skin

Question 1

3 main regions

Answer 1

• epidermis: outermost superficial region
• dermis region: middle
• hypodermis: deepest region (subcutaneous tissue)

Question 2

epidermis: where to find it

Answer 2

the outer skin is exposed to external environment

Question 3

epidermis: function

Answer 3

protection and reduction of water loss

Question 4

epidermis: composed of

Answer 4

composed of keratinized, stratified (more than 2 cells thick) squamous (flat cells) epithelial cells including:

• keratin
• melanocytes
• Merkel cells
• Langerhans cells

Question 5

keratin

Answer 5

durability

Question 6

melanocytes

Answer 6

produces melanin

Question 7

Merkel cells

Answer 7

touch receptors associated with sensory nerve endings

Question 8

Langerhans cells

Answer 8

white blood cells (immune system)

Question 9

epidermis: no vessels, why?

Answer 9

no blood vessels because it nourished through diffusion from capillaries of the dermis

Question 10

epidermis 5 layers

Answer 10

1. stratum corneum
2. stratum granulosum
3. stratum spinosum
4. stratum basale
5. dermis

Question 11

stratum corneum 5

Answer 11

1st layer
cells are dead
represented only by flat membranous sacs filled with keratin
glycolipids in extracellular space

Question 12

stratum granulosom 5

Answer 12

2nd layer
cells are flattened
organelles deteriorating
cytoplasm full of lamellated granules (release lipids)
and keratohyaline granules

Question 13

stratum spinosum 3

Answer 13

3rd layer

cells contain thick bundles of intermediate filaments made up of pre-keratin

Question 14

stratum basale 3

Answer 14

4th layer
cells are actively mitotic stem cells
some newly formed cells become part of the more superficial layers

Question 15

stratum lucidum 4

Answer 15

(palms of hands and soles of feet)

• transparent layer
• flat translucent dead cells
• protection against UV.

Question 16

Dermis 5

Answer 16

• extensive cutaneous blood flow
• nutritive (10%) and thermoregulatory (90%)
• extensive nerve supply
• sensory receptors: mechanoreceptors, thermoreceptors, and nociceptors (pain)
• highly elastic and tough due to the meshwork of collagen, elastic and reticular fibers,

Question 17

collagen

Answer 17

support

Question 18

reticular fibers

Answer 18

thinner than collagen but still provide support

Question 19

elastic

Answer 19

flexibility

Question 20

Dermis:cells 3

Answer 20

• fibroblasts
• adipose (fat Cells)
• macrophages

Question 21

Dermis: two main layers

Answer 21

• upper papillary layer

- Reticular layer

Question 22

upper papillary layer 5

Answer 22

• Loose connective tissue
• Contain protrusions into epidermis called “PAPILLAE”
• Fine capillaries to carry waste away + provide nourishment and oxygen
• Nerve endings for heat, cold, pain, and touch (Meissner’s corpuscles)
• Double row of papillae -> better gripping by hands and feet + distinctive fingerprint patterns

Question 23

Reticular Layer: 6

Answer 23

• Elastic network of tough collagen fibres interwoven with elastic fibres
• Collagen fibres arranged in special pattern
• Incisions made parallel to these lines during surgery =>wound heals faster
• Contains sebaceous and sweat glands, arrector pili muscle and hair follicle
• Pacinian corpuscles are distributed through the dermis and function as pressure receptors
• Stretch marks in pregnancy due to breaks in collagen and elastic fibres

Question 24

hypodermis 3

Answer 24

• subcutaneous layer
• thicker than the dermis
• area for formation and storage of fat due to adipose tissue

Question 25

sweat glands 3

Answer 25

- different types of sweat glands prevent overheating of the body - eccrine sweat glands=palms, soles of the feet +forehead - apocrine sweat glands =auxillary and anogenital areas

Question 26

sebaceous glands 6

Answer 26

- located in dermis - lubrication and protection - cluster of cells - connected to hair follicles - sebum=> fight bacteria+fungus - blackheads due to blocked glands

Question 27

hair: 5

Answer 27

- shaft=protrudes from skin - root= embedded in skin - follicle= surrounds hair - arrector pilli muscle= bundle of smooth muscle= hair erection + sebum released from the sebaceous glands.

Question 28

hair function: 5

Answer 28

- maintaining warmth - alerting the body to the presence of insects on the skin - guarding the scalp against physical trauma, heat loss, and sunlight.

Question 29

vellus: 2

Answer 29

pale fine body hair, found in children and the adult female

Question 30

terminal hair: 5

Answer 30

the coarse, long hair of eyebrows, scalp, heat loss+ sunlight.

Question 31

functions of the skin:5

Answer 31

1. ) protection 2) thermoregulation 3. ) sensory perception 4. ) excretion 5. ) vitamin D synthesis

Question 32

skin function: protection 3

Answer 32

- non-specific immunity - anatomical barrier against infection - melanin- screen out excess UV rays

Question 33

skin function: sensory perception 2

Answer 33

- millions of nerve endings | - receptor for pain, heat and pressure

Question 34

skin function: excretion 2

Answer 34

- excretion of lactic acid and sodium chloride | - urea

Question 35

skin function: vitamin d synthesis 5

Answer 35

- vitamin d precursor is in skin + exposure to UV light turns precursor to an inactive form of vitamin d - modification by liver and kidney enzymes turn the inactive form to active form of vitamin d - vitamin d promotes the absorption of calcium and phosphate through the intestine