Skin Structure and Function 3

Question 1

What is the name of the interface between the epidermis and dermis?

Answer 1

Dermo-epidermal junction

Question 2

2 groups of purposes of the DEJ?

Answer 2

Support, anchorage, adhesion, growth and differentiation of epidermal cells
Semi-permebale membrane acting as a barrier and filter

Question 3

How is the DEJ related to the above epithelium (the epidermis)?

Answer 3

It is the basement membrane

Question 4

3 parts of the DEJ?

Answer 4

Lamina lucida
Lamina densa
Sub-lamina densa zone

Question 5

What are the components of the dermis? (6)

Answer 5

Fibres (collagen, elastin)
Cells (fibroblasts, macrophages, mast cells, lymphocytes, Langerhans cells)
Ground substance
Blood vessels
Lymphatics
Nerves

Question 6

What does collagen do to the skin?

Answer 6

Makes it very strong

Question 7

What type of collagen is in the dermis?

Answer 7

Matrix of type I and type III collagen

Question 8

What does elastin do to the skin?

Answer 8

Makes it spring back into shape

Question 9

What do fibroblasts do?

Answer 9

Secrete collagen

Question 10

What is the purpose of macrophages in the dermis?

Answer 10

Scavengers, antigen presentation

Question 11

What is the purpose of mast cells in the dermis?

Answer 11

Chemical messengers

Question 12

What is ground substance?

Answer 12

A gel like substance that surrounds cells absorbing water

Question 13

What are 2 examples of ground substances?

Answer 13

Mucopolysaccharides

Glycosaminoglycans

Question 14

What are the 2 parts of the dermis?

Answer 14

Papillary dermis (thin)
Reticular dermis (thicker) - contain appendages

Question 15

How does exposure to UV light age the skin?

Answer 15

By destroying the collagen and elastin fibres

Question 16

What is solar elastosis?

What is this process known as?

Answer 16

Accumulation of abnormal elastin in the dermis of the skin, or in the conjunctiva of the eye, which occurs as a result of the cumulative effects of prolonged and excessive sun exposure = photoageing

Question 17

What are the names of the 2 plexus of blood vessels that form in the dermis?

Answer 17

Superficial vascular plexus
Deep vascular plexus
(these are horizontal plexus)

Question 18

Flow of blood from arterioles to collecting venules?

Answer 18

arterioles -> precapillarly spincters -> arterial capillaries -> venous capillaries -> post-capillary venules -> collecting venules

Question 19

What type of lymphatic vessels does lymph in the skin flow from and to?

Answer 19

smaller non-contractile vessels -> larger contractile lymphatic trunks

Question 20

Somatic sensory nerve supply of the dermis? + what they sense?

Answer 20

Free nerve endings (for pain)
Special receptors:
Pacinian (pressure/ temperature) corpuscles
Meissners (vibration) corpuscles

Question 21

What areas of the body have many meissners corpuscles?

Why?

Answer 21

Finger tips and around mouth

Very sensitive to fine touch

Question 22

What do the autonomic nerves of the dermis supply?

Answer 22

Blood vessels

Glands

Question 23

What are the 3 types of skin glands?

Answer 23

Eccrine glands
Apocrine glands
Sebaceous glands (part of the pilosebaceous unit)

Question 24

Are sebaceous glands hormone sensitive?

Answer 24

Yes - they are dormant pre-puberty

Question 25

What do sebaceous glands produce?

Answer 25

Sebum

Question 26

What is sebum made up of? (4)

Answer 26

Squalene Wax esters Triglycerides Free fatty acids

Question 27

Where do sebaceous glands mainly open onto?

Answer 27

Hair follicles

Question 28

Function of sebum? (2)

Answer 28

Control moisture loss | Protection from bacterial and fungal infection

Question 29

Where are apocrine sweat glands mainly found?

Answer 29

Sexual areas e.g. axillae, nipple and perineum

Question 30

Are apocrine sweat glands hormone dependant?

Answer 30

Yes - tend to start working at puberty

Question 31

what do apocrine sweat glands produce?

Answer 31

An oily fluid that smells after bacterial decomposition - "scent gland"

Question 32

Do apocrine or eccrine sweat glands open onto the hair follicle?

Answer 32

apocrine

Question 33

Where are eccrine sweat glands found?

Answer 33

Everywhere although the palm, soles and axillae in particular (not found in lips and genitals)

Question 34

What nerve supply do eccrine glands receive? | Stimulation?

Answer 34

Sympathetic cholinergic nerve supply | Mental, thermal and gustatory (taste) stimulation

Question 35

How many eccrine sweat glands does the body have?

Answer 35

2 - 4 million

Question 36

3 functions of sweat? - eccrine sweat glands

Answer 36

Cooling by evaporation (combination of slat and water causes sweat to evaporate) Moistens palms/ soles to aid grip Salt loss