EXAM 1: BIOS 255/BIOS255 (2026/2027
UPDATE) ANATOMY AND PHYSIOLOGY III
COMPLETE GUIDE | 100% CORRECT| GRADE
A -CHAMBERLAIN
AT CHAMBERLAIN COLLEGE OF NURSING
BIOS 255: Anatomy & Physiology III – Exam 1
Question 1: Which of the following channels respond to changes in membrane
potential?
A. Ligand-gated channels
B. Voltage-gated channels
C. Mechanically-gated channels
D. Leak channels
Answer: Voltage-gated channels
Rationale: Voltage-gated channels open or close in response to changes in the
electrical potential across the plasma membrane. These channels are essential for the
initiation and propagation of action potentials in neurons and muscle cells. Unlike
ligand-gated channels, they are not activated by chemical signals. Mechanically-gated
channels respond to physical deformation, while leak channels allow passive
movement of ions.
Question 2: Which of the following regulatory proteins covers the myosin-binding
sites on actin?
A. Tropomyosin
B. Troponin
C. Actin
D. Myosin
Answer: Tropomyosin
Rationale: Tropomyosin is a protein that lies along the groove of actin filaments,
,blocking the myosin-binding sites during muscle relaxation. Troponin binds calcium to
move tropomyosin and expose binding sites. Actin is the filament itself, and myosin is
the motor protein. This regulation ensures controlled contraction of skeletal muscles.
Question 3: Calcium must bind to which protein to initiate skeletal muscle
contraction?
A. Tropomyosin
B. Troponin
C. Actin
D. Myosin
Answer: Troponin
Rationale: Calcium ions bind to troponin, causing a conformational change that
moves tropomyosin away from the myosin-binding sites on actin. This allows myosin
heads to attach to actin filaments, initiating contraction. Without calcium binding to
troponin, muscle contraction cannot occur.
Question 4: What do the papillary muscles do?
A. Pump blood
B. Anchor AV valves via chordae tendineae
C. Generate impulses
D. Regulate blood pressure
Answer: Anchor AV valves via chordae tendineae
Rationale: Papillary muscles contract to pull on the chordae tendineae, preventing
the atrioventricular valves from prolapsing into the atria during ventricular
contraction. They do not pump blood or generate electrical impulses. Their function is
critical for maintaining one-way blood flow and preventing regurgitation.
,Question 5: Which layer of a blood vessel contains smooth muscle and elastic fibers
to control vessel diameter?
A. Tunica intima
B. Tunica media
C. Tunica externa
D. Endothelium
Answer: Tunica media
Rationale: The tunica media is the middle layer of blood vessels, consisting primarily
of smooth muscle and elastic fibers. It regulates vessel diameter through
vasoconstriction and vasodilation, influencing blood pressure and flow. The tunica
intima lines the lumen, and the tunica externa provides structural support.
Question 6: Cardiac output is defined as:
A. The amount of blood returning to the heart per minute
B. The amount of blood pumped out of the left ventricle per minute
C. The resistance in the arteries
D. The total blood volume in the body
Answer: The amount of blood pumped out of the left ventricle per minute
Rationale: Cardiac output (CO) measures the efficiency of the heart as a pump,
calculated as heart rate multiplied by stroke volume. It determines how much blood is
delivered to tissues and organs per minute. Venous return contributes to stroke
volume but is not cardiac output itself. Resistance and total blood volume influence
blood pressure indirectly.
Question 7: Which of the following blood vessels contain valves to prevent backflow?
A. Arteries
B. Veins and venules
C. Capillaries
D. Arterioles
Answer: Veins and venules
Rationale: Veins and venules contain valves that prevent retrograde flow of blood,
, particularly in the extremities, ensuring unidirectional flow toward the heart. Arteries
and arterioles operate under higher pressure and do not require valves. Capillaries are
too small to have valves and rely on pressure gradients.
Question 8: The main variable that physiologically determines blood pressure
includes:
A. Blood volume
B. Cardiac output
C. Resistance to flow
D. All of the above
Answer: All of the above
Rationale: Blood pressure is determined by the interaction of cardiac output, blood
volume, and peripheral resistance. Cardiac output reflects heart pumping, blood
volume affects the filling of vessels, and resistance to flow is controlled by vessel
diameter and blood viscosity. Any changes in these variables directly influence blood
pressure.
Question 9: Which of the following is the pacemaker of the heart?
A. AV node
B. SA node
C. Bundle of His
D. Purkinje fibers
Answer: SA node
Rationale: The sinoatrial (SA) node initiates the electrical impulse for heart
contraction, setting the normal rhythm of the heart. The AV node, bundle of His, and
Purkinje fibers conduct impulses but do not generate the primary rhythm. This intrinsic
pacemaker maintains automaticity of cardiac function.
