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Physiology > Midterm 2 > Flashcards

Midterm 2 Flashcards

1
Q

The contractile portion of the thin filament is composed of what protein?

A

Actin

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2
Q

What is the protein component of the thin filament that binds to calcium thereby initiating skeletal muscle contraction?

A

Troponin C

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3
Q

The shortening of a skeletal muscle fiber during contraction involves which of the following?

A

Shortening of sacromeres

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4
Q

The repeated, oscillating interaction between actin and myosin that results in the generation of force by a skeletal muscle is called what?
(2 answers)

A

Crossbridge cycling or sliding filament theory

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5
Q

What converts the myosin head into the high-energy state?

A

ATP is hydrolyzed into ADP+Pi

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6
Q

The release of an inorganic phosphate from the myosin molecule directly results in which of the following?

A

Power Stroke

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7
Q

In order for the crossbridge cycling to occur, the actin-myosin complex must be broken by which of the following?

A

Bind of the ATP myosin

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8
Q

The sequence of events that links the action potential to changes in skeletal muscle force development is called what?

A

Excitation-contraction coupling

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9
Q

Contraction of skeletal muscle fibers is stimulated by what type of neuron?

A

efferent motor neurons

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10
Q

The binding of calcium to troponin will directly cause which of the following?

A

The movement of tropomyosin, thereby exposing myosin-binding site on the actin molecule

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11
Q

What is the function of T tubules?

A

Allow for electrical signals to move deeper into the cell

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12
Q

What is a motor unit?

A

Single motor neuron paired with many muscle fibers

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13
Q

When an action potential is generated within a motor neuron, ________.

A

Neurotransmitter is released from axon and diffused to muscle Depolarized wave travels across membrane of muscle cell Down through the T-tubules

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14
Q

Which of the following is the property of skeletal muscle whereby an increase in the frequency of action potentials enhances the force developed by the muscle cell?

A

Summation

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15
Q

Which of the following statements about summation and tetanus is FALSE?

A

The maximum tension developed during summation and tetanus is treppe

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16
Q

As skeletal muscle is further stretched beyond the length where optimum force is developed, ________.

A

The thin filaments are pulled away from thick filaments, thereby reducing their ability to interact with myosin

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17
Q

As the sarcomere length of skeletal muscle is reduced beyond the length where optimum force is developed, ________.

A

The thin filaments overlap one another, thereby reducing their ability to interact with myosin

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18
Q

What is an increase in the number of active motor units that would increase the force developed by a skeletal muscle called?

A

Recruitment

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19
Q

When blood leaves the heart, it first enters what type of blood vessel?

A

Pulmonary Arteries

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20
Q

The opening and closure of the atrioventricular and semilunar valves is driven by ________.

a. differences in pressure across the valve
b. contraction and relaxation of the valve
c. contraction of the valve
d. contraction of muscles attached to the valves
e. contraction of the ventricle and atria that pull the valves into place

A

a. differences in pressure across the valve

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21
Q

Closure of the atrioventricular valve occurs when ________.

a. the valve contracts
b. the papillary muscle contracts
c. pressure inside the ventricle is greater than pressure inside the atrium
d. pressure inside the ventricle is less than pressure inside the atrium
e. the atrium contracts

A

c. pressure inside the ventricle is greater than pressure inside the atrium

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22
Q

What are the two major regions of the heart containing pacemaker cells?

A

The sinoatrial node and the atrioventricular node

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23
Q

The term autorhythmicity refers to the heart’s ability to ________.

A

Generate its own contractile cycle

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24
Q

Conduction through which of the following is slow to allow atria to contract before the ventricles?

A

AV node

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25
Q

What is an ectopic focus?

A

AKA ectopic pacemaker: A cluster of myocardial cells located away from the SA node that take over and regulate the cardiac pace.

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26
Q

The rapid depolarization phase of a pacemaker cell action potential is caused by which of the following types of ion movement?

a. movement of potassium through funny channels
b. movement of sodium through funny channels
c. movement of sodium and calcium through funny channels
d. movement of calcium through T-type channels
e. movement of calcium through L-type channels

A

e. movement of calcium through L-type channels

27
Q

Which of the following ion channels must open for a cardiac pacemaker cell to depolarize to threshold for an action potential?

a. funny channels only
b. T-type calcium channels only
c. both funny channels and T-type calcium channels
d. both funny channels and L-type calcium channels
e. L-type calcium channels only

A

c. both funny channels and T-type calcium channels

28
Q

What is the function of the sodium-calcium exchanger in cardiac muscle?

A

Removes calcium from cells

29
Q

Which of the following components of an ECG represents ventricular depolarization?

A

QRS complex

30
Q

Which of the following components of an ECG represents ventricular repolarization?

A

T Wave

31
Q

If damage to the AV node slowed down conduction through this tissue, what would be observed on an ECG?

A

A longer PR interval

OR More P waves and less QRS (sometimes none) Same as a third degree block

32
Q

During isovolumetric relaxation, ________.

a. the AV and semilunar valves are open and ventricular pressure is increasing
b. the AV and semilunar valves are closed and ventricular pressure is increasing
c. the AV and semilunar valves are open and ventricular pressure is decreasing
d. the AV and semilunar valves are closed and ventricular pressure is decreasing
e. the AV valves are open, the semilunar valves are closed, and ventricular pressure is decreasing

A

d. the AV and semilunar valves are closed and ventricular pressure is decreasing

33
Q

What is occurring during ventricular ejection?

a. the AV and semilunar valves are closed as ventricular pressure is increasing
b. the AV valves are open and the semilunar valves are closed as blood is leaving the ventricles
c. the AV and semilunar valves are open as blood is leaving the ventricles
d. the AV valves are closed and the semilunar valves are open as blood is leaving the ventricles
e. the AV valves are open and the semilunar valves are closed as ventricular pressure is increasing

A

d. the AV valves are closed and the semilunar valves are open as blood is leaving the ventricles

34
Q

Ejection of blood from the right ventricle will continue until ________.

