NAME _________________________________
STUDENT NUMBER _____________________
BIO310
MID-TERM TEST 2
November 21, 2006
12:15 pm – 1:45pm
No Aids Required
PART A
3 WRITTEN ANSWERS
ANSWER IN THE SPACE PROVIDED
RETURN THE ANSWER SHEET AND THE QUESTIONS TO THE INVIGILATOR WHEN
COMPLETED
PART A _____________/
PART B ______________/
Total ______________/
1) You donate 1 litre of blood to the Red Cross blood drive.
A. Explain the immediate cardiovascular challenge and response. (you do not need second
messenger pathways) [12 marks]
B. After a few hours plasma volume has returned to near normal. This is too quick for renal
mechanisms and is not because of drinking fluid. Explain how this happened.[4 marks]
A:
Immediate Challenge:
Decrease BV
Decrease VR (decrease atrial stretch)
Decrease SV (because decrease EDV)
Decrease CO
Decrease MAP
Response:
Detected by baroreceptors
Increase SNS, decrease PNS
Increase HR
Increase contractility
Vasoconstriction -> increase TPR
Venoconstriciton -> increase Psf, VR, CO
Since MAP=HRxSVxTPR these responses bring MAP towards normal
B:
Fluid would be recovered by increased reabsorption of fluid at the capillaries
NFP = (Pc-PIF) – (c - IF)
vasoconstriction by SNS decrease capillary pressure (vaso- more important than veno const)
Normally filtration at arteriole end and reabsorption at venule end, almost in balance, 0.85 reabs/filt
but if Pc decreases then there will be an increase in reabsorption because deltaP decreases and NFP
decreases favoring reabsorption
3) One of the effects of caffeine is to increase the level of cAMP inside all cells. Explain how
caffeine affects cardiovascular function to increase mean arterial blood pressure. [6 marks]
Two effects:
1) ‘funny’ sodium channels control pacemaker potential, which controls HR. Increasing
cAMP increases probability of ‘funny’ channel opening therefore increase HR
2) cAMP will activate PKA in myocytes and cause increase contractility by activating
DHP receptors, RyR and calcium pump. Increasing contractility will cause decrease in
end-systolic volume
Therefore since MAP = HR x (EDV-ESV) x TPR, increase HR and decrease EDV (increase SV)
will increase MAP
4) A heart attack leads to a hypoeffective heart. Would infusion of 3 L of iso-osmotic solution be
an effective short term treatment? Explain using cardiac- and vascular-function curves. [5 marks]
hypereffective
B
CO
C
5
A
normal Blood loss
CVP or RAP
•
•
•
Hyper effective increase CO and therefore VR
• (from A to B)
Blood loss decreases VR (from B to C)
Blood loss would restore CO towards normal
1. Which of the following changes would most increase the resistance to blood flow in a blood
vessel?
A. halving the diameter of the vessel
B. doubling the diameter of the vessel
C. halving the length of the vessel
D. doubling the length of the vessel
E. decreasing the hematocrit from 50% to 40%
2. The pacemaker of the heart is normally the
A. sinoatrial node.
B. atrioventricular node.
C. mitral valve.
D. bundle of His.
E. left ventricle.
3. Which of the following statements about the SA node is true?
A. The cells will not depolarize until it receives sympathetic stimulation.
B. The pacemaker potential is caused by calcium entering the cell via slow channels.
C. The pacemaker potential is slower in achieving threshold when acetylcholine is applied to
the SA cells.
D. The pacemaker potential is slower in achieving threshold when epinephrine is applied to the
SA cells
E. None of the choices are true.
4. If electrical propagation through the bundle of His were reduced, which of the following events
would you expect to occur?
A. There would be a slowing of the rate of contraction of the ventricles.
B. The atria would contract more frequently than the ventricles.
C. The SA node would no longer set the pace for atrial contraction.
D. Both there would be a slowing of the rate of contraction of the ventricles and the atria
would contract more frequently than the ventricles would occur.
5. The plateau of the action potential in atrial cells is shorter than in ventricular cells. This could
result from which of the following:
A. More potassium leaving the atrial cell during the plateau phase
B. Less calcium entering the atrial cell during the plateau phase
C. Less sodium entering the atrial cell during the plateau phase
D. A and B
E. A, B and C
6. If the lymphatic system fails, which of the following is true?
A.
