T1: Structure and function of skin, hair, nails Flashcards
1
Q
Skin
General
A
- largest organ in body
- weighs 4kg
- covers 2m²
2
Q
Skin
Skin layers
A
- epidermis
- dermis
- hypodermis
3
Q
Skin: epidermis
Epidermal layers
A
- stratum corneum: horny cell layer, dead keratinocytes found here
- stratum granulosum
- stratum spinulosum: prickle cell layer, langerhans cells found here
- stratum basale: melanocytes found here, separated from dermis by BM
4
Q
Skin: epidermis
Melanocytes
A
- dendritic cells
- basal cell layer
- melanosomes: all skin colours have equal melanocytes but size of melanosomes differ (light = small, dark = big)
- VITILIGO: melanocytes killed over time, can’t produce melanosomes
- ALBINISM: tyrosinase enzyme def (no melanin)
5
Q
Skin: epidermis
Langerhans cells
A
- bone marrow derived immune cells
- stratum spinosum
- alert immune system if you come into contact with infection/allergen
6
Q
Skin: epidermis
Merkel cells
A
- neuroendocrine cell
- basal cell layer
- touch receptor
7
Q
Skin: dermis
Structures
A
- collagen
- elastin
- proteoglycan
- fibroblast
- macrophages
- mast cells
- neurovascular bundles (blood vessels, nerves, lymhatics)
- adnexal structures
8
Q
Skin: subcut tissue
General
A
- made up of lobules, septae
- contain blood vessels, nerves, lymphatics
- shock absorber
- heat insulator
9
Q
Skin: muscles
Smooth
A
- arrector pili muscles
- attached to hair follicle below sebaceous glands, pull up hair when goosebumps for better insulation
- scrotum, areola
10
Q
Skin: muscles
Skeletal
A
- forehead
- eyelid
- lip
- neck
- cross-striations
11
Q
Skin
Functions
A
- mechanical barrier: physical, chemical, biological, other noxious substances
- body temperature regulation
- immunological organ
- electrolyte regulation (sweating)
- vit d synthesis
- social + sexual interactions – skin is what other people see
12
Q
Hair
Structures
A
- infundibulum: acne = area keratinised and clogged
- sebaceous gland: provides oily layer around hair for protection
- isthmus: between sebaceous gland and bulge
- bulge: bone marrow of hair, multipotent hair stem cells, kill area = dead forever
- dermal papilla: where hair grows from
13
Q
Hair
Cycle
A
- anagen: growth phase (3 yrs)
- catagen: hair falls out (3 wks)
- telogen: resting phase (3m)
14
Q
Hair
Pigmentation
A
- melanocytes in bulb, produce melanin + melanosomes, given to keratinocytes as hair grows
- hair colour dependant on melanosome size
15
Q
Hair: glands
Sebaceous
A
- found where hair is present (not on palms+ soles)
- modified ones that open onto skin found in eyelids
- holocrine gland produces sebums (oily layer) around hair
- part of pilosebaceous unit
