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FUNCTIONS OF THE SKIN
I only realized the importance of the sense of touch after the doctor told me that I might lose it. Our sense of touch takes on such an important role in our lives. Yet many of us take it for granted and do not see that the skin is actually vital to us.
Here are 10 functions of our skin:
1) Protective layer
- defense from the external environment
2) Sensation:
- sense of touch
3) Heat Regualtion:
- dilation and constriction of blood vessels and shunt vessels.
4) Controls rate of evaporation:
- prevents excessive water loss
5) Storage:
- stores lipids and water
6) Synthesis:
- synthesizes Vitamin D from UV rays
7) Excretion:
- sweat excretes small amounts of urea
8) Absorption:
- In humans, for certain forms of medication administration, such as adhesive patch. E.g. Nicotine patch
- in animals, their skin is their respiratory organ
9) Water resistance:
- a water resistant barrier
10) Aesthetics:
- affects how we look and the image we portray to others
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Structure |
Function |
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The Epidermis is the relatively thin, tough, outer layer of the skin. Most of the cells in the epidermis are keratinocytes. These cells slowly migrate up toward the surface of the epidermis. Once they reach the skin surface, they are gradually shed and are replaced by younger cells pushed up from below. |
EPIDERMIS |
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1 |
Hair
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Grows hair by packaging old cells together. Attached to it is a sebaceous gland and a sebum-producing gland. There are structures called papilla, made up of connective tissue and a capillary loop It is covered with epidermal cells and constantly divide to grow new skin cells. (Other structures include arrector pili muscle.)
It is attached to the hair follicle. When it contracts, it causes our hair to stand in its ends. Skin around the hair will be raised as well, resulting in what we commonly call ‘goose pimples’.
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The dermis is a thick layer of fibrous and elastic tissue that makes the skin flexible and strong. It is the skin's supporting tissue and is particularly rich in nerve endings. |
DERMIS |
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2 |
Sweat Glands
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It is a coiled tube which forms a tight knot, surrounded by many blood capillaries, from the down growth of epidermis.
Secreted sweat from the sweat glands flows through the sweat duct, then the swear pore, which is an opening to the surface of our skin.
Secretes sebum
Consists of water, dissolved salts, and small amounts of urea (excretes small amounts of metabolic waste product) |
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3 |
Sensory Receptor
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Gives the sensation of touch
Modified dendrites of sensory neurons which allows us to sense pain, pressure and temperature changes in our surroundings.
They are mechanoceptors, responding to pressure, or any kind of mechanical stimulus causing a deformation of the corpuscle. |
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4 |
Nerve fibre |
Nervous impulses from the receptors move along the nerve fibre to the central nervous system to bring about a response. |
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5 |
Blood vessels |
They provide nutrients to the skin and help regulate body temperature. Heat makes the blood vessels enlarge (dilate), allowing large amounts of blood to circulate near the skin surface, where the heat can be released. Cold makes the blood vessels narrow (constrict), retaining the body's heat. |
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Below the dermis lies a layer of fat that helps insulate the body from heat and cold, provides protective padding, and serves as an energy storage area. The fat is contained in living cells, called fat cells, held together by fibrous tissue. |
HYPODERMIS |
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6 |
Sub-cutaneous fat |
Insulating layer for heat loss prevention which is made up of adipose cells (tissue) |
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Click here to learn more about receptor endings
- "You shrink like in the washing machine"
- "Because the water in the tub soaks the water out of your skin"
Recently, I began to wonder it if was really true. I posted this question on several science forums, went to the library to read up on it, and I got the answers.
Actually, the above answers (by moms and dads) were common misconceptions about the shriveling of our skin after a bath/swim! It is in fact the exact opposite! Most people have the impression that they have such fingers because the lose bodily fluids. But it is because there is increased absorption! So let me explain this to you in greater details.
Prune Fingers
The wrinkles that occur in skin after prolonged exposure to water are sometime referred to as prune fingers or water aging. This is a temporary skin condition where the skin on the palms of hand or feet becomes wrinkly. Why is this so?
The epidermis is made up of four layers - the stratum corneum, granular layer, squamous cell layer and basal cell layer. In the stratum corneum, there are dead keratin cells. Keratin is a protein found in hair, nails, and the outermost layer of our skin. When our skin is immersed in water for too long, the dead keratin cells absorb the water. This increases the surface area of our outermost layer of the skin. By right, when the surface area increases, our skin would detach from the other layers! However, the outer layer is tightly attached to the living tissue. Therefore, it wrinkles up to accommodate the increase in surface area.
This happens to our hands and feet and not to other parts of the body. This is because those are the parts of our body with the thickest later of the dead keratin cells. Also, the top layer of skin on fingers and toes is more porous as compared to the layers of skin underneath, and thus they are better at absorbing water. On the other hand, the dermis will not absorb as much water as the epidermis. This is why not our entire finger swells.
If this inflation were the same everywhere, the finger would be just swelling and become fatter. But the skin is not uniform. It is tensed in the direction of the length of the finger. Therefore, the epidermis swells following that direction. And if you look closely, our toes wrinkle as well!
Answer: It is because our body is subjected to a lot of wear and tear so the thick skin is actually a form of protection! Imagine playing basketball with skin on your hands as thin as those on your back! Wouldn’t be so much fun, would it?
Once we step out of the tub, the water from our skin evaporates into the atmosphere and our skin is restored to its original form.
Of course, there is the other form of wrinkling which is due to old age. But since “prune fingers” is what we normally experience, I posted the explanations. Now you guys know what happens about your fingers and toes whenever you immerse in water for too long!
(Lim Fang Ting)
http://en.wikipedia.org/wiki/Wrinkle
http://www.madsci.org/posts/archives/2004-07/1090270850.An.r.html
Designer: US
Base codes: detonatedlove♥
Featuring: The skin
