Ch.5 A&P

What are the two types of skin

•Thick (hairless) skin

•Thin (hairy)

what are the major functions of the skin

prevents entry of toxic substances

reduces water loss

regulation of body temp

contains sensory receptors and immune system cells

lipid storage

vitamin D synthesis

waste excretion

what are the two distinct regions of the skin

epidermis-superficial region (avascular; does not have blood cells)

dermis-underlies epidermis (vascular;has blood cells)

Subcutaneus layer (hypodermis)

anchors skin to underlying tissue but is not technically apart of the skin

provides insulation, energy store, blood flow to/from skin,

Epidermis contains how many layers of skin

four layers (thin skin) or five layers (thick skin

Epidermis layers summed up

1.) flattening,

2.) loss of organelles,

3.) accumulation of protective substances, and

4.) cell death as cells move toward the skin surface.

what are the four types of cells found in epidermis

keratinocytes, melanocytes, Dendritic (langerhans) cells, and tactile (merkel) cells

what is the function of keratinocyte cells

predominant cell type, produces keratin (fiber proteins)

what is the function of melanocyte cells

pigment producing cells

what is the function of Epidermal dendritic(Langerhans) cells?

antigen presenting cells of the immune system

what is the function of tactile (Merkel) cell

touch receptors at base of epidermis (ex:base of fingertips)

freckles=

areas of localized melanin secretion

moles (nevi)

benign, usually pigmented tumor

Skin cancers usually arise from what

non-pigmented cells in deep layers (basal cell carcinomas) or from melanocytes (melanomas).

name the five layers of skin

1. stratum basale

2. stratum spinosum

3. stratum granulosum

4. Stratum lucidum (only in thick skin)

5. Stratum corneum

Explain this layer of skin: Stratum basale

deep, singular layer of continuously dividing stem cells

Explain this layer of skin: Stratum spinosum

cells with weblike prekeratin filaments attached to desmosomes

Explain this layer of skin: Stratum granulosum

a thin layer of cells in the epidermis of the skin that contains lipid-rich granules and is located between the stratum spinosum and the stratum corneum

Explain this layer of skin:Stratum lucidum

several rows of flat, dead cells seen only in thick skin

Explain this layer of the skin: Stratum corneum

20-30 layers of dead, flat keratinized cells that protect against abrasion, water loss, and infection

what is the Reticular layer

dense irregular connective tissue

what are smooth muscle fibers associated with

hair follicles, glands, skin of scrotum

Skeletal muscle fibers anchored to dermis provide what

voluntary movement (ex:facial expressions)

what do Contractions of arrector pili cause?

goose bumps (in response to cold, fear, etc.)

Each follicle has oil-producing glands called what

sebaceous glands

what is the (hard/translucent part of the nail)

keratin layers

changes in form/color of the lunula part of the nail indicate what

cutaneous or systemic disorders

Sweat (sudoriferous) glands

widely distributed; specialized epithelial cells secrete sweat (H 2 O w/ salts and wastes including urea and uric acid) by merocrine or apocrine secretion

name the two types of sweat glands and explain each

eccrine sweat glands-Respond to high body temperature, emotional stress

Apocrine sweat glands-Respond to emotional stress, sexual arousa

Ceruminous glands

lining of external ear canal; secrete cerumen (earwax)

mammary glands do what

secrete milk

sebaceous glands

associated w/ hair follicules; specialized epithelial cells produce sebum (fatty material)

what are the primary drivers of body temp regulation?

skeletal muscle, cardiac muscle, and liver cells

what does radiation do for the body

The body both radiates heat and absorbs radiated heat (from sun

or other warm objects/organisms)

what does conduction do for the body

heat leaves/enters by direct molecular contact (from

warmer to cooler surface)

what does convection do for the body

heat leaves/enters as air passes over body

Evaporation does what for the body

heat is LOST as liquid changes to gaseous water

explain the cooling mechanisms of the body

•warm blood stimulates hypothalamic control center of the brain

1. dermal blood vessels dialate

2. some deep blood vessels contract

3. increased heart rate and blood flow from core of body to surface

4. sweat glands secrete sweat

explain the warming mechanisms of the body

•cooled blood stimulates hypothalamic control center of the brain

1. dermal blood vessels constrict reducing blood flow to skin

2. Sweat glands are inactive

3. nervous system activated skeletal muscles to contract (shivering), non-shivering thermogenesis in babies/adults via

   brown fat mitochondria

Hyperthermia (heat exhaustion)

core tb is too high; results from prolonged heat exposure

hypothermia

tb is too low; results from prolonged cold exposure, illness, anaethesia.

is a fever controlled hyperthermia or hypothermia

hyperthermia; caused by the effects of pyrogens on the hypothalamic body temperature set-poin

name the three major types of skin cancer

-basal cell carcinoma

-squamous cell carcinoma

-melanoma

explain the key to survival in early detection of melenoma

ABCD Rule:

•A:asymmetry- the two sides of the pigmented area do not match

• B:border irregularity-exhibits indentations

• C:color-contains several colors

• D: diameter-larger than 6mm

what can burns lead to

renal shutdown and circulatory shock

name+ explain. the three types of burns

first degree: epidermal damage only (localized redness, swelling, and pain)

second degree:epidermal and upper dermal damage, blisters appear.

third degree: entire thickness of skin involved, skin color turns gray- white, cherry red, or fully black; no edema is seen and area is not painful because endings are destroyed