A

Pressure in the pulmonary artery is greater than pressure in the right ventricle

35
Q

The increase in ventricular volume early in diastole reflects ________.

a. the relaxation of the ventricle
b. the back-flow of blood from the aorta
c. the increased stiffness of the heart
d. the contraction of the atria moving blood into the ventricle
e. the passive movement of blood through the atrium and into the ventricle

A

e. the passive movement of blood through the atrium and into the ventricle

36
Q

The small increase in ventricular pressure observed late in diastole is caused by ________.

a. blood moving into the atria from vena cava
b. ventricular relaxation
c. atrial contraction
d. ventricular contraction
e. atrial relaxation

A

c. atrial contraction

37
Q

The SA node is innervated by ________.

A

The sympathetic and the parasympathetic nervous system

38
Q

Which of the following is an effect of parasympathetic activity to the heart?

a. The rate of spontaneous depolarization in SA nodal cells decreases.
b. cAMP is activated
c. SA nodal cells are depolarized.
d. Postganglionic neurons release acetylcholine, which binds to nicotinic cholinergic receptors in the SA node.
e. Heart rate is increased.

A

a. The rate of spontaneous depolarization in SA nodal cells decreases.

39
Q

When air is no longer moving through the respiratory tract and the airway is open to the environment, the pressure within the lung is equal to ________.

A

Atmospheric pressure

40
Q

The difference between what two pressures drives air into and out of the lungs?

A

Atmospheric and intra-alveolar (intra-pulmonary)

41
Q

Which of the following occurs when intra-alveolar pressure exceeds atmospheric pressure?

A

Air moves out of the lung

Expiration

42
Q

Equilibration of pressure between the intrapleural space and the alveoli will lead to which of the following?

A

A pneumothorax, the lung with collapse

43
Q

As the lungs expand, intra-alveolar pressure ________ and air moves ________ the lungs.

A

Decreases; into

44
Q

As the volume of the lung increases, atmospheric pressure ________.

A

REMAINS THE SAME

45
Q

The surface tension of the alveolus is reduced by surfactants produced by what type of cells?

A

Alveolar type 2

46
Q

What is the volume of air moved into and out of the lungs in a single breath during unforced breathing called?

A

Tidal volume

47
Q

The tidal volume and inspiratory reserve volume together make up which of the following?.

A

Inspiratory capacity

48
Q 
Which of the following measurements cannot be determined by a spirometer?
A. vital capacity
B. tidal volume
C. residual volume
D. inspiratory capacity
E. inspiratory reserve volume
A

C. residual volume

49
Q

A healthy person can normally exhale what percentage of his/her vital capacity in one second?

A

Between 70 and 80 percent

50
Q

A majority of the protein present within blood is synthesized within what organ?

A

Liver

51
Q

Which of the following statements is NOT accurate with respect to erythrocytes?

A

they migrate into infected regions of tissue

52
Q

Erythrocytes are synthesized in what organ and under the control of what chemical?

A

Bone marrow; erythropoietin

53
Q

Old red blood cells are removed from the blood by macrophages in what organ?

A

Spleen

54
Q

Iron is transported in blood bound to what molecule?

A

transferrin

55
Q

Which of the following is the first step of hemostasis?

A

Vascular spasm or Vasoconstriction

56
Q

Formation of a platelet plug is initiated by ________ binding to ________.

A

Platelets; collagen fibers in the connective tissue beneath the endothelium

“Platelet plus is initiated by exposure of blood to damaged endothelium and underlying collagen”

57
Q

The end-diastolic volume minus the end-systolic volume is the ________.

A

Stroke volume

58
Q

Which of the following describes the effect of end-diastolic volume on stroke volume?

A

“An increase in end diastolic volume increases the stroke volume” (Starling’s law of the heart)
Stroke volume depends on end diastolic volume, the contractility of the ventricle, the pressure required to pump blood into the aorta and venous return of the blood to the heart.

59
Q

An increase in venous return would result in a(n) ________.

A

a. According to Starling’s law, an increase in venous return results in a more effective contraction.
b. The more blood the heart collects blood from venous return, the more it is able to distribute through cardiac output.
c. Matched increase in cardiac output

60
Q

Which of the following decreases heart rate?

A

Parasympathetic Nervous activity

61
Q

Which of the following is true of the ventricular filling phase of the cardiac cycle?

A

Diastolic event, one AP causes atrial contraction which pushes 20% of the blood through

Most blood flows passively into the ventricles through open AV valves.
Ventricular filling occurs before atrial contraction (phase 1)

62
Q

The increased aortic pressure that occurs during systole reflects a(n) ________.

A

Ejection, opening of Semilunar valve, low pressure in the artery

63
Q

Which of the following is FALSE of sympathetic activity to the SA node?
TRUE THINGS:

A

increases heart rate because it increases firing of the SA node,
binds NE to beta receptors,
leads to the production of cAMP through second messenger system,
increases the length of activation of HCN channels and sodium influx, cells reach threshold sooner

Physiology (4 decks)

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