Question

Shivering and cold in winter is caused by
A) Voluntary action of striated muscles
B) Voluntary action of unstriated muscles
C) Involuntary action of striated muscles
D) Involuntary action of unstriated muscles

Answer 1

Hint: Muscles in our bodies are of three types: striated voluntary or skeletal muscles, striated cardiac muscles, and striated or smooth involuntary muscles. Each kind has special characteristics and functions.

Complete Answer:
- In winter the external temperatures can drop quite low. In such conditions, our bodies have to be able to maintain a warmer temperature to keep our tissues functioning and healthy. Shivering is one of those heat generating homeostatic mechanisms.
- This process involves the skeletal muscles that start to make very small, continuous contractions. This process generates heat by burning energy in the form of ATP. The ATP is produced from carbohydrate, lipid, and protein oxidation. Because of this the mechanism can be maintained for several hours. The main muscle fibres used are the type II fibres.
- However, shivering is not under our conscious control, but a response to extended exposure to colder temperatures.
- Shivering does use the striated muscles which are our skeletal muscles, but it is an involuntary response. Option A is incorrect.
- The smooth muscles are not involved in the process of shivering, therefore both option B and D are incorrect.
- Though our striated, skeletal muscles are voluntary, the process of shivering is an involuntary protective function of these tissues. Option C is the correct answer.

Hence the correct answer is option C.

Note: Shivering does not only occur in response to cold temperatures, we can shiver even when we are unwell and our body temperatures increase. The process radiates heat and makes us feel cold, and therefore we shiver in response.