Midterm 2

Question 1

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

Answer 1

Actin

Question 2

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

Answer 2

Troponin C

Question 3

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

Answer 3

Shortening of sacromeres

Question 4

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

Answer 4

Crossbridge cycling or sliding filament theory

Question 5

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

Answer 5

ATP is hydrolyzed into ADP+Pi

Question 6

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

Answer 6

Power Stroke

Question 7

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

Answer 7

Bind of the ATP myosin

Question 8

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

Answer 8

Excitation-contraction coupling

Question 9

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

Answer 9

efferent motor neurons

Question 10

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

Answer 10

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

Question 11

What is the function of T tubules?

Answer 11

Allow for electrical signals to move deeper into the cell

Question 12

What is a motor unit?

Answer 12

Single motor neuron paired with many muscle fibers

Question 13

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

Answer 13

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

Question 14

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?

Answer 14

Summation

Question 15

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

Answer 15

The maximum tension developed during summation and tetanus is treppe

Question 16

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

Answer 16

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

Question 17

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

Answer 17

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

Question 18

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

Answer 18

Recruitment

Question 19

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

Answer 19

Pulmonary Arteries

Question 20

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

Answer 20

a. differences in pressure across the valve

Question 21

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

Answer 21

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

Question 22

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

Answer 22

The sinoatrial node and the atrioventricular node

Question 23

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

Answer 23

Generate its own contractile cycle

Question 24

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

Answer 24

AV node

Question 25

What is an ectopic focus?

Answer 25

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

Question 26

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

Answer 26

e. movement of calcium through L-type channels

Question 27

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

Answer 27

c. both funny channels and T-type calcium channels

Question 28

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

Answer 28

Removes calcium from cells

Question 29

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

Answer 29

QRS complex

Question 30

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

Answer 30

T Wave

Question 31

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

Answer 31

A longer PR interval | OR More P waves and less QRS (sometimes none) Same as a third degree block

Question 32

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

Answer 32

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

Question 33

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

Answer 33

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

Question 34

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

Answer 34

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

Question 35

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

Answer 35

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

Question 36

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

Answer 36

c. atrial contraction

Question 37

The SA node is innervated by ________.

Answer 37

The sympathetic and the parasympathetic nervous system

Question 38

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.

Answer 38

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

Question 39

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 ________.

Answer 39

Atmospheric pressure

Question 40

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

Answer 40

Atmospheric and intra-alveolar (intra-pulmonary)

Question 41

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

Answer 41

Air moves out of the lung | Expiration

Question 42

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

Answer 42

A pneumothorax, the lung with collapse

Question 43

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

Answer 43

Decreases; into

Question 44

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

Answer 44

REMAINS THE SAME

Question 45

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

Answer 45

Alveolar type 2

Question 46

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

Answer 46

Tidal volume

Question 47

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

Answer 47

Inspiratory capacity

Question 48

``` 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 ```

Answer 48

C. residual volume

Question 49

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

Answer 49

Between 70 and 80 percent

Question 50

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

Answer 50

Liver

Question 51

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

Answer 51

they migrate into infected regions of tissue

Question 52

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

Answer 52

Bone marrow; erythropoietin

Question 53

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

Answer 53

Spleen

Question 54

Iron is transported in blood bound to what molecule?

Answer 54

transferrin

Question 55

Which of the following is the first step of hemostasis?

Answer 55

Vascular spasm or Vasoconstriction

Question 56

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

Answer 56

Platelets; collagen fibers in the connective tissue beneath the endothelium “Platelet plus is initiated by exposure of blood to damaged endothelium and underlying collagen”

Question 57

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

Answer 57

Stroke volume

Question 58

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

Answer 58

“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.

Question 59

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

Answer 59

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

Question 60

Which of the following decreases heart rate?

Answer 60

Parasympathetic Nervous activity

Question 61

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

Answer 61

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)

Question 62

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

Answer 62

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

Question 63

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

Answer 63

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