Chapter 6 Integumentary System

Skin Picture p.118 & p.123

The Integumentary System Membranes of epithelium and connective tissues that cover body surfaces and lines cavities and organs. 2 or more tissues grouped together = organs 4 Membranes: Serous Mucous Synovial Cutaneous (skin) Skin Video

Types of Membranes SEROUS Lines body cavities that lack openings to the outside Thorax - Parietal pleura/Visceral pleura Abdomen – Parietal peritoneum/Visceral peritoneum Contains simple squamous epithelial and loose connective tissue Cells secrete serous fluid to lubricate

Types of Membranes MUCOUS Lines cavities that open to outside of body Oral & nasal cavities, digestive, respiratory, urinary, reproductive Contains epithelium and loose connective tissue Mucous cells secrete mucus

Types of Membranes SYNOVIAL Inner linings of joint cavities, between ends of bones, and freely movable joints Knees, shoulder, phalanges Contains loose connective tissue & adipose tissue Synovial cells secrete a thick, colorless synovial fluid that lubricate the ends of bones.

Adipose (fat) Beneath skin NAME LOCATION EXTRAS Adipose (fat) Beneath skin Insulates & cushions, stores energy…average adult has 40-50 billion fat cells

CUTANEOUS (SKIN) Largest (by weight) and very versatile organ Vital in maintaining homeostasis: Regulates body temperature Limits water loss Houses sensory receptors Synthesizes various biochemicals Excretes wastes 2.5 Layers Epidermis Dermis Subcutaneous (not a true layer of skin because it’s beneath the skin!) Basement membrane separates these layers

EPIDERMIS Outer layer of stratified squamous epithelial tissue and lacks blood vessels Keratinization: older cells harden, cytoplasm fills with strands of tough, fibrous, keratin-waterproof protein (stratum corneum) Stratum corneum -avascular (lacks blood vessels) old, hard, dead cells Stratum basale - gets blood supply from dermis-cells grow and divide and move/pushed up

Stratified squamous Layers of thin cells that reproduce deep within and push old cells outward. Keratinization – process which a protein accumulates as skin ages…causes cells to harden and die

Epithelial Tissue Covers all body surfaces, lines internal organs/body cavities and gland tissues No blood vessels, but are nourished thru diffusion from underlying connective tissues Reproduce quickly (heals quickly) Functions: secretion, absorption, excretion, sensory receptors

EPIDERMIS The growth and loss of cells is balanced Cell reproduction increases where skin is rubbed or pressed regularly, causing thickened areas called calluses. Functions (protective) Shields underlying tissues from water loss Mechanical injury Harmful chemicals Keeps out disease

EPIDERMIS Contains melanocytes (cells) that produce melanin Absorbs light energy to protect deeper cells from the sun’s ultraviolet rays. Produces skin/hair color Amount of melanin produced and size of granules determines how light/dark your skin is, as well as genetics, sunlight, blood in surface vessels (high O2 = pink & low O2 = blue –cyanosis) All people have the same number of melanocytes…differences occur in melanin amount and size!

DERMIS Inner layer that contains fibrous connective tissue, epithelial, smooth, nervous, and blood tissues Thicker Tough & elastic (due to collagen & elastic fibers) Contains blood vessels Give nutrients to all skin cells and regulates body temp (if hot blood vessels expand to release heat, if cold blood vesslesl contsrict to keep heat in) Bed sores Contains nerve fibers, hair follicles, sebaceous glands, and sweat glands

Subcutaneous (hypodermis) Beneath dermis/continuous from Contains loose connective and adipose tissue Insulates Binds skin to underlying organs

Accessory Organs 1) Hair follicles Hair is found everywhere except palms, soles, lips, nipples, and external reproductive organs Hair is dead epidermal cells (keratinized) Arrector pili muscle attached to hair follicle Contracts in cold or upset (goosebumps) Color from melanin More = darker Less = lighter None = albinism/old age Trichosiderin = red shaft Hair follicle Cell division occurs here

Congential generalized hypertrichosis-”werewolves”

Accessory Organs 2) Sebaceous Glands (holocrine glands) Attached to hair follicles Secrete oily mixture of fat and cell debris called sebum Keeps hair and skin soft, pliable and waterproof * Acne: overactive and inflamed sebaceous gland that becomes plugged and surrounded by small, red elevations (pimples/blackheads)

Accessory Organs 3) Nails Protective coverings over the ends of fingers and toes. consist of stratified squamous epithelial cells overlying the nail bed, with the lunula as the most actively growing region of the nail root. As new cells are produced, older ones are pushed outward and become keratinized.

Accessory Organs 4) Sweat Glands (sudoriferous glands) Sweat = water, salt, waste (urea & uric acid) Apocrine gland (emotional – pain, nervous, upset, frightened) armpit and groin Exocrine gland (hair follicles) palms and soles of feet Eccrine gland (heat and exercise) most abundant forehead, neck, back

Sweat Glands

4 Major Types of Tissues (pg. 95) Epithelial covering Connective support Muscle movement Nervous control

Body Temperature Regulation Increased temp – Nervous system signals blood vessels to dilate (open), sweat glands to secrete, heat is lost…sweat evaporates cooling the skin Decreased temp – Nervous system signals blood vessels to constrict (smaller), sweat glands become inactive, heat is retained…muscles contract involuntarily to generate heat Normal 98.6˚F/ 37˚C Hypothermia below 95˚F Hyperthermia above 106˚F

Videos Integumentary System Part 1 Integumentary System Part 2