HBY 531 MEDICAL PHYSIOLOGY

Lecture Exam 1

2003

Section 1: Answer the following using:

A = increase

B = not change

C = decrease

1. If glycerol is added to the normal solution bathing a cell, steady state cell volume will _______________.

2. If a neurotransmitter causes a reduction in cellular Na/K ATPase activity, steady state [Na⁺]_i will _______________.

3. Using the single channel patch clamp technique, it is seen that application of cAMP at the intracellular face of a K⁺-channel protein causes the fraction of time spent in the closed state to decrease. In the cell that was patch clamped, a rise in intracellular cAMP would ________________ the membrane K⁺-conductance due to this channel.

4. Assume Cl^- is in not actively transported. If a cell’s resting voltage is caused to abruptly change from -70 mV to -80 mV, over the next few minutes [Cl^-]_i will _______________.

5. A decrease in [Na⁺]_i will cause a mammalian nerve action potential overshoot to _______________.

6. If the voltage dependent K⁺-channels in a nerve axon are blocked, the time between action potential peak and return to rest will _______________.

7. The relative refractory period is partly because the voltage dependent K⁺-conductance is ______________ed.

8. Myasthemia gravis causes deterioration of the ACh-Rs and as a consequences the amplitude of MEPPs will _______________.

9. During facilitation, postsynaptic receptor density will ______________.

10. During contractile activity of skeletal muscle cell, creatine phosphate levels will _______________.

11. During normal physiological activity, when a smooth muscle is stretched, isometric tension will _______________.

12. Increasing the intestinal (luminal) concentration of amino acids will ____ the negativity of the transepithelial potential (measured with respect to the serosa).

13. Increasing the inward cAMP concentration in intestinal secretory cells will ____ the inward Cl^- current across the apical membrane.

14. Increasing the circulating concentration of ADH (antidiuretic hormone) will ____ the water permeability (L_p) of kidney collecting-duct cells.

15. Traveling to a high altitude will cause hypoxia (low blood O₂ levels), and this will ____ the circulating levels of erythropoietin.

16. A decrease in the circulating levels of erythropoietin will ____ the number of pluripotent stem cells in the marrow.

17. The duration of norepinephrine release at adrenergic nerve terminals will _________ in the presence of yohimbine, a specific a2 adrenergic receptor antagonist.

18. During prolonged exposure to succinylcholine, the intracellular K+ within skeletal muscle cells will be expected to ____________.

19. Following infusion of phenoxybenzamine (a non-specific a adrenergic receptor antagonist) into the blood supply of a skeletal muscle, blood flow through that muscle will be expected to:

20. Acetylcholine release at cholinergic synapses will _______ in the presence of botulinum toxin.

Section 2: For each of the following, choose the single best response.

21. An intravenous solution is made containing (in mM): NaCl =140; KCl =5; CaCl₂ =2;

glucose =10. Assuming osmotic coefficients are unity, the osmolarity of this solution is

A. 157 mOsm

B. 314 mOsm

C. 304 mOsm

D. 300 mOsm

E. 306 mOsm

22. A cell is initially in equilibrium with a bathing solution containing concentrations of permeants s_o =150 mM and impermeants S_o =150 mM. This cell is transferred to a large bath containing S_o =300 mM. The ratio of final volume to initial volume is

A. ½

B. 2

C. 3

D. 1/3

E. 1

23. Primary (ATP driven) active transport is not directly used to control the intracellular concentration of

A. Na⁺

B. K⁺

C. H⁺

D. Ca²⁺

E. Cl^-

24. The lipid matrix of a biomembrane is impermeable to

A. proteins.

B. sugars.

C. anions.

D. cations.

E. All of the above.

25. The conductance of a biomembrane is not dependent on

A. membrane capacitance.

B. open channel conductance.

C. open channel probability.

D. channel insertion.

E. channel synthesis/degradation.

Questions 26-28 refer to the figure below

26. [Cl]_o = ?

A. 15 mM

B. 150 mM

C. 147 mM

D. 300 mM

E. Cannot be determined

27. R_i = ?

A. -93 mV

B. -60 mV

C. -70 mV

D. -80 mV

E. Cannot be determined

28. [A]_i = ?; Z = ?

A. 154 mM, -1.00

B. 128 mM, -1.09

C. 128 mM, -1.00

D. 154 mM, -1.09

E. Cannot be determined

29. The peak of a smooth muscle action potential is 0 mV. If E_Ca = +100mV and E_K = -100 mV, what is the ratio of g_Ca/g_K at the action potential peak?

A. 1

B. 2

C. 3

D. 4

E. 5

30. Threshold for an action potential is

A. the current at which the voltage changes sign.

B. the current at which the voltage is zero.

C. the voltage at which the current first becomes outward.

D. the voltage at which the current first becomes inward.

E. the voltage at which the current change is zero.

31. Voltage dependent inactivation leading to loss of action potential activity occurs because

A. too many m-gates close.

B. too many n-gates close.

C. too many h-gates close.

D. too many m-gates open.

E. too many h-gates open.

32. The normal repolarization of a nerve axon action potential is due to

A. spontaneous inactivation of Na-channels.

B. voltage dependent activation of K-channels.

C. closure of h-gates.

D. opening of n-gates.

E. All of the above.

33. An increase in which of the following would slow action potential propagation velocity?

A. Radius of the axon.

B. Length constant for passive voltage spread.

C. Peak g_Na.

D. Peak g_K.

E. Membrane capacitance.

34. Myelination does not

A. involve Schwan cells.

B. increase propagation velocity.

C. increase membrane capacitance.

D. create modes of Ranvier.

E. occur in mammals.

35. Botulinum toxin reduces Ca-entry into the presynaptic terminal at the neuromuscular junction. Which of the following could not occur following botulinum poisoning?

