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BIO NMDCAT Muscles
nmdcat.online July 28, 2026

A biological exception to the general rule that all striated muscles are voluntary and all smooth muscles are involuntary is found in:

A. The muscle of the heart
✓
B. The muscles of the iris
C. The muscles of the diaphragm
D. The muscles attached to hair follicles

📝 Explanation

Cardiac muscle represents a biological exception: it is striated like skeletal muscle but is completely involuntary in its control, like smooth muscle. It operates automatically without conscious thought.

📖 Additional Information

  • The muscle of the heart
  • The muscles of the iris
  • The muscles of the diaphragm
  • The muscles attached to hair follicles

Cardiac muscle represents a biological exception: it is striated like skeletal muscle but is completely involuntary in its control, like smooth muscle. It operates automatically without conscious thought.

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