topic 12: integumentary Flashcards
what are the three layers of the skin
-epidermis
-dermis
-hypordermis
describe the structure of the epidermis
-layer of non vascular stratified epithelium cells of varrying thickness.
new cells are produced in the deepest layer (stratum corneum) of the epidermis and are pushed upwards to the surface
the surface cells are continuously lost as dead cells (scruf/dandruff)
what are the layers of the epidermis
-basal layer
-spinous layer
-grannular cell layer
-stratum corneum
BSGS
structure of the dermis
-made up of dense connective tissues made up of elastic and collagen fibres
-rich in blood supply, nerve fibres
-includes the hair follicle, sebaceous gland and sweat gland
structure of the hypodermis
-made up of loose connective tissues and fat
-contains elastic fibres-> giving skin flexibility
functions of the skin
-sensory
-protection
-production
-storage
-thermoregulation
-communication
(SPPTC)
explain the sensory function
-surface of the skin contains many nerve endings to detect, temperature, touch and pain
explain the protection function
skins acts as a barrier between internal structure and external environment
-prevent entry of miccroorganism
-prevent entry of toxic or harmful substances
-protect against damage from water loss and uv light
-protect unerlying structure from injury
explain production
skin has glands
sweat glands: secretes sweat
sebaceous gland: secrete sebum
scent gland: secrete phermones
uv light from sun convert 7-dipycholestrol present in sebum into vitamin D
explain storage function
skin stores fat and excess energy and keeps animal warm (hypodermis layer)
explain thermoregulation function
Heat loss – dilation of surface blood vessel
and sweating from the skin glands assists in
the loss of water that evaporate and cool the
skin surface
* Heat gain – constriction of surface blood
vessel conserves heat in the body
* Insulation – adipose tissue under the skin
insulates the body (preventing heat loss).
Hairs traps a layer of warm air.
explain the communication function
-colour of skin provides visual communication
-secretion of phermones
what are the different glands found in the skin
-sweat glands
-sebaceous glands
-tail glands
-anal glands
describe the sebaceous gland and its functions
where: surround the hair follicle
secretion: sebum
function: form a thin, oily, water repellant layer over skin surface
gives coat hair a shiny appearance
-prevent bacterial growth on skin surface (anticeptic properties)
describe the sweat gland and its function
sweat gland: open into hair follicle or to skin surface
function: sweat evaporates from skin surface-> colling down of body + removes some waste from the body
describe the tail gland and its function
where: dorsal surface of the base of the tail
glands: rich with sweat glands and sebaceous glands
function: assist with recognition and identification of individual animals
describe the anal gland and its functions
-pair of glands on the side of the anus, has a single small duct opening to the anus
fucntion: powerful smelling secretion. unique smell coat the feces and serves as territory marking and attracting mates
describe the structures of the hair
hair shaft: part of the hair visible above the skin
hair root: burried within skin
hair follicle: steucture in the skin that surrounnds the root of the hair
hair bulb: depest part of the hair follicle that expands
hair papilla: located at the base of the hair bulb, cluster of dermal cells called the papilla- rich with blood cells )remebre the hair follicle is found in the dermal later of the skin)
web of nerve ending enclose the hair root making it an important touch receptor when hair is bent (when bend-> will cause transmittion of nerve impulses to the brain)
arrector pili muscle: small smooth muscle attached to each hair follicle
controlled by sympethatic nervous system
function: contraction of the muslce pulls that hair to an erect position
what are the phases of the hair growth cycle
-anagen (growth phase)
-catagen (transitional phase)
-telogen (resting phase)
(ACT)
describe the growth cycle of hairs
anagen phase: hair follcles are actively producing new cells, hair shaft continues to lengthen
catagen: short transitional period, hair follicle shrink and detaches from blood supply
telogen: aka resting phase. hair follicle remains dormant and disconnected from the blood supply. without nourishment (from blood supply) , hair stops growing
early anagen: after telogen phase is complete, hair follicle reenters anagen phase and entire hair cycle begins again. the new hair shaft start to push out the old hair shaft, shedding of the old hair occurs
what are the different types of hair
-guard hairs
-wool hairs
-sinus hairs
description of guard hair and function
-long and coarser than other hair
function: to prevent water from soaking into coat and offer protection against mechanical damage
description and function of wool hair
-softer and wavier and lie closer to the body surface
function: creates and insulating later and helps to regulate body temp
description and function of sinus hair
long and corse hair that entends beyond body’s outline
base of each hair is connected to blood filled sinus with rich blood supply
when hair moves-> stimulates the nerve fibre-> send nerve impulse to brain for intepretation
structure and function of claws
structure: beak shaped, formed as two layers of epidermis (no pain)
claws are composed of keratinased epithelium and form the horny outer covering of the distal of each digit
function: protect the distal pahalanges during walking and weight bearing and to provide grip.
claws also have a ventral groove (back of nail) filled with softer corn know as the sole 2
differenece between cat and dog claws
dog: thick and strong
cat: finer and sharper (used as weapon for offence)
at rest, cat can retract their claws into pockets of skin by elastic ligaments
difference between cat and dog footpad: forepaw
dog: six pads-four digital pad+i carpal pad +1 metacarpal pad
cat: 7 pad-5 digital bad, i carpal pad, 1 metacarpal pad
difference between cat and dog footpad: hindpad
both dog and cat have 5pads: 1 metatarsal and 4 digital pads
function of the carpal pad
lies distal to the carpal bone and protects the area when an animal is running at high speed
function of footpads
structure: made of thick layer of fat and connective tissues (needs flexibility)
its outer surface is the thoughest and thickest skin on the body
function: protect underlying joints and act as shock absorbers as the animals walk/run
