Question

Mark the statement that is incorrect for smooth muscles.

• A. Smooth muscles from the muscular component of the visceral organs such as blood vessels, urinary bladder, ciliary body etc
• B. Smooth muscles cells do not have the troponin tropomyosin mechanism of controlling contraction
• C. Irritability is shown by all smooth muscles except ciliary muscles
• D. Hair root muscles and muscles on the large blood vessels are in example of multi-unit smooth muscles

Answer 1

The correct option is C Irritability is shown by all smooth muscles except ciliary muscles

1. Smooth muscles are involuntary and involved in muscular contraction of visceral organs. Eg : blood vessels, urinary bladder, ciliary body etc.

2. The troponin tropomyosin mechanism of controlling contraction is present in skeletal muscles and absent in smooth muscles.

3. Irritability is shown by muscles innervated with nerves. Ciliary muscles are dually innervated by Autonomic nervous system and hence show irritability.

4. Multiunit smooth muscle fibres function seperately as multiple independent found in muscles of eye, piloerector muscles, muscles of large blood vessels.

So, the correct option is 'Irritability is shown by all smooth muscles except ciliary muscles'.