Deck 42: Regulation of Perfusion

Question 1

Ph ar m ac om ec ha nic al c ou plin g in va sc ula r s m oo th m us cle

A) Links mem brane potential to contraction
B) Links binding of a neurotransmitter or hormone to contraction
C) Links binding of neurotransmitter to mem brane potential
D) R eq uir es a m em br an e p ote ntia l ch an ge on the m us cle ce ll
E) Requires a mem brane potential change on the SR m embrane

Answer 1

B

Question 2

Ele ctr om ec ha nic al c ou plin g in va sc ula r s m oo th m us cle

A) Links electric fields around the myofilaments to the production of force
B) Couples mem brane potential of one cell to that of another
C) Is responsible for the formation of the functional syncytium
D) Couples membrane depolarization to the influx of Ca₂+
E) Directly links MLCK to a m embrane channel

Answer 2

D

Question 3

Inh ibitin g th e a ctiv ity of M LC P s ho uld

A) Increase the force of contraction without Increasing [Ca₂+]
B) Increase the force of contraction due to Increased [Ca₂+]
C) Increase th e fo rc e o f c on tra ctio n b ec au se of Decreas ed m yos in lig ht c ha in phosphorylation
D) Decrease the force of contraction due to decreased [Ca₂+]
E) Decreas e th e fo rc e o f c on tra ctio n b ec au se of Decreas ed m yos in lig ht c ha in phosphorylation

Answer 3

A

Question 4

Sym pa the tic s tim ula tion ge ne ra lly

A) Constricts vessels by acting through a
B) Constricts vessels by acting through þ
C) Dilates vessels by acting through a
D) Constricts vessels by acting through þ
E) Have no effect as parasympathetic fibers only innervate vascular tissue

Question 5

In vasoconstriction, the layer of the arteriole or small artery that contracts is the

A) T un ica ad ve ntitia
B) Tu nica m ed ia
C) T un ica intim a
D) Endothelial cell layer
E) External elastic lamina

Question 6

C on tra ctio n o f va sc ula r s m oo th m us cle is c on tro lled by

A) Myosin light chain kinase
B) Myosin light chain phosphatase
C) The state of light chain phosphorylation
D) Ca₂+ binding to calmodulin that activates MLCK
E) All of the above

Question 7

The state of contraction of vascular smooth muscle is determined most directly by the

A) Occ upanc y of receptors for vasoco nstrictors or vasodilators
B) State of phosphorylation of myosin light chains
C) Activat ion of acto-myosin cross bridges by Ca₂+
D) M em br an e p ote ntia l of t he sm oo th m us cle ce lls
E) Electrical coupling of smooth muscle cells through gap junctions

Question 8

Which of the following is a vasoc onstrictor?

A) NO
B) En do the lin
C) Thromboxane A 2
D) H ep ar in
E) Ang iote ns in II

Question 9

Which of the following is a vasod ilator?

A) Thromboxane A 2
B) Norepinephrine
C) Endothelin
D) An gioten sin II
E) Va so pr es sin

Question 10

Increasing the res ista nc e o f th e a rte rio les in a va sc ula r be d m ain ly

A) Increases the pressure in the arterioles
B) Increases the perfusion of the tissue
C) Increases the pressure in the capillaries
D) Increases the filtration of fluid out of the capillaries
E) Decreases the pressure in the capillaries

Question 11

Which of the following does not Increase the capillary pressure?

A) Increased arterial pressure
B) Vasodilation
C) Venoconstriction
D) Increased caliber of the aterioles
E) Increased caliber of the veins

Question 12

The m yogenic response of vascular smooth muscle refers to

A) Relaxation in response to stress
B) Contraction in response to stretch
C) Contraction in response to NO
D) Contraction in response to adenosine
E) Co ntrac tion in re spo nse to AII (a ngio tens in II)

Question 13

Sympathetic activation of arterioles causes

A) Vasoconstriction
B) Vasodilation
C) Venoconstriction
D) Venodilation
E) Both A and C are correct

Question 14

MLCK stands for

A) Myosin light chain kinase
B) Myofilament-like creatine kinase
C) Myofiliament-linked creatine kinase
D) Myofilament-linked cholesterol kinase
E) Muscle length-dependent creatine kinase