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
Q

what is first line of defence in epidermis

A

langerhans cells

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26
Q

Langerhans Cells where are they found

A

all layers except stratum corneum, but most common in the upper layer of stratum spinosum

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27
Q

langerhans cells are antigen presenting cells and so

A
  • immune function
  • phagocytose antigens & then present to T lymphocytes
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28
Q

merkel cells

A
  • 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
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29
Q

what cells are mechanoreceptors for touch

A

merkel cells

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30
Q

dermis

A
  • connective tissue layer
  • few cells
  • amorphous ground substance
  • collagen, reticular & elastin fibres
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31
Q

2 layers of dermis

A

papillary layer
* underlying the epidermis
* loose connective tissue
* thinner

reticular layer
* continuous with hypodermis
* dense connective tissue
* thicker

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32
Q

cells in dermis

A
  • cells include fibroblasts & migratory connective tissue cells
  • macrophages, mast cells/histiocytes, plasma cells
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33
Q

in dermis what provides strength

A
  • collagen & reticular fibres provide strength
  • elastin fibres vary with age and location
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34
Q

dermis contains

A
  • 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
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35
Q

in thick skin, junction between the dermis and epidermis consists of:

A
  • epidermal pegs
  • dermal papillae
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36
Q

hypodermis aka

A

subcutis
hence, subcutaneous injections (s.c.), hypodermic
needles etc

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37
Q

hypodermis connective tissue

A

loose connective tissue

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38
Q

what does hypodermis do

A

anchors skin to underlying structures

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39
Q

adipose tissue in hypodermis

A
  • variable amounts of adipose tissue
  • panniculus adiposus
  • especially thick in pigs & marine mammals (“blubber”)
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40
Q

smooth muscle in hypodermis

A
  • variable amounts of smooth muscle
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41
Q

does hypodermis contain striated muscle

A
  • may contain striated muscle
  • voluntary movement of skin
  • cattle & horses twitching in response to flies
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42
Q

what is hair

A
  • Flexible fibre
  • Composed of keratinised (i.e. dead) epithelial cells
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43
Q

hair is formed within a

A

hair follicle

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44
Q

hair follicle

A
  • epithelial invagination
  • extends to reticular layer of dermis or hypodermis
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45
Q

cells that from the hair constitute the

A

hair bulb

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46
Q

hair bulb contains _____ that from an epithelium over the ____

A

matrix cells
papilla

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47
Q

papilla of hair bulb contains

A

blood capillaries

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48
Q

within the follicle the root of the hair surrounded by

A
  • inner root sheath
  • outer root sheath
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49
Q

The free part of a hair is the

A

shaft

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50
Q

The portion of hair within the follicle is the

A

root

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51
Q

3 zones of hair in transverse section

A
  • medulla
  • cortex
  • cuticle
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52
Q

medulla of hair

A
  • produced by the matrix
  • cuboidal cells
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53
Q

cortex of hair

A
  • produced by the matrix
  • densely packed squamous keratinised cells
  • contain melanin
  • from melanocytes in matrix
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54
Q

cuticle of hair

A
  • produced by the matrix
  • single layer of overlapping squamous cells
  • shape & size of cuticle is species specific
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55
Q

surrounding the cuticle of hair is an

A

inner root sheath

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56
Q

inner root sheath produced by the

A

matrix

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57
Q

inner root sheath 3 layers

A
  • 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
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58
Q

surrounding the inner root sheath is the

A

outer root sheath

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59
Q

outer root sheath produced by

A

the matrix

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60
Q

outer root sheath

A
  • number of layers of cells
  • resembles stratum spinosum
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61
Q

