CH 5: Intergymentary System Flashcards
1
Q
intergumentary system
A
- skin
- hair
- oil and sweat glands
- nails
- sensory receptors
2
Q
skin
A
- aka cutaneous membrane
- largest organ in the body
- about 22 feet squared (2 metre squared)
- 1-2mm thick on average
- weighs about 10lbs (4.5kg)
3
Q
organ
A
two or more tissues that work together (epithelial, connective, muscular, nervous)
4
Q
skin - functions
A
- thermoregulation
- blood reservoir
- protection
- cutaneous sensations
- synthesis of vitamin D
- excretion and absorption
5
Q
thermoregulation
A
- homeostatic regulation of body
- lowering body temperature
- perspiration: heat released with sweat evaporation
- vasodilation: increase in blood flow in dermis
more blood in dermis –> more heat loss –> cooling effect
- raising internal body temperature
- vasoconstriction of surface vessels
- decreased sweat production
- contraction of skeletal muscles
6
Q
perspiration
A
- heat released with sweat production
- means of thermoregulation - lowering body temperature
7
Q
vasodilation
A
- increases blood flow in the dermis: more blood in dermis –> more heat loss –> cooling effect
- means of thermoregulation - lowering body temperature
8
Q
lowering body temperature
A
- means of thermoregulation
- perspiration: heat released with sweat evaporation
- vasodilation: increase in blood flow in dermis
more blood in dermis –> more heat loss –> cooling effect
9
Q
raising internal body temperatures
A
- means of thermodynamics
- vasoconstriction of surface vessels
- decreased sweat production
- contraction of skeletal muscles
10
Q
blood reservoir
A
- due to large number of blood vessels in the dermis, the skin acts as a blood reservoir
- carries 8-10% of tot blood in a resting adult
11
Q
factors providing protection to the skin - list
A
- keratin
- lipids
- sebum
- acidic pH (pH 5.5)
- melanin pigment
- two types of macrophages that help fight pathogens: Langerhan cells and dermal macrophages
12
Q
factors providing protection to the skin
A
- keratin
- protects underlying tissues from microbes, heat, abrasion, chemicals
- lipids
- slow evaporation and prevent dehydration
- restricts entry of water and other chemicals
- sebum
- prevents skin and hair from drying out
- contains bactericidal chemicals
- acidic pH (pH 5.5)
- prevents growth of some microbes
- melanin pigment
- shields against damaging rays of UV light
- two types of macrophages that help fight pathogens:
- Langerhan cells: intraepidermal macrophages that alert the immune system - they are dendritic cells
- dermal macrophages: engul microbes that have invaded past the epidermis
13
Q
keratin
A
protects underlying tissues from microbes, heat, abrasion and chemicals
14
Q
lipids
A
- slow evaporation and prevent dehydration
- restrict entry of water and other chemicals
15
Q
sebum
A
- prevents skin and hairs from drying out
- contains bactericidal chemicals
16
Q
acidic pH of 5.5
A
prevents growth of some microbes
17
Q
melanin pigment
A
shields against damaging rays of UV light
18
Q
types of macrophages that help fight pathogens
A
- Langerhans cells: intradermal macrophages that alert the immune system
- dermal macrophages: engulf microbes that have invaded past the epidermis
19
Q
Langerhans cells
A
- intradermal macrophages that alert the immune system
- make about 5% of epidermis
- type of dendritic cell
20
Q
dermal macrophages
A
engulf microbes that have invaded past the epidermis
21
Q
cutaneous sensations
A
- sensations that arise in the skin
- skin contains many receptors for:
- tactile sensations (touch, pressure, vibration and tickling)
- thermal sensations (hot and cold)
- pain sensations (indicates impending or actual tissue damage)
22
Q
synthesis of vitamin D
A
- requires activation of a precursor molecule in the skin by UV light
- enzymes from the liver and kidneys then modify the activated molecule to produce calcitrol (most active form of vitamin D)
23
Q
calcitriol
A
most active form of vitamin D
24
Q
excretion and absorption
A
- > 600mL of water, small amounts of salt, CO2, ammonia and urea are excreted through the skin
- drugs can be administered transcutaneously (patches and creams)
25
skin - general structure
