PURDUE BIO 204 EXAM 2 2026/2027
WITH 650 QUESTIONS AND
EXPERT-VERIFIED CORRECT
ANSWERS | ALREADY GRADED
A+ | GUARANTEED SUCCESS
Why do cardiomyocytes rely on aerobic metabolism? - ANSWER-The continuous
pumping action of the heart requires a constant energy supply. Aerobic
metabolism, particularly oxidative phosphorylation in mitochondria, is the most
efficient way to produce ATP.
What structural features make cardiomyocytes unique compared to other muscle
cells? - ANSWER-They are branched, striated cells with intercalated discs that
allow synchronized contraction.
,What structures make up intercalated discs, and what are their functions? -
ANSWER-Desmosomes anchor cells together; gap junctions allow electrical
signals to pass between cells for coordinated contractions.
Why are gap junctions essential for cardiac function - ANSWER-They enable
rapid electrical communication between cells, ensuring synchronized contractions
What are intercalated discs? - ANSWER-Specialized adhesive junctions that
connect adjacent cardiac cells.
What is a functional syncytium in the heart? - ANSWER-It refers to the
coordinated contraction of cardiac muscle cells, allowing them to work together as
a single unit. This is made possible by intercalated discs. There are two functional
syncytia in the heart: the atrial and ventricular syncytia, which contract
independently to ensure efficient blood flow.
What happens during Phase 0 of cardiac muscle action potential? - ANSWER-
Rapid influx of Na⁺ causes depolarization
Why does Phase 2 (plateau phase) occur during cardiac action potential? -
ANSWER-The influx of Ca²⁺ balances K⁺ efflux, prolonging depolarization for
sustained contraction.
(a) Which channels maintain the resting membrane potential of -90 mV in
cardiomyocytes? (b) why are they called "rectifier" channels - ANSWER-(a) The
inward rectifier potassium (K⁺) channels primarily maintain the negative resting
potential of -90 mV in cardiomyocytes by allowing potassium ions (K⁺) to flow out
of the cell. (b) They are called "rectifier" channels because they preferentially
allow ion flow in one direction (in this case inward)
,What ions play a role in the action potential within the contractile myocardium?
can you draw a graph representing the movements of ions through all the phases? -
ANSWER-Sodium, Potassium, and Calcium ions. (For the graph, please refer to
the slides)
Why phase 2 in the action potential of cardiomyocytes is called the "plateau"
phase? - ANSWER-It is characterized by a prolonged period of sustained
depolarization, where the membrane potential remains relatively constant for an
extended duration. This creates a flat or "plateau-like" appearance on the AP graph,
distinguishing it from the rapid changes seen in other phases.
What is the absolute refractory period? - ANSWER-The interval during which
cardiac cells cannot be stimulated to produce a new action potential, regardless of
stimulus strength
What is the relative refractory period? - ANSWER-A phase where cardiac cells
can be excited, but only by a stronger-than-normal stimulus
What happens first the absolute (ARP) or the relative (RRP) refractory periods? -
ANSWER-The ARP occurs first, spanning from the beginning of depolarization
(Phase 0) to approximately midway through repolarization (Phase 3) of the cardiac
action potential.
(a) What is fibrillation? (b) Why does a long absolute refractory period prevent
fibrillation in cardiac cells? - ANSWER-(a) A state of rapid and disorganized heart
contractions. (b) It ensures orderly contractions by preventing premature re-
excitation of cells.
How does calcium influx during plateau phase contribute to effective pumping? -
ANSWER-It strengthens contractions needed for complete ejection of blood from
ventricles.
, Why do skeletal muscle cells not have a plateau phase in the action potential? -
ANSWER-It allows for faster cycling between contraction and relaxation, which is
essential for the function of skeletal muscles in movement and posture control.
What is the cardiac cycle? - ANSWER-The sequence of events that occur during 1
complete heartbeat.
What are the two main phases of the cardiac cycle? - ANSWER-Systole
(contraction) and diastole (relaxation)
What is the force promoting blood flow and valve opening and closing? -
ANSWER-Pressure changes (pressure gradient). Fluid flows from a high-pressure
point to a low-pressure point.
What happens during ventricular filling, and why is this phase mostly passive? -
ANSWER-All chambers are relaxed, AV valves are open, and blood flows
passively from the atria to the ventricles due to pressure gradients.
Why does atrial systole occur after passive ventricular filling? - ANSWER-Atrial
contraction ensures the ventricles are completely filled with blood before they
contract.
What is the name of the cavity where the heart is located? - ANSWER-The
thoracic cavity, specifically within the mediastinum.
Why is the heart positioned between the lungs in the mediastinum? - ANSWER-
This central location protects the heart and optimizes its ability to pump blood to
both pulmonary and systemic circuits.
