or the Integumentary System Human Skin Facts Skin

or the Integumentary System

Human Skin Facts • Skin is the largest organ of the body. • The skin has a surface area of 1 to 2 square meters and weighs 4 to 5 kilograms

Human Skin Facts • You have approximately 19, 000 skin cells on every square inch of your body. • We keep renewing our skin our entire lives.

The Integumentary System is made up of…. . • Skin • Sweat Glands • Oil Glands • Hair • Nails Main Function = Protection

The skin varies in thickness from 1. 5 to 4. 0 mm and has 2 distinct regions…. • Epidermis – composed of epithelial cells, it is the outermost protective shield • Dermis – the underlying layer composed of fibrous connective tissue, it is tough and leathery

Epidermis • It is a keratinized stratified squamous epithelium –the deep layers of the epidermis undergo constant mitosis and the bottom layer cells are pushed toward the surface. • Keratin is the fibrous protein that gives the epidermis its protective quality

Dermis • The dermis binds the body together like a body stocking (our hide) • It is richly supplied with nerve fibers, blood vessels, and lymphatic vessels • Hair follicles, oil glands and sweat glands reside in the dermis.

What Contributes to Skin Color? • Melanin – a pigment that ranges in color from yellow to reddish-brown to black • Carotene – a yellow to orange pigment • Hemoglobin – pinkish hue of fair skin caused be oxygenated hemoglobin in red blood cells

Homeostatic Imbalance • Cyanosis – skin appears blue because of lack of oxygen • Erythema (redness) – fever, hypertension, inflammation, embarrassment • Pallor or blanching – anemia, low blood pressure, fear, or emotional stress

• Jaundice – yellow cast due to liver disorder • Bronzing – metallic appearance due to Addisons disease (hypofunction of adrenal cortex) • Bruises or hematomas – clotted blood under the skin

Sweat Glands • 2. 5 million person Sweat is a filtrate of the blood made up of 99% water, salts, vitamin C, antibodies, dermicidin (a microbe killer), urea, uric acid, ammonia, lactic acid, any ingested drugs Sweat is usually acidic - p. H 4 -6

Sebaceous (Oil) Glands • Secrete sebum (an oily secretion) • Sebum lubricates hair and skin, slows water loss from skin, and has a bactericidal action Blocked sebaceous glands form whiteheads, if the blocking material dries it is called a blackhead

Nails -Scalelike modifications of epidermis containing hard keratin

Hair • Hair follicles make flexible strands consisting of dead cells made of hard keratin

Hair Variations……. Kinky hair – a cs. of the shaft is flat Wavy hair - a cs. of the shaft is oval Straight hair - a cs. of the shaft is round • Hair color is created by melanin from the base of the hair follicle