- epidermis
- dermis
- hypodermis (not skin)
26
epidermis
- makes skin
| - made of keratinized stratified squamous epithelium
27
dermis
- makes skin
| - primarily dense irregular connective tissue, with nervous and muscle tissues
28
hypodermis
- does not make skin
- aka subcutaneous/subQ layer
- formed of areolar and adipose tissue
29
cells of epidermis - list
- keratinocytes
- stem cells
- melanocytes
- Langerhans cells
- tactile epithelial cells
30
keratinocytes
- main cells of epidermis (90%)
- produce protein keratin (made by ribosomes)
- produce lamellar granules
31
keratin
- tough and fibrous protein that helps protect the skin and underlying tissue from heat, microbes, chemicals and abrasion
- produced by keratinocytes
32
lamellar granules
- release waterproof sealant that protects against water entry/loss - inhibits entry of foreign materials
- produced by keratinocytes
33
stem cells
- located in basal layer of epidermis
| - constantly divide and differentiate into keratinocytes
34
melanocytes
- make 8% of epidermis
- "melano" = black
- located in basal layer of epidermis
- produce pigment melanin and transfer it into keratinocytes via melanosomes
- melanin contribute to skin colour and absorb UV light, protecting the keratinocytes from damage
35
melanin
- produced by melanocytes
| - contributes to skin colour and absorbs UV light, protecting the keratinocytes from damage
36
tactile epithelial cells
- aka Merkel cells
| - make contact with tactile discs and transmit touch sensations
37
epidermis - layer
- stratum basale
- stratum spinosum
- stratum granulosum
- stratum lucidum
- stratum corneum
38
stratum basale
- deepest layer
- single row of cuboidal or columnar keratinocytes
- contains some epidermal stem cells that continually divide and differentiate into the keratinocytes that make the more superficial layers
- contains melanocytes
- cell attachment to each other by desmosomes or to basement membrane by hemidesmosomes (attach to keratin if attachment is inside the cell)
39
stratum spinosum
- spinosum = spiny
- 8-10 layers of keratinocytes held together by desmosomes
- O2 diffuses from the dermis
- cells in more superficial layers become flattened
- provides strength and flexibility to skin
- most metabolically active layer of the skin
- keratinocytes synthesize and fill up with keratin - coarse bundles in intermediate filaments
- melanin transferred to keratinocytes by endocytosis from nearby melanocytes
40
stratum spinosum - function
- provides strength and flexibility to skin
- most metabolically active layer of the skin
- keratinocytes synthesize and fill up with keratin - coarse bundles in intermediate filaments
- melanin transferred to keratinocytes by endocytosis from nearby melanocytes
41
stratum granulosum (function included)
- 3-5 layers of flat dying cells that are undergoing apoptosis
- transitional layer (from metabolically active stratum spinosum layer to dying cells stratum granulosum layer to dead cells more superficial layer)
- contains lamellar granules that release lipid-rich secretions
- water repellant sealant
- secretions fill up the spaces between dead cells of the stratum granulosum, stratum lucidum and stratum corneum
42
apoptosis
programmed cell death
43
stratum lucidum
- lucid = clear
- present only in thick skin
- fingertips, palms of hands, soles of feet, plantar surface of toes
- 4-6 layers of clear, flat dead cells (keratinocytes)
- contains large amounts of keratin and thickened cell membranes
44
stratum corneum
- corne = horn or horny
- 25-30 layers of flattened dead cells filled with keratin and surrounded by lipids (water-repellant)
- keratinocytes surrounded by secretions of the lamellar granules
- cells have thin flat plasma membranes surrounding packages of keratin
- continuously sloughed off
- serves as barrier to injuries, heat, water, chemicals and microbes
45
stratum corneum - function
serves as barrier to:
- injuries
- heat
- water
- chemicals
- microbes
46
types of skin
- thin skin
| - thick skin
47
thin skin
- epidermis is 0.10-0.15mm thick
- covers most of the body
- lacks a stratum lucidum + has thinner strata spinosum and corneum
