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AGRC1041 > integument 1,2,3 > Flashcards

integument 1,2,3 Flashcards

1
Q

integument

A
  • skin and
  • structures derived from it:
  • hair
  • nails
  • glands
  • hooves
  • horns
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2
Q

functions of skin

A
  • Environmental Barrier; prevents water loss
  • Physical Protection; areas of wear & tear highly cornified
  • Temperature Regulation
  • sensory reception
  • secretion
  • social functions
  • locomotion
  • protection from UV
  • immune responses
  • protection from parasites and microbes
  • calcium homeostasis
  • capture of prey
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3
Q

calcium homeostasis

A
  • vitamin D produced by skin in response to sunlight
  • converted to calcitriol
  • negative consequence of head-to-toe SPF 30+
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4
Q

skin consists of 2 layers

A
  • Epidermis: ectoderm
  • Dermis: mesoderm
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5
Q

Hypodermis

A
  • not formally “skin”
  • loose connective tissue layer
  • attaches skin to underlying
    fascia, muscle & bone
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6
Q

hypodermis contains

A

adipocytes

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7
Q

appendages such as hair, horns and hooves are

A

keratinized

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8
Q

epidermis epithelium

A
  • stratified squamous epithelium keratinised
  • avascular
  • Four – five layers:
  • stratum basale (B)
  • stratum spinosum (S)
  • stratum granulosum (G)
  • stratum lucidum (L)
  • stratum corneum (C)
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9
Q

where does epidermis get its nutrients and O2 from

A

O2 & nutrients from
vascularised dermis

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10
Q

what would skin with non-keratinized stratified squamous epithelium be

A

mucous membrane

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11
Q

Stratum basale/germinativum

A
  • cuboidal or columnar cells
  • mitotic
  • separated from dermis by basal lamina
  • desmosomes & hemidesmosomes
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12
Q

Stratum spinosum

A
  • thickest layer
  • especially in hairless areas
  • large polyhedral cells becoming flatter
  • cell separation increased making desmosomes highly visible
  • cells appear prickly
  • ‘prickle cell layer’
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13
Q

Stratum granulosum

A
  • thinner layer
  • flattened cells
  • most superficial cells lost nuclei
  • cells contain keratohyalin
  • precursor to keratin
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14
Q

Stratum corneum

A
  • dead cells
  • nuclei & organelles lost
  • cells filled with keratin
  • surface cells sloughed
  • layer thickest in areas subject to greatest wear & tear
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15
Q

Stratum lucidum

A
  • clear, translucent layer
  • some non-hairy areas
  • eleidin replaces keratohyalin
  • a derivative of keratin
  • cells dead & lack organelles
  • areas where epidermis v. thick
  • footpads
  • planum nasale
  • teat
  • reduces friction & shear forces between granulosum & corneum
  • may be water repellent
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16
Q

4 cell types of epidermis

A
  • Keratinocytes
  • Melanocytes
  • Langerhans Cells
  • Merkel Cells
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17
Q
  • Keratinocytes
A
  • most numerous epidermal cell
  • progressive keratinisation
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18
Q

Melanocytes

A
  • stratum germinativum
  • also in root sheath of hair & ducts of glands
  • contain melanin, bound in melanosomes
  • eumelanin: brown-black
  • phaemelanin: yellow-red
  • transfer melanosomes to keratinocytes
  • melanocytes vary in number & distribution: species, season, exposure to sunlight, neoplasia (melanoma)
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19
Q

Although melanocytes produce the melanin,
they transfer it to

A

keratinocytes

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20
Q

Melanin is produced via oxidation of the amino acid _____

A

tyrosine

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21
Q

Mutation in tyrosinase responsible for most common form
of _____

A

albinism

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22
Q

albinism

A
  • Melanin is produced via oxidation of the amino acid tyrosine
  • Mutation in tyrosinase responsible for most common form of albinism
  • autosomal recessive
  • Skin, hair & eyes have little, or no, melanin
  • eyes appear red due to blood vessels
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23
Q

leucism

A
  • Failure in differentiation, or migration, of neural crest cells
  • affects all pigment cells, including melanocytes
  • exception: cells of retina
  • eyes often appear blue
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24
Q

