(16) Integumentary System Flashcards
► Comprises the skin, hair, claws, pads, and skin glands, including the glands of the paranal sinus and the mammary glands
► Largest organ
Common Integument
These are the functions of?
Functions
► Protection of underlying structures from abrasion,
thermal and chemical injury, against invasion by
microorganisms, against desiccation and overhydration
► As sensory organ, has receptor for the perception of
touch, pressure, vibration, tension, noxious stimuli,
heat, cold, and harmful chemicals
► Secretion e.g. pheromone, mammary gland
► Site of Vitamin D synthesis
Common Integument
preservation of excessive heat loss and dissipation of excessive body heat
Thermoregulation
What tissue serve as a reservoir for fat, electrolytes, water, carbohydrates, and proteins
subcutaneous tissues
► The thin organ covering the body, protecting underlying
tissues from injury, drying and bacterial invasion
► Helps regulate body temperature, excretes water and
salts through sweat glands, senses the environment and
synthesizes vitamin D3
The Skin (Cutis)
The Skin (Cutis) consist of two layers:
a superficial “ epidermis “ of stratified squamous epithelium and an underlying connective tissue, the “ dermis “
lies on a layer of loose connective tissue, the ? – functions as a moveable support for the skin allowing it to glide over underlying tissues
subcutis or hypodermis
► Superficial (outer) layer
► Avascular stratified squamous epithelium that is nearly free
of nerve endings
► Multiple layers of cells that are constantly renewed
Epidermis
From deep to superficial, the five histologic layers are as follows:
► Stratum basale
► Stratum spinosum
► Stratum granulosum
► Stratum lucidum
► Stratun corneum
The first two layers of histological lauers are often called the?
germinal layer (stratum germinativum)
► Fibrous protein of stratum corneum
Keratin
► Drying and hardening of the superficial cells that renders the surface of the skin tough and resistant to drying
Keratinization and cornification
► Local increase in thickness in response to continuous trauma.
Callus
► An undulating sheet with fingerlike projections into the underlying connective tissue the dermis
Epidermal pegs
► consists of a connective tissue bed containing blood vessels, lymphatics, muscles, and nerve endings covered by stratified squamous epithelium
► It bear ridges and nipplelike projection (the dermal papillae) that interdigitate with the overlying epidermis
Dermis (Corium)
2 layers of dermis:
► papillary layer
► reticular layer
► A local disruption of association between layers (epidermal pegs and dermal papillae) usually due to trauma
Blister
► Pigment cells found in the cytoplasm of the stratum basale that generates pigment granules
Melanocytes
► Brown, yellowish-brown or black pigments
Melanin