Plasma protein concentration decreases
B.
Capillary pressure increases
C.
Interstitial fluid pressure decreases
D.
Interstitial osmotic pressure increases
7. In an electrocardiogram, the QRS complex represents the
A. depolarization of the atria.
B. repolarization of the atria.
C. depolarization of the ventricles.
D. repolarization of the ventricles.
E. the delay at the AV node.
8. For initiation of cardiac muscle contraction:
A. Extracellular calcium is the major source for cardiac contraction.
B. Calcium from the sarcoplasmic reticulum is the major source for cardiac contraction.
C. Troponin is not required for contraction in cardiac muscle.
D. None of the above choices are correct
9. Which of the following statements about the cardiac cycle is true?
A. During isovolumetric relaxation, blood flows from the atria into the ventricles.
B. Closure of the atrioventricular valves occurs at the onset of systole.
C. Blood flows into the ventricle only after atrial contraction.
D. The aortic valve closes when ventricle pressure is greater than aortic pressure
10. During the cardiac cycle,
A. the volume of blood leaving the left side of the heart is greater than the volume leaving the
right side.
B. the pressure of blood leaving the right side of the heart is greater than that leaving the left
side.
C. the duration of systole is greater than that of diastole.
D. the duration of diastole is greater than that of systole.
11. During isovolumetric ventricular contraction,
A. rapid filling of the ventricles occurs.
B. no blood enters or leaves the ventricles.
C. the maximum volume of blood is ejected.
D. ventricular pressure is at a maximum.
E. none of these things would occur.
12. The heart valves open and close due to
A. stimulation by the sympathetic and parasympathetic nerves.
B. a pressure difference on the two sides of the valve.
C. Na+ and K+ fluxes during ventricular depolarization.
D. turbulent flow in the atria and ventricles.
E. none of the choices are correct.
13. With regard to the regulation of heart rate, which is correct:
A. stimulation of parasympathetic nerves to the heart causes a slowing of heart rate.
B. stimulation of sympathetic nerves to the heart causes an increase in heart rate.
C. a person whose heart lacks autonomic innervation has a faster heart rate at rest than a person
with a normally innervated heart.
D. All of the above are correct
14. The Frank-Starling mechanism of the heart describes
A. the relationship between end-diastolic volume and stroke volume.
B. the relationship between length and tension in cardiac muscle.
C. the relationship between end-diastolic volume and heart rate.
D. A and B
E. A, B and C
15. Metabolic control of blood vessel radius refers to:
A. increased metabolic activity that results in vasoconstriction.
B. increased metabolic activity that results in vasodilation.
C. decreased blood flow to tissues that results in vasoconstriction.
D. decreased blood flow to tissues that results in vasodilation.
16. What mechanisms ensure adequate blood flow to the muscles during exercise?
A. Local metabolic control.
B. Hormonal control of vasodilation
C. Sympathetic nervous system
D. A and B
E. A, B and C.
17. In which of the following vascular beds are local factors more important than SNS activity for
determining arteriole radius?
A. brain
B. skin
C. muscle
D. gut
18. Flow of blood in the veins is influenced by
A. the blood pressure difference between veins and atria.
B. the skeletal pump.
C. the decrease of thoracic pressure and increase of abdominal pressure due to diaphragm
movement.
D. valves in the veins.
E. All of the choices are correct.
19. During exercise, blood flow to the kidneys and abdominal organs ______because of ___
A. increases; increased sympathetic stimulation of alpha-adrenergic receptors in the smooth
muscle of arterioles supplying them
B. decreases; increased sympathetic stimulation of alpha-adrenergic receptors in the smooth
muscle of arterioles supplying them
C. increases; local metabolic control
D. decreases; local metabolic control
E. does not change; flow autoregulation
20. Which of the following is not likely to result in edema?
A. blockage of lymph vessels
B. prolonged standing
C. heart failure
D. elevated plasma protein concentrations
20. Decreased action potential frequency from the aortic baroreceptor would lead to:
A. vasoconstriction
B. reduced heart rate
C. reduced ventricular contractility
D. all of the above