Question

Which one is not supplied exclusively with involuntary muscles?
A. iris
B. Gland ducts
C. urethra
D. Coats of blood vessels

Answer 1

Hint: Involuntary muscles are those muscles which do not work under the control or will of a person. The cells of these muscles are elongated , spindle shaped , broad from the middle and have tapering ends. These muscles do not have alternate dark or light bands and so they give smooth appearance.

Complete answer:
The structure in which only involuntary muscles are present and not voluntary they are said to have exclusive supply of involuntary muscles. These muscles line the hollow organs and are involuntary. e.g, posterior region of oesophagus, stomach , intestine, lungs, urinary bladder, urogenital tract. The transportation of food through the digestive tract and gametes through the genital tract occurs due to the contraction of smooth muscles.
Now let us match this with the given options :-
Iris :- this structure has involuntary muscles so they contract and relax without our control. Thus this option is not correct.
Gland ducts :- they pour their secretion without our will so they have involuntary muscles only. Thus this option is not correct.
Urethra :- it consists of two sphincters one is voluntary and other is involuntary . So it is not exclusively supplied with involuntary muscles. Thus this option is not correct.
Coats of blood vessels :- they are only supplied with involuntary vessels so do not work according to our will and supply blood every time . Thus this option is not correct.

Our required answer is c that is urethra.

Note: Cardiac muscles are also involuntary muscles that do not work according to our will power. Cardiac muscles are present in the heart . When an organ or an organ system only have involuntary muscles and no voluntary muscles it is called exclusively supply of involuntary muscles.