Human Anatomy Medical Science Teaching Model For School Bilological Class

5pcs/carton, 91x27x29cm, 8kgs

This model shows layers of skin, first rudiments of hair, sweat gland, sense organs of skin. Connected with side hinges. On base.

Human skin shares anatomical, physiological, biochemical and immunological properties with other mammalian lines, especially pig skin. Pig skin shares similar epidermal and dermal thickness ratios to human skin; pig and human skin share similar hair follicle and blood vessel patterns; biochemically the dermal collagen and elastic content is similar in pig and human skin; and pig skin and human skin have similar physical responses to various growth factors.

Skin has mesodermal cells, pigmentation, such as melanin provided by melanocytes, which absorb some of the potentially dangerous ultraviolet radiation (UV) in sunlight. It also contains DNA repair enzymes that help reverse UV damage, such that people lacking the genes for these enzymes suffer high rates of skin cancer. One form predominantly produced by UV light, malignant melanoma, is particularly invasive, causing it to spread quickly, and can often be deadly. Human skin pigmentation varies among populations in a striking manner. This has led to the classification of people(s) on the basis of skin color.

In terms of surface area, the skin is the second largest organ in the human body (the inside of the small intestine is 15 to 20 times larger). For the average adult human, the skin has a surface area of between 1.5-2.0 square metres (16.1-21.5 sq ft.). The thickness of the skin varies considerably over all parts of the body, and between men and women and the young and the old. An example is the skin on the forearm which is on average 1.3 mm in the male and 1.26 mm in the female. The average square inch (6.5 cm²) of skin holds 650 sweat glands, 20 blood vessels, 60,000 melanocytes, and more than 1,000 nerve endings.[better source needed] The average human skin cell is about 30 micrometres in diameter, but there are variants. A skin cell usually ranges from 25-40 micrometres (squared), depending on a variety of factors.

Skin is composed of three primary layers: the epidermis, the dermis and the hypodermis.