Hair and Skin Flashcards

1
Q

what does integument mean?

A
  • consists of skin and its derivatives
  • most extensive organ system in the body
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2
Q

what are some uses of integument?

A
  • insulation and waterproofing
  • protection
  • weapons
  • camouflage
  • thermoregulation
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3
Q

what are the three distinct layers of the skin?

A
  • epidermis - outer layer
  • dermis - a connective tissue layer
  • hypodermis - subcutaneous layer
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4
Q

what is a melanocyte?

A

pigment cells which give skin colour

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5
Q

what tissue type is the epidermis made out of?

A

stratified squamous epithelium

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6
Q

what is the deepest layer of the epidermis?

A

stratum germinativum/basale

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7
Q

what happens when cells get pushed to the top of the epidermis in the stratum basale layer?

A

they become flat, lose their nucleus and become filled with keratin

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8
Q

how do the cells replicate in the epidermis?

A

mitosis

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9
Q

where are melanocytes found?

A

stratum germinativum/basale

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10
Q

what are some characteristics of stratum spinosum?

A
  • nucleated
  • less cell division
  • normally 1-2 cells thick
  • where hair is absent, 20 cells thick
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11
Q

what are some characteristics of stratum granulosum?

A
  • cells flatten
  • infiltration with keratin
  • cells lose organelles and dies
  • where hair is absent, 8 cells thick
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12
Q

what are some characteristics of stratum lucidum?

A
  • only in thick skin (nose+pawpads)
  • clear layer
    -consists of dead skin cells containing lipids
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13
Q

what are some characteristics of stratum corneum?

A
  • consists of completely keratinized, flattened, dead skin cells called corneocytes
  • comprises up to 3/4 of thickness of the epidermis
  • provides waterproof covering
  • continually sloughing
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14
Q

what is the dermis?

A
  • has two layers
  • makes up the thickness
  • vascular tissue
  • responsible for the structural strength of the skin
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15
Q

what is found in the dermis?

A
  • blood vessels
  • lymphatic vessels
  • nerves
  • hair follicles
  • sebaceous glands
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16
Q

what are the two layers of the dermis?

A
  • papillary
  • reticular
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17
Q

what are some characteristics of the papillary layer of the dermis?

A
  • loose connective tissue
  • forms finger-like ridges (papillae) that project into epidermis
  • helps to hold epidermis and dermis together
  • help thermoregulation
  • removes waste
  • blood vessels provide nutrients to stratum basale
18
Q

what are some characteristics of the reticular layer of the dermis?

A
  • below the papillary layer
  • dense, irregular connective tissue
  • lots of fibres in parallel bundles
  • most of skin’s strength and elasticity comes from this layer
  • makes up 80% of the dermis
19
Q

what is the hypodermis?

A
  • subcutaneous layer
  • loose connective tissue permits free movement
20
Q

what does the hypodermis contain?

A
  • adipose cells
  • blood vessels
  • nerves
  • sensory receptors
  • lymphatics
21
Q

what are some characteristics of paw pads?

A
  • thick layers of fat + connective tissue
  • supports weight of animal
  • highly pigmented
  • usually contain all 5 epidermal layers
  • contain sweat glands
  • provide protective barrier against abrasion and temp
22
Q

what do paw pads contain?

A
  • claws
  • digital pads
  • dew claw
  • metacarpal pads
  • carpal pads
23
Q

what are some characteristics of planum nasale?

A
  • usually pigmented
  • only has three epidermal layers
  • thin stratum corneum
  • contains no glands
24
Q

what is lichenification?

A
  • process of skin thickening
  • ability to respond to pressure, chronic low-grade trauma or inflammation by producing a thicker keratinised layer
25
Q

what are some characteristics of hair?

A
  • essential for survival
  • can provide camouflage
  • can help animal communicate
26
Q

what are the three layers of hair?

A
  • medulla (inner layer, two/three layers of loosely arranged cells containing soft keratin)
  • cortex (stiffer+more rigid, contains hard keratin, thickest of three layers)
  • cuticle (outer layer, single layer of cells, hard keratin,cells overlap to prevent mats)
27
Q

what happens to hair cells as they move up the follicle?

A

they become keratinized

28
Q

what happens in the anagen phase of hair growth?

A

maximum length that an anagen hair can achieve is genetically determined

29
Q

what happens in the catagen phase of hair growth?

A

period of transition between the anagen and telogen

30
Q

what happens in the telogen phase of hair growth?

A

resting period which can last from weeks to years depending on location and type of hair

31
Q

what is produced at the base of the hair follicle?

A

melanin in melanocytes

32
Q

what are the two forms of melanin that a dog has?

A
  • red/yellow
  • brown/black
33
Q

what are the three hair types?

A
  • guard hair (thick + long, give protection, arrector pili muscle attached)
  • wool hair (soft, undercoat, thinner + softer)
  • tactile hair (whiskers, thicker than guard hair)
34
Q

what is the arrector pili muscle?

A
  • smooth muscle attached to hair follicle
  • controlled by the sympathetic nervous system
  • forces sebum from sebaceous glands fo moisture
  • makes hair stand up
35
Q

what are sebaceous glands?

A
  • found all over body
  • glands found in dermis
  • may be simple or multiple/compound alveolar
  • single duct that empties into hair follicle or surface of skin
36
Q

what are the suderiferous glands?

A
  • sweat glands
  • simple coiled tube
  • two types: eccrine + apocrine
  • located in the dermis or hypodermis
37
Q

what is the apocrine gland?

A
  • duct empties into the hair follicles
  • found in ear canal and long haired dogs
38
Q

what is the eccrine gland?

A
  • connected to skin by long duct - pore
  • found in foot pass and deep layers of fat
39
Q

what are the tail glands?

A
  • dorsal base of tail
  • sensitive to change in levels of sex hormones
  • secretions assist in scent recognition
40
Q

what are anal glands?

A
  • found adjacent to anal opening, connected to lateral margin by a small duct
  • lined with sebaceous and apocrine glands
  • contents are expressed when defecating or frightened
  • territory marking/scent
41
Q

what are mammary glands?

A
  • specialised skin glands
  • produce colostrum and milk
  • present in male and female
  • milk secreting units = alveoli
  • largest ducts empty into gland sinus + continuous with the teat sinus
42
Q

what are the claws?

A
  • important for maintaining traction
  • tools for defence + catching prey
  • retractable in cats
  • each claw is wrapped around the bony ungual process of the most distal bone of each toe
  • dew claws are the remains of digits undergoing regressions