langerhan cells derived from

A

bone marrow

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25
what is first line of defence in epidermis
langerhans cells
26
Langerhans Cells where are they found
all layers except stratum corneum, but most common in the upper layer of stratum spinosum
27
langerhans cells are antigen presenting cells and so
* immune function * phagocytose antigens & then present to T lymphocytes
28
merkel cells
* Merkel Cells * common origin with Schwann cells * lobed, irregular nuclei * stratum germinativum * planum rostrale/nasale * external root sheath of sinus/tactile hairs * mechanoreceptors for touch
29
what cells are mechanoreceptors for touch
merkel cells
30
dermis
* connective tissue layer * few cells * amorphous ground substance * collagen, reticular & elastin fibres
31
2 layers of dermis
papillary layer * underlying the epidermis * loose connective tissue * thinner reticular layer * continuous with hypodermis * dense connective tissue * thicker
32
cells in dermis
* cells include fibroblasts & migratory connective tissue cells * macrophages, mast cells/histiocytes, plasma cells
33
in dermis what provides strength
* collagen & reticular fibres provide strength * elastin fibres vary with age and location
34
dermis contains
* cells include fibroblasts & migratory connective tissue cells * macrophages, mast cells/histiocytes, plasma cells * collagen & reticular fibres provide strength * elastin fibres vary with age and location * blood & lymph vessels * nerves * sebaceous glands, sweat glands, hair follicles * smooth & skeletal muscle * continuous with hypodermis
35
in thick skin, junction between the dermis and epidermis consists of:
* epidermal pegs * dermal papillae
36
hypodermis aka
subcutis hence, subcutaneous injections (s.c.), hypodermic needles etc
37
hypodermis connective tissue
loose connective tissue
38
what does hypodermis do
anchors skin to underlying structures
39
adipose tissue in hypodermis
* variable amounts of adipose tissue * panniculus adiposus * especially thick in pigs & marine mammals (“blubber”)
40
smooth muscle in hypodermis
* variable amounts of smooth muscle
41
does hypodermis contain striated muscle
* may contain striated muscle * voluntary movement of skin * cattle & horses twitching in response to flies
42
what is hair
* Flexible fibre * Composed of keratinised (i.e. dead) epithelial cells
43
hair is formed within a
hair follicle
44
hair follicle
* epithelial invagination * extends to reticular layer of dermis or hypodermis
45
cells that from the hair constitute the
hair bulb
46
hair bulb contains _____ that from an epithelium over the ____
matrix cells papilla
47
papilla of hair bulb contains
blood capillaries
48
within the follicle the root of the hair surrounded by
* inner root sheath * outer root sheath
49
The free part of a hair is the
shaft
50
The portion of hair within the follicle is the
root
51
3 zones of hair in transverse section
* medulla * cortex * cuticle
52
medulla of hair
* produced by the matrix * cuboidal cells
53
cortex of hair
* produced by the matrix * densely packed squamous keratinised cells * contain melanin * from melanocytes in matrix
54
cuticle of hair
* produced by the matrix * single layer of overlapping squamous cells * shape & size of cuticle is species specific
55
surrounding the cuticle of hair is an
inner root sheath
56
inner root sheath produced by the
matrix
57
inner root sheath 3 layers
* root sheath cuticle: similar to hair cuticle, cells interdigitate with hair cuticle * Huxley’s layer: 1-3 layers cuboidal epithelium, deeply staining * Henle’s layer, single layer of flattened cells
58
surrounding the inner root sheath is the
outer root sheath
59
outer root sheath produced by
the matrix
60
outer root sheath
* number of layers of cells * resembles stratum spinosum
61
Separating the outer root sheath & the dermis is the
glassy membrane
62
Fibres & cells of dermis form a
dermal root sheath
63
Associated with some hair follicles are
sebaceous & apocrine sweat glands
64
Arrector pili muscle
* smooth muscle * attached to dermal root sheath & inserts into the reticular layer of the dermis * erects hair: insulation, display
65
sinus (tactile) hairs