Separating the outer root sheath & the dermis
is the

A

glassy membrane

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62
Q

Fibres & cells of dermis form a

A

dermal root sheath

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63
Q

Associated with some hair follicles are

A

sebaceous & apocrine sweat glands

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64
Q

Arrector pili muscle

A
  • smooth muscle
  • attached to dermal root sheath & inserts into the reticular layer of the dermis
  • erects hair: insulation, display
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65
Q

sinus (tactile) hairs

A
  • 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
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66
Q

skin appendages: most are _____ structures of epidermal origin

A

keratinized

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67
Q

tori

A
  • pads
  • contact surfaces of extremities
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68
Q

tori consists of what 3 layers

A
  • epidermis; extensive stratum corneum
  • dermis; high papillary layer
  • subcutaneous cushion (pulvinus); adipose tissue, glands
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69
Q

scales are formed by

A

highly keratinized stratum corneum over a fold of skin

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70
Q

only mammals w scales

A

pangolids

71
Q

Guard or Primary Hairs

A
  • form the topcoat
  • long
  • thicker & stronger
  • cortex & medulla
72
Q

Wool or Secondary Hairs

A
  • form the undercoat
  • shorter
  • finer & less strong
  • lack a medulla
  • fleece of sheep entirely wool hairs
  • also some genetically selected furs
73
Q

horse mane

A

juba

74
Q

horse tail

A

cirrus cordaw

75
Q

primary hair follicles

A
  • larger diameter
  • extend into reticular layer of dermis
  • sebaceous & apocrine sweat glands
  • arrector pili muscle
  • hair = primary or guard hair
76
Q

secondary hair follicles

A
  • smaller diameter
  • more superficial in dermis
  • may have sebaceous gland; lack apocrine sweat gland
  • no arrector pili muscle
  • hair = secondary or wool hair
77
Q

single hair follicle

A

a single hair originates from follicle

78
Q

compound hair follicle

A
  • several hairs share a common follicular opening
  • usually one primary hair & several secondary hairs
79
Q

horse, cow, buffalo follicles

A

evenly spaced single follicles

80
Q

pig follicles

A

single follicles in clusters of 3

81
Q

dog follicles

A

compound follicles in clusters of 3

1 primary (guard) hair + many secondary (wool) hairs

82
Q

cat follicles

A

compound follicles in clusters of 5 surrounding 1
single follicle

~3 primary hairs + 6-12 secondary hairs

83
Q

Hair growth is cyclical & passes through 3 stages

A

anagen, catagen & telogen

84
Q

anagen

A
  • active growth phase
  • matrix cells of bulb divide
85
Q

catagen

A
  • 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
Q

telogen

A
  • 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
Q

where are hair follicle stem cells

A

in outer root sheath

88
Q

hair follicle stem cells contribute

A

to follicle
regeneration & growth
during anagen

89
Q

what stage does shedding occur

A

during anagen

club hairs pushed out by new developing hair

90
Q

shedding is usually seasonal and occurs in what seasons

A

spring and autumn

91
Q

in winter and cold climates what stage is hair in

A

telogen

92
Q

claws are produced by _____ over ___ phalanx

A

epidermis
3rd

93
Q

corium

A

(= dermis = “quick”) continuous with periosteum

94
Q

claw plate

A

consists of two walls joined at dorsal crest

95
Q

claw folds

A

fold of skin proximally

96
Q

hyponichium

A

sole; ventral; softer than claw plate

97
Q

how do cats withdraw their claws

A

medial & lateral dorsal elastic ligaments

98
Q

how do cat claws extend

A

Contraction of deep digital flexor extends claws

99
Q

declawing cuts the

A

third phalanx

100
Q

horns are present in both

A

sexes

101
Q

horns are ____ structures produced by ______ over corium (dermis)

