SKIN

Question 1

Thermoregulation by blood supply

Answer 1

Respond to thermoreceptors in skin
Arteriovenous shunts are anastomoses between arterioles and venules - many in dermis
Shunts open or close respectively to decrease or increase blood flow to superficial vascular plexus in papillary dermis

Question 2

Mechanism of tanning

Answer 2

DNA damage due to UV - signals for MSH (melanocyte stimulating hormone)
MSH binds to MC1R (melanocortin 1 receptor)
MC1R - stimulates transcription and increase melanin synthesis and increase cell transfer
Melanosome will be transported to basal keratinocyte = more melanin

Question 3

Protection against microorganisms

Answer 3

Langerhan cells - small cells in non-basal layers of skin - dendritic cells
APC - form a network in epidermis - part of immune system

Question 4

4 main layers of the epidermis

Answer 4

Cornified layer
Granular layer
Spiny layer
Basal layer

Question 5

Cornified layer

Answer 5

Outer protective layer of the epidermis

Cells are keratitnised - cytoplasm full of keratin

Question 6

Granular layer

Answer 6

Layers of cells with prominent granules of keratohyalin
Precursor of keratin
Cells are differentiating to form the outermost layer

Question 7

Spiny layer

Answer 7

Keratinocytes have many desmosomes (junctions) - visible as ‘spines’ between cells - strong bonds holding the epidermis together

Question 8

Basal layer

Answer 8

1st single layer, containing stem cells, and attached to dermis

Question 9

Melanocytes

Answer 9

Synthesises melanosomes (pigment granules) and transfers them to basal dendrites through long dendrites

Question 10

2 layers of dermis

Answer 10

Thin papillary layer

Deeper reticular layer

Question 11

Dermis

Answer 11

Tensile strength and elasticity
Blood vessels, skin glands and sensory receptors
Made up of layers of connective tissue characterised by interconnected mesh of elastin and collagen fibres - produced by fibroblasts

Question 12

Dermal epidermal border

Answer 12

Dermal papillae - finger like protrusions of dermal connective tissue into epidermal layer
Rete ridges - extensions of epidermis into dermal layer

Question 13

Hypodermis

Answer 13

Help insulate deeper tissue

Anchors skin to the muscle with connective tissue

Question 14

What does hair interact with

Answer 14

Apocrine glands
Sebaceous glands
Arrector pili muscle
Nerve receptors

Question 15

Follicular keratinocytes

Answer 15

produce hard keratin hair
Keratinocytes filled with hard keratin flatten out and are slowly pushed up the follicle - resulting in root and shaft formation

Question 16

Endocrine sweat glands

Answer 16

Normal sweat glands, watery secretion on to skin surface

Question 17

Apocrine sweat gland

Answer 17

Secrete into hair follicle

Oily fluid in humans

Question 18

Sebaceous gland

Answer 18

Secrete oily sebum into hair follicle

Conditioner for hair and skin, prevents dryness and flaking

Question 19

Eponychium

Answer 19

Proximal skin fold that forms the cuticle
Semi-circular layer of dead skin keratinocytes that covers the junction where the nail enters the skin preventing entry of pathogens

Question 20

Encapsulated endings

Answer 20

Pacinian corpuscles
Merkel's discs
Meissner's corpuscles
Ruffini endings
Root hair plexus
Krause end bulbs

Question 21

Pacinian corpuscle detects

Answer 21

Vibration or brief touch

Question 22

Merkel’s discs detect

Answer 22

Sustained touch or pressure

Question 23

Meissner’s corpuscles detect

Answer 23

Moving touch or vibration

Question 24

Ruffini endings detect

Answer 24

Steady pressure

Question 25

Root hair plexus detect

Answer 25

Hair displacement

Question 26

Krause end bulbs detect

Answer 26

touch/pressure

possibly thermoreceptors