Skin Structure and Function 3 Flashcards
What is the name of the interface between the epidermis and dermis?
Dermo-epidermal junction
2 groups of purposes of the DEJ?
Support, anchorage, adhesion, growth and differentiation of epidermal cells
Semi-permebale membrane acting as a barrier and filter
How is the DEJ related to the above epithelium (the epidermis)?
It is the basement membrane
3 parts of the DEJ?
Lamina lucida
Lamina densa
Sub-lamina densa zone
What are the components of the dermis? (6)
Fibres (collagen, elastin) Cells (fibroblasts, macrophages, mast cells, lymphocytes, Langerhans cells) Ground substance Blood vessels Lymphatics Nerves
What does collagen do to the skin?
Makes it very strong
What type of collagen is in the dermis?
Matrix of type I and type III collagen
What does elastin do to the skin?
Makes it spring back into shape
What do fibroblasts do?
Secrete collagen
What is the purpose of macrophages in the dermis?
Scavengers, antigen presentation
What is the purpose of mast cells in the dermis?
Chemical messengers
What is ground substance?
A gel like substance that surrounds cells absorbing water
What are 2 examples of ground substances?
Mucopolysaccharides
Glycosaminoglycans
What are the 2 parts of the dermis?
Papillary dermis (thin) Reticular dermis (thicker) - contain appendages
How does exposure to UV light age the skin?
By destroying the collagen and elastin fibres
What is solar elastosis?
What is this process known as?
Accumulation of abnormal elastin in the dermis of the skin, or in the conjunctiva of the eye, which occurs as a result of the cumulative effects of prolonged and excessive sun exposure = photoageing
What are the names of the 2 plexus of blood vessels that form in the dermis?
Superficial vascular plexus
Deep vascular plexus
(these are horizontal plexus)
Flow of blood from arterioles to collecting venules?
arterioles -> precapillarly spincters -> arterial capillaries -> venous capillaries -> post-capillary venules -> collecting venules
What type of lymphatic vessels does lymph in the skin flow from and to?
smaller non-contractile vessels -> larger contractile lymphatic trunks
Somatic sensory nerve supply of the dermis? + what they sense?
Free nerve endings (for pain)
Special receptors:
Pacinian (pressure/ temperature) corpuscles
Meissners (vibration) corpuscles
What areas of the body have many meissners corpuscles?
Why?
Finger tips and around mouth
Very sensitive to fine touch
What do the autonomic nerves of the dermis supply?
Blood vessels
Glands
What are the 3 types of skin glands?
Eccrine glands
Apocrine glands
Sebaceous glands (part of the pilosebaceous unit)
Are sebaceous glands hormone sensitive?
Yes - they are dormant pre-puberty
What do sebaceous glands produce?
Sebum
What is sebum made up of? (4)
Squalene
Wax esters
Triglycerides
Free fatty acids
Where do sebaceous glands mainly open onto?
Hair follicles
Function of sebum? (2)
Control moisture loss
Protection from bacterial and fungal infection
Where are apocrine sweat glands mainly found?
Sexual areas e.g. axillae, nipple and perineum
Are apocrine sweat glands hormone dependant?
Yes - tend to start working at puberty
what do apocrine sweat glands produce?
An oily fluid that smells after bacterial decomposition - “scent gland”
Do apocrine or eccrine sweat glands open onto the hair follicle?
apocrine
Where are eccrine sweat glands found?
Everywhere although the palm, soles and axillae in particular (not found in lips and genitals)
What nerve supply do eccrine glands receive?
Stimulation?
Sympathetic cholinergic nerve supply
Mental, thermal and gustatory (taste) stimulation
How many eccrine sweat glands does the body have?
2 - 4 million
3 functions of sweat? - eccrine sweat glands
Cooling by evaporation (combination of slat and water causes sweat to evaporate)
Moistens palms/ soles to aid grip
Salt loss
