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• skin and accessory organs make up the integumentary system.

• Type of cutaneous membrane

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Skin

Integumentary System

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Types of Membranes

A. Serous membranes: • line body cavities that lack openings to the outside• Thorax/abdomen, cover the organs within these

cavities.• epithelium+ loose connective tissue • secrete serous fluid: lubricant

B. Mucous membranes: • line cavities and openings that lead to the outside• Oral/nasal cavities, openings of the digestive,

reproductive, respiratory, urinary systems• consist of epithelium+connective tissue • cells secrete mucus.

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C. Synovial membranes

• Only connective tissues

• line the joint cavities.

• Secrete lubricating synovial fluid.

D. cutaneous membrane

• consists of the skin

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Skin and Its Tissues • large organ• Functions:

– maintaining homeostasis through temperature regulation, – protection of underlying tissues, – retardation of water loss, – housing sensory receptors, – synthesizing certain chemicals, – excreting wastes.

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. Consists:

- outer epidermis

- dermis

- subcutaneous layer (hypodermis).

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Epidermis1. stratified squamous epithelium2. lacks blood vessels3. reproducing cells (stratum basale), at base of

epidermis, well-nourished by dermal bv4. Cells are pushed outward as new cells are formed,

and become keratinized as they die. 5. 4-5 layers:

1. stratum basale, 2. stratum spinosum, 3. stratum granulosum, 4. stratum corneum 5. stratum lucidum in palms and soles

4. functions: protects against water loss, mechanical injury, chemicals, and microorganisms.

5. Melanocytes, lie deep epidermis and dermis, produce pigment called melanin to protect from sun's UV rays

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Skin Color 1. results from combination of genetic,

environmental, and physiological factors.

2. Genetic differences in skin color result from differing amounts of melanin and in the size of melanin granules.

3. Exposure to sunlight causes darkening of skin as melanin production increases.

4. Circulation within dermal blood vessels affects skin color.

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Dermis1. binds epidermis to underlying tissues.2. Epidermal ridges and dermal papillae

cause the border to be uneven.3. Connective tissue+collagen+elastic fibers

within a gel-like ground substance4. blood vessels, nerve fibers, sensory

fibers, hair follicles, sebaceous glands, sweat glands.

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Subcutaneous Layer: hypodermis1. loose connective+insulating adipose2. binds the skin to underlying organs3. blood vessels

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Accessory Organs of the Skin Nails – protective coverings ends fingers/toes.– stratified squamous epithelial cells over the

nail bed, lunula the most actively growing region of the nail root: as new cells are produced, older ones are pushed outward and become keratinized.

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Hair Follicles 1. Hair in all regions of the skin.2. Individual hairs develop from cells at the base

of the hair follicle, an invagination of epidermis that dips down into the dermis.

3. As new cells are formed, old cells are pushed outward and become keratinized, and die forming the hair shaft.

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4. smooth muscle cells, arrector pili muscle, attaches to each hair follicle and cause goose bumps when cold or frightened.

5. Hair color is determined by genetics; melanin from melanocytes is responsible for most hair colors. Dark hair has eumelanin while blonde and red hair have pheomelanin.

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Sebaceous Glands

- associated with hair follicles

- secrete sebum that waterproofs and moisturizes the hair shafts.

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Sweat Glands: sudoriferous glands• eccrine, respond to body temperature• apocrine, respond to body

Temperature, stress, sexual arousal.

• ceruminous glands, secrete wax in the ear canal.

• Mammary glands, secrete milk

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Regulation of Body Temperature A. Proper temperature regulation is vital to maintaining

metabolic reactions.B. Skin plays a major role in temperature regulation with

the hypothalamus controlling it.C. heart and skeletal muscle, produce heat.D. Heat lost fom the skin through radiation.E. body responds to:

- excessive heat by dilation of dermal bv+sweating.-excessive cooling by constricting dermal bv, inactivating sweat glands, and shivering.

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Healing of Wounds and Burns A. body's normal response to injury: Inflammation, bv dilate >

more permeable, tissues become red+swollen,.B. Superficial cuts are filled in by reproducing epithelial cells.C. Deeper cuts are closed off by clots, covered by scabs, and

eventually filled in by fibroblasts, making connective tissue. Blood vessels extend into the area, injured tissues are replaced, and the scab falls off.

D. Large wounds leave scars and healing may be accompanied by the formation of granulations.

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