Q.4 What are the organs of humans which work for homeostasis? Describe skin and lungs in detail.
Answer:
Humans have highly developed systems for homeostasis. The following are the main organs which work for homeostasis:
1. Lungs
They remove excess carbon dioxide and keep it in balance.
2. Skin
Skin performs role in maintenance of body temperature and also removes excess water and salts.
3. Kidneys:
They filter excess water, salts, urea, uric acid etc. from the blood and form urine.
Explanation Skin /What is skin? Write its function.
a. Structure of skin
Our skin consists of two layers:
1. Epidermis is the outer protective layer without blood vessels.
2. Dermis is the inner layer containing blood vessels, sensory nerve endings, sweat and oil glands, hairs and fat cells. hairs and fat cells. Free Ilm.Com
b. Roles of Skin
i. Regulation of body Temperature Thin layer of fat cells in the dermis insulates the body. Contraction of small muscles attached to hair forms ‘Goosebumps’. It creates an insulating blanket of warm air.

ii. Cooling effect
Skin helps in providing cooling effect when sweat is produced by sweat glands and excess body heat escapes through evaporation. Metabolic wastes such as excess water, salts, urea and uric acid are also removed in sweat.
Lungs
i.Removal of carbon dioxide
Lungs maintain the concentration of carbon dioxide in blood. During cellular respiration our cells produce carbon dioxide. From cells, this carbon dioxide diffuses into tissue fluid and from there into blood. Blood carries carbon dioxide to lungs from where it is removed in air.