Skin Physiology

Question 1

Identify skin layers

Answer 1

• stratum corneum
• stratum granulosum
• stratum spinosum
• basal cell layer
• DEJ (BMZ)
• Papillary dermis

Question 2

which 3 pigments contribute to skin color?

Answer 2

• Melanin: dark color
• Carotene: most obvious in palms and soles of feet
• hemoglobin: pinkish hue of skin

Question 3

what synthesizes Melanin?

Answer 3

It is synthesized by Melanosomes (organelle)

Question 4

what are the 2 types of Melanosomes?

Answer 4

1-Eumelanosomes: synthesize from Tyrosine eumelanin, a dark pigment (africans)
2-Pheomelanosomes: that make from tyrosine and cysteine Phemelanin (orange pigment) (Whites europeans)

Question 5

Genes implicated in skin tones?

Answer 5

-OCA2
MC1R
SLC24A5

Question 6

What is Melanin?

Answer 6

a high molecular weigh polymer

Question 7

Melanocytes are derived from?

Answer 7

Neural crest

-Melanocytes inject melanosomes into keratinocytes

Question 8

how is regulated skin pigmentation?

Answer 8

Stimulus=> a-melanocortin stimulating hormone (MSH)=>Melanocortin-1 receptor (MC1R)=> Tyrosinase=>Eumelanin/ Pheomelanin production

Question 9

What is a transporter gene mutation?

Answer 9

OCA2 P-protein Tyrosine

Albinism and blue eyes

Question 10

SLC24A5 (threonine)

Answer 10

Light

Question 11

SLC24A5 (Alanine)

Answer 11

Dark

Question 12

Endogenous pigmentation protects?

Answer 12

• from Solar radiation
• absorbing free radicals
• tanning reactions

Question 13

facultative pigmentation?

Answer 13

tanning in light skinned people

premature aging of skin

Question 14

Natural tanning process occurs in response to?

Answer 14

UVR

Question 15

natural tanning process characterized by?

Answer 15

• increased number of melanocytes
• increased dendricity of melanocytes
• increased size and number of melanosomes
• increased proliferation of keratinocytes

Question 16

Why is there skin pigmentation?

Answer 16

1- Prevention of photolysis
2-photosyntesis
Vit D3/ Folic acid

Question 17

UVA

Answer 17

penetrates deeper

Question 18

OCA2 mutation?

Answer 18

oculocutaneous albinism

Question 19

identify appendages of the skin?

Answer 19

Glands (sweat, sebaceous), hair, nails

Question 20

identify types of sweat glands?

Answer 20

• Eccrine sweat glands: palms and soles of feet
• Apocrine: axillary and anogenital areas
• Ceruminous: ext. ear canal
• Mammary glands: secretion of milk

Question 21

types of nervous or reflex sweating?

Answer 21

• cortical (emotional) eccrine sweating
• hypothalamic (thermoragulator)
• Medullary (gustatory)
• spinal cord transection
• intrasympathetic
• Axon reflex

Question 22

identify innervation of sweat glands?

Answer 22

anatomically sympathetic
functionally: parasympathetic
Nerves are Sympathetic cholinergics

Question 23

sweating after direct heat is a ?

Answer 23

non-nervous sweating

• does not involve sudomotor nerves
• it is unaffected by acclimatization
• no seasonal variation in response

Question 24

how is the regulation of chemical content of sweat?

Answer 24

CFTR controls amount of water associated with Cl transport

Question 25

how is heat produced?

Answer 25

it is produced in the core (Liver)

Question 26

Where are located the core sensors?

Answer 26

-primarily in Hypothalamus and spinal cord

Question 27

Hypothalamic neurons are located in?

Answer 27

-preoptic and anterior region

Question 28

what are hypothalamic centers

Answer 28

centers set to respond to very small changes in temperature. Finely controlled

Question 29

when do hypothalamic centers mature?

Answer 29

Late in development: problem for premature infants!

Question 30

What are the mechanisms for removal of body heat?

Answer 30

infrared radiation evaporation convection conduction

Question 31

What are the mechanism for conservation of body heat?

Answer 31

- increased heat production - vasoconstriction - protective clothing

Question 32

Effect of alcohol in body heat?

Answer 32

dilation of peripheral blood vessels | Hypothermia

Question 33

In warm conditions how heat is regulated?

Answer 33

- heat lost by radiation - more blood flow through dilated capillaries - shunt vessel constricted diverting blood to capillaries

Question 34

in cold conditions?

Answer 34

- less blood flow in capillaries - shunt vessel dilated to divert blood from capillaries - cyanosis

Question 35

receptors in cold conditions?

Answer 35

-active vasoconstriction | alpha-adrenergic= smooth muscle to contract

Question 36

in warm conditions?

Answer 36

active vasodilation beta-adrenergic decrease smooth muscle activity (dilates) M3 (NO)-AchR= decrease SmM (All sympathetic)

Question 37

What are the failures in temperature control

Answer 37

- fever - drugs acting on hypothalamus - abnormal sweating - Malignant hyperthermia= increase Ca release, stiffness - erythroderma - menopausal flushing - age

Question 38

What is trans-epidermal water loss (TEWL)?

Answer 38

water lost though skin in normal circumstances | -barrier to water loss: stratum corneum

Question 39

How lipophilic materials penetrates the skin barrier?

Answer 39

Easily | eg. Strogens are highly lipophilic

Question 40

how is the sensory function of the skin?

Answer 40

- tactile sensation =>rapidly adaptating receptor - thermal sensations=> adaptating - pain sensation (non-adaptating!) - itch sensation (nociceptors)

Question 41

identify neuro-inflammatory functioning of the skin

Answer 41

- Axon reflex - Neuropeptides - bradykinin - Mast cells

Question 42

identify receptors of fine touch and fine discrimination?

Answer 42

- Meissener's corpuscle | - Merkel cells

Question 43

identify receptor of crude appreciation of signal, that sense vibration and are general not specific?

Answer 43

- Pacinian corpuscle | - Ruffini endings

Question 44

What is Triple response of Lewis?

Answer 44

-cutaneous response from stroking the skin= Wheal -release of Histamine (skin) -red spot= capillary dilatation -Flare= redness due to arteriolar dilatation mediated by axon reflex Wheal

Question 45

What cells are involved in this immediate hypersensitivity response?

Answer 45

Mast cells and basophils effector cells involved

Question 46

The release of Histamine triggers response of?

Answer 46

CGRP= arterial vasodilation in the area

Question 47

Epidermis develops from?

Answer 47

Ectoderm

Question 48

Dermis and Hypodermis from?

Answer 48

Mesoderm

Question 49

In adolescent skin become oilier and acne appear due to

Answer 49

Sex steroids

Question 50

Skin shows effect of environmental assaults around?

Answer 50

30 y/o

Question 51

Skin in the old?

Answer 51

- skin thinner - dry and itchy - intolerance to cold due to fat layer decreases - decrease elasticity - decrease numbers of Melanocytes and more risk of Cancer