A

keratin
epithelium

102
Q

horns are over ____ process of frontal lobe

A

cornual

103
Q

periosteum of horns is continuous with

A

corium

104
Q

corium has numerous _____ that extend into horn

A

papillae

105
Q

horn consists of _____ and _____ horn

A

tubular and non tubular

106
Q

tubular and non tubular horn

A
  • tubular horn formed over
    corial papillae
  • spaces filled with non-tubular horn
107
Q

skin at base of horn is the

A

epiceras

108
Q

nerve supply to horns

A
  • cornual branch of zygomaticotemporal nerve
  • goat has additional nerve: infratrochlear nerve
109
Q

blood supply of horns

A
  • cornual arteries
  • dorsal branch
  • ventral branch
110
Q

antlers consist entirely of

A

bone, NOT keratin

111
Q

antlers

A
  • 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
Q

antlers; growth from ____ on frontal bone

A

pedicle

113
Q

how do antlers shed

A
  • 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
Q

antler bone growth

A
  • 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
Q

skin glands form as downgrowths of the

A

epidermis into hypo-/dermis

116
Q

skin glands May be of _____ or _____ to an area

A

general distribution
specialized

117
Q

general distributed skin glands include

A
  • Sebaceous glands
  • Sweat glands
  • apocrine sweat glands
  • merocrine sweat glands
118
Q

what glands are usually associated with hair follicles

A

Sebaceous & apocrine sweat glands

119
Q

are merocrine sweat glands usually associated w hair follicles

A

no

120
Q

3 methods of secretion in exocrine glands

A

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
Q

Holocrine:

A
  • sebaceous glands
  • secretory products accumulate and cell ruptures
  • death of cell
122
Q

merocrine (eccrine)

A
  • sweat glands
  • vesicles are released via exocytosis when vesicle membranes fuse with the cell membrane
  • most common form of secretion
123
Q

apocrine

A
  • sweat glands
  • secretory vesicles accumulate at apical portion of cell
  • mass of cytoplasm and vesicles is then pinched off
124
Q

sebaceous glands gland type and type of secretion

A
  • Simple branched alveolar or compound, alveolar (acinar) glands
  • holocrine secretion; sebum, cholesterol and triglycerides
125
Q

sebaceous gland structures

A

Pilosebaceous canal lined with stratified squamous epithelium

inflammation –> hyperkeratinisation –>
blockage –> atrophy –> exacerbation

126
Q

in sebaceous glands basal cells may contain

A

melanocytes (sebum pigmented)

127
Q

sebaceous glands associated with

A

all primary, & most secondary, hairs

128
Q

sebaceous glands aggregations in

A

eyelids, lips & external ear

129
Q

functions of sebum

A
  • bacteriostatic & fungistatic
  • reduces water loss from skin
  • vehicle for vitamin D precursors
  • distribution of pheromones
130
Q

what type of glands are apocrine glands

A

simple coiled tubular

131
Q

where are apocrine sweat glands located

A

Located in the dermis or hypodermis, below hair papilla

132
Q

apocrine sweat glands have _____ mode of secretion, so what cells involved

A

apocrine, myoepithelial cells

133
Q

apocrine sweat glands are restricted to

A

primary hair follicles

134
Q

secretion of apocrine sweat glands

A
  • species variable but…
  • water
  • Na+ & K+
  • albumin
135
Q

horse sweat

A

high levels of albumin, also a unique protein called latherin, “lathering up”

136
Q

apocrine sweat glands in thermoregulation for
horses and cattle
dogs and sheep
pig

A
  • horses & cattle: significant role
  • dogs & sheep: present, but insignificant role
  • pig: poorly developed
137
Q

do apocrine sweat glands have anything to do with pheromones

A

play a role in the distribution of pheromones

138
Q

merocrine sweat glands type of glnad

A

simple coiled tubular glands

139
Q

merocrine sweat glands have what cells

A

Myoepithelial cells

140
Q

Merocrine Sweat Glands are _____ in dermis/hypodermis than apocrine sweat glands

A

deeper

141
Q

merocrine sweat glands are _____ of hair follicles

A

independent

142
Q

merocrine sweat glands are limited to 2 areas

A
  • digital tori: especially in dogs
  • nasolabial region: ungulates
143
Q

secretory product of merocrine sweat glands

A

Secretory product very watery

144
Q

functions of merocrine sweat glands

A
  • Functions uncertain:
  • little role in thermoregulation
  • non-slip surface?
  • moisturise skin?
  • scent marking?
145
Q

