Subcutaneous tissue is the fatty layer found below the dermis. It is also called the adipose or the subcutis tissue. It varies in thickness according to age, sex, and general health of the individual. The subcutaneous tissue contains fats for energy, gives smoothness and contour to the body, and acts as a protective cushion for the outer skin. Arteries and lymphatics maintain circulation to the body.
The stratum granulosum, known as the granular layer , consists of cells that resemble granules. These cells are transforming into a harder form of protein. The stratum mucosum is also known as the basal cell layer . Basal cells are continuously being reproduced. It is the deepest layer of the epidermis. This layer also contains melanocytes that produce the coloring matter known as melanin and determines skin color. Melanocytes also react to ultraviolet rays to darken the skin for added protection. The middle layer, the dermis, provides a tough, flexible foundation for the epidermis. In the dermis, body temperature is regulated by sweat glands and blood vessels. It also contains arector pilli muscles, papillae, and hair follicles. Nerve endings send sensations of pain, itching, touch, and temperature to the brain. The skin is moisturized by oil glands that produce sebum. The dermis consists of two layers. The papillary layer connects the dermis to the epidermis. Tactile corpuscles are nerve fiber endings that contain looped capillaries. Tactile corpuscles are responsible for the sense of touch. The papillary layer also contains some of the melanin. The reticular layer is the deepest layer of the dermis. It contains fat cells, blood vessels, lymph vessels, oil glands, sweat glands, hair follicles, and arrector pilli muscles. The reticular layer supplies the skin with oxygen and nutrients. Nerves of the skin Sensory nerves are receptors and send messages to the brain causing reactions to heat, cold, touch, pressure, and pain. Motor nerve fibers, attached to the hair follicles, are distributed to the arrector pilli muscles which may cause goose flesh when you are frightened or cold. Glands of the skin There are two types of duct glands contained in the skin that pull out minerals from the blood to create new substances. The suderiferous glands are the sweat glands and the sebaceous glands are the oil glands. Sweat glands excrete perspiration. This secretion is odorless when excreted, but in a short period of time produces an offensive odor due to the bacteria on the skin’s surface feeding on the fats of its secretion. Perspiration is controlled by the nervous system. About 1-2 pints of liquid containing salts are excreted daily through the sweat pores in the skin. The sweat glands consist of a coiled base or fundus and a tube-like duct Nourishment of the skin Blood and lymph circulate through the skin providing nourishment essential for growth and repair of the skin, hair, and nails. Functions of the skin The major functions of the skin are sensation, heat regulation, absorption, protection, excretion, and secretion. The functions of the skin can easily be remembered using the acronym SHAPES: ● S ENSATION: Response to heat, cold, pressure, and pain. ● H EAT REGULATION : Maintains body temperature of 98.6. Terminology ● Acute : Rapid onset with severe symptoms of short duration. ● Allergy : Reaction due to extreme sensitivity to normally harmless substances. ● Blepharoplasty : Eyelid surgery. ● Chemical peel : Chemical solution applied to skin areas causing a mild, controlled burn of the skin. ● Chronic : Long duration, usually mild, but often recurring. ● Contagious : Communicable; by contact. ● Dermabrasion : Sandblasting irregularities of the skin. ● Dermatologist : A medical skin specialist. ● Dermatology : Study of the skin, its nature, functions, and treatment. ● Diagnosis : Recognition of a disease by its symptoms.
The secretory nerve fibers regulate the excretion of perspiration from the sweat glands and regulate the flow of sebum to the surface of the skin.
that ends at the skin surface forming the pores. Sweat glands are more numerous on the palms, soles, forehead, and armpits. Body temperature is regulated by the sweat glands that also aid in the elimination of waste. Oil glands secrete sebum through little sacs whose ducts open in to the hair follicles. These glands are found in all parts of the body with the exception of the palms and soles. The oily substance produced by the oil glands is called sebum . Sebum lubricates the skin and preserves the pliability of the hair. When the duct becomes clogged with hardened sebum, a blackhead is formed.
● A BSORPTION: Substances can enter the body through the skin and affect it to a minor degree. ● P ROTECTION: From bacterial invasion. ● E XCRETION: Sweat glands excrete perspiration. ● S ECRETION: Sebum is secreted by the sebaceous glands. ● Disease : A pathological condition of the body, organ, or mind making it incapable of carrying on normal functions. ● Disorder : Abnormal condition usually not contagious. ● Epidemic : Emergence of a disease that affects a large number of people simultaneously. ● Etiology : Study of the causes of diseases. ● Immunity : Freedom from or resistance to disease. ● Infectious : Invasion of body tissue by bacteria that cause disease. ● Inflammation : Skin disorder characterized by redness, pain, edema, and heat. ● Injectable fillers : Tiny injections of collagen to soften wrinkles.
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