Copy of Elec Act of Heart - AI Parse Questions (5/28/2026)
star
star
star
star
star
Last updated about 2 hours ago
41 questions
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
Question 1
1.
Question 2
2.
Question 3
3.
Question 4
4.
Question 5
5.
Question 6
6.
Question 7
7.
Question 8
8.
Question 9
9.
Question 10
10.
Question 11
11.
Question 12
12.
Question 13
13.
What happens to the heart if the nerves that innervate it are destroyed?
Question 14
14.
Question 15
15.
Question 16
16.
Question 17
17.
Question 18
18.
Question 19
19.
Question 20
20.
Question 21
21.
Question 22
22.
Question 23
23.
Question 24
24.
Question 25
25.
Question 26
26.
Question 27
27.
Question 28
28.
Question 29
29.
Question 30
30.
Question 31
31.
Question 32
32.
Question 33
33.
Question 34
34.
Question 35
35.
Question 36
36.
Question 37
37.
Question 38
38.
Question 39
39.
Question 40
40.
What is the effect of the long refractory period in cardiac muscle?
Question 41
41.
Which ion primarily enters cardiac muscle cells during depolarization?
K+
Cl-
Na+
Ca²⁺
What triggers the initial spike in the cardiac action potential?
Opening of K+ channels
Membrane depolarization
Closing of Na+ channels
Ca²⁺ influx
What is the role of the SA node in the heart?
It acts as a valve
It serves as the pacemaker
It filters blood
It connects atria and ventricles
What channels are activated during the pacemaker potential?
Only Na+ channels
Only K+ channels
Na⁺, K⁺, and Ca²⁺ channels
Cl- channels
What happens to K+ channels during the plateau phase of the cardiac action potential?
They open immediately
They close after 0.2 to 0.3 seconds
They remain open indefinitely
They inactivate
How does the AV node contribute to heart function?
It generates action potentials
It provides a conductive bridge between atria and ventricles
It stores electrical impulses
It regulates blood flow
What is the AV delay?
A) Time taken for the impulse to travel from the SA node to the AV node
B) Time taken for the ventricles to contract
C) Time taken for the atria to relax
D) Time taken for electrical impulses to stop
Which statement is true regarding cardiac muscle contractions?
A) They can sustain prolonged contractions
B) They are coordinated through gap junctions
C) They can occur independently of each other
D) They rely solely on CNS input
What ion is primarily responsible for the rising phase of the action potential in the SA node?
A) Na⁺
B) K⁺
C) Ca²⁺
D) Cl⁻
During the cardiac action potential, what balances the K⁺ that leaks out of the cell?
A) Na⁺
B) Cl⁻
C) Ca²⁺
D) Mg²⁺
What occurs when cardiac muscle cells are interconnected by gap junctions?
A) They contract independently
B) They participate in coordinated contractions
C) They become electrically isolated
D) They lose their striations
How does cardiac muscle differ from skeletal muscle in terms of stimulation?
A) Cardiac muscle contracts without CNS input
B) Cardiac muscle requires constant neural stimulation
C) Skeletal muscle can contract indefinitely
D) Cardiac muscle is less responsive to electrical impulses
A) The heart stops beating
B) The heart continues to beat
C) The heart beats irregularly
D) The heart becomes paralyzed
The heart stops beating
The heart continues to beat
The heart beats irregularly
The heart becomes paralyzed
What is the primary role of Purkinje fibers?
A) To slow down conduction in the ventricles
B) To provide rapid conduction in the ventricles
C) To store blood
D) To filter electrical impulses
To slow down conduction in the ventricles
To provide rapid conduction in the ventricles
To store blood
To filter electrical impulses
What is a key feature of the cardiac muscle's action potential?
A) It is short and quick
B) It has a long duration
C) It occurs only with neural input
D) It does not involve Ca²⁺
It is short and quick
It has a long duration
It occurs only with neural input
It does not involve Ca²⁺
What is the function of the SA node in isolated conditions?
A) It beats at a slower rate
B) It beats faster than the AV node
C) It does not beat
D) It becomes inactive
It beats at a slower rate
It beats faster than the AV node
It does not beat
It becomes inactive
What happens to the membrane potential after K⁺ channels close?
A) It rapidly depolarizes
B) It hyperpolarizes
C) It remains constant
D) It repolarizes slowly
It rapidly depolarizes
It hyperpolarizes
It remains constant
It repolarizes slowly
What is the primary influence on the rate and strength of cardiac contractions?
A) Hormones
B) Neural impulses
C) Blood pressure
D) Body temperature
Hormones
Neural impulses
Blood pressure
Body temperature
What role does the connective tissue play between the atria and ventricles?
A) It conducts electrical impulses
B) It provides insulation
It conducts electrical impulses
It provides insulation
Question text is missing.
[Option missing]
It provides insulation
It stores blood
It facilitates contraction
Which part of the heart is responsible for the fastest intrinsic rhythm?
AV node
Purkinje fibers
SA node
Atrial muscle
What is the main consequence of the long duration of the cardiac action potential?
Increased heart rate
It allows for relaxation between contractions
It promotes faster heart rates
It allows for continuous contraction
What is the main ion that enters the cell during the depolarization phase?
Na+
K+
Ca2+
Cl-
How does the cardiac action potential differ from that of skeletal muscle?
Cardiac action potentials are shorter
Cardiac action potentials do not involve Na+
Cardiac action potentials can be generated without CNS input
Cardiac action potentials are not striated
What happens immediately after the impulse passes the AV node?
It stops
It slows down
It is rapidly conveyed via the Purkinje network
It becomes erratic
Which ion's influx is primarily responsible for the plateau phase in cardiac action potentials?
Na+
K+
Ca2+
What is the ionic flow during the pacemaker potential primarily due to?
Na⁺ channels only
K⁺ channels only
Na⁺, Ca²⁺, and K⁺ channels
Cl⁻ channels
What is the significance of the long refractory period in cardiac muscle?
It allows continuous contraction
It prevents overstimulation and allows for relaxation
It increases heart efficiency
It decreases heart rate
What triggers the rapid rise in the pacemaker potential?
Opening of K⁺ channels
Inward flow of Na⁺ and Ca²⁺
Closing of Na⁺ channels
Outward flow of K⁺
What is the primary function of the Purkinje fibers in the heart?
To generate electrical impulses
To transmit impulses quickly throughout the ventricles
To store blood
To connect the atria and ventricles
How does the heart ensure all parts of the ventricles beat in unison?
Through hormonal signals
Via gap junctions
By synaptic transmission
Through nerve impulses
What happens to the cardiac action potential after it reaches the threshold?
It stops
It becomes erratic
It repeats
It leads to muscle fatigue
What is the consequence of the AV node's function in the heart?
It speeds up heart rate
It allows for atrial contraction before ventricular contraction
It blocks impulses entirely
It has no effect on heart rhythm
Which channels are primarily involved in the cardiac action potential?
Only Na⁺ channels
Na⁺, K⁺, and Ca²⁺ channels
Only K⁺ channels
Cl⁻ and Na⁺ channels
What happens to the action potential cycle after reaching the threshold?
It stops
It becomes erratic
It repeats
It leads to muscle fatigue
What is the main ion responsible for the plateau phase in cardiac action potentials?
Na⁺
K⁺
Ca²⁺
Cl⁻
What is the role of the SA node in the heart's conduction system?
It serves as a valve
It initiates the heartbeat
It connects atria and ventricles
It filters blood
How does the heart respond to the destruction of the nerves that innervate it?