- lacks epidermal ridges and has fewer sweat glands and sensory receptors
- hair and sebaceous glands are present
48
thick skin
- epidermis is 0.6-4.5mm thick
- found only on palms of hands and soles of feet
- distinct stratum lucidum and thicker stratum corneum
- lacks hair follicles and sebaceous glands
49
keratinization and growth of epidermis
1. stem cells divide and differentiate into keratinocytes
2. as the keratinocytes are pushed towards the surface, they fill with keratin
3. as the keratinocytes move farther away from the blood supply, they receive less and less nutrients and eventually die (apoptosis)
- whole process from where cells form in stratum basale, rise to surface, become keratinized and slough off, takes about 4 weeks
- hormones like EGF (epidermal growth factor) controls this process
50
keratinization
replacement of cell contents with keratin protein occurs as cells move to the skin surface
51
keratinized cells
dead cells that are filled with keratin
52
dermis
- is connective tissue layer composed of:
- collagen and elastic fibers
- fibroblasts
- macrophages
- adipose cells
- contains hair follicles, glands, nerves and blood vessels
- has 2 regions:
- papillary region (top 20%)
- reticular region (bottom 80%)
53
papillary region
- top 20% of dermis
- composed of areolar connective tissue containing thin collagen and fine elastic fibers
- elasticity
- contains capillaries that supply the epidermis with blood
- contains receptors for sensations of cold, pain, vibration, fine touch, tickle and itch
- finger-like prejections called dermal papillae project into the undersurface of the epidermis
- increase SA for anchoring the epidermis to the dermis
- contain capillary loops
- epidermal ridges determine pattern of fingerprints
54
dermal papillae
finger-like projections that project into the undersurface of the epidermis
- increase SA for anchoring the epidermis to the dermis
- contain capillary loops
55
epidermal ridges
determine patter of fingerprints
- conforms to the pattern of the dermal papillae
- increase grip of the hand or foot by increasing friction
- increase SA --> increase # of corpuscles of touch --> increased tactile sensitivity
- open sweat glands on ridges = finger/footprints
56
reticular region
- bottom 80% of dermis
- composed of dense irregular connective tissue and some coarse elastic fibers
- contains interlacing collagen and elastic fibers
- gives skin strength, extensibility, and elasticity
- packed with oil glands, sweat gland ducts, fat, and hair follicles
- stretch marks are dermal tears from extreme stretching
57
stretch marks
dermal tears from extreme stretching
58
melanin - pigment
- ranges from pale yellow to reddish-brown to black
- produced in epidermis by melanocytes
- everyone has same # of melanocytes: difference in skin colour is due to difference in amounts of melanin produced
- combinations of genetics and environment
- exposure to UV light increases production of melanin
- protective mechanism: melanin protects DNA by absorbing UV radiation
59
melanin pigment - function
protective mechanism: melanin protects DNA by absorbing UV radiation
60
tattooing
- permanent coloration of skin in which a foreign pigment is injected into the skin
- in the dermis: is stable as there is no rate of turnover
61
epidermal wound healing - abrasions/minor burns
1. basal cells divide and migrate across the wound
- they synthesize new basement membrane along the way
- contact inhibition with other cells stops migration
2. basal cells then differentiate into keratinocytes and the epidermis gets regenerated upwards
- cell division is more rapid than normal skin cell division
- the full thickness of the epidermis is restored as a resurt of further cell division
62
scar formation
when injury extends past the epidermis into the dermis and the SQ layer - repair process is more complex
63
deep wound healing - stages
- inflammatory phase
- cleans and prepares the area for repair
- repair phase
- repairs the dermis and epidermis
- scar tissue is formed
64
deep wound healing - inflammation
1. cells near injury site secrete signaling molecules
- includes mast cells and Langerhans cells
