Chapter 4 Skin and Body Membranes

Body Membranes Body Membranes: Covers surfaces, lines body cavities and forms protective (lubricating) sheets around organs.

I. Classification of Body Membranes A. 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 Membrane A.Ex. Synovial membrane B.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