and I've got a lot to do in that class. I'll keep studying the neuro tomorrow but ....well, everything needs to be studied. One day at a time.

Thursday, July 2, 2009

Tri-2, Wk8 Day 99 - Thursday


Made it! and, unlike the last break we had from school, I'll actually be able to use this one to my benefit. Two of the four days we were off during our last break got wholly used up for pledging but this one is all mine. I've got to make the best of it.

I've already eaten and read through chapter 14 in neuroanatomy. I'm looking at taking a nap now. I *really* need the rest. I'm already planning on going to my boot camp tomorrow.

Today's picture is of the heart. We're simultaniously studying the heart in gross anatomy and physiology. Naturally, this study is being done with significantly more detail than I ever knew existed.

Wednesday, July 1, 2009

Tri-2, Wk8 Day 98 - Wednesday



Only one more day to go before a nice 3 day break!

Readers may have noticed that I started a blog entry titled Eight Syllable Words yesterday. This is something I thought of doing a while ago - I keep coming upon these huge words and I kind of wanted to start collecting them as I came across them in my studies. The list includes pretty much any nifty multi-syllabic word and will have a permanent link along the right hand column.

We had our neuro test today and I'm positive I got one of the questions correct. The remaining 59, I'm not so sure about.

We actually get out of school tomorrow at 11 o'clock but there is neuro tutoring scheduled from 4 to 6 p.m. so ..... do I get home at 12 or stay for tutoring and get home at 7 p.m.?
It's a 7 hour time difference which is kind of huge and to stay means keeping myself occupied for 5 hours until tutoring starts ....
living far away is a bitch ....

I'll probably come home because I'm dead tired now and will probably only get 3 hours of sleep tonight due to the micro midterm tomorrow morning at 7:20 :)

Today's Picture -
We play with E. coli (escherichia coli) pretty much every day in our microbiology lab so I thought I'd share a few pictures of E. coli. The bottom picture is just E. coli with a pretty green stain - the top picture is more like the staining we do in class, known as gram staining. We also play with various staph and strep types of bacteria.

One interesting and new thing to me in micro lab was a microscope procedure known as oil immersions. After we get our bacteria properly stained and focused in at high power then there is one more lens we can use but first we put a drop of oil on the bacteria then use the oil immersion lens - it's just a way to see the bacteria better.

Eight Syllable Words

Nine Syllable Words
  1. corticopontocerebellar - neuroanatomy
  2. dysdiadochokinesia - neuroanatomy (a posterior cerebellar syndrome) - difficult to perform rapidly alternating opposite movements)

Eight Syllable Words
  1. electronystaymography - neuro, a test which may detect characteristic nystagmus.

Seven Syllable Words
  1. cytomegalovirus - microbiology
  2. photophosphorylation - multiple classes
  3. hemianesthesia - neuro
  4. geniculocalcarine - neuro

Six Syllable Words
  1. flocculonodular - Neuroanatomy - lobe on the cerebellum
  2. pontomedullary - Neuroanatomy
  3. posterolateral - multiple classes
  4. vestibulospinal - Neuroanatomy
  5. encephalopathy - microbiology
  6. teratogenesis - microbiology (the induction of defects during embryonic development)
  7. supratentorial - neuro
  8. opacification - neuro

Five Syllable Words
  1. corticopontine - neuroanatomy
  2. dorsolateral - neuroanatomy
  3. juxtarestiform - neuroanatomy
  4. pleomorphism - microbiology
  5. phylogenetic - microbiology
  6. peptidoglycan - microbiology
  7. eutrophication - microbiology
  8. magnocellular - neuro
  9. parvicellular - neuro

Four Syllable Words
  1. emboliform - Neuroanatomy
  2. fasciculus - Neuroanatomy
  3. fastigial - Neuroanatomy
  4. diaphragma - neuro
Three Syllable Words
  1. palpebrae - neuro, gross, physio - eyelids

Acronyms
  1. MLF - medial longitudinal fasciculus - Neuroanatomy
  2. CJD - Creutzfeldt-Jakob disease - microbiology
  3. EBV - Epstein-Barr virus - microbiology (a human cancer virus)
  4. RSV - Rous sarcoma virus - microbiology
  5. PAGE - polyacrylamide gel electrophoresis - microbiology