Integumentary System

Accessory Structures

hair, nails, glands

Skin functions (5)

protection (1st layer of defense); homeostasis (insulation and sweating); energy storage (largest deposit of adipose in hypodermis); sensation (nerve endings); secretion (salt, water, and organic wastes)

Epidermis

made of layers of living and dead cells; lacks blood vessels

Dermis

contains blood vessels, glands, and hair; provides unique fingerprints, strength and sensation

Hypodermis

contains adipose tissue and loose CT; regulates temperature, has bigger blood vessels and nerves, absorbs shock

Stratum Basale

are stem cells (keratinocytes), contains melanocytes (~25%) and merkel cells (sensory; touch perception

Vitamin D Process

Sun+Skin makes inactive vitamin D, goes into blood, kidney/liver makes calcitrol (active), goes back into blood to help absorb/regulate calcium and phosphorus

Stratum Spinosum

form densosomes (attach to each other in layers); slightly mitotic (dividing), keratinocytes (start producing keratin); Langerhan’s macrophages (immune cells)

Stratum Granulosum

Kertinocytes (produce large amounts of keratin), cells eventually die (lack of O2); contains Langerhan’s cell(?); rich in KERATOHYALIN and LIPIDS to create skin’s barrier

Keratin

durable, water resistant protein in hair, skin, and nails

Stratum Lucidum

clear; dead, keratinized cells; contains eleidin (gel-like substance) that forms a waterproof barrier; only present in palms, soles of feet, and calluses

Stratum Corneum

oldest layer of cells; dead, flattened, and keratinized; outermost protective layer; sheds after 7-10 days.

ABCDE Rule

Cancer rule: Asymmetrical, border irregularity, color change, diameter > 6mm, evolution or change over time

Dermis Layers

Papillary layer (loose areolar CT) and Reticular layer (dense irregular CT)

Papillary layer

top layer; areolar tissue; nerves and blood vessels deliver nutrients to the epidermis; FORMS FINGERTIPS and IMPORTANT FOR GRIP

Reticular layer

bottom layer; dense irregular tissue; gives skin strength and flexibility; COLLAGEN: prevents overstretching/tearing; ELASTIN: allows stretch

Wrinkling of skin (in water)

nerve cells cause blood vessels in dermis to constrict

Subcutaneous injections

absorbed directly into bloodstream

Hypodermis purpose

provides insulation, shock absorption, and energy reserve

Colors of hair

high eumelanin: black; low: blonde; pheomelanin and eumelanin: red

Rule of nines

face (9), torso (32), arm (9), leg (18), groin (1)

First degree burn

epidermis only; red and painful; sunburns

Second degree burns

epidermis and upperdermis; blistering; boiling water

Thrid degree burn

epidermis and full dermis; white of black; painless (nerve damage)

fourth degree burn

all layers (including hypodermis); can see bone

Male pattern baldness

genetic; higher testosterone, higher risk

Alopecia

autoimmune disorder; no hair

Acne

sebaceous gland become blocked; sebum builds up; can be infected with bacteria causing pus

Psoriasis

autoimmune disorder; causes rash (triggered by infection, stress, or cold)

Skin Cancer

moles, basal cell carcinoma, squamous cell carcinoma, melanoma

Moles

benign tumors from melanocytes

Basal Cell Carcinoma

originate in straum basale

Squamous Cell Carcinoma

originate in the squamous cells of the stratum spinosum

Melanoma

malignant tumors develop from melanocytes (deadly)

Cyanosis

buling of skin bc lack of O2 in blood

Jaundice

yellowing of skin bc liver not filtering bilirubin

Erythema

reddness of skin due to heat, fever, etc.

Albinism

genetic; prevents body from making melanin

Rickets

softening and curving of bone due to Vitamin D decifiency (can’t absorb calcium)

Vitiligo

autoimmune disease

Freckles

cluster of melanocytes (increase in melanin production due to sun exposure)

Melanin levels

lighter skin = faster vitamin D production; darker skin = more UV protection

Fungal Infections

itchy, not dangerous; treated with antifungals; athlete’s foot, toenail fungus, ringworm

Bacterial Infections

cause fluid/pus filled sores; antibiotics; Impetigo, MRSA

Viral Infections

painful fluid-filled blisters; no cure, preventable; chicken pox, shingles, herpes

Warts

benign tumors cause by HVP (removed through acid, abrasion, freezing)

Dermatitis

general term for skin irritation, rash, etc.

Eczema

type of dermtitis cause by immune overreaction to harmless substances (dust); treated with over-the-counter corticosteroids

Krause end/Bulbous corpuscle

sensitive to cold (top)

Ruffini endings

in joints; sense body orientation and movement (top)

Pacinian corpuscles

deep pressure touch and high frequency vibration (bottom)

Meissner’s corpuscles/Tactile corpuscles

light touch and low frequency vibration (top)

Merkel discs nerve endings

light tough, texture, and edges (top)

Free nerve endings

pain, temperature, itch, touch; send signals to brain/spinal cord

Hair structure

(in to out) medulla; cortex; cuticle

Hair bulb

contains hair root and stem cells; hair is produced

Hair papilla

contains nerves and blood vessels

Root Sheath

extension of stratum spinosum; surrounds hair root

Hair root

living cells

Hair shaft

dead cells

Arrectot pilli

muscle attacing hair to epidermis; makes hair stand; creates goosebumps; provides thermal insulation (smooth muscle)

Sebaceous Glands

secrete sebum oil into hair to moisturize

Apocrine Glands

secrete oily pheremone; puberty; around armpits and genitals; degraded by bacteria to creat odor

Eccrine (Merocrine) Glands

secretes saltwater (sweat) throughout body to cool down

Nails

keartinized version of cornuem

Cuticle

overlap of corneum; keeps bacteria out of nail root

Nail bed

contains stratum basale and spinosum

Nail Matrix

contains stem cells

Types of membranes

epithelial (mucous, serous, and cutaneous) and connective (synovial)

Membrane coverage

outside of body, organs, moveable joints

Mucous membrane

lines cavities open to environment (digestive, respiratory, reproductive)

Serous membranes

lines closed cavities; secretes serous fluid (organs)

Cutaneous membrane

forms skin

Parietal membrane

away from organ

Viseral membrane

touching organ

Synovial membrane

made of only CT; around synovial joint (moveable); cushions tendons and ligaments; surrounded by synovial fluid; reduce friction