skin structure and function Flashcards
Embryological source of Epidermis?
Ectoderm cells form the single-layered periderm.
Then the numbers of layers gradually increase.
Periderm cells are cast off.
What is the embryological origin of the dermis?
It is formed from mesoderm, below ectoderm
The emryological origin of melanocytes is ….
…the neural crest
What are the layers of the epidermis?
- keratin layer (stratum corneum)
- granular layer (stratum granulosum)
- prickle cell layer (stratum spinosum)
- basal layer (stratum basale)
What is the cause of psoriasis?
Rapid growth of keratinocytes
What type of cells are present in the basal layer?
small cuboidal cells
What cell type makes up the prickle/spineous cell layer?
larger polyhedral cells
What cell type is present in the granular layer?
cells with large heratohyalin granules
-these contain filaggrin and involucrin
What are korneocytes?
overlapping non-nucleated cell remnants
What are the important components of keratinocytes?
- 80% keratin and filaggrin
- lamellar granules which release lipids
_____ glands are associated with hairs.
sebaceous
The ___ ___ is the embryological origin of melanocytes.
neural crest
What epidermal layers are melanocytes found in?
basal layer and above
What is vitiligo?
An autoimmune disease resulting in loss of melanocytes.
-treat with phototherapy
What is albinism?
Genetic disorder resulting in loss of melanin production by melanocytes.
Nelson’s Syndrome is…
excess melanin due to melanin stimulating hormones produced by the pituitary.
Langerhans cells originate from the ____ layer in the embryo.
mesenchymal
What is the role of Langerhans cells?
Antigen presenting cells
-carry antigen from skin to lymph nodes
Merkel cells are _____
mechanoreceptors
-found in the basal layer
What is the cause of Merkel cell carcinoma?
viral infection
What is the function of the arrector pili muscle?
moving the hair shaft up
What is Telogen effluvium?
Mass progression into the Telogen phase of hair cycle
-e.g. post partum
What is Alopecia areata?
autoimmune hair loss
-destruction of hair papilla
The layers of the dermis are:
- Lamina lucida
- lamina densa
- Sub-lamina densa zone
Cause of Epidermolysis Bullosa?
Genetic
-damaged dermo-epidermal junction
Function of elastin in dermis?
provides elasticity
Dermis contains __% collagen and __% elastin
80% collagen, 4% elastin
____ corpuscles detect pressure. _____ corpuscules detect vibration.
Pacinian - pressure
Meissner - vibration
Neurofibromatosis results in the overgrowth of ___ ____
nerve endings
What is the function of the Sebaceous gland?
Secretion of sebum into the pilary canal
-become blocked in acne
Apcorine sweat glands are found in ___ and ____. They secrete ___ ____
found in Axillae and Perineum
secrete oily fluid
-function unknown
Eccrine glands are found where?
While skin surface
Functions of eccrine glands?
Cooling by evaporation
moistens soles and palms for grip
What are the metabolic functions of skin?
- Vitamin D metabolism
- Thyroid hormone metabolism
