The Integumentary System

Layers Of The Skin

Functions of the Integumentary System Epithelial tissue – covers and protects the body from dehydration, infection and injury Connective tissue – holds skin onto the muscle “organic glue” Muscle tissue - interacts with hairs in skin to respond to stimuli Nervous tissue – helps detect external stimuli; such as pain or pressure

Layers of the Skin Epidermis – outermost layer – made of 25-30 layers of dead, flattened cells - inner layer – contains living cells that divide to replace dead cells. Contains melanin, a pigment, that helps protect the body from solar radiation. Dermis – contains blood vessels, nerves, nerve endings, hair follicles, sweat glands and oil glands. Thickness varies in different parts of the body Subcutaneous (hypodermis) – consists of fat and connective tissue – helps the body absorb impact, retain heat and store food

Nerve Receptors in the Skin

The Structure of Hair Hair is composed of strong structural protein called keratin. This is the same kind of protein that makes up the nails and the outer layer of skin.

Structure of Fingernails Nails are made of modified hard keratin The function of nails is to protect the distal phalanges. Nail growth occurs at the nail root.

Parts of the Integumentary System found in other Animals Antlers - Feathers – Horns - Scales -

Diseases of The Integumentary System Acne - Acne is an inflammation of the sebaceous glands. It is usually found in adolescents as a result of hormonal changes in the body. The symptoms are blackheads and pus filled sacs. These symptoms are caused by the blockage of the hair follicle by dirt, cosmetics, excess oil, or bacteria. Treatment includes frequent, thorough cleansing of the skin as well as medication.  

Skin Cancer -Skin cancer is found in three basic forms: basal cell, squamous cell and melanoma. Basal cell cancers are the most common type. Skin cancer is the most common form of cancer. If diagnosed early enough it is usually treatable by removing the lesions and/or radiation therapy. Skin cancer is usually the result of exposure to the sun, radiation or irritating chemicals. Symptoms are a mole or birthmark that changes in size, color, thickness, or texture. It may also be a new spot or growth that develops but does not heal.

Warts - Warts are formally called verrucae and are caused by viral infections of the skin. Symptoms are a rough, hard, elevated, rounded surface on the skin. Occasionally small black "seeds" can be seen within the wart. If the warts do not resolve by themselves they are removed by electricity, liquid nitrogen, acid or chemicals.