Human Physiology

Lesson 09 : Functions of Skin

Functions of Skin and Skin Glands

Can you imagine the state of animal body without skin. How ugly the body will look like, or how the organs will perform their functions etc. etc. In layman terms skin simply covers the body and provides beauty to it. Physiologically skin is an important organ and performs variety of useful functions as listed below:

1. Protection of Internal Organ is one of the most important functions of skin. Through skin, the organs are protected against:
1. Mechanical injuries like cuts, abrasions etc.
2. Radiations such as ultraviolet rays are absorbed into epidermis layer therefore, not allowed to penetrate into soft tissue. Exposure to UV rays results in development of skin cancers in man.
3. Hair coat specially protects from cold waves, radiations, sharp objects. Special hairs present in whiskers of dog, cat and horse are sensitive to touch, thus providing information to animal about surrounding objects.
4. Epidermis also protects the skin from dehydration, as there is a continuous tendency of moisture to flow from body to the environment. Thus skin prevents possible desiccations of body.
2. Thermoregulation: Man being homeothermic species tends to maintain their body temperature within narrow limit. Skin has a significant role in maintaining body temperature through:
   
   1. Cutaneous Circulation: Skin blood vessels are arranged in parallel manner and heat from out-coming blood is transferred to in-coming blood. During winter season, skin blood flow is minimized, thus preventing undesirable heat loss and during summer season skin blood flow is enhanced that favour heat loss.
   
   
   2. Sweating: The sweat glands are involved directly in thermoregulation. During summer when body temperature rises, the sweat secretion occurs which spreads on skin surface and evaporates slowly. The evaporation of sweat provides thermal cooling effect.
   
   
    
3. Excretion: Skin to some extent also acts as an excretory organ. The sebacious glands present in dermis continuously secrete oily secretion called sebum. This secretion is accompanied with excretion of lipid soluble substances from the body. Sebum also provide typical shiny luster to the skin and protects from infections also.

Role of Skin in Thermoregulation: The thermoregulatory function of skin has already been described earlier. The function of thermoregulation can be performed very effectively due to availability of enormous surface area of skin over the animal body.