Dermatology: DEJ and Structure & Function of Dermal Components

Question 1

What is the DEJ?

Answer 1

Dermo-epidermal junction is the interface between the epidermis and dermis

Question 2

Function of DEJ?

Answer 2

Key role in epithelial-mesenchymal interaction inc:

Support, adhesion, growth and differentiation of epidermal cells

Semi-permeable membrane acting as a barrier and filter

Question 3

Constituent layers of the DEJ?

Answer 3

Lamina lucida - contains collagen fibres

Lamina densa - more dense

Question 4

Two types of disease of the DEJ and examples?

Answer 4

Inherited - conditions result in skin fragility due to a mutated protein in the DEJ, e.g: epidermolysis bullosa (simplex or dystrophic)

Acquired - auto-antibodies produced to proteins in the DEJ, e.g: epidermolysis pemphigus, pemphigoid, dermatitis herpetiformis

Question 5

What is Bullous pemphigoid?

Answer 5

An autoimmune disease where an antibody is produced against the lamina lucida; this is an acquired blistering disorder

Question 6

What are Epidermolysis Bullosa simplex and dystrophica?

Answer 6

Genetic disease resulting in attack on the protein of the lamina densa

Features of DES include mittening and lack of fine function of hands

Question 7

Components of the dermis?

Answer 7

Cells, e.g: mainly fibroblasts (which make collagen), macrophages, mast cells, lymphocytes, Langerhan cells

Fibres (mainly collagen but also elastin)

Ground substance (consists of proteins that absorb water, e.g: GAGs)

Blood vessels, lymphatics, nerves

Question 8

Functions of the cells in the dermis?

Answer 8

Fibroblasts secrete collagen

Macrophages are scavengers and are involved with antigen presentation

Lymphocytes are involved with immune reactions

Langerhan cells (also present in the epidermis) and involved with antigen presentation

Mast cells are chemical messengers

Question 9

What is dermographism and how does it occur?

Answer 9

Exaggerated wealing tendency when the skin is stroked; this can be due to mast cell proliferation and activation resulting in excessive histamine release

Question 10

What is photoaging?

Answer 10

Characteristic change to skin induced by chronic UVA and UVB exposure which can cause collagen degradation

Question 11

Cause of angiomas?

Answer 11

Localised overgrowth of blood vessels; histology will show many rbcs and dilated vascular spaces

Question 12

Somatic sensory nerve supply in the skin?

Answer 12

Supplied in dermatomal pattern; there are:

Free nerve endings

Special receptors like Pacinian (for pressure sensations) and Meissners (vibration) corpuscles

Question 13

Autonomic nerve supply in skin?

Answer 13

To blood vessels, nerves and glands

Question 14

Label the sensory and motor nerves, as well as the corpuscles?

Answer 14

Question 15

What is neurofibromatosis?

Answer 15

Rare disease that is either inherited or caused by spontaneous mutation; there is nerve proliferation resulting in neurofibromas appearing on the skin

Question 16

3 types of skin glands?

Answer 16

Sebaceous glands - part of the pilosebaceous unit and open on to a hair follicle

Eccrine glands

Apocrine glands

Question 17

Distribution of sebaceous glands and functions?

Answer 17

Widely distributed, with the largest glands being present on the face, chest and back; they are hormone-sensitive and so are quiescent pre-puberty

They produce sebum, control moisture loss and provide protection against bacterial and fungal infection

Question 18

Label the pilosebaceous unit?

Answer 18

Question 19

Cause of acne?

Answer 19

Mixture of increased sebum, blocked ducts and bacterial activity

Question 20

Apocrine glands function and location?

Answer 20

Develop as part of the pilosebaceous unit, mainly in the sexual regions, e.g: axillae and perineum; they are androgen-dependent and produce an oily fluid that has an odour, following bacterial decomposition

Question 21

Eccrine glands function and location?

Answer 21

Empty directly onto and along the whole skin surface, particularly at the palms, soles and axillae; they have a sympathetic cholinergic nerve supply

They cool the body by evaporation and moisten palms/soles to aid grip

Question 22

Label the 3 different types of glands?

Answer 22

Question 23

Label the image of skin and a hair follicle?

Answer 23

Question 24

Label the image of the DEJ?

Answer 24

Question 25

Label the components of the dermis?

Answer 25