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Physiology and Pharmacology > The Integumentary System > Flashcards

The Integumentary System Flashcards

1
Q

integumentary system key points

A

skin and accessory organs: hair, nails and cutaneous glands
largest organs. - 12-15% body weight
regulates fluid loss, barrier to external envirnoment
often can indicate underlying issues

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2
Q

structure - layers

A

epidermis = upper most layer
dermis
(hypodermis - areolar (loose arrangement of collagenous tissue with elastin fibres) or adipose tissue between skin and muscle - not actually skin)

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3
Q

dermis

A

connective tissue, beneath epidermis
thicker than epidermis 0.2-2mm
mainly collagen with elastic and reticular fibres, 2 zones (unclear boundary)

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4
Q

zone 1 of dermis

A

papillary layer

thin region of loose connective tissue (areolar) allowing mobility of leukocytes, mast and macrophage cells

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5
Q

zone 2 of dermis

A

reticular layer
thick layer of dense irregular connective tissue, less cells, but often with adipocyte clusters
stretching of skin causes striae = stretch marks

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6
Q

fibroblasts

A

porduce proteins, laminin and fibronectin of ECM

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7
Q

accessory organs

A

hair, nails, oil and sweat glands - all in dermal layer
rich layer of blood and lymphatic vessels
includes arteriovenous anastomoses - important in thermoregulation
numerous nerve endings

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8
Q

dermal - epidermal boundary

A 
wavy boundary of finger like projections increasing connection to:
dermal papille (raised areas e.g. finger prints) - pointing towards outside
epidermal ridges - point into body

tall dermal papille facilitate nerve fibres reaching close to surface in highly sensitive areas

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9
Q

epidermis

A

keratinised stratified sqaumous epithelium

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10
Q

skin types

A

thick - palms, feet, no hair, 5 layers of stratum

thin - rest of body, 4 layers

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11
Q

layers of stratum

A

basale
spinosum
granulosum
(lucidum - only in thick skin)
corneum
- lack blood vessels, diffusion from underlying connective tissue
- self regernation throughout life cycle, 2-4 weeks

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12
Q

cells of epidermis (5)

A 
stem cells
keratinocytes
melanocytes
langerhans
mencel cells
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13
Q

stem cells in epidermis

A

give rise to keratinocytes only in deepest layer of epidermis, in contact with basement mem, maintain ability to replicate

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14
Q

keratinocytes in epidermis

A

80-90% cell composition of epidermis, make keratin

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15
Q

melanocytes in epidermis

A

synthesis melanin

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16
Q

langerhans in erpidermis

A

dendritic cells of skin, originate in bone marrow

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17
Q

mencel cells in epidermis

A

touch receptors, in contact with dermal nerve fibres

18
Q

stratum basale

A

aka germinativum
single layer of cuboidal cells (low columnar cells)
keratinocytes most prevalent, mitotically active on basement mem
melanocytes = skin colour = pheomelanin - red soluble pigment e.g. lips, eumelanin - brown insoluble pigment
tactile/mecel cells = connected to sensory nerves

19
Q

melanocytes

A

release melanin - UV absorbent, antioxidant and radial scavenging - protect the skin from UV damage
melanin providing pigment depends on:
carotene pigment (orange/yellow) in subcutaneous fat and stratum corneum - in heels of feet
amount of blood and oxygen content
melanosomes - branching process, phagocytoses by keratinocytes to surround nucleus sun side - to protect from radiation

20
Q

stratum spinosum

A

several layers of keratinocytes
usually thickest layer, except in thick skin
deepest mitotic cell, pushed up and cease to divide - become more squamous
produce keratin filamentscausing cells to flatten (more in upper layers)
KCs stronly linked by desmosomes
tight junctions ensure water retention
dendritic cells present

21
Q

stratum granulosum

A

3-5 layers of flats keratinocytes
post-mitotic, bound by tight junctions
contain dark staininng keratohyalin granules (cytoplasmic organelles packed with electron dense proteins), which bind to cytoskeleton and converted to keratin by transglutaminases
cells undergo apoptosis
produce glycoplipid filled vesicles - spread over cells surface, forms waterproof barrier between spinosum
tight junctions contribute to epithelial barrier by preventing leakage of solutes

