Integumentary System: Membranes, Skin Layers, and Glands

Serous membranes

Lines body cavities like the thorax, abdomen, as well as organs within the cavities (consists of simple squamous & loose connective, lubricates chest and abdomen via serous fluid)

Mucous membranes

Lines cavities & tubes that open to the outside: oral, nasal, respiratory, reproductive systems

(epethelium over loose connective)

Synovial membranes

form the inner lining of joint cavities, between ends of long bones and secrete a thick fluid called synovial fluid

Cutaneous membrane

The skin; composed of epidermal and dermal layers

Skin (integument)

Largest organ in the body

Functions: Body temp, conserve water, house sensory organs, etc)

Epidermis

Outer layer of skin,
several layers,
lacks a direct blood supply,
nourished by the dermal blood vessels,
pushes older cells outwards.

Skin color

due largely to melanin, varies by size and number of pigment granules

Dermis

Dermal papilae=unevenness between dermis and epidermis
Middle layer of skin,
produces fingerprints
Blood vessels carry nutrients for ALL parts of the skin

Hypodermis

lies under the dermis and consists mostly of loose connective & adipose tissue

Collagen and Elastic fibers

share blood vessels with dermis
(adipose is part of its main function of insulating)

Hair follicles

-epidermal cells

-tube like depression (root of cells)

-nourished by dermal vessels, protected by connective tissues

-pushes older cells outwards

Sebaceous Glands

Holocrine glands

outermost layer of epidermis

Secrete sebum (oil and fat)

sebum makes things soft pliable, and waterproof

Nails

protective coverings

the most actively growing part on the ends - Lunala

divides and becomes keratinized, pushes older cells outward

Sweat glands

AKA sudoriferous, exocrine glands widespread in skin

Eccrine glands

most numerous gland, respond to body temperature changes.

Apocrine sweat gland

becomes active at puberty (emotional sweating and other non body temp related sweating)

Stratum corneum

(1st)outermost layer of epidermis, thick, protective, prevents waterloss.

Stratum lucidium

(2nd)Clear flat dead keratinocytes appears translucid and thin just above the granulosumm (palms and soels of feet ; thick skin)

stratum granulosum

(3rd)consists of several layers, having drastic keratinocyte appearance (pigment granuls accumulate)

Stratum spinosum

(4th)Several cell-layered thick, weblike system, keratin layers appear spikey

Stratum Basale

Deepest epidermal layer and cell division

Arrector pili muscle

causes hair to stand erect and goose bumps to appear