Integumentary System Chapter 45. 4

Integumentary System Hair Skin Nails

Functions Covers your body Retains body fluids Protects against diseases Protects from injuries Eliminates waste products Regulates body temperature Produces Vitamin D

Skin Human body’s largest organ Skin is capable of repairing itself through a lot of wear and tear throughout a lifetime Made up of layers Epidermis Dermis Subcutaneous

Epidermis Outer layer of the skin Composed of many sheets of flattened, scaly epithelial cells TOP layer (corneal)of epidermis is mostly DEAD cells UNDERNEATH the top layer (basal) are living cells that are rapidly dividing

Epidermis cont’d Cells of the epidermis contain KERATIN Protein that gives the skin its rough, leathery texture AND waterproof quality Cells also have MELANIN Brown pigment that gives skin its color Melanocytes are the melanin-producing cells Absorbs harmful UV radiation Darker skin is due to more melanin being produced Heredity and “tanning” Light skinned people need to be careful with UV radiation Can cause mutations in DNA, which lead to SKIN CANCER

Dermis Inner, thicker layer of the skin Composed of living cells and specialized structures Sensory neurons Blood vessels Hair follicles Glands Nail

Sensory Neurons Allow you to sense conditions and signals from your environment Temperature Pressure Pain

Blood Vessels Allow blood to flow to your dermis, providing nourishment to your living cells

Hair Follicles Average adult has 5 million hairs on their body Protects and insulates the body Hair follicle is the cavity deep in the dermis where the hair grows out from Tiny muscles are attached to your hair follicles Goosebumps Hair is actually composed of dead, keratin-filled cells that overlap each other like shingles on a roof Hair color is due to melanin Heredity

Glands Exocrine Glands-glands that release secretions through ducts 2 Main exocrine glands of the skin are OIL and SWEAT glands

Oil Glands Oil glands Prevent hair from drying out Produce SEBUM-fatty substance Coats the surface to prevent water loss Softens skin and hair Can be toxic to some bacteria Production controlled by hormones Adolescence and increased hormones result in higher activity of oil glands Dead skin, bacteria and sebum cause ACNE

Sweat Glands Releases excess water, salts, and urea Helps regulate body temperature Sweat is produced when body becomes hot As sweat evaporates, the body cools

Fat and Pores Fat is used to insulate body Pores allow fluids to leave the body Sweat, Oil Oil or sweating clogging a pore can cause blackheads or pimples

Nails Protect the end of fingers and toes Composed mainly of keratin Nails grow about 1mm per week Growth begins at nail root Nails rest on a nail bed which is composed of blood vessels, giving your nails their pink tint

Skin Diagram

Muscle and Integumentary Vocab Quiz Tomorrow (Friday) Muscle and Integumentary Vocab Quiz Tomorrow (Friday)!!! Chapter 45 Quiz Monday!!!