* Hairs that are modified for sensory function * Follicle extends deep into hypodermis * Inner & outer dermal root sheaths surround a blood-filled sinus * pressure on hair transmitted to blood sinus * multiplies signal * transmits to nerve endings in sinus wal
66
skin appendages: most are _____ structures of epidermal origin
keratinized
67
tori
* pads * contact surfaces of extremities
68
tori consists of what 3 layers
* epidermis; extensive stratum corneum * dermis; high papillary layer * subcutaneous cushion (pulvinus); adipose tissue, glands
69
scales are formed by
highly keratinized stratum corneum over a fold of skin
70
only mammals w scales
pangolids
71
Guard or Primary Hairs
* form the topcoat * long * thicker & stronger * cortex & medulla
72
Wool or Secondary Hairs
* form the undercoat * shorter * finer & less strong * lack a medulla * fleece of sheep entirely wool hairs * also some genetically selected furs
73
horse mane
juba
74
horse tail
cirrus cordaw
75
primary hair follicles
* larger diameter * extend into reticular layer of dermis * sebaceous & apocrine sweat glands * arrector pili muscle * hair = primary or guard hair
76
secondary hair follicles
* smaller diameter * more superficial in dermis * may have sebaceous gland; lack apocrine sweat gland * no arrector pili muscle * hair = secondary or wool hair
77
single hair follicle
a single hair originates from follicle
78
compound hair follicle
* several hairs share a common follicular opening * usually one primary hair & several secondary hairs
79
horse, cow, buffalo follicles
evenly spaced single follicles
80
pig follicles
single follicles in clusters of 3
81
dog follicles
compound follicles in clusters of 3 1 primary (guard) hair + many secondary (wool) hairs
82
cat follicles
compound follicles in clusters of 5 surrounding 1 single follicle ~3 primary hairs + 6-12 secondary hairs
83
Hair growth is cyclical & passes through 3 stages
anagen, catagen & telogen
84
anagen
* active growth phase * matrix cells of bulb divide
85
catagen
* hair bulb begins to regress * matrix cells stop dividing * follicle shrinks * dermal papilla shrinks * bulb fuses to hair shaft * moves to the level of the sebaceous gland
86
telogen
* resting phase * these hairs have a club-shaped base & so are termed club hairs * base of hair surrounded by germ cells * responsible for forming new follicle * club hairs remain in follicle until pushed out by new growth during the next anagen
87
where are hair follicle stem cells
in outer root sheath
88
hair follicle stem cells contribute
to follicle regeneration & growth during anagen
89
what stage does shedding occur
during anagen club hairs pushed out by new developing hair
90
shedding is usually seasonal and occurs in what seasons
spring and autumn
91
in winter and cold climates what stage is hair in
telogen
92
claws are produced by _____ over ___ phalanx
epidermis 3rd
93
corium
(= dermis = “quick”) continuous with periosteum
94
claw plate
consists of two walls joined at dorsal crest
95
claw folds
fold of skin proximally
96
hyponichium
sole; ventral; softer than claw plate
97
how do cats withdraw their claws
medial & lateral dorsal elastic ligaments
98
how do cat claws extend
Contraction of deep digital flexor extends claws
99
declawing cuts the
third phalanx
100
horns are present in both
sexes
101
horns are ____ structures produced by ______ over corium (dermis)
keratin epithelium
102
horns are over ____ process of frontal lobe
cornual
103
periosteum of horns is continuous with
corium
104
corium has numerous _____ that extend into horn
papillae
105
horn consists of _____ and _____ horn
tubular and non tubular
106
tubular and non tubular horn
* tubular horn formed over corial papillae * spaces filled with non-tubular horn
107
skin at base of horn is the
epiceras
108
nerve supply to horns
* cornual branch of zygomaticotemporal nerve * goat has additional nerve: infratrochlear nerve
109
blood supply of horns
* cornual arteries * dorsal branch * ventral branch
110
antlers consist entirely of
bone, NOT keratin
111
antlers
* Consist entirely of bone, not keratin * Branched * Restricted to males (except in caribou & reindeer) * development dependent on reproductive cycle * testosterone * males compete for females * Produced & shed annually
112
antlers; growth from ____ on frontal bone
pedicle
113
how do antlers shed
