Structure and Function Flashcards
Roughly how many skin diseases are known?
> 2000
Describe the difference between the EPIDERMIS and the DERMIS
Epidermis = outer layer of stratified squamous epithelium
Dermis = below epidermis, made of connective tissue, often described as “leather”
In terms of embryology, where does the epidermis come from?
the ectoderm
In terms of embryology, where does the dermis come from?
The mesoderm
What part of the embryo do melanocytes (pigment cells) come from?
The neural crest
What layers of the skin are present at week 4 of foetal development?
Periderm
Basal Layer
Dermis
What layers of the skin are present at week 16 of foetal development?
Keratin Layer Granular Layer Prickle Cell Layer Basal Layer Dermis
melanocytes also migrate from neural crest
What layers of the skin are present at week 26 of foetal development?
Epidermis Appendages Dermo-epidermal junction Dermis Subcutis (Fat)
Name the appendages found in the epidermis and dermis of the skin
melanocytes
sebaceous gland
hair follicle
arector pili muscle
What is the function of the arector pili muscle in animals?
Controls temperature
Muscle contraction allows animal to stand its fur on end to decrease temp
What are Blaschko’s Lines?
growth patterns of skin that do not follow nerves/vasculature/lymphatics
e.g if a rash were to start at the nipple and progress down the inner arm
If a patient displays a rash in a developmental pattern, what can be assumed about their condition?
It was acquired pre-natally
During what week of foetal development could a mutation occur which causes all cells in a specific section to be affected?
Week 11
What type of epithelium is found at the epidermis and how thick is it?
Stratified squamous epithelium
~ 1.5 mm thick
What type of cell predominantly makes up the epidermis?
95% epidermis = keratinocytes
Name 3 other types of cell found in the epidermis
Melanocytes
Langerhans cells
Merkel cells
What is the function of the thick layer of keratin on the surface of the epidermis?
Thick layer of keratin = dead skin cells from proliferation
Stops water and bacteria penetrating the skin
Describe the epidermal variation between the scalp, the armpit and the palms of hands/sole of the foot
Scalp = hair, normal amount of sweat glands Armpit = hair, extra apocrine sweat gland adjacent to hair follicle (produces smell) Hands/feet = no hair , but extra sweat glands
Give an example of “mechanical trauma” that would cause calluses to develop on the hands
playing guitar
Describe the ratio of epidermis to dermis in the skin of the abdomen
EPIDERMIS = thin
DERMIS - thick
What 3 factors regulate skin growth?
Growth Factors
Cell Death
Hormones
Name conditions where the predominant feature is a loss of control of skin growth
Cancer
Psoriasis
What produces the thick scabs in psoriasis?
Cells multiply too quickly and skin grows too fast
layer of keratin on surface is larger and does not fall off
=> leaving behind scabs
Where do keratinocytes come from?
The basement membrane
