Self Guide Self Test LAB 9

Question 1

The source of calcium in skeletal muscle is:

a) the sarcoplasmic reticulum

b) extracellular sources

c) both 1 and 2

Answer 1

the sarcoplasmic reticulum

Question 2

The source of calcium in cardiac muscle is:

a) the sarcoplasmic reticulum

b) extracellular sources

c) both 1 and 2

Answer 2

both 1 and 2

Question 3

The means of excitation for skeletal muscle is:

a) 1. the nervous system

b) 2. inherent contractions initiated by pacemaker cells

c) both 1 and 2

Answer 3

1. the nervous system

Question 4

The means of excitation for cardiac muscle is:

a) 1. the nervous system

b) 2. inherent contractions initiated by pacemaker cells

c) both 1 and 2

Answer 4

2. inherent contractions initiated by pacemaker cells

Question 5

Innervation of skeletal muscle is through

a) 1. the Somatic Nervous System

b) 2. the Autonomic Nervous System

c) both 1 and 2

Answer 5

1. the Somatic Nervous System

Question 6

Innervation of cardiac muscle is through

a) 1. the Somatic Nervous System

b) 2. the Autonomic Nervous System

c) both 1 and 2

Answer 6

2. the Autonomic Nervous System

Question 7

The length of the refractory period in skeletal muscle is approximately:

a) 2-3 msec

b) 20-30 msec

c) 200 msec or more

Answer 7

2-3 msec

Question 8

The length of the refractory period in cardiac muscle is approximately:

a) 2-3 msec

b) 20-30 msec

c) 200 msec or more

Answer 8

200 msec or more

Question 9

Using the figure below, match the events occuring during the labelled phases of the cardiac cycle. Responses (A, B, C) may be used more than once.

-The inability of cardiac muscle to be tetanized is the result of _____

-The muscle is absolutely refractory during ______

-An extra-systole can be initiated during _____

-The muscle in non-refractory during _____

-Membrane depolarization occurs during ______

-Membrane repolarization occurs during _______

Answer 9

-The inability of cardiac muscle to be tetanized is the result of __B___

-The muscle is absolutely refractory during ___B___

-An extra-systole can be initiated during ___C__

-The muscle in non-refractory during ___A__

-Membrane depolarization occurs during ___A___

-Membrane repolarization occurs during ____C___

Question 10

Using the figure below, match the events occuring during the labelled phases of the cardiac cycle. (E or D)

-Electrical events are represented by _____

-Mechanical events are represented by ______

-Curve for which the units would be measured in grams _______

-Curve for which the units would be measured in mV _______

Answer 10

-Electrical events are represented by ___D__

-Mechanical events are represented by ___E___

-Curve for which the units would be measured in grams ____E___

-Curve for which the units would be measured in mV ___D____

Question 11

Which ion is responsible for the long plateau phase of the ventricular muscle action potential?

a) Ca++

b) Na+

c) Cl-

d) K+

Answer 11

Ca++

Question 12

The long plateau phase of the fast response action potential of cardiac muscle:

a) is responsible for long refractory period seen in cardiac muscle.

b) prevents cardiac muscle from tetanizing

c) allows the heart to serve as a pump because the ventricles have time to fill with blood before another contraction can be induced.

d) keeps cardiac muscle in the depolarized state so another contraction cannot be initiated until the heart has had time to contract and refill.

e) All of the above are true.

Answer 12

All of the above are true.

Question 13

On the diagram below, a large stimulus was applied to the heart during the relative refractory period of a normal contraction. # ____ is an extra- systole, # _____is the compensatory pause, and # _____ is a physiological example of Starling’s Law.

a) 1. c, d, e

b) 2. a, b, e

c) 3. c, d, c

d) both 1 and 3

Answer 13

both 1 and 3

Question 14

During the cardiac cycle, an extra systole can be induced by electrical stimulation during:

a) the latent period.

b) the absolute refractory period.

c) the relative refractory period.

d) systole.

Answer 14

the relative refractory period.

Question 15

The two systems of control over cardiac function are Autoregulation via Einthoven’s Law and the nervous system control via somatic nerves.

a) True

b) False

Answer 15

False

Question 16

Starling’s law of the heart: (multiple answers)

a) is the result of the length-force relationship also observed in skeletal muscle

c) states that, within physiological limits, the heart pumps out the blood that returns to it within each cycle.

d) is observed in the absence of any nervous or hormonal control.

f) can also be described as autoregulation.

g) is the result of cardiac fiber length being proportional to end-diastolic volume.

h) is demonstrated by an increased force of contraction with increased stretch of cardiac muscle.

j) is demonstrated by a decreased force of contraction with decreased stretch of cardiac muscle.

