Ch. 5

Question 1

skin

Answer 1

1st line of defense, largest organ 7% body weight, last a life time

Accessories: hair, nail, skin gland

Question 2

Function of Integumentary System Protection

body temperature regulation, Vitamin D synthesis, Sensation, Secretion

Answer 2

Protection- First line defense against bacteria/virus

protect from UV ray and dehydration

Too hot- Dermal vessel dilate
vessel carry blood to surface

Too cold- Dermal blood vessel constrict
Prevent heat escape

Calcium Absorption

Sensory receptor

Waste lost through sweat

Question 3

Protective function

Answer 3

Mechanical damage- keratin toughen skin

pressure receptor- alert possible damage

Chemical damage- Keratinized cell relatively impermeable

pain receptor- alert possible damage

Bacterial damage- acid seretion inhibit bacteria

phagocyte- ingest foreign substance and pathogens

UV radiation- melanocyte produce melanin

dessication- drying out

keratin- waterproof

Question 4

Skin Region

Answer 4

Epidermis- superficial

Dermis- underlies epidermis
-made of fibrous connective, nerve, muscle

Hypodermis (SubCutaneous) not skin but share function

• mostly adipose absorb shock and insulate
• Anchor skin to underlying structure-muscle

Question 5

Epidermis

Answer 5

keratinized stratified squamous epithelium

5 layer- 
Stratum basale
Stratum spinosum
Stratum granulosum
Stratum lucidum 
Stratum corneum

4 cell type- 
Keratinocytes
Melanocytes
Dendritic (Langerhans) cells
Tactile (Merkel) cells

Question 6

stratum basale (Germinativum)

Answer 6

Deepest epidermal layer

single row of stem cell, actively mitotic, produce 2 daughter cells. 25-45 days to surface dies on journey.

Question 7

Stratum Spinosum (prickly layer)

Answer 7

several layers thick by desmosomes

web-like system of intermediate pre-keratin

abundant melanosomes and dendritic cells

Question 8

Stratum granulosm (granular level)

Answer 8

Thin 4-6 layer

cell appearance change- cell flatten
-cell accumulate keratohyaline granules which help form keratin in upper layer

water resistant glycolipid slow water loss

cell above this layer die

Question 9

stratum Lucidum (clear layer)

Answer 9

only in thick skin, thin, translucent

Question 10

stratum corneum (horny layer)

Answer 10

20-30 rows of dead anucleated keratin membranous sacs 3/4 epidermal thick

dead but functions: protect from: abrasion, environment and water loss, barrier against bio physical and chem assault.

Question 11

keratinocytes

Answer 11

produce fibrous protein keratin, most cells of epidermis, connected by desmosomes

pushed upward, become dead scale-like, millions rub off.

Question 12

melanocytes

Answer 12

10-25% of deepest epidermis produce melanin and protect apical surface from UV

transfer melanin to keratinocyte

synthesize melanin

Question 13

dendritic (langerhans cells)

Answer 13

macrophage- key activators of immune system

formed in bone

Question 14

tactile (merkel cells)

Answer 14

sensory touch receptors

spike appearance

connect to nerve cell from dermis

Question 15

dermis

Answer 15

strong, flexible

2 layers: Papillary and Reticular

contains: nerve fiber, blood and lymphatic vessel, epidermal follicle, oil and sweat gland.

Question 16

Papillary layer

Answer 16

upper dermal layer (uneven).

fingerlike projection/ indent epidermis/

(Tactile)Meissner corpuscles-light touch receptor

free nerve endings- pain receptor

Epidermal ridges collectively make- friction ridges
- grip, touch, fingerprint

Question 17

Reticular layer

Answer 17

deepest layer, blood vessel, sweat gland, oil gland

Lamellar Pacinian corpuscle- vibration/pressue receptor

Ruffini ending- skin stretch/ finger position

dense fibrous connective tissue

elastic fiber

phagocyte

cleavage line- most collagen fiber parallel to skin surface.

Question 18

Skin color pigment

Answer 18

melanin- pigment made in skin, natural sunscreen

carotene- yellwo to orange pigment found in stratum corneum

hemoglobin- oxygen-carrying pigment in bloodcell

Question 19

Hair

Answer 19

dead keratinized cell of hard keratin

Function: warn of insect, physical trauma, heat loss, sunlight

gray hair- decrease melanin production, increased air bubble in shaft.

Question 20

hair follicle

Answer 20

dermis and epidermis

hair bulb- hair follicle receptor, sensory nerve endings, hair matrix,

arrector pili- smooth muscle attached to follicle

hair papilla- dermal tissue- blood supply

Question 21

hair thinning and baldness

Answer 21

alopecia- immune system attacks hair follicle

true baldness- genetically determined

Question 22

nails

Answer 22

pick small objects, made of keratinized epidermal cells

Question 23

sweat gland (sudiferous)

Answer 23

all skin except nipple and some genitalia

2 types: eccrine- secret sweat
thermoregulation- sympathetic nervous system

Apocrine- armpit and anogenitalia- sweat fat protein

Question 24

Sebaceous (oil) gland

Answer 24

widely distributed come from hair.
active at puberty

secrete sebum- oily holocrine, softens hair and skin

Question 25

burns classification

Answer 25

first- epidermal

second- epidermal and upper dermal

third- entire skin removed, nerve ending destroyed

Question 26

deep wound healing

Answer 26

injury extend to dermis and subcutaneous layer