Hair and Skin Flashcards
1
Q
what does integument mean?
A
- consists of skin and its derivatives
- most extensive organ system in the body
2
Q
what are some uses of integument?
A
- insulation and waterproofing
- protection
- weapons
- camouflage
- thermoregulation
3
Q
what are the three distinct layers of the skin?
A
- epidermis - outer layer
- dermis - a connective tissue layer
- hypodermis - subcutaneous layer
4
Q
what is a melanocyte?
A
pigment cells which give skin colour
5
Q
what tissue type is the epidermis made out of?
A
stratified squamous epithelium
6
Q
what is the deepest layer of the epidermis?
A
stratum germinativum/basale
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
8
Q
how do the cells replicate in the epidermis?
A
mitosis
9
Q
where are melanocytes found?
A
stratum germinativum/basale
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
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
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
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
14
Q
what is the dermis?
A
- has two layers
- makes up the thickness
- vascular tissue
- responsible for the structural strength of the skin
15
Q
what is found in the dermis?
A
- blood vessels
- lymphatic vessels
- nerves
- hair follicles
- sebaceous glands
16
Q
what are the two layers of the dermis?
A
- papillary
- reticular
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
what are some characteristics of hair?
- essential for survival
- can provide camouflage
- can help animal communicate
26
what are the three layers of hair?
- 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
what happens to hair cells as they move up the follicle?
they become keratinized
28
what happens in the anagen phase of hair growth?
maximum length that an anagen hair can achieve is genetically determined
29
what happens in the catagen phase of hair growth?
period of transition between the anagen and telogen
30
what happens in the telogen phase of hair growth?
resting period which can last from weeks to years depending on location and type of hair
31
what is produced at the base of the hair follicle?
melanin in melanocytes
32
what are the two forms of melanin that a dog has?
- red/yellow
- brown/black
33
what are the three hair types?
- guard hair (thick + long, give protection, arrector pili muscle attached)
- wool hair (soft, undercoat, thinner + softer)
- tactile hair (whiskers, thicker than guard hair)
34
what is the arrector pili muscle?
- smooth muscle attached to hair follicle
- controlled by the sympathetic nervous system
- forces sebum from sebaceous glands fo moisture
- makes hair stand up
35
what are sebaceous glands?
- 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
what are the suderiferous glands?
- sweat glands
- simple coiled tube
- two types: eccrine + apocrine
- located in the dermis or hypodermis
37
what is the apocrine gland?
- duct empties into the hair follicles
- found in ear canal and long haired dogs
38
what is the eccrine gland?
- connected to skin by long duct - pore
- found in foot pass and deep layers of fat
39
what are the tail glands?
- dorsal base of tail
- sensitive to change in levels of sex hormones
- secretions assist in scent recognition
40
what are anal glands?
- 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
what are mammary glands?
- 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
what are the claws?
- 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