L) is demonstrated when an increased venous return results in an increased cardiac output.

Answer 16

A, C, D, F, G, H, J, L

Question 17

Starling’s law of the heart holds that the _____, the greater the force of contraction.
(multiple answers)

a) lower the venous return

b) greater the venous return

c) smaller the end-diastolic volume

d) greater the end-diastolic volume

e) greater the length of myocardial fibers

f) shorter the length of myocardial fiber

Answer 17

B, D, E

Question 18

The SA-node is innervated by:

a) the Parasympathetic nervous system only

b) the Sympathetic nervous system only

c) both the Parasympathetic and Sympathetic nervous systems

Answer 18

c) both the Parasympathetic and Sympathetic nervous systems

Question 19

The AV-node is innervated by:

a) the Parasympathetic nervous system only

b) the Sympathetic nervous system only

c) both the Parasympathetic and Sympathetic nervous systems

Answer 19

c) both the Parasympathetic and Sympathetic nervous systems

Question 20

The atria are innervated by:

a) the Parasympathetic nervous system only

b) the Sympathetic nervous system only

c) both the Parasympathetic and Sympathetic nervous systems

Answer 20

c) both the Parasympathetic and Sympathetic nervous systems

Question 21

The ventricles are innervated by:

a) the Parasympathetic nervous system only

b) the Sympathetic nervous system only

c) both the Parasympathetic and Sympathetic nervous systems

Answer 21

b) the Sympathetic nervous system only

Question 22

The parasympathetic nervous system:
(multiple answers)

a) uses acetylcholine as a neurotransmitter

c) function can be altered by cholinergic agonists and antagonists

e) reduces heart rate via stimulation of the SA-node

g) increases K+ permeability of cells in the SA-node

j) makes the membrane potential in the SA-node more negative.

k) hyperpolarizes the membrane potential in the SA-node.

m) decreases prepotential slope of slow response cardiac action potentials.

O) causes the membrane potential to take longer to reach threshold.

Answer 22

A, C, E,G,J K, M,O,

Question 23

The sympathetic nervous system:
(multiple options)

b) uses norepinephrine as a neurotransmitter

d) function can be altered by adrenergic agonists and antagonists

f) increases heart rate via stimulation of the SA-node

H) increases Ca++ permeability of cells in the SA-node

j) makes the membrane potential in the SA-node less negative.

L) increases prepotential slope of slow response cardiac action potentials.

n) causes the membrane potential to reach threshold faster.

O) stimulates ventricular muscle cells by increasing the rate of force development, rate of relaxation, and maximal force developed.

Answer 23

B,D, F, H, J, L,, N, O,

Question 24

The ______ Nervous System increases the intracellular Ca++, which permits a more rapid & forceful contraction, _____ the rate of re-uptake of Ca++ by sarcoplasmic reticulum following contraction, which _____ plateau phase of ventricular fast response action potential or QT interval making it possible to cause a _____ heart rate.

a) Parasympathetic; decreases; lengthens; slower

b) Parasympathetic; increases; shortens; faster

c) Sympathetic; decreases; lengthens; slower

d) Sympathetic; increases; shortens; faster

Answer 24

d) Sympathetic; increases; shortens; faster

Question 25

In the following diagram of pacemaker firing, the increased rate firing of figure C compared to the intrinsic rate seen in Figure B could be the result of:
(multiple answers)

a) decreased threshold potential.

b) decreased prepotential slope.

c) hyperpolarization of the cell membrane.

d) binding of epinephrine to receptors

e) binding of acetylcholine to receptors

f) warming of the sinus venosus

Answer 25

d) binding of epinephrine to receptors

f) warming of the sinus venosus

Question 26

The flow chart shown below best represents:

a) The turtle heart experiment in which the temperature of the fluid bathing the sinus venosus is increased.

b) The turtle heart experiment in which the temperature of the fluid bathing the sinus venosus is decreased.

c) The turtle heart experiment in which the ventricle is injected with epinephrine.

Answer 26

b) The turtle heart experiment in which the temperature of the fluid bathing the sinus venosus is decreased.

Question 27

The flow chart shown below best represents:

a) The turtle heart experiment in which the temperature of the fluid bathing the sinus venosus is increased.

b) The turtle heart experiment in which the temperature of the fluid bathing the sinus venosus is decreased.

c) The turtle heart experiment in which the ventricle is injected with epinephrine.

Answer 27

a) The turtle heart experiment in which the temperature of the fluid bathing the sinus venosus is increased.

