physio questions??

[cutedoc12]

---

Members don't see this ad.

Q.the primary effect of substituting a rigid arterial system for a compliant arterial system wud be that
1.continuous flow in the capillaries wud change into pulsatile flow
2.arterial pulse pressure wud diminish
3.diastolic pressure wud not be affected
4.systolic pressure wud not be affected

Q.venous return wud be reduced during

1.a forced expiration with the glottis closed
2.rhythmic muscular exercise
3.plasma transfusion
4.blood transfusion
5.all of above
6.none of above

Q.during exercise muscle tissue accumulates lactic acid..as a result erythrocytespassing through the capillaries in the muscle

1.release more co2
2.absorbs more co2
3.release more o2
4.both 1 and 3
5.both 2 and 3

Q.the effect on the basal heart rate of cutting successfully the vagus and the sympathetic nerves in an animal reveals

1.predominance of vagal over sympathetic innervation in determining heart rate.
2.predominance of sympathetic over vagal
3.the effects of vagi and sympathetics on heart rate are equal and opposite
4. none of above



CAN ANYONE PLEASE EXPLAIN THE ANSWERS GIVEN ????

 

[SeventhSon]

Q.the primary effect of substituting a rigid arterial system for a compliant arterial system wud be that
1.continuous flow in the capillaries wud change into pulsatile flow
2.arterial pulse pressure wud diminish
3.diastolic pressure wud not be affected
4.systolic pressure wud not be affected

Q.venous return wud be reduced during

1.a forced expiration with the glottis closed
2.rhythmic muscular exercise
3.plasma transfusion
4.blood transfusion
5.all of above
6.none of above

Q.during exercise muscle tissue accumulates lactic acid..as a result erythrocytespassing through the capillaries in the muscle

1.release more co2
2.absorbs more co2
3.release more o2
4.both 1 and 3
5.both 2 and 3

Q.the effect on the basal heart rate of cutting successfully the vagus and the sympathetic nerves in an animal reveals

1.predominance of vagal over sympathetic innervation in determining heart rate.
2.predominance of sympathetic over vagal
3.the effects of vagi and sympathetics on heart rate are equal and opposite
4. none of above



CAN ANYONE PLEASE EXPLAIN THE ANSWERS GIVEN ????

dont have time to explain the wrong answers its finals week

1) maybe you'll hate me, but think of the body as a circuit with a resistor and a capacitor in parallel. The higher the compliance of your arteries, the more blood is "stored" in the arteries at peak systolic and then when the "spring" is released, it will be "pulsed" downstream into capillary bed. Think of a rigid tube... there is no pulsatile flow because there is never any distension of a rigid container

the only way to really illustrate this is to draw diagrams of arterial pressure both vs. the spatial distance of the circulation, and the pressure as a function of time at a fixed point. I think books do a really poor job of explaining the significance of these 2 different graphs.

2) expiration against a closed glottis increases intrathoracic pressure, and the SVC runs through this space before it dumps into the heart. The SVC collapses and less blood goes back to the heart

3) bohr effect and haldane effect... protonated histidine residues cause Hb to go towards the "tense" state, where oxygen dumping is better. It so happens that the ability of the N-terminal amino groups to accept CO2 is also increased in the tense state

4) there is no concept here... i vaguely remember learning in class that if you cut the vagus (para) your heart rate goes up 30 bpm, whereas if you remove sympathetic tone to your heart, you go down by 10 bpm, thus demonstrating that parasympathetic tone dominates in normal conditions

 

[cutedoc12]

thanks a lot SEVENTHSON for putting ur valuable time in explaining these questions....gud luck.

 

[DragonWell]

dont have time to explain the wrong answers its finals week

1) maybe you'll hate me, but think of the body as a circuit with a resistor and a capacitor in parallel. The higher the compliance of your arteries, the more blood is "stored" in the arteries at peak systolic and then when the "spring" is released, it will be "pulsed" downstream into capillary bed. Think of a rigid tube... there is no pulsatile flow because there is never any distension of a rigid container

the only way to really illustrate this is to draw diagrams of arterial pressure both vs. the spatial distance of the circulation, and the pressure as a function of time at a fixed point. I think books do a really poor job of explaining the significance of these 2 different graphs.

I think I understand your explanation (very well done BTW), but based on it, I came to a different conclusion. It sounded like the question was saying that in a rigid system, there is only pulsatile flow, because the elastic "buffering" of the arteries is eliminated - therefore each pulse of increased pressure is transmitted directly into the capillaries, instead of into the walls of the arteries and then slowly being released, producing continuous flow downstream. Clinically, I guess I was equating this to seeing increased pulse pressure in atherosclerosis. Maybe I am missing some key concepts...

Edit: If you've got a Guyton sitting around p 173-175 explains this pretty well. "the degree of damping [ie. change in flow in capillaries] is ...proportional to the product of resistance times compliance". Therefore decreased compliance = decreased damping = pulsatile flow.

 

[SeventhSon]

i agree with your correction. good catch. Flow is naturally pulsatile by the virtue of the heart's pulsatility, and capacitance serves to dissipate this.

 

[cutedoc12]

well i am giving my NBDE-1 in jan....and this explanation seems to me like an OVERHEAD TRANSMISSION......ooooooooooppssssss!!!!!!!!!
anywayz thnx for ur efforts...

 

[cutedoc12]

.Q1 in the resting state in man the avg difference bw the o2 content of arterial and venous blood is......5 volumes percent.....how is it calculated?????

Q2 the absorption of calcium from the small intestine is increased by.....lowering the ph in the intestine.....how??

Q3 the concentration of which of the following amino acids can be used as an estimation of the amount of collagen present in a tissue?
hydroxyproline
proline

Q4 which of the following may normally leave the bodyby the way of lungs??
lipids
acetone
glucose
chlorides

can anyone explain ????......