10: Integumentary System

Question 1

the integumentary system

Answer 1

consists of skin, nails, hair
made up of cutaneous membrane (skin) and accessory structures (hair, exocrine glands, nails)
functions: protection, temperature maintenance, synthesis and storage or nutrients, sensory reception, excretion and secretion

Question 2

epidermis layers

Answer 2

made of cells called keratinocytes

stratum basale = base layer, attached to basement membrane, has stem cells (basal cells) that divide continuously and melanocytes, forms epidermal ridges

stratum spinosum = keratinocytes are bound together by desmosomes

stratum granulosum = keratinocytes produce keratin, keratin fibres develop as cells so become thinner and flatter, gradually cells die

stratum lucidum = appears as a glassy layer in thick skin only

stratum corneum = layers of flat dead keratinocytes, water resistant

Question 3

skin colour

Answer 3

two pigments - carotene and melanin
carotene = orange-yellow pigment, epidermis, in carrots
melanin = made by melanocytes, absorbs UV radiation, red/yellow or brown/black
blood vessels in dermis = reddish tint to skin

Question 4

sunlight

Answer 4

when exposed to sunlight epidermal cells convert a cholesterol related steroid into vitamin D
carcinoma = any cancer of epithelial tissue
malignant melanoma = cancerous melanocytes that grow rapidly

Question 5

dermis

Answer 5

two layers: superficial papillary layer and deep reticular layer
papillary layer = areolar tissue, supports and nourishes epidermis, capillaries, lymphatic vessels, sensory neurons
reticular layer = dense irregular connective tissue - elastic and collagen fibres,
fibroblasts
arteries form cutaneous plexus (deeper network) and subpapillary plexus (small arteries)

Question 6

subcutaneous layer (hypodermis)

Answer 6

interwoven with connective tissue fibres from reticular layer
stabilises position of skin
areolar tissue with many fat cells - energy reserve and shock absorber
distribution of subcutaneous fat changes as we grow

Question 7

hair

Answer 7

keratinous strand produced by epithelial cells of hair follicles
hair papilla = bottom of hair follicle
hair matrix = forms hair by repeated divisions of stem cells
grows 0.3mm a day

Question 8

hair layers

Answer 8

surface layer = cuticle = overlapping layers of cells
underlying layer = cortex = thick layers of hard keratin
core layer = medulla = flexible soft keratin

Question 9

functions of hair

Answer 9

head hair: protects scalp from UV light, cushion a light blow, provide insulation for skull
nostril and ear hair: keep out foreign particles

Question 10

sebaceous glands

Answer 10

discharge oily lipid secretion into hair follicles or onto skin called sebum

Question 11

apocrine sweat glands

Answer 11

secrete odorous products into hair follicles in armpits, around nipples and in pubic region

Question 12

eccrine sweat glands

Answer 12

secrete perspiration - watery
cool surface of skin and lower body temp

Question 13

nails

Answer 13

protect dorsal surfaces of fingers and toes
nail body = visible = dense mass of dead keratinised cells

Question 14

injury

Answer 14

four phases to heal
1. inflammation - mast cells trigger inflammatory response which enhances blood flow and attracts phagocytes

2. migration - scab forms, restricts entry of microorganisms, cells of stratum basale migrate along edges of wound
3. proliferation - scab undermined by epidermal cells
4. scarring - shallow depression, scar tissue

Question 15

burns

Answer 15

first degree = only surface of epidermis affected
second degree = entire epidermis and some of dermis is damaged
third degree = extend into hypodermis, less painful as sensory nerves destroyed