A. Increased MEPP duration.

B. Decreased ACh release.

C. Weakness.

D. Paralysis.

E. Unchanged MEPP amplitude.

36. At the neuromuscular junction, the ACh receptor

A. is inhibitory.

B. is selective for anions.

C. has two ACh binding sites.

D. conducts an outward current.

E. is a slow synapse.

Questions 37-38 refer to the figures below.

37. The post synaptic current change )I_ps is most probably

A. excitatory.

B. inhibitory.

C. selective for Na.

D. selective for K.

E. selective for cations.

38. The post synaptic conductance change )g_ps is

A. 100 mS/cm²

B. 10 mS/cm²

C. 1 mS/cm²

D. 0.1 mS/cm²

E. 0.01 mS/cm²

39. A cardiac muscle cell

A. requires extracellular Ca to contract.

B. is not usually striated.

C. contracts once for each " motor neuron action potential.

D. is relatively large and contains many nuclei.

E. has no transverse tubular system.

40. The dark region at the center of a sarcomere is called the

A. Z-line

B. I-band

C. H-zone

D. M-line

E. A-band

41. In smooth muscle, which of the following does not directly require ATP?

A. Ca-uptake by the SR.

B. Crossbridge cycling.

C. The Na/K pump that establishes E_Na and E_K.

D. Myosin kinase activity.

E. Ca-entry during the action potential.

42. A skeletal muscle cell can generate maximum active isometric tension at a sarcomere length of 2.5 :M, where the H-zone is 0.1 :m, then active isometric tension falls linearly to zero as the sarcomeres are stretched from 2.5 :M to 3.9 :M. How long is each thin filament from Z-line to its end?

A. 0.5 :M

B. 0.7 :M

C. 1.2 :M

D. 1.5 :M

E. 1.9 :M

43. An epithelium bathed with identical Ringer’s solutions

on both sides exhibits the potential profile shown on

the right. Assuming that E_Na is +50 mV, E_K is

-100 mV and E_Cl is -70 mV, then which of the

following is correct?

A The apical-membrane potential is -60 mV

measured with respect to the mucosa.

B If the tight junctions are permeable to cations,

then there will be paracellular secretion of both

Na⁺ and K⁺ from serosa to mucosa.

C If the basolateral membrane has K⁺-permeable

channels, then there will be an outward K⁺ current

across the basolateral membrane.

D A, B and C are all true statements.

E A, B and C are all false statements.

44. Regarding epithelial tight junctions, which of the following statements is TRUE?

A Tight epithelia always have more junctional strands (“kisses”) than leaky epithelia.

B The junctions facilitate transport of intracellular metabolites from one cell into a neighboring cell.

C The junctions facilitate migration of basolateral-membrane proteins into the apical membrane.

D Tight-junctional permeability decreases in response to an increase in the intracellular Ca⁺⁺ concentration.

E They exhibit specific transepithelial permeability properties that mediate paracellular transport.

45. Which of the following cells cannot undergo diapedesis?

A erythrocytes (RBCs)

B leukocytes (WBCs)

C reticulocytes

D granulocytes (e.g., neutrophils, eosinophils plus basophils)

E agranulocytes (e.g., monocytes plus lymphocytes)

46. Which of the following proteins is an intracellular iron storage protein capable of binding to (encapsulating) more than 100 iron atoms?

A hemoglobin

B myoglobin

C mobilferrin

D ferritin

E transferrin

47. What is the underlying cause of pernicious anemia in untreated gastrectomy patients?

A lack of vitamin B₁₂ (cobalamin) in the diet

B lack of intrinsic factor secreted by gastric parietal cells

C lack of folate (folic acid) in the diet

D inability to absorb dietary iron

E reduced circulating levels of erythropoietin

48. Primary afferents that convey sensory input from the bladder to the micturition center in the pons have cell bodies (i.e., somas) that reside within the: (D)

a. pons

b. medulla

c. dorsal root ganglia of lumbar nerves

d. inferior vagal ganglion

e. parasympathetic ganglia located within the bladder wall

49. Cutting which of the following nerves would be expected to result in a diminished capacity for the detrusor muscle of the bladder to contract? (D)

a. the pudendal nerve

b. lumbar splanchnic nerves that run to the inferior mesenteric ganglion

c. the hypogastric nerve.

d. pelvic splanchnic nerves that run to the bladder

e. both b and c

50. During a massive stimulation of the sympathetic-adrenal medulla system (i.e., a fight or flight response), all of the following responses would be expected EXCEPT: (C)

a. in increase in heart rate

b. an increase in glucose metabolism

c. an increase in gastrointestinal motility and secretion

d. papillary dilation

e. airway dilation

51. Which of the following drugs or toxins will result in skeletal muscle paralysis? (E)

a. curare

b. succinlycholine

c. botulinum toxin

d. tetrodotoxin (TTX)

e. all of the above