The Integumentary The Integumentary SystemSystem

Review of membranesReview of membranes

Types of membranes1.serous

◦ line body cavities that do not open to the outside

visceral – covers the organ parietal – covers the cavity

◦ made up of epithelium and loose connective tissue

◦ secrete serous fluid for lubrication

Serous membraneSerous membrane

Types of membranesTypes of membranes

2. mucous ◦ line cavities with openings to the

outside oral and nasal cavities openings of digestive, reproductive,

respiratory, and urinary systems

◦ made up of epithelium on loose connective tissue

◦ contain goblet cells to secrete mucus

mucous membranes of mucous membranes of stomachstomach

Types of membranesTypes of membranes

3. synovial ◦ line joint cavities◦ consist only of connective tissues◦ secrete lubricating synovial fluid

4. cutaneous membrane - skin

Synovial membraneSynovial membrane

Cutaneous membraneCutaneous membrane

The Integumentary The Integumentary SystemSystemintegumentary = coveringcomposed of skin, sweat and oil

glands, hair, nailsmini-excretory system

◦ removes urea, salts, water through sweatlarge organcomposed of 3 distinct layers

◦ epidermis◦ dermis◦ hypodermis

Functions of Functions of Integumentary SystemIntegumentary System1. protection from abrasion, uv

radiation, keeps out bacteria/viruses and prevents water loss

2. sensation of heat, cold, touch, pressure, pain

3. vitamin D production4. temperature regulation5. excretion of wastes

EpidermisEpidermisoutermost layercomposed mostly of keratinized

stratified squamous epitheliumavascularcomposed of 4-5 layersgrow new epidermis every 25-45

days

layers of epidermislayers of epidermis

1. stratum basale – layer of reproducing cells at base of epidermis

◦cuboidal or columnar cells◦nourished by blood vessels of dermis◦millions of cells produced daily◦push older cells to surface where

they become keratinized resist abrasion, produce permeability

barrier

layers of epidermislayers of epidermis

2. stratum spinosum3. stratum granulosum4. stratum corneum

◦ most superficial◦ dead, squamous cells filled with keratin◦ 25 or more layers thick◦ areas subjected friction form calluses

* stratum lucidum (palms and soles)

skin colorskin colormelanocytes: cells in stratum

basale◦produce melanin

yellow to brown to black protects cells from uv radiation freckles and moles – melanin

concentrated in one spot Racial differences determined by amount,

kind and distribution of melanin.

skin colorskin colorcyanosis (bluish colored skin)

◦caused by low oxygen in bloodredness

◦blushing, fever, hypertension, inflammation, allergy

pallor◦fear, anger, anemia, low blood

pressure, impaired blood flow

skin colorskin colorjaundice

◦liver disorders, excessive bilebruises

◦blood clotted in tissue spaces (hemotoma)

◦unusual bruises: low vitamin C, hemophilia

albinism◦recessive genetic trait◦deficiency of melanin◦fair skin, white hair, unpigmented irises

DermisDermismade mostly of

connective tissue◦ collagen, elastic

fibers Collagen is directional;

causes stress lines.

binds epidermis to underlying tissue

vascular, carry nutrients to upper layers and regulate temperature

DermisDermis2 layersdermal papillae

◦ nerve fibers, sensory fibers (Meissner corpuscles), hair follicles

Dermal Papillae are projections from the dermal layer into the epidermal layer.◦ help to deliver oxygen/nutrients from the

vascular system to the epidermal layer

dermal papillae dermal papillae

Meissner corpusclesMeissner corpuscles

DermisDermisreticular layer

◦ deepest skin layer◦ blood vessels, sweat and oil glands, deep

pressure receptors (Pacinian corpuscles)

HypodermisHypodermissubcutaneous layerloose connective and adipose tissuesnot part of the skin; base layer it

rests uponattaches skin to underlying organscontains blood vessels that supply

the skinno real boundary between dermis

and subcutaneous layersstores fat for padding and insulation

Accessory organs of the Accessory organs of the skin skin 1. Hair extension of epidermis deep into

dermis found over most of human body

◦ mostly useless produced in hair bulb which rests on

dermal papillae columns of keratinized epithelial cells

◦ continues to grow as new cells are added at the root

HairHair

Parts of the hairshaft – above

surface of skin◦ Medulla – soft center◦ Cortex - hard◦ Cuticle – outer

covering single layer of

overlapping cells that holds hair in follicle

root – part of hair in follicle

hair follicle – below surface of skin

hairhairhair bulb – base of follicle where hair grows cell division – living cells

push up and become keratinized

arrector pili – small bands of smooth muscle

connect each side of hair follicle to dermal layer

contraction – goose bumps

arrector piliarrector pili

hair colorhair colorgenetic traitmelanin in hair bulbfades with ageno melanin = white hair

Accessory structuresAccessory structures2. Nails thin plate; keratinized stratum corneum cellsparts of nail◦ free edge◦ nail body (part that is seen)◦ nail root – covered by skin◦ nail matrix – gives rise to cells that form nail

lunula – whitish crescent at base of nail

◦ nail bed – place of attachment◦ cuticle – stratum corneum on nail body

Accessory organs of Accessory organs of skinskin3. Sebaceous glandssimple, branched grape-like glandconnected by duct to superficial part of

folliclenot on palms or solesproduce sebum – oily, lipid-rich

◦ lubricates hair and surface of skin◦ waterproofs and moisturizes◦ kills bacteria◦ whiteheads/blackheads – blocked glands◦ acne – infected glands

Accessory organs of Accessory organs of skinskin4. Sweat glands – two typesmerocrine

◦ simple, coiled gland ◦ located in all areas of skin◦ most numerous in palms, soles◦ respond to body temperature◦ secrete water and some salts◦ open to surface of skin via sweat pores◦ Sweat on skin cools body.

Accessory organs of Accessory organs of skinskinapocrine

◦ simple, coiled, tubular gland◦ Secretions are thick and organic.

broken down by bacteria to produce body odor

◦ open into hair follicles of axillary and genital areas◦ become active at puberty

modified sweat glands◦ ceruminous – produce earwax◦ mammary – produce milk