2. signaling molecules:
- dilate blood vessels via vasodilation
- attract phagocytes by chemotaxis
3. phagocytes squeeze out between blood vessel endothelial cells = extravasation
4. phagocytes ingest bacteria and cell debris
- platelets form a clot which prevents spreading of infection
65
vasodilation
dilating of blood vessels
66
chemotaxis
means by which phagocytes are attracted in case of an inflammation
67
extravasation
phagocytes squeeze out between blood vessel endothelial cells
68
deep wound healing - repair
1. blood clot forms
2. blood vessels reform
3. fibroblasts synthesize scar tissue
4. basal cells divide and migrate beneath scab towards each other
5. epidermis regenerates upwards
6. scab eventually falls off as regenerating epidermis pushes up
69
skin cancer - types
- basal cell carcinoma
- squamous cell carcinoma
- malignant melanomas
70
basal cell carcinoma
- 78% of all skin cancers
- arise from cells of stratum basale
- rarely metastasize
71
squamous cell carcinoma
- 20% of all skin cancers
- arise from keratinocytes in stratum spinosum
- may or may not metastasize
72
malignant melanoma
- 2% of all skin cancer - most common cancer in young women
- arise from melanocytes
- metastasize rapidly: can kill a person within months of diagnosis
- key to tx is early detection: watch for changes in ABCDE (Asymmetry, Border, Colour, Diameter, Evolving)
73
risk factors for skin cancer
1. skin type
- light-coloured skin that never tans but burns is at higher risk
2. sun exposure
- increased sun exposure (location, altitude, outdoor lifestyle)
3. family history
- some cancers are hereditary
- skin cancer rates are higher in some families than in others
4. age
- older people are more prone to skin cancers owing to longer total exposure to sunlight
5. immunological status
- immunosuppression increases risks
74
risk factors for skin cancer - list
- skin type
- sun exposure
- family history
- age
- immunological status
75
hair
- present on most skin surfaces except palms of hands and soles of feet
- all hair starts as very thin, non-pigmented, downy hairs called lanugo, which prior to birth is replaced by two types of hairs:
- terminal hairs: long, coarse, heavily pigmented hairs (ex. eyebrows, eyelashes, scalp at birth and axillary and pubic regions after puberty)
- vellus hairs: short, fine, pale hairs that are barely visible to the naked eye ("peach fuzz")
76
lanugo
- thin, non-pigmented, downy hairs (how all hairs start)
| - replaced by terminal hairs and vellus hairs prior to birth
77
terminal hairs
- long, coarse, heavily pigmented hairs
| - ex. eyebrows, eyelashes, scalp at birth and axillary abd pubic regions after puberty
78
vellus hairs
- short, fine, pale hairs that are barely visible to the naked eye
- peach fuzz
79
hair - functions
- prevents heat loss
- decreases sunburn
- eyelashes help protect eyes
- touch receptors (ex. hair root plexus) sense light touch
80
shaft
superficial portion of hair - above skin surface
81
root
portion of hair that penetrate deep into the dermis or SQ layer
82
structure of hair
- each hair is a column of dead, tightly packed, keratinized cells held together by extracellular proteins
- shaft and root consist of 3 layers of cells: medulla, cortex and cuticle
- hair follicle surrounds the root (when hair falls out, the follicle remains)
- consists of 2 layers of cells (internal and external root sheaths) and 1 layer of connective tissue (=dermal root sheath)
83
medulla
- 2-3 layers of irregular cells found in shaft and root of hair
- may be lacking in thinner hair
- may/may not contain pigment granules
84
cortex
elongated cells forming major portions of shaft of the hair
85
cuticle of the hair
single layer of flat, heavily keratinized cells
86
bulb
at the base of each hair follicle and surrounds root sheath
87
papilla
contains areolar connective tissue and blood vessels to nourish the growing hair
88
matrix
- surrounds the papilla
- is the germinal layer that is responsible for hair growth
- epidermal stem cells of the stratum basale
89
melanocytes (hair)
produce hair pigment in the matrix cells and passes it into cells of the cortex and medulla
90
hair growth cycle
- growth stage