22
Q

stratum lucidum

A

mechanincal barrier against damage
only in thick skin
thin transleucent zone
contains keratinocytes, densely packed, no nuclei/organelles
indistinct cell boundaries
granules of eledin in proteoplasm - product of keratohyalin
surrounded by oily layer

23
Q

stratum corneum

A

most superficial - 15-30 layers
upper terminally differentiated dead keratinocytes - these undergo desquamation, comes off as ‘dead skin’
stratum disjunction beneath apical acid mantle and lipid barrier
stratum compactum - cohesive
cornified envelope: keratins, enclosed within amalgam of proteins, cross linked by transglutaminases
surounded by lipid envelope

24
Q

accessory structures

A

nails
hair
glands

25
Q

nails

A

derivatives of stratum corneum, nail invaginates into finger, flat in primates
composed of dead scaly cells, densely packed with ‘hard’ keratin fibres
new cells added by mitosis in nail matrix - 1mm a week
appearance can indicate health issues
e.g. iron deficieny = flat/concaved nails
long term hypoxemia = clubbed

26
Q

hair

A

slender filaments of keratinised (dead) cells from follicle
found almost everywhere
changes during lifetime:
foetus = lanugo hair - fine, downy, unpigmented
velus hair = similarly fine and umpigmented
terminal hair = longer, coarser, pigmented

27
Q

hair follicle

A 
bulb grows around bud of vascular connective tissue: dermial papilla
hair matrix above = mitotically active
3 layer:
medulla - loosely arranged cells
cortex - keratinised cuboidal cells
cuticle - surface, scaly cells
28
Q

glands in skin

A

skin can be moist, sebaceous or neither depending on glands in that area
sebaceous - secrete lipids, antibacterial layer

29
Q

5 types of skin glands

A 
merocrine
apocrine
sebaceous
ceruminous
mammary
30
Q

merocrine glands

A

sweat glands
cuboidal, single layer
watery perspiration to skin associated with myoepithelial cells

31
Q

apocrine glands

A

sweat
ducts lead to follicles
‘scent’ glands, respond to stress and sexual stimulation

32
Q

sebaceous glands

A

oily sebum

lubricates skin and hair

33
Q

ceruminous glands

A

external ear - wax

34
Q

mammary glands

A

in females

35
Q

barrier function of skin

A

prevent water loss, physcial injury and infection by mircobes
physical barrier = cross linekd keratin layer on scaffold of keratinocytes
biochemical barrier = slightly acidic, ph 4-6, bactericidal agents: saturated and unsaturated fatty acids inhibit growth of bacteria and lysozyme cleaves cross linkage in bacterial cell walls - cis-6-hexadecanoic (C6H) can inhibit induction of antibiotic resistance

36
Q

immunological barrier of skin

A

langerhans cells in stratum spinosum
able to self renew, take up and process antigens:
- migrate to lymph nodes for antigen presentation
or
- present antigens to skin lymphocytes - which circulate to secondary lymphoid organs, activating immune response

37
Q

temperature regulation - integumentary system

A

apical skin - areas that can divert blood straight to venous side, stop blood perfusing to surface or can encourage it too, therefore releasing heat or locking it away
less blood to apical skin = reduce heat loss
e.g. nose, lips, ears

38
Q

skin in thermoregulation

A

thermoreceptors in epidermis
counter current heat exchange between arterial and veous blood flow in extremities
over perfused for nutritional requirements: true capillaries provide nutrition, arteriovenous anastomoses assist in thermoreg.
hypothalamus regulates ANS

39
Q

anastomoses

A

connection between tubular structures e.g. blood vessels

40
Q

thermoregulation

A

dectection = hypothalamus
piloerection = hairs stand up = insulation
constriction or vasdilation of anastomoses
merocrine sweat glands cool body by evaporation

41
Q

overall pathway:

increased body temperature

A

e.g. when exercising
hypothalamus detects change
sweat glands activated = evaporation
skin blood vessels dilate = capillaries fill woth warm blood and heat radiates from skin
body temp decreases and hypothalamus returns to normal

42
Q

overall pathway:

decrease in body temperature

A

e.g. going outside
hypothalamus detects change
skeletal muscles activated = shivering generates more heat
skin blood vessels constrict = blood diverted from skin to deeper tissues - reducing heat loss from surface
body temp increases and hypothalamus shuts off

Physiology and Pharmacology (17 decks)

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