* Restriction of blood supply to base of antler at end of breeding season * shedding of antler * response to decreasing day length * decreased testosterone--> loss of calcium
114
antler bone growth
* Bone originally covered by skin * dermis (corium) & epidermis * soft keratin called velvet * restriction of blood supply causes sloughing of velvet & bone of antler dies
115
skin glands form as downgrowths of the
epidermis into hypo-/dermis
116
skin glands May be of _____ or _____ to an area
general distribution specialized
117
general distributed skin glands include
* Sebaceous glands * Sweat glands * apocrine sweat glands * merocrine sweat glands
118
what glands are usually associated with hair follicles
Sebaceous & apocrine sweat glands
119
are merocrine sweat glands usually associated w hair follicles
no
120
3 methods of secretion in exocrine glands
Holocrine: sebaceous glands * secretory products accumulate and cell ruptures * death of cell Merocrine (eccrine): sweat glands * vesicles are released via exocytosis when vesicle membranes fuse with the cell membrane * most common form of secretion Apocrine: sweat glands * secretory vesicles accumulate at apical portion of cell * mass of cytoplasm and vesicles is then pinched off
121
Holocrine:
* sebaceous glands * secretory products accumulate and cell ruptures * death of cell
122
merocrine (eccrine)
* sweat glands * vesicles are released via exocytosis when vesicle membranes fuse with the cell membrane * most common form of secretion
123
apocrine
* sweat glands * secretory vesicles accumulate at apical portion of cell * mass of cytoplasm and vesicles is then pinched off
124
sebaceous glands gland type and type of secretion
* Simple branched alveolar or compound, alveolar (acinar) glands - holocrine secretion; sebum, cholesterol and triglycerides
125
sebaceous gland structures
Pilosebaceous canal lined with stratified squamous epithelium inflammation --> hyperkeratinisation --> blockage --> atrophy --> exacerbation
126
in sebaceous glands basal cells may contain
melanocytes (sebum pigmented)
127
sebaceous glands associated with
all primary, & most secondary, hairs
128
sebaceous glands aggregations in
eyelids, lips & external ear
129
functions of sebum
* bacteriostatic & fungistatic * reduces water loss from skin * vehicle for vitamin D precursors * distribution of pheromones
130
what type of glands are apocrine glands
simple coiled tubular
131
where are apocrine sweat glands located
Located in the dermis or hypodermis, below hair papilla
132
apocrine sweat glands have _____ mode of secretion, so what cells involved
apocrine, myoepithelial cells
133
apocrine sweat glands are restricted to
primary hair follicles
134
secretion of apocrine sweat glands
* species variable but... * water * Na+ & K+ * albumin
135
horse sweat
high levels of albumin, also a unique protein called latherin, “lathering up”
136
apocrine sweat glands in thermoregulation for horses and cattle dogs and sheep pig
* horses & cattle: significant role * dogs & sheep: present, but insignificant role * pig: poorly developed
137
do apocrine sweat glands have anything to do with pheromones
play a role in the distribution of pheromones
138
merocrine sweat glands type of glnad
simple coiled tubular glands
139
merocrine sweat glands have what cells
Myoepithelial cells
140
Merocrine Sweat Glands are _____ in dermis/hypodermis than apocrine sweat glands
deeper
141
merocrine sweat glands are _____ of hair follicles
independent
142
merocrine sweat glands are limited to 2 areas
* digital tori: especially in dogs * nasolabial region: ungulates
143
secretory product of merocrine sweat glands
Secretory product very watery
144
functions of merocrine sweat glands
* Functions uncertain: * little role in thermoregulation * non-slip surface? * moisturise skin? * scent marking?
145
central control of sweating by
hypothalamus & brain stem co-ordinate effects of heat, exercise & stress
146
sweating regulated via release of
adrenaline & acetylcholine
147
describe how sweating is regulated
* adrenal gland releases adrenaline into the blood * sympathetic nerves release ACh adjacent to glands or into blood * Act on secretory cells & myoepithelial cells * control rate of production & rate of expulsion, respectively
148
External Auditory Meatus
* sebaceous & apocrine glands * cerumen (earwax) * otitis externa
