#1
What is the primary function of cardiac muscle tissue?
To contract and pump blood throughout the body.
ExplanationMainly responsible for heart contractions.
#2
Which statement best describes the structure of cardiac muscle cells?
They are uninucleated with intercalated discs.
ExplanationSingle nucleus with specialized cell-to-cell junctions.
#3
Which ion is primarily responsible for initiating contraction in cardiac muscle cells?
Calcium (Ca2+)
ExplanationCalcium ions trigger muscle contractions.
#4
What is the role of intercalated discs in cardiac muscle tissue?
To facilitate communication between cells.
ExplanationAllow electrical and mechanical coupling.
#5
Which of the following best describes the energy source for cardiac muscle contraction?
ATP generated from oxidative phosphorylation
ExplanationATP produced through cellular respiration.
#6
Which neurotransmitter is primarily responsible for slowing the heart rate?
Acetylcholine
ExplanationSlows down heart contractions.
#7
Which of the following factors can increase the contractility of cardiac muscle?
Sympathetic nervous system stimulation
ExplanationEnhances heart muscle contractions.
#8
Which hormone increases heart rate and force of contraction?
Epinephrine
ExplanationBoosts heart activity.
#9
What is the refractory period in cardiac muscle?
The time during which the heart cannot contract again.
ExplanationRecovery phase after contraction.
#10
Which of the following is NOT a characteristic of cardiac muscle cells?
Voluntary control
ExplanationInvoluntary muscle regulation.
#11
What happens when the calcium ions are removed from the cytoplasm of cardiac muscle cells?
Relaxation of the muscle
ExplanationMuscle relaxation due to ion removal.
#12
What is the role of the sarcoplasmic reticulum in cardiac muscle cells?
To store and release calcium ions
ExplanationRegulates calcium levels for muscle function.
#13
Which of the following is a characteristic of cardiac muscle compared to skeletal muscle?
Presence of intercalated discs.
ExplanationDistinctive cell-to-cell connections.