Structure/ function of the skin Flashcards
How are the blood vessels arranged in the epidermis?
-In 3 layers
Top ones= help with heat regulation, supply epidermis and upper hair follicle
Middle layer= serves the glands, erector pili muscles, mind hair follicles
Bottom layer= helps with hair growth, lower hair follicle
On a histological image what wraps around the sebaceous glands?
-Erector pili muscles
What is the predominant cell type of the hypodermis?
Lipocytes (adipose cells)
Why is the hypodermis susceptible to disease?
Poorly vascularised
In which layer of the skin are insoluble fibres and soluble polymers found and what is their role?
- Dermis
- Insoluble fibres: collagen and elastin: give tensile strength
- Soluble polymers: proteoglycans and hyaluronan: resist/ absorb compressive forces
Describe the motor nerves of the skin
-Adrenergic and cholinergic fibres
What causes an itch?
-Cytokines and chemokines e.g. Il-31 and TSLP
What are epitrichial glands?
- Sweat glands that are associated with a hair follicle
- They are located below the sebaceous gland
What are atrichial glands?
- Sweat glands not associated with a hair follicle.
- Found on the paws/ nose of carnivores
List some of the specialised sweat glands
- Mammary glands
- Interdigital glands of small ruminants
- External ear canal
Which layer of the epidermis is often absent in haired skin?
The stratum granulosum
also stratum lucidum
Which species have epidermal rete ridges?
- Pigs
- Horses (mane and base of tail)
Describe keratinocytes
- Large with a complex cytoskeleton
- Cytoskeleton includes actin
- Cytoskeleton attached to tight junctions (cell - cell), desmosomes (cell-cell), desmosomes (cell-dermal proteins)
- K14 and K5 in basal layers
- K10 in upper layers
- Kcs differentiates under influence of Ca
Which layer of the epidermis has a stem cell function?
Stratum basale
What are the signs of transglutaminase 1 mutation in jack russels?
- Severe hyperkeratosis
- Cornified evelopes are thin
Where are melanocytes derived from?
The neural crest
What are the two types of melanin?
- Eumelanin: black- brown
- Phaeomelanin: reddish yellow
Whats the name of the pigment that melanocytes produce?
Melanosome - they send out dendrites to push packets of melanosomes to the cell to protect the nuclei from UV light
What are Langerhans cells?
- Antigen presenting cells
- Activate T-lymphocytes
Where does the sebaceous gland attach to the hair follicle?
-At the isthmus
What’s the different between a simple/ compound hair follicle?
Simple= single hair from 1 orifice Compound= multiple hairs from same orifice
What regulates the hair cycle?
- Photoperiod
- Temperature
- Hormones
- Nutrition
What effect do different hormones have on the hair cycle?
- Thryoid= +
- Growth homrones= +
- Oestrogen= -
- Corticosteroids= -
Describe catagen
- Occurs in mid dermis
- Involution of hair bulb/ dermal papilla
- Upward migration of follicle and papilla
- Develops a thick glassy membrane
