Chapter 4Skin and Body Membranes

Body Membranes•Body Membranes: Covers

surfaces, lines body cavities and forms protective (lubricating) sheets around organs.

I. Classification of Body MembranesA. Epithelial Membranes: simple organs made

of an epithelial sheet combined with a layer of connective tissue.1. Cutaneous Membrane: Integumentary

System (Skin)* Exposed to air/dry membrane

2. Mucous Membrane (mucosa)* Lines body cavities that are open to

the exterior (ex: respiratory, digestive, urinary, reproductive tracts)

Epithelial Membranes, cont’d

3. Serous Membrane (serosa)* Occurs in pairs:

- Parietal Layer lines body cavity- Visceral Layer covers the organs

* Ex: Peritoneum – lines abdominal cavity, Pleura – surrounds lungs,Pericardium – surrounds heart

A.Connective Tissue MembraneA.Ex. Synovial membraneB.Lines fibrous capsules

surround joints.

*Membranes make FLUIDS and MUCUS!

• Cutaneous membrane, sweat & oil glands, hair and nails

A.Basic Skin Functions~ Protection, insulations, excretion,

synthesis of vitamin D~ Cutaneous sensory receptors –

touch pressure, temperature, and pain receptors

II. Integumentary System

B. Structures of the Skin~ Tissue of the Skin

* Epidermis – outer layer/stratified squamous epithelium capable of keratinizing (hard and tough)

~ Burn or friction may cause epidermis and dermis to separate (blister)

Structures of the Skin, cont’d

~ Subcutaneous tissue/hypodermis – adipose* anchors skin to underlying organs* function: shock absorber, insulates, and forms curves

1. Epidermis• Avascular• Kerantinocytes (keratin – fibrous

protein)

1. Epidermis, cont’d…

• 5 Layers–Stratum basale (geminitivum)–Stratum spinosum–Stratum granulosum–Stratum lucidum–Stratum corneum

1. Epidermis, cont’d…

•Melanocytes (melanin)–Sunlight stimulates melanin production (tan)–Freckles & Moles – accumulation of melanin

2. Dermis – “hide” - Leather• 2 Layers• Papillary layer – fingerprints,

Meissner’s corpuscles – touch & pain.• Reticular layer – blood vessels &

glands; collagen & elastic fibers; Pacinian corpuscles – deep pressure

2. Dermis, cont’d…

• Fever – • Dermal capillaries swell• Skin red & warm• Heat radiates from skin

2. Dermis, cont’d…

• Decubitus Ulcers (bed sores)• Poor circulation• Dead skin cells

C. Skin Color• Pigment (melanin & carotene)

C. Skin Color, cont’d…

• Dermal blood vessels (oxygenated blood)• Cyanosis – poorly oxygenated blood

(blue)• Erthema - blushing• Pallor or blanching - pale• Jaundice – Yellow; liver disorder• Bruises – black or blue (hematoma

– blood mass)

D. Appendages of skin• Sebaceous glands (oil)• Sebum – lubricant• Kills bacteria• Active – adolescent (hormones)• Acne – infection of oil gland

D. Appendages of skin, cont’d…

• Sweat glands • Eccrine sweat glands• Sweat• Antibacterial• Body heat regulation

D. Appendages of skin, Sweat glands, cont’d…

• Apocrine sweat glands• Axillary – milky, yellowish,

odorless• Bacteria causes body odor• Activated - puberty

D. Appendages of skin, cont’d…

• Hair• Hair follicle/hair root/hair

shaft/cuticle (split ends)• Hormones stimulate hair

growth• Hair color - melanin

D. Appendages of skin, cont’d…

•Nails• Keratinized dead cells•Nail bed – pink/rich blood

supply• Lunula – white crescent at base

of nail