BIO 251
BIOS 251 Anatomy and Physiology
Exam 3 UPDATED 2025 with Correct
Answers
Cardiac output is determined by what two variables?
A) stroke volume and ejection fraction
B) heart rate and ejection fraction
C) end-diastolic volume and end-systolic volume
D) heart rate and stroke volume
E) preload and afterload - Correct Ans-D
Regulation of the heart (or any organ or tissue) by neural input, circulating hormones, or
any other factor originating from outside the organ is referred to as ________ control.
A) intrinsic
B) neurogenic
C) extrinsic
D) voluntary
E) myogenic - Correct Ans-C
Which of the following structures is poorly innervated by the parasympathetic nervous
system and, therefore, an increase in parasympathetic activity has little effect on this
structure?
A) ventricles
B) conduction pathway
C) sinoatrial node
D) Purkinje fibers
E) atrioventricular node - Correct Ans-A
The SA node is innervated by the
A) sympathetic nervous system only.
B) somatic nervous system only.
C) parasympathetic nervous system only.
D) sympathetic and parasympathetic nervous systems.
E) sympathetic, parasympathetic, and somatic nervous systems. - Correct Ans-D
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) SA nodal cells are depolarized.
C) Heart rate is increased.
D) cAMP is activated.
E) Postganglionic neurons release acetylcholine, which binds to nicotinic cholinergic
receptors in
the SA node. - Correct Ans-A
1|Page
, BIO 251
Which of the following is a FALSE statement about sympathetic activity to the SA node?
A) Norepinephrine binds to beta1 adrenergic receptors.
B) Potassium channel closing is enhanced.
C) cAMP levels in the pacemaker cells increases.
D) Funny channel opening is enhanced.
E) The rate of spontaneous depolarization is increased. - Correct Ans-B
Under resting conditions, heart rate is primarily under the control of what control
system?
A) the parasympathetic nervous system
B) the somatic nervous system
C) the sympathetic nervous system
D) intrinsic mechanisms
E) epinephrine - Correct Ans-A
An increase in heart rate can be mediated through which of the following?
A) a decrease in parasympathetic nervous activity only
B) a decrease in sympathetic activity only
C) an increase in sympathetic activity only
D) an increase in parasympathetic activity and a decrease in sympathetic activity
E) a decrease in parasympathetic activity and an increase in sympathetic activity -
Correct Ans-E
Which of the following would NOT result from an increase in ventricular contractility?
A) increased ejection fraction
B) increased stroke volume
C) decreased end-diastolic volume
D) decreased end-systolic volume
E) increased proportion of end-diastolic volume that is ejected - Correct Ans-C
Which of the following best describes the effect of sympathetic activity on ventricular
contractile cells?
A) The rates of contraction and relaxation both decrease, whereas the force of
contraction increases.
B) The rates of contraction and relaxation both increase, whereas the force of
contraction decreases.
C) The rate of contraction and the force of contraction both increase, whereas the rate
of relaxation decreases.
D) The rates of contraction and relaxation and the force of contraction all increase.
E) The force of contraction increases, whereas the rates of contraction and relaxation
are not
affected. - Correct Ans-D
Which of the following describes the effect of end- diastolic volume on stroke volume?
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BIOS 251 Anatomy and Physiology
Exam 3 UPDATED 2025 with Correct
Answers
Cardiac output is determined by what two variables?
A) stroke volume and ejection fraction
B) heart rate and ejection fraction
C) end-diastolic volume and end-systolic volume
D) heart rate and stroke volume
E) preload and afterload - Correct Ans-D
Regulation of the heart (or any organ or tissue) by neural input, circulating hormones, or
any other factor originating from outside the organ is referred to as ________ control.
A) intrinsic
B) neurogenic
C) extrinsic
D) voluntary
E) myogenic - Correct Ans-C
Which of the following structures is poorly innervated by the parasympathetic nervous
system and, therefore, an increase in parasympathetic activity has little effect on this
structure?
A) ventricles
B) conduction pathway
C) sinoatrial node
D) Purkinje fibers
E) atrioventricular node - Correct Ans-A
The SA node is innervated by the
A) sympathetic nervous system only.
B) somatic nervous system only.
C) parasympathetic nervous system only.
D) sympathetic and parasympathetic nervous systems.
E) sympathetic, parasympathetic, and somatic nervous systems. - Correct Ans-D
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) SA nodal cells are depolarized.
C) Heart rate is increased.
D) cAMP is activated.
E) Postganglionic neurons release acetylcholine, which binds to nicotinic cholinergic
receptors in
the SA node. - Correct Ans-A
1|Page
, BIO 251
Which of the following is a FALSE statement about sympathetic activity to the SA node?
A) Norepinephrine binds to beta1 adrenergic receptors.
B) Potassium channel closing is enhanced.
C) cAMP levels in the pacemaker cells increases.
D) Funny channel opening is enhanced.
E) The rate of spontaneous depolarization is increased. - Correct Ans-B
Under resting conditions, heart rate is primarily under the control of what control
system?
A) the parasympathetic nervous system
B) the somatic nervous system
C) the sympathetic nervous system
D) intrinsic mechanisms
E) epinephrine - Correct Ans-A
An increase in heart rate can be mediated through which of the following?
A) a decrease in parasympathetic nervous activity only
B) a decrease in sympathetic activity only
C) an increase in sympathetic activity only
D) an increase in parasympathetic activity and a decrease in sympathetic activity
E) a decrease in parasympathetic activity and an increase in sympathetic activity -
Correct Ans-E
Which of the following would NOT result from an increase in ventricular contractility?
A) increased ejection fraction
B) increased stroke volume
C) decreased end-diastolic volume
D) decreased end-systolic volume
E) increased proportion of end-diastolic volume that is ejected - Correct Ans-C
Which of the following best describes the effect of sympathetic activity on ventricular
contractile cells?
A) The rates of contraction and relaxation both decrease, whereas the force of
contraction increases.
B) The rates of contraction and relaxation both increase, whereas the force of
contraction decreases.
C) The rate of contraction and the force of contraction both increase, whereas the rate
of relaxation decreases.
D) The rates of contraction and relaxation and the force of contraction all increase.
E) The force of contraction increases, whereas the rates of contraction and relaxation
are not
affected. - Correct Ans-D
Which of the following describes the effect of end- diastolic volume on stroke volume?
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