central control of sweating by

A

hypothalamus & brain stem

co-ordinate effects of heat, exercise & stress

146
Q

sweating regulated via release of

A

adrenaline & acetylcholine

147
Q

describe how sweating is regulated

A
  • 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
Q

External Auditory Meatus

A
  • sebaceous & apocrine glands
  • cerumen (earwax)
  • otitis externa
149
Q

2 glands of upper and lower eyelids that both contribute to waxy coating on eyelid margins

A

Meibomian glands
* sebaceous glands
* can form cysts
* can form adenomas
* Sx removal

Glands of Moll
* apocrine glands

150
Q

Infraorbital Sinus in Sheep

A
  • pouch of thin skin rostral to eye
  • large sebaceous glands
  • some apocrine glands
  • larger in rams
  • secretion functions as a territorial marker
151
Q

Mental Organ in Pig

A
  • large sinus hairs & apocrine glands form a raised papilla
  • intermandibular space
  • tactile & marking function
152
Q

Horn Glands in Goat

A
  • large sebaceous glands
  • associated with hair follicles
  • larger in billies
  • strong odour during breeding season
153
Q

Circumoral Glands in Cat

A
  • large sebaceous glands
  • upper & lower lip
  • territory (& people) marking
154
Q

Inguinal Pouch in Sheep

A
  • 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
Q

Preputial Glands

A
  • sebaceous glands
  • apocrine glands
  • significant in stallion & boar
  • studies in mice:
  • role in attracting females
156
Q

Tail Glands in Dogs & Cats

A
  • 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
Q

Mammary Glands

A
  • 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
Q

Glands of the Anal Sacs

A
  • 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
Q

Circumanal Glands in Dogs

A
  • perianal skin
  • superficial portion
  • sebaceous glands
  • deep portion
  • hepatoid cells of unknown function
  • dog-to-dog communication
  • common site of neoplasia
160
Q

Interdigital Pouch in Ruminants

A
  • skin pouches at dorsal tip of interdigital space
  • sebaceous glands
  • merocrine glands
  • waxy secretion
  • trail marker
161
Q

Carpal Glands in Pig & Cat

A
  • merocrine glands
  • in boars
  • mark sows at mating
162
Q

Blood supply to the skin lies in the

A

dermis

163
Q

blood supply forms 3 interconnected plexi

A
  • Deep plexus: hypodermis/deep dermis
  • Intermediate plexus: reticular layer
  • Superficial plexus: papillary dermis
164
Q

lymph vessels in skin

A
  • arise from lymph capillaries in the papillary layer
  • drain into subcutaneous lymphatic plexus
165
Q

Cutaneous Innervation

A
  • 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
Q

Sympathetic fibres

A

smooth muscle of blood vessels, arrector pili, myoepithelial cells

167
Q

Somatic afferent (sensory)

A

dermis & epidermis (touch, pain, temperature, pressure)

168
Q

Somatic efferent (motor)

A

rarely: striated cutaneous muscle fibres

169
Q

Free Nerve Endings

A
  • fine nerve terminals devoid of myelin
  • innervate hair follicles
  • abundant in sinus hairs
  • receptors for temperature, touch & pain
170
Q

Encapsulated Endings

A
  • terminals surrounded by connective tissue cells
  • e.g. Meissner’s corpuscles
  • touch receptors
171
Q

Lamellated Endings

A
  • concentric layers of connective tissue cells
  • footpads
  • pressure receptors
172
Q

what nerve ending sense temp, touch and pain

A

free nerve endings

173
Q

what nerve ending sense pressure

A

lamellated endings

174
Q

what nerve endings invovled in meissner’s corpuscle and touch

A

encapsulated ending