- regression stage
- resting stage
91
growth stage
- 85% of all hair at any given time
- lasts for 2-6 years
- matrix cells at the base of the hair root divide --> increase length
- cells in this phase are keratinizing and differentiating
- new cells are added to the base and push out/up the root of old hair
92
regression stage
- lasts 2-3 weeks
- hair moves away from blood supply in papilla
- hair matrix cells stop dividing
93
resting stage
- lasts for 3 months
- matrix cells are inactive and hair follicle atrophies
- old hair falls out as growth stage begins again
94
hair-related structures
- hair root plexus
| - arrector pili muscle
95
hair root plexus
nerve ending surrounding the hair bulb
- detects hair movement
- sensitive to touch
96
arrector pili muscle
smooth muscle in dermis that is attached to a hair follicle
- contracts with cold, fear, emotions
- causes hair to erect
97
sebaceous glands
- usually open to the neck of hair follicles
- can open directly to the surface in some regions
- usually found in dermis
- holocrine glands that produce sebum (released on skin surface)
- sebum contains cholesterol, proteins, fats and salts
- function: moistens hair, waterproofs and softens skin and inhibits growth of bacteria and fungi
- acne: inflammation of sebaceous glands caused by bacteria
98
sebaceous glands - functions
- moisten hair
- waterproof and soften skin
- inhibit growth of bacteria and fungi
99
sebum - components
- cholesterol
- proteins
- fats
- salts
100
acne
inflammation of sebaceous glands caused by bacteria
101
sudoriferous glands
- located in dermis
| - 2 types (both merocrine glands): eccrine and apocrine
102
eccrine glands
type of merocrine gland of sudoriferous glands
- duct empties at the surface
- eccrine = secretion outwardly
- found in most areas of skin, especially forehead palms and soles
- secretory portion located mostly in the reticular dermis
- produce about 400-600mL of perspiration daily
- function: thermodynamic (regulate body temperature through evaporative cooling)
103
eccrine glands - function
thermodynamic (regulate body temperature through evaporative cooling)
104
apocrine glands
type of merocrine gland of sudoriferous glands
- duct opens into hair follicle
- found in axillary and pubic regions
- secretions are more viscous than from eccrine glands
- secretion is not by apocrine secretion
- not functional until puberty
- not involved in thermoregulation
105
eccrine glands - location
palms and soles
106
apocrine glands - locations
in axilllary and pubic regions but not functional until puberty
107
ceruminous glands
- aka wax glands
- modified apocrine (sweat) glands that produce waxy secretion in ear canal
- secretory portion in SQ layer, deep to sebaceous glands
- excretory ducts open to the surface or into sebaceous ducts
108
cerumen
- aka earwax
- contains secretions of oil and wax glands
- helps form a sticky barrier to impede the entrance of foreign bodies
109
cerumen - function
helps form a sticky barrier to impede the entrance of foreign bodies
110
nail
plate of tightly packed, hard, dead, keratinized, epidermal cells
111
nail - parts
- nail plate (body)
- nail root
- eponychium (cuticle)
- nail matrix
- hyponychium
112
nail plate (body)
- visible portion of the nail (appears pink due to underlying capillaries)
- comparable to stratum corneum, except with stronger/tougher keratin that does not slough off
113
nail root
- buried under skin layers
| - lunule is white due to thickened epithelium underneath
114
eponychium
- aka cuticle
| - narrow band of epidermis
115
nail matrix
- below the nail root
- germinal layer that produces growth
- cells move superficially, die and become tightly packed keratinized cells
116
hyponychium
- thickened region of the stratum corneum under the free edge of the nail
- junction between the free edge and skin of the fingertip
- secures nail to fingertip
117
nails - function
- protect the distal end of the digits
- provide support and counterpressure to palmar surface of fingers to enhance perception and manipulation
- allow us to grasp and manipulate small objects and can be used to scratch and groom the body in various ways
