Question

intercalated discs and pacemaker cells are characteristic of ______ tissue.

○ all types of muscle

○ skeletal muscle

○ cardiac muscle

○ smooth muscle

○ nerve

Explanation:

1. Recall the characteristics of different muscle and nerve tissues:

• Skeletal muscle: Striated, voluntary, no intercalated discs or pacemaker cells.
• Smooth muscle: Non - striated, involuntary, no intercalated discs or pacemaker cells.
• Nerve tissue: Composed of neurons and glial cells, no intercalated discs or pacemaker cells related to muscle function.
• Cardiac muscle: Striated, involuntary, has intercalated discs (for electrical and mechanical connection between cells) and pacemaker cells (to initiate heart contractions).
• "All types of muscle" is incorrect as skeletal and smooth muscle don't have both intercalated discs and pacemaker cells.

1. Based on the above analysis, intercalated discs and pacemaker cells are characteristic of cardiac muscle.

Answer:

C. cardiac muscle