Q: Where is cardiac muscle found?
A: In the myocardium layer of the heart wall.
2. Q: What type of muscle is cardiac muscle – voluntary or involuntary?
A: Involuntary.
3. Q: What is the shape of a cardiac muscle cell?
A: Branched and cylindrical.
4. Q: How many nuclei do cardiac muscle cells typically have?
A: Usually one centrally located nucleus; occasionally two.
5. Q: What structures connect adjacent cardiac muscle cells?
A: Intercalated discs.
6. Q: What is the function of intercalated discs?
A: They allow mechanical and electrical coupling between cells through desmosomes and gap junctions.
7. Q: Do cardiac muscle cells show striations?
A: Yes, similar to skeletal muscle due to actin and myosin filaments.
8. Q: What is the significance of gap junctions in cardiac muscle?
A: They permit the rapid spread of action potentials, enabling synchronized contraction.
9. Q: Which organelle is abundant in cardiac muscle cells and why?
A: Mitochondria – because cardiac muscle needs continuous energy for contraction.
10. Q: What distinguishes cardiac muscle from skeletal muscle under a microscope?
A: Cardiac muscle has branching fibers, central nuclei, and intercalated discs, whereas skeletal muscle is unbranched, multinucleated, and lacks intercalated discs.
11. Q: Name one pathological change seen in cardiac muscle after myocardial infarction.
A: Coagulative necrosis with loss of striations and infiltration of neutrophils.
12. Q: Why is cardiac muscle fatigue-resistant?
A: Due to its rich supply of mitochondria and continuous blood supply.
13. Q: Can cardiac muscle regenerate after injury?
A: Very limited capacity; most damage results in fibrosis.
14. Q: Which ion plays a key role in cardiac muscle contraction?
A: Calcium (Ca²⁺).
15. Q: What type of muscle is cardiac muscle embryologically derived from?
A: Mesoderm (specifically splanchnic mesoderm).