UPDATE) ANATOMY AND PHYSIOLOGY III
COMPLETE GUIDE | 100% CORRECT| GRADE
A -CHAMBERLAIN
AT CHAMBERLAIN COLLEGE OF NURSING
BIOS 255: Anatomy & Physiology III – Exam 1
Question 1: Which of the following channels respond to changes in membrane
potential?
A. Ligand-gated channels
B. Voltage-gated channels
C. Mechanically-gated channels
D. Leak channels
Answer: Voltage-gated channels
Rationale: Voltage-gated channels open or close in response to changes in the
electrical potential across the plasma membrane. These channels are essential for the
initiation and propagation of action potentials in neurons and muscle cells. Unlike
ligand-gated channels, they are not activated by chemical signals. Mechanically-gated
channels respond to physical deformation, while leak channels allow passive
movement of ions.
Question 2: Which of the following regulatory proteins covers the myosin-binding
sites on actin?
A. Tropomyosin
B. Troponin
C. Actin
D. Myosin
Answer: Tropomyosin
Rationale: Tropomyosin is a protein that lies along the groove of actin filaments,
,blocking the myosin-binding sites during muscle relaxation. Troponin binds calcium to
move tropomyosin and expose binding sites. Actin is the filament itself, and myosin is
the motor protein. This regulation ensures controlled contraction of skeletal muscles.
Question 3: Calcium must bind to which protein to initiate skeletal muscle
contraction?
A. Tropomyosin
B. Troponin
C. Actin
D. Myosin
Answer: Troponin
Rationale: Calcium ions bind to troponin, causing a conformational change that
moves tropomyosin away from the myosin-binding sites on actin. This allows myosin
heads to attach to actin filaments, initiating contraction. Without calcium binding to
troponin, muscle contraction cannot occur.
Question 4: What do the papillary muscles do?
A. Pump blood
B. Anchor AV valves via chordae tendineae
C. Generate impulses
D. Regulate blood pressure
Answer: Anchor AV valves via chordae tendineae
Rationale: Papillary muscles contract to pull on the chordae tendineae, preventing
the atrioventricular valves from prolapsing into the atria during ventricular
contraction. They do not pump blood or generate electrical impulses. Their function is
critical for maintaining one-way blood flow and preventing regurgitation.
,Question 5: Which layer of a blood vessel contains smooth muscle and elastic fibers
to control vessel diameter?
A. Tunica intima
B. Tunica media
C. Tunica externa
D. Endothelium
Answer: Tunica media
Rationale: The tunica media is the middle layer of blood vessels, consisting primarily
of smooth muscle and elastic fibers. It regulates vessel diameter through
vasoconstriction and vasodilation, influencing blood pressure and flow. The tunica
intima lines the lumen, and the tunica externa provides structural support.
Question 6: Cardiac output is defined as:
A. The amount of blood returning to the heart per minute
B. The amount of blood pumped out of the left ventricle per minute
C. The resistance in the arteries
D. The total blood volume in the body
Answer: The amount of blood pumped out of the left ventricle per minute
Rationale: Cardiac output (CO) measures the efficiency of the heart as a pump,
calculated as heart rate multiplied by stroke volume. It determines how much blood is
delivered to tissues and organs per minute. Venous return contributes to stroke
volume but is not cardiac output itself. Resistance and total blood volume influence
blood pressure indirectly.
Question 7: Which of the following blood vessels contain valves to prevent backflow?
A. Arteries
B. Veins and venules
C. Capillaries
D. Arterioles
Answer: Veins and venules
Rationale: Veins and venules contain valves that prevent retrograde flow of blood,
, particularly in the extremities, ensuring unidirectional flow toward the heart. Arteries
and arterioles operate under higher pressure and do not require valves. Capillaries are
too small to have valves and rely on pressure gradients.
Question 8: The main variable that physiologically determines blood pressure
includes:
A. Blood volume
B. Cardiac output
C. Resistance to flow
D. All of the above
Answer: All of the above
Rationale: Blood pressure is determined by the interaction of cardiac output, blood
volume, and peripheral resistance. Cardiac output reflects heart pumping, blood
volume affects the filling of vessels, and resistance to flow is controlled by vessel
diameter and blood viscosity. Any changes in these variables directly influence blood
pressure.
Question 9: Which of the following is the pacemaker of the heart?
A. AV node
B. SA node
C. Bundle of His
D. Purkinje fibers
Answer: SA node
Rationale: The sinoatrial (SA) node initiates the electrical impulse for heart
contraction, setting the normal rhythm of the heart. The AV node, bundle of His, and
Purkinje fibers conduct impulses but do not generate the primary rhythm. This intrinsic
pacemaker maintains automaticity of cardiac function.
