The Integumentary System (SKIN)
The cutaneous membrane also called the skin serves coats the body externally. The skin and its derivatives such as the sweat and oil glands, hair and nails are generally called the integumentary system. The cutaneous membrane is a dry membrane and is exposed to air.
Functions of the SKIN
The integument or the skin with its derivatives serves the following function:
- Covers the body.
- Protects the body from mechanical damage. This function is done by insulating and cushioning the deeper body organs. Examples of mechanical damage are bumps and cuts. When a person is bumped, the uppermost layer of the skin toughens or hardens the cells. The toughening of the cells is due to the presence of keratin in the upper layer of the skin. Pressure receptors in the skin send an impulse to the nervous system about a possible damage. These receptors alert an individual to bumps and provide a great deal of information about the external environment.
- 3. Protects the body from chemical damage. Acids and bases, when exposed to the body at high levels, can cause extreme damage to the internal organs. However, because of the presence of tough keratinized cells, damage to internal organs is prevented.
- Protects the body from bacterial damage. In preventing infection, one of the most important considerations to consider is an unbroken skin surface. The skin secretes urea, salt and water (acidic) when a person sweats, thus, inhibiting bacterial growth. Phagocytes are also located in the skin which is responsible for ingesting foreign substances and pathogens. Hence, bacterial penetration to deeper body tissues is prevented.
- Protects from ultraviolet radiation. The pigment or color of the skin depends on the presence of melanin. This melanin that is produced by the melanocytes is good at protecting the body from the damaging effects of the sunlight or UV damage.
- Protects the body from thermal damage. When the body is exposed to extreme heat or cold the heat and cold receptors located in the skin alerts the nervous system of the tissue-damaging factors. The brain, in response sends impulses to the site of damage or possible damage for the body’s compensatory mechanism.
- Protects the body from drying out. The skin’s outermost part, the epidermis, contains a waterproofing glycolipid and keratin in order to prevent water loss from the body surface.
- Regulation of heat loss and heat retention. The body must maintain a constant core temperature. Any change in the environmental temperatures could possibly alter the required core temperature. The skin contains a rich capillary network and sweat glands which are controlled by the nervous system. These mechanisms play an important role in regulating heat loss or retention in the body. When the body is needs to loss heat, the skin receptors alert the nervous system which in response activates the sweat glands (sweat helps cool the body in a hot environment). The blood is also flushed into the skin capillary beds, making heat loss possible. When the body needs to retain heat, the blood is NOT allowed to be flushed into the capillary skin beds. This is the main reason why during cold weather, the palms of the hands are pale.
- Acts as mini-excretory system. The perspiration contains urea, uric acid and salts.
- Synthesizes Vitamin D. The skin produces proteins that are vital for the synthesis of the Vitamin D. When a person is exposed to sunlight, modified cholesterol molecules in the skin are converted to Vitamin D.