3 Skin Structure •The skin is the body’s largest organ. It has a surface area of around 2 square metres. •The skin accounts for about 16 percent of a person’s body weight. Skin consists of two main layers: the outer epidermis and the inner dermis.
Epidermis Cells in the deepest layer of the epidermis are alive and they divide constantly to make new cells. The new cells are pushed towards the surface of your skin. They eventually die and become filled with keratin, an exceptionally tough protein. Keratin provides the body with a durable
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2 EIN-O’s INTRO
Even though there is an incredible variation in body shapes and sizes, all humans share common features and the same working parts. The human body is built from trillions of cells. Similar cells group together to form tissues (a Latin word that means “woven”). Types of tissues include nervous tissue, muscle tissue, connective tissue and epithelial tissue. And when tissues group together, they can make organs that pump blood (heart), digest food (stomach) and breath air (lungs). The Bio Signs series is an assortment of 6 human anatomy models. The detailed models are the: Brain and Skull, Eye, Head and Torso, Heart, Skin, and Teeth and Gums.
This I Know Guide provides an introduction to: the Skin
Skin The skin is found all over the body. It is flat, pliable and tough, between 0.5 and 4mm thick. It’s purpose is to protect the body from damage, infection and drying out.
4 overcoat, which protects deeper cells from damage, infection and drying out.
packed with hair follicles, sweat and oil glands. The oil glands produce a lubricant that keeps skin soft and prevents hair from becoming brittle.
Heat Control The skin's blood vessels, sweat glands and hairs play a vital role in regulating body temperature. To cool down: •blood vessels widen and allow heat to escape through the skin. •sweating occurs, and as sweat dries, it draws heat away from the skin.
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Hair Hair is a characteristic feature found in mammals. Its function is to provide insulation to keep the body warm and to protect the skin. For humans, we have lost the need for having insulating hair over much of our bodies.
Cells on the surface of your skin rub and flake off steadily and are continuously replaced with new ones. About every 30 days, your body produces a totally new epidermis.
may be coloured. Tiny muscles are attached to the skin, called a follicle. The hair shaft is hollow and may be coloured. Tiny muscles are attachedto the side of the hair, so that when they contract, the hair is raised. In mammals with insulating hair, like polar bears, raising the hair serves to increase the thickness of the coat, which keeps the mammal warmer. In humans, this happens to us when we get cold, and we call this getting “goose pimples”.
Each hair grows from a small pit in the skin, called a follicle. The hair shaft is hollow and
Dermis The inner dermis contains strong collagen and elastic fibres pierced by blood vessels. It also contains touch, pressure and pain sensors and is
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6 •hairs lie flat so not much warm air gets trapped between the skin and hairs.
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10 Sebaceous Gland Sweat Gland
Skin parts
To retain heat, the opposite happens: blood vessels narrow, less sweat is produced and hairs stand up on end to trap warm air around the body.
•Sweat Gland - releases sweat to help cool body
Skin Colour
•Sebaceous Gland - releases oil to keep hair and skin flexible
Skin contains specialised cells called melanocytes. They produce melanin, a brown substance, which absorbs some of the Sun's harmful ultraviolet rays. Fair-skinned people only have melanin in the lower layers of their epidermis. People with dark skin have larger amounts of melanin in all layers. Freckles and moles are nothing else but small patches of skin with more melanin than in the surrounding area.
•Hair Follicle - cavity in skin where hair grows
•Pressure Receptor - detects pressure and vibrations Hair Follicle
Blood Vessels
Fat Cells
Pressure Receptor
•Blood Vessels - carries blood and heat into and away from skin •Fat Cells - helps to insulate body