149
2 glands of upper and lower eyelids that both contribute to waxy coating on eyelid margins
Meibomian glands * sebaceous glands * can form cysts * can form adenomas * Sx removal Glands of Moll * apocrine glands
150
Infraorbital Sinus in Sheep
* pouch of thin skin rostral to eye * large sebaceous glands * some apocrine glands * larger in rams * secretion functions as a territorial marker
151
Mental Organ in Pig
* large sinus hairs & apocrine glands form a raised papilla * intermandibular space * tactile & marking function
152
Horn Glands in Goat
* large sebaceous glands * associated with hair follicles * larger in billies * strong odour during breeding season
153
Circumoral Glands in Cat
* large sebaceous glands * upper & lower lip * territory (& people) marking
154
Inguinal Pouch in Sheep
* folds of skin near udder or scrotum * large sebaceous glands * apocrine glands * brown waxy substance * communication * where animals have been lying * location of udder * reduces friction between udder & thigh
155
Preputial Glands
* sebaceous glands * apocrine glands * significant in stallion & boar * studies in mice: * role in attracting females
156
Tail Glands in Dogs & Cats
* also called supracaudal glands * area of sparse hair on dorsum of tail * large sebaceous glands * apocrine glands * in cats most marked in males * noticeable secretion during breeding season * in dogs can become hyperplastic and/or infected * territorial marking
157
Mammary Glands
* highly modified apocrine sweat glands * compound tubulo-alveolar gland * apocrine secretion releases fats * merocrine secretion releases proteins & carbohydrates * myoepithelial cells control milk let down
158
Glands of the Anal Sacs
* anal sacs are invaginations of skin * at junction of hairy & non-hairy skin * 4.00 & 8.00 * present in dogs and cats * apocrine glands in the dog * apocrine & sebaceous glands in the cat * secretion discharged at defecation * territorial marker * tendency in dogs to become impacted * colloquially referred to as blocked “anal glands” * actually the sacs that blocked, not the glands * may require Sx resection * less likely to become impacted in cats, but possible
159
Circumanal Glands in Dogs
* perianal skin * superficial portion * sebaceous glands * deep portion * hepatoid cells of unknown function * dog-to-dog communication * common site of neoplasia
160
Interdigital Pouch in Ruminants
* skin pouches at dorsal tip of interdigital space * sebaceous glands * merocrine glands * waxy secretion * trail marker
161
Carpal Glands in Pig & Cat
* merocrine glands * in boars * mark sows at mating
162
Blood supply to the skin lies in the
dermis
163
blood supply forms 3 interconnected plexi
* Deep plexus: hypodermis/deep dermis * Intermediate plexus: reticular layer * Superficial plexus: papillary dermis
164
lymph vessels in skin
* arise from lymph capillaries in the papillary layer * drain into subcutaneous lymphatic plexus
165
Cutaneous Innervation
* Nerve supply varies with area * Network of fibres within the hypodermis * spread to the dermis * small branches to the epidermis * supply glands, muscle & hair * sensory nerve endings * Sympathetic fibres; smooth muscle of blood vessels, arrector pili, myoepithelial cells * Somatic afferent (sensory); dermis & epidermis (touch, pain, temperature, pressure) * Somatic efferent (motor); rarely: striated cutaneous muscle fibres
166
Sympathetic fibres
smooth muscle of blood vessels, arrector pili, myoepithelial cells
167
Somatic afferent (sensory)
dermis & epidermis (touch, pain, temperature, pressure)
168
Somatic efferent (motor)
rarely: striated cutaneous muscle fibres
169
Free Nerve Endings
* fine nerve terminals devoid of myelin * innervate hair follicles * abundant in sinus hairs * receptors for temperature, touch & pain
170
Encapsulated Endings
* terminals surrounded by connective tissue cells * e.g. Meissner’s corpuscles * touch receptors
171
Lamellated Endings
* concentric layers of connective tissue cells * footpads * pressure receptors
172
what nerve ending sense temp, touch and pain
free nerve endings
173
what nerve ending sense pressure
lamellated endings
174
what nerve endings invovled in meissner's corpuscle and touch
encapsulated ending

AGRC1041 (20 decks)

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