Question 28

Which of the following statements is/are true? (Multiple answers)

a) Decreasing the temperature of the fluid bathing the pacemaker caused a decreased rate of contraction and increased stroke volume.

b) Increasing the temperature of the fluid bathing the pacemaker caused a decreased rate of contraction and increased stroke volume.

c) Altering only the temperature of the fluid bathing the heart does not affect overall metabolic needs of an organism.

d) If overall metabolic needs of an organism are not affected, there is no need for CO to increase or decrease.

Answer 28

A, C, D

Question 29

Decreasing the temperature of the fluid bathing the sinus venosus:
(multiple answers)

a) increases heart rate

b) decreases heart rate

c) increases the rate of diffusion of ions (Ca++, Na++) across the membrane during the prepotential

d) decreases the rate of diffusion of ions (Ca++, Na++) across the membrane during the prepotential

e) makes the prepotential slope more shallow

f) makes the prepotential slope steeper

g) follows Fick’s law of diffusion

h) affects Einthoven’s Law

Answer 29

B, D, E, G

Question 30

Increasing the temperature of the fluid bathing the sinus venosus:
(multiple answers)

a) increases heart rate

b) decreases heart rate

c) increases the rate of diffusion of ions (Ca++, Na++) across the membrane during the prepotential

d) decreases the rate of diffusion of ions (Ca++, Na++) across the membrane during the prepotential

e) makes the prepotential slope more shallow

f) makes the prepotential slope steeper

g) affects Fick’s law of diffusion

h) affects Einthoven’s Law

Answer 30

A, C,F,G

Question 31

Vagal tone
(multiple answers)

Answer 31

a) is a tonic stimulation by the Parasympathetic Nervous System of the SA-node.

c) reduces the inherent rate of contraction by about 20-30 beats per minute in humans

f) affects the heart rate during rest and repose conditions.

Question 32

Cutting the right vagus nerve:
(multiple answers)

a) eliminates vagal tone.

b) causes the heart rate to decrease

c) causes the heart rate to increase

d) causes the heart to stop beating

e) has no effect on the heart rate

Answer 32

A, C

Question 33

In the diagram, Figure ____ represents normal sino-atrial node action potentials. Figure _____ represents vagal stimulation and Figure _____ represents a fight or flight response.

a). A; B; C

b) B; A; C

c) C; B; A

d) B’ C; A

Answer 33

b) B; A; C

Question 34

Stimulation of the right vagus nerve innervating the turtle heart:

a) eliminates vagal tone.

b) causes the heart rate to decrease

c) causes the heart rate to increase

d) has no effect on the heart rate

Answer 34

b) causes the heart rate to decrease

Question 35

Identify the various stages of the vagal escape experiment on the myogram below.
(C, A, F, D, B)

-Period where heart rate is the result of vagal tone ____

-Slowing of normal heart rate due to Parasympathetic stimulation ____

-Vagal escape ____

-Vagal arrest ____

-Alternate pacemaker controls heart _____

Answer 35

-Period where heart rate is the result of vagal tone _A___

-Slowing of normal heart rate due to Parasympathetic stimulation __B__

-Vagal escape __F__

-Vagal arrest __C__

-Alternate pacemaker controls heart ___D__

Question 36

Vagal arrest is the result of:
(multiple answers)

a) continuing vagal stimulation until the heart stops beating

b) continuing vagal stimulation that causes the prepotential slope of action potentials in the sinus venosus to approach zero.

h) binding of large quantities of acetylcholine to cholinergic receptors in the sinus venosus.

Answer 36

A, B, H

Question 37

Vagal stimulation following the addition of atropine results in:

a) eliminates vagal tone

b) causes the heart rate to decrease

c) causes the heart rate to increase

d) causes the heart to stop beating

e) no change in the heart rate

Answer 37

e) no change in the heart rate

Question 38

The effect of atropine is the result of:

Answer 38

b) cholinergic receptors being blocked by the atropine so acetylcholine cannot alter heart function.

Question 39

The flow chart shown below best represents:

a) The turtle heart experiment in which the temperature of the fluid bathing the sinus venosus is increased.

b) The turtle heart experiment in which the temperature of the fluid bathing the sinus venosus is decreased.

c) The turtle heart experiment in which the ventricle is injected with epinephrine.

Answer 39

c) The turtle heart experiment in which the ventricle is injected with epinephrine.

Question 40

With an injection of epinephrine into the heart, heart rate and force of contraction (stroke volume) both increase, leading to an increased cardiac output. This is because:

(multiple answers)

c) increased heart rate helps compensate for the decreased stroke volume that can be the result of an increased heart rate which decreases filling time.

d) ejection fraction increases when the ventricles are stimulated by the SANS and that helps keep stroke volume from falling due to the increased heart rate.

