Thursday, October 25, 2012

Functions of Human Skin

Skin Physiology

Skin is an organ of human body parts were located outside and only a few are limiting part of the body. Area of ​​the skin in humans in adults in the estimate of about 1.5 m2 with a weight of about 15% of the overall weight.

Human skin consists of three main parts namely skin layers: the epidermis, dermis, and the hypodermic. The epidermis skin layer consists of a rich stratum corneum keratin, stratum lucidum, stratum granulosum-rich keratohyalin, stratum spinosum and stratum basal mitotic. Dermis composed of fibers such as supporting collagen and elastin. While hypodermic composed of fat cells, nerve endings edge, blood vessels and lymph vessels.

Function of the skin
Skin has many functions, which are useful in maintaining body homeostasis. These functions can be divided into the function of protection (protection), absorption, excretion, perception, body temperature regulation (thermoregulation), and the formation of vitamin D.

1. Skin as a protector


The skin has a layer of skin that serves as a protective body of each section deepest layer of the skin to the outside, such as:

- Tue Keratin serves to protect the skin from microbes, abrasion (friction), heat, and chemicals. Keratin is a hard structure, rigid, and neat and tight as a brick on the surface of the skin.

- Lipids are removed to prevent evaporation of water from the surface of the skin and dehydration, but it also prevents the entry of water from outside the body through the skin.

- Oily sebum from the sebaceous glands to prevent skin and hair from dryness and contains substances bakterisid are used to kill bacteria on the skin surface. With the sebum, together with the excretion of sweat, will produce acid mantle with a 5-6.5 pH levels that could inhibit the growth of microbes.

- Pigment melanin which serves to protect the skin from the effects of harmful UV rays. In the stratum basal cells into melanocytes release melanin pigment cells in the vicinity. This pigment is in charge of protecting the genetic material from the sun, so that genetic material can be stored properly. In the event of interference protection by melanin, the malignancy may arise. Melanin is the pigment layer of the skin that serves as a conduit and skin discoloration. For that wear Hand Body Lotion to prevent the skin from sun exposure, because it is easy to change the skin pigment.

- In addition, there are cells that act as a protective immune cells. The first is the Langerhans cells, which represent the microbial antigens. Then there is a charge of phagocytic cells memfagositosis microbes that enter through keratin and Langerhans cells.

2. Absorption function

Skin can not absorb water, but can absorb lipid-soluble materials such as vitamin A, D, E, and K, certain drugs, oxygen and carbon dioxide. Skin permeability to oxygen, carbon dioxide and water vapor allows the skin take part in respiratory function. In addition, some toxic materials can be absorbed as acetone, CCl4, and mercury. Some drugs are also designed to dissolve fat, such as cortisone, so it can penetrate the skin and releases histamines in inflammation.

Absorption ability of skin affected by thin thick skin, hydration, moisture, metabolism and type vehikulum. Absorption can take place through the gap between cells or through the mouth of the gland but more channels through epidermal cells rather than through the mouth of the gland.

3. Excretion function


The skin also serves as a disposal of a liquid that comes out of the body sweat beruoa intermediaries owned two sweat glands, the sebaceous glands and sweat glands:

- Sebaceous glands

Sebaceous glands are glands attached to hair follicles and release is known as sebum lipids into the lumen. Sebum released during muscular contraction arektor pili suppress sebaceous glands so that sebum released to the hair follicles and the skin surface. Sebum is a mixture of triglycerides, cholesterol, protein, and elektrolig. Sebum serves to inhibit the growth of bacteria, lubricate and protect the keratin.

- Sweat glands

Although the stratum corneum water-resistant, but about 400 ml of water can come out with a way to evaporate through the sweat glands each day. For someone who works in the room 200 ml to excrete the extra sweat, and for active people working outdoors will produce more sweat glands open so sweat issued more than those working indoors. In addition to removing water and heat, sweat is also a means to excrete salt, carbon dioxide, and the results of two organic molecules that protein breakdown of ammonia and urea.

There are two kinds of sweat glands in the production of the body, the apocrine sweat glands and sweat glands merokrin.

- Apocrine sweat glands found in the axillary regions, breasts and pubis, and active at the age of puberty and produce a thick sweat, a lot and a characteristic odor. Apocrine sweat glands work when there is a signal from the nervous system and hormones that mioepitel cells that surround the glands to contract and push apocrine sweat glands. Consequently apocrine sweat glands release sekretnya (sweating) to the hair follicles and to the outer surface.

- Sweat glands merokrin (ekrin) contained in the palms of the hands and feet. Sekretnya contain water, electrolytes, organic nutrients, and metabolic waste. PH levels ranging from 4.0 - 6.8. The function of the sweat glands merokrin is set surface temperature, excrete water and electrolytes as well as protection from a foreign agent by making the attachment of foreign agents and produces dermicidin, a small peptide antibiotic properties.

4. Perceptual functions

Skin contains sensory nerve endings in the dermis and subcutaneous. Heat stimuli played by Ruffini bodies in the dermis and subcutaneous. To cold played by Krause bodies are located in the dermis, the body is located in the papillae Meissner tactile dermis contribute to the feeling, as Merkel Ranvier agency located in the epidermis. While the pressure of starring in the epidermis Paccini body. Sensory nerves are more numerous in the area that erotic.

5. Functions as body temperature regulation (thermoregulation)

Skin contribute to body temperature regulation (thermoregulation) in two ways: transpiration and adjusts blood flow in capillaries. At high temperatures, the body will sweat in large quantities and widen blood vessels (vasodilation) so the heat will be carried out of the body. Conversely, at low temperature, the body will secrete less sweat and narrowing of blood vessels (vasoconstriction), thereby reducing the heat expenditure by the body.

6. The function of the formation of vitamin D

Synthesis of vitamin D performed by activating the precursor 7 dihydroxy cholesterol with the help of ultraviolet light. Enzymes in the liver and kidneys then modify precursors and produce calcitriol, the active form of vitamin D. Calcitriol is a hormone that plays a role in absorbing calcium foods from the gastrointestinal tract into the blood vessels.

The body is able to produce vitamin D on its own but still not able to meet the body's needs so completely that giving vitamin D is made or can be obtained from food sources, fruits and vegetables that contain lots of vitamin D are still needed. In human skin can also express emotion because of the blood vessels, sweat glands, and the muscles under the skin.

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