WITH 650 QUESTIONS AND
EXPERT-VERIFIED CORRECT
ANSWERS | ALREADY GRADED
A+ | GUARANTEED SUCCESS
Why do cardiomyocytes rely on aerobic metabolism? - ANSWER-The continuous
pumping action of the heart requires a constant energy supply. Aerobic
metabolism, particularly oxidative phosphorylation in mitochondria, is the most
efficient way to produce ATP.
What structural features make cardiomyocytes unique compared to other muscle
cells? - ANSWER-They are branched, striated cells with intercalated discs that
allow synchronized contraction.
,What structures make up intercalated discs, and what are their functions? -
ANSWER-Desmosomes anchor cells together; gap junctions allow electrical
signals to pass between cells for coordinated contractions.
Why are gap junctions essential for cardiac function - ANSWER-They enable
rapid electrical communication between cells, ensuring synchronized contractions
What are intercalated discs? - ANSWER-Specialized adhesive junctions that
connect adjacent cardiac cells.
What is a functional syncytium in the heart? - ANSWER-It refers to the
coordinated contraction of cardiac muscle cells, allowing them to work together as
a single unit. This is made possible by intercalated discs. There are two functional
syncytia in the heart: the atrial and ventricular syncytia, which contract
independently to ensure efficient blood flow.
What happens during Phase 0 of cardiac muscle action potential? - ANSWER-
Rapid influx of Na⁺ causes depolarization
Why does Phase 2 (plateau phase) occur during cardiac action potential? -
ANSWER-The influx of Ca²⁺ balances K⁺ efflux, prolonging depolarization for
sustained contraction.
(a) Which channels maintain the resting membrane potential of -90 mV in
cardiomyocytes? (b) why are they called "rectifier" channels - ANSWER-(a) The
inward rectifier potassium (K⁺) channels primarily maintain the negative resting
potential of -90 mV in cardiomyocytes by allowing potassium ions (K⁺) to flow out
of the cell. (b) They are called "rectifier" channels because they preferentially
allow ion flow in one direction (in this case inward)
,What ions play a role in the action potential within the contractile myocardium?
can you draw a graph representing the movements of ions through all the phases? -
ANSWER-Sodium, Potassium, and Calcium ions. (For the graph, please refer to
the slides)
Why phase 2 in the action potential of cardiomyocytes is called the "plateau"
phase? - ANSWER-It is characterized by a prolonged period of sustained
depolarization, where the membrane potential remains relatively constant for an
extended duration. This creates a flat or "plateau-like" appearance on the AP graph,
distinguishing it from the rapid changes seen in other phases.
What is the absolute refractory period? - ANSWER-The interval during which
cardiac cells cannot be stimulated to produce a new action potential, regardless of
stimulus strength
What is the relative refractory period? - ANSWER-A phase where cardiac cells
can be excited, but only by a stronger-than-normal stimulus
What happens first the absolute (ARP) or the relative (RRP) refractory periods? -
ANSWER-The ARP occurs first, spanning from the beginning of depolarization
(Phase 0) to approximately midway through repolarization (Phase 3) of the cardiac
action potential.
(a) What is fibrillation? (b) Why does a long absolute refractory period prevent
fibrillation in cardiac cells? - ANSWER-(a) A state of rapid and disorganized heart
contractions. (b) It ensures orderly contractions by preventing premature re-
excitation of cells.
How does calcium influx during plateau phase contribute to effective pumping? -
ANSWER-It strengthens contractions needed for complete ejection of blood from
ventricles.
, Why do skeletal muscle cells not have a plateau phase in the action potential? -
ANSWER-It allows for faster cycling between contraction and relaxation, which is
essential for the function of skeletal muscles in movement and posture control.
What is the cardiac cycle? - ANSWER-The sequence of events that occur during 1
complete heartbeat.
What are the two main phases of the cardiac cycle? - ANSWER-Systole
(contraction) and diastole (relaxation)
What is the force promoting blood flow and valve opening and closing? -
ANSWER-Pressure changes (pressure gradient). Fluid flows from a high-pressure
point to a low-pressure point.
What happens during ventricular filling, and why is this phase mostly passive? -
ANSWER-All chambers are relaxed, AV valves are open, and blood flows
passively from the atria to the ventricles due to pressure gradients.
Why does atrial systole occur after passive ventricular filling? - ANSWER-Atrial
contraction ensures the ventricles are completely filled with blood before they
contract.
What is the name of the cavity where the heart is located? - ANSWER-The
thoracic cavity, specifically within the mediastinum.
Why is the heart positioned between the lungs in the mediastinum? - ANSWER-
This central location protects the heart and optimizes its ability to pump blood to
both pulmonary and systemic circuits.