Answer 40

C, D

Question 41

Which of the following statements are true for both increasing the temperature of the fluid surrounding the sinus venosus and stimulating the heart with epinephrine?
(multiple answers)

a) Heart rate increases

e) Filling time decreases.

Answer 41

A, E

Question 42

In the figure below, match the labelled phase with the correct description

Options:

Diastole
relative refractory period
absolute refractory period
systole

FOR:
a, b, c, d

Answer 42

A = Systole
B= absolute refractory period
C= diastole
D= relative refractory period

Question 43

Using the drawing below, identify the time during the cardiac cycle when stimulating the turtle heart ventricle with a large extrinsic stimulus results in an extra-systole.

a) A
b) B
c) C
d) D

Answer 43

D

Question 44

During the cardiac cycle, an extra systole can be induced by electrical stimulation during:

a) the latent period.

b) the absolute refractory period.

c) the relative refractory period.

d) systole

Answer 44

c) the relative refractory period.

Question 45

Match each term in the left column with the best definition from the right column.

LEFT:
systole
diastole
extra-extole
relative refractory period
absolute refractory period
non-refractory

RIGHT:
- Contraction induced by a stimulus applied during the relative refractory period of the cardiac cycle

-relaxation phase of the cardiac cycle

-phase of cardiac cycle when a contraction cannot be induced no matter how strong the stimulus

-muscle is in polarized state with resting membrane potential of -85mV

-phase of cardiac cycle when an supra-threshold stimulus can induce a contraction

-contraction phase of the cardiac cycle

Answer 45

systole = contraction phase of the cardiac cycle

diastole = relaxation phase of the cardiac cycle

extra-extole = contraction induced by a stimulus applied during the relative refractory period of the cardiac cycle

relative refractory period= phase of cardiac cycle when an supra-threshold stimulus can induce a contraction

absolute refractory period= phase of cardiac cycle when a contraction cannot be induced no matter how strong the stimulus

non-refractory =muscle is in polarized state with resting membrane potential of -85 mV

Question 46

Match each description with the appropriate event illustrated on the figures below.

Options:
- Extra-systole

-Compensatory pause

-Vagal arrest

-Vagal escape

Where to put:
C
D
G
H

Answer 46

C = Extra-systole
D= Compensatory pause
G= Vagal arrest
H= Vagal escape

Question 46

The compensatory pause is seen because:

a) the wave of depolarization from the sinus venosus reaches the ventricular muscle during the absolute refractory period of the extra-systole.

b) the wave of depolarization from the sinus venosus reaches the ventricular muscle during the relative refractory period of the extra-systole

c) the heart needs time to reset before another contraction can occur.

d) the large voltage of the extrinsic stimulus “shocks” the heart and it takes time to recover.

Answer 46

a) the wave of depolarization from the sinus venosus reaches the ventricular muscle during the absolute refractory period of the extra-systole.

Question 47

Match each description with the appropriate event illustrated on the figures below.

OPTIONS:
-Alternate pacemaker takes over

-result of stimulation during absolute refractory period

-prepotential of slow response action potential slope approaches zero

-result of extrinsic stimulus during relative refractory period

Where to put:
C
D
G
H

Answer 47

C= Result of extrinsic stimulus during relative refractory period

D=Result of stimulation during absolute refractory period

G=Prepotential of slow response action potential slope approaches zero

H=Alternate pacemaker takes over

Question 48

You are given a turtle heart preparation with the Stannius Ligatures I and II tied properly. You count the ventricular rate and find it to be 12 beats per minute. Based on what you’ve learned, what rates might you expect to find for sinus venosus and atria, respectively?
Group of answer choices

a) 12 beats/min, 12 beats/min

b) 15 beats/min, 20 beats/min

c) 20 beats/min, 15 beats/min

d) 9 beats/min, 6 beats/min

Answer 48

c) 20 beats/min, 15 beats/min

Question 49

Match the two types of Stannius Ligatures with the appropriate description.

-Stannius Ligature I

-Stannius Ligature II

AND

-between atria and ventricle

-between sinus venosus atria

Answer 49

Stannius Ligature I = between sinus venosus atria

Stannius Ligature II= between atria and ventricle

Question 50

When Stannius Ligatures I and II are tied on a turtle heart, the ______ the lowest (shallowest) prepotential slope, the ______ an intermediate prepotential slope and the ______ the greatest (steepest) prepotential slope.

a) sinus venosus has; atria have; ventricles have

b) ventricles have; sinus venosus has; atria have

c) atria have; sinus venosus has; ventricles have

d) ventricles have; atria have; sinus venosus has

Answer 50

d) ventricles have; atria have; sinus venosus has