Anatomy and Function of Skin Flashcards Preview

10. Dermatology > Anatomy and Function of Skin > Flashcards

Flashcards in Anatomy and Function of Skin Deck (16)
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1

List the 4 layers of the skin.

What other 3 structures are found in the skin?

Epidermis
Basement membrane
Dermis
Subcutaneous tissue

Glands
Hair follicles
Capillaries

2

List the 4 layers of the epidermis, from outer to inner.

Stratum corneum
Stratum granulosum
Stratum spinosum
Stratum basale

3

What is the embryological origin of the skin?

Ectoderm

4

Describe the embryological development of the skin. This occurs at 5 different stages.

Consider:
a) When are the skin layers formed?
b) How are additional skin structures formed?
c) Where do melanocytes come from?

Week 5:
-Single layer of cuboidal epithelium

Week 7:
-Periderm (single layer of squamous epithelium)
-Basal layer of cuboidal epithelium

Month 3:
-Epidermal proliferation into dermis forms hair follicles and sweat glands
-Cells in epithelial root sheath proliferate to form a sebaceous gland bud

Month 4:
-Periderm of squamous epithelium
-Intermediate layer of several cell layers
-Basal layer of cuboidal epithelium

Early foetal period:
-Melanoblasts invade epidermis from the neural crest

5

What is the normal pH of the skin?

Why?

pH 5.4

Presence of lactic acid, amino acids

6

What is the most important immune cell in the skin?

Where is it usually found?

Briefly describe its function.

Langerhans cells

Location: stratum basale

Function:
Antigen presentation to T cells in local lymph nodes

7

List the 3 functions of the skin.

Give 3 examples of each.

1. Protection, e.g.
PHYSICAL:
Mechnical impact
Pressure
IMMUNOLOGICAL:
Micro-organisms

2. Regulation, e.g.
Temperature
Fluid balance
Vitamin D

3. Sensation, e.g.
Temperature
Touch
Pain

8

Briefly describe the effects of UV light on the skin. (4)

1. Direct cellular damage, e.g.
a. Photoaging
b. DNA damage
c. Carcinogenesis
d. Loss of normal protective function against UV

2. Altered immunological functions

3. Impaired DNA repair
a. p53 mutations may lead to cancer

4. Long term skin changes

9

List 7 long term skin changes as a result of UV light damage.

Loss of skin elasticity
Increased fragility of skin
Abnormal pigmentation
Haemorrhage of blood vessels
Wrinkles
Premature aging
Easy bruising

10

List 5 types of receptor in the skin.

Consider their structure.

Encapsulated nerve endings:
1. Meissner corpuscles
2. Ruffini's corpuscles
3. Pacinian corpuscles

Free nerve endings:
4. Merkel cells
5. Free nerve endings

11

Consider the 3 types of encapsulated receptors in the skin. For each, what is its:

a) Location?
b) Function?

Meissner corpuscles
Location: below basement membrane
Function: light touch

Ruffini's corpuscles
Location: dermis
Function: deep pressure; stretching

Pacinian corpuscles
Location: deep dermis
Function: deep touch; rapid deformation of skin; proprioception

12

Consider the 2 types of free nerve ending receptors in the skin. For each, what is their:

a) Location?
b) Function?

Merkel cells
Location: stratum basale
Function: gentle/localised pressure

Free nerve endings
Location: throughout skin
Function: pain; temperature

13

Describe the process of vitamin D synthesis in the skin. (2)

1. Solar UBV photons are absorbed by 7-dehydrocholesterol in skin
a. This is converted to pre-vitamin D3

2. Pre-vitamin D3 is converted into active vitamin D3 in the plasma membrane of skin cells

14

List 4 long term consequences associated with vitamin D deficiency.

Increased risk of common cancers
Increased risk of autoimmune disease
Increased risk of infectious disease
Increased risk of cardiovascular disease

15

Describe the process of allergy in the skin. (3)

1. Irritants/allergenic compounds are taken up by Langerhans cells, which migrate to lymph nodes

2. Langerhans cells present antigens to T cells

3. T cells then mount an immune response against the allergen

16

What is the difference between initial exposure and repeat exposure in skin allergy?

Initial sensitisation: takes 10-14 days for a reaction to occur

Repeat exposure: reaction occurs within hours