Integumentary system

Question 1

Arrector pili

Answer 1

A microscopic band of smooth muscle that elevates the hair follicle

Question 2

Contact inhibition

Answer 2

The cessation of cell division in cells that touch each other

Question 3

Epidermis cells

Answer 3

Epidermal cells are
90% keratinocytes (keratin = tough fibrous protein that protects)
8% melanocytes (melanin = pigment that contributes to skin colour; eumelanin= brown/black, pheomelanin = reddish / yellow)
2% Langerhans cells; immune cells that are involved in skin ‘surveillance’

Question 4

Fingerprints

Answer 4

Ridges formed during foetal development. Increase surface area and enhance grip by creating friction. Unique to each individual

Question 5

Granulation tissues

Answer 5

Connective tissue that fills wound

Question 6

Integumentary system, inc layers

Answer 6

Skin. Largest organ in the body. Covers external body & continues with mucous membranes internally, consists of 3 layers; epidermis, dermis, subcutaneous layer (adipose layer), contains accessory structures (glands, hair, nails)

Question 7

Scar tissue

Answer 7

A mark on the skin or other body tissues where a wound, burn or sore has not healed completely and fibrous connective tissue has developed. Contains denser collagen fibres, fewer hairs, glands and nerve endings and blood vessels (whiter)
Two types of scar tissue:
1) Hypertrophic scar – stays within the boundary of the wound
2) Keloid scar – Takes up a larger space than the wound (normally raised)

Question 8

Sensory nerve endings

Answer 8

3 types:
Meissner’s corpuscle; sensitive to light pressure
Pacinian corpuscle; sensitive to deep pressure
Free nerve ending; sensitive to pain & temperature

Question 9

Skin colour;

Answer 9

Brown: Pigmentation due to varying degrees of melanin produced by melanocytes. People of different races have the same number of melanocytes but different amounts and types of melanin (eumelanin/ pheomelanin)
Pink: Colour due to level of blood circulation and oxyhaemoglobin
Natural Yellow: Colour caused by carotenes (pigment that gives egg yolk / carrots colour)
Yellow: Colour from pathology due to bilirubin.
Albinos are unable to synthesis melanin

Question 10

Skin Functions

Answer 10

Functions; Protection, Thermoregulation (body temperature), Vit D production, Sensation, Absorption, Excretion

Question 11

Skin functions; Protection

Answer 11

Against dehydration & external factors such as chemicals, toxins, trauma, light & microbes
Physical barrier - Closely packed keratinised cells & melanin
Sebum - Contains fatty acids which inhibit microbial growth
Sweat - Contains lysozymes, which are enzymes that break down bacteria
Nerve sensors - Induce protective reflexes
Desquamation - Shedding of the skin cells help remove microbes

Question 12

Skin functions; Thermoregulation

Answer 12

Thermo = temperature
Normal body temp = 35.5 – 37.5 ‘C (98-100F). Heat is produced by liver, muscles & digestive organs. Adipose tissue = insulator. Heat loss by respiration through convection & evaporation (movement of heat through liquid / gases) Temperature control centres are the hypothalamus & medulla oblongata.
Thermoregulation occurs via activity of sweat glands (water evaporates off skin) & blood vessels (vasodilation/vasoconstriction). Both stimulated by ANS

Question 13

Skin functions; Hyperthermia criteria

Answer 13

> 38.5’C. (Hyper = elevated)
When core temp. elevates above 38.5’C. Life threatening = 40’c, Death – 45’C.

Question 14

Skin functions; Hypothermia criteria

Answer 14

<35’C. (Hypo = low). When core temperature drops below that required for normal metabolism & body functions. Death usually below 25’C

Question 15

Skin functions: Vitamin D formation

Answer 15

UV light activates a Vitamin D precursor in the skin. The kidneys convert the precursor to calcitriol, which acts as a hormone to increase uptake of calcium & phosphorus (supporting bone density). Vitamin D is stored in the liver

Question 16

Skin functions: Absorption

Answer 16

Substances absorbed through the skin:
Lipid-soluble molecules: (Vit. A, D, E, K, medications, essential oils, O2 & CO2)
Toxins: Acetone, carbon tetrachloride, lead & mercury, arsenic, poison oak & ivy, chemicals

Question 17

Skin functions: Excretion

Answer 17

Substances excreted through the skin: Salt (sodium chloride), Water, Urea, Ammonia

Question 18

Skin layers;

Answer 18

The skin consists of 3 main layers:
1) Epidermis (epi= above) The superficial (surface) layer of skin formed of tightly packed cells - epithelial tissue (keratised epithelium, a protective waterproof barrier). Replacement occurs 40 days.
2) Dermis; The middle layer of skin, formed of connective tissue. Also contains accessory structures – sweat glands, hair & sebaceous glands
3) Subcutaneous layer (sub = below): An insulating & protective layer of fatty tissue that connects the dermis to the deeper-lying muscle & bone

Question 19

Epidermis layers

Answer 19

5 Layers =
1) Stratum corneum
2) Stratum lucidum
3) Stratum Granulosum
4) Stratum Spinosum
5) Stratum basale.

1st layer - stratum corneum
Outer layer (1st)
25-30 layers of flattened dead keratinocytes
Cytoplasm replaced by keratin
Are shed (desquamated)

2nd layer - stratum lucidum
3-5 layers of dead cells
Only present in thick skin

3rd layer - stratum Granulosum
3-5 layers of cells undergoing apoptosis (self-suicide) (1/2 living)

4th layer - Stratum Spinosum
8-10 layers of new (living) keratinocytes

5th layer - stratum basale
Single row dividing to form new keratinocytes

Question 20

Skin layers: Dermis

Answer 20

The middle and thickest layer in skin, formed of connective tissue. Contains a matrix of collagen (strength) & elastic fibres (stretch & recoil).
Also includes accessory structures – sweat glands, hairs & erector pili muscles and sebaceous glands, arterioles & capillaries, lymph vessels & nerve endings and fibroblasts and immune cells.

Question 21

Skin layers: Dermis; Hairs

Answer 21

Hairs are concentric columns of dead keratinised cells bonded together by proteins. Arrector pili connects the hair follicle to the dermis. When the hair is erect, it traps a layer of air next to the skin (part of thermoregulation)

Question 22

Skin layers; Dermis; Sebaceous Glands

Answer 22

Secrete sebum - keeps hair soft, provides waterproofing for the skin & is anti-microbial. (Mainly on face, scalp, lips, eyelids, nipples, labial folds, glans penis)Skin layers; Dermis; Sebaceous Glands

Question 23

Skin layers; Dermis; sweat (sudoriferous) glands

Answer 23

Consists of a gland, duct & a pore. Excretion of urea (waste). Body heat used to evaporate sweat – helps regulate body temperature, smell = bacteria breaking down substances in sweat such as fatty acids, excessive sweating leads to dehydration and sodium (NA+) depletion

Question 24

Wound healing;
Deep wound

Answer 24

Affects dermis & subcutaneous layer. Three phases:
Inflammatory; migration of leukocytes to clean up microbes/foreign tissue, blood clot forms – scab, epithelial cells migrate to repair basement membrane
Proliferative: Granulation tissue formed with laying of collagen& blood vessels, extensive growth & repair of epithelial cells
Remodelling; 3 weeks – 6 months, scab off & scar tissue remains (fibrosis)

Question 25

Wound healing; Superficial wound

Answer 25

Includes abrasions & burns. Basal cells move across the gap until contact inhibition occurs. Epithelial growth factor causes multiplication of the basal cells until space is filled