Blogging early Wed morning for my Tuesday entry. I got up around 2:30 a.m. this morning to get some extra studying in for my physio test today. I sure hope it goes well. I kind of have in my mind to at least get 80% or better in each of my classes but, that would only get me a grade of a C in physio. I just need to get this test over then shift the focus to pathology & embryology since those test are coming up next. I think Micro II is around the corner as well but I don't have an exact date for that test. We start out today with two hours of philosophy but that class seems a bit more like a professional development class since our main project is to write up a complete business proposal. I think I'll be able to get some extra physio review in during that class - no review during diversified because that's when we spend time adjusting each other. Logan Basic is after that and I'll need to be paying attention in that class which leaves my one hour lunch break to review as much as possible before our test.
For today's test, we're going to have 75 questions and 60 minutes to complete the test which comes out to 48 seconds a question. It's *really* going to be tight. I'll probably spend 3-5 minutes drawing out diagrams to help answer many of the questions and think I'll just rip the cover off the test and use the back of that paper for my illustrations that way I can have a single piece of paper out & to the side of my test instead of continuously flipping back and forth throughout the test to find a specific drawing for a specific question.
I never did get an online blogged review of the material which has tended to help before.
Today's picture is of the "Hamburger Shift" ...I'll be darned - just getting that picture to put up helps me to understand a few things and also ties in a couple other concepts. For the Hamburger Shift you'd basically only need to remember that carbon dioxide and chlorine move in the same direction while bicarbonate moves in the opposite direction but now I can see that when the CO2 moves into a cell that it combines w/ water to give carbonic acid which then dissociates into a bicarbonate (which leaves the RBC) which is a viable reason why chlorine then enters to RBC (to keep the charges blanced). But, better than that is the acid dissociates into H+ (as well as the bicarbonate which leaves the cell) and the extra hydrogens is what causes the pH to drop thereby causing the environment of the RBC to become more acidic. I then recall from biochemistry a concept known as the Bohr effect which states the affinity of oxygen to hemoglobin is diminished in an acidic environment so as the CO2 enters the RBC, which it would do in the capillaries when picking up CO2 waste products, then the H+ is released, causing the pH to drop then the hemoglobin (or oxyhemoglobin) will have a greater tendency to release it's oxygen which is what the tissue cells need anyway - the extra release causes a greater concentration of O2 which then may readily diffuse across cell membranes to get to the tissue cells which needs the O2 to keep functioning. It's all pretty cool. :)
I remember when I was first learning about the Bohr effect I kept making up little stories about it. I'd say a car was the hemoglobin and the tires were the oxygen which is a nice analogy because each hemoglobin (Hb) can hold up to four oxygen. I'd say the car is driving along then it enters a tunnel which has a high concentration of acid in the air so the tires fall off the car. :)
Or you could think of a relationship between hemoglobin and oxygen - they get along just fine but whenever the get into an acidic environment their relationship just falls apart.
There is another chemistry reaction here but I can't recall the exact name. The principle is summed up by saying when you push the universe, the universe pushes back - I think that was the gist behind the principle. Now, I'm thinking maybe it was a different principle. But, I can see how the reaction is driven (CO2 + H2O > H2CO3 > HCO3 + H+).
In the tissue cells there is a preponderance of CO2 which will drive the reaction to the right. At the end of the reaction is the HCO3 which is the bicarbonate ion which has a negative charge and the H+ which drives down the pH.
We then just need to keep in mind the three ways that CO2 is transported back to the pulmonary system to get reoxygenated and ...let's see.... I remember 23, 7 and 70 -
23% of the CO2 gets transported by hitching a ride on the hemoglobin (then called carbaminohemoglobin) . 7% of the CO2 is dissolved in the blood plasma and 70% of the CO2 travels by way of HCO3
Wow - it's getting late - gotta run! :)
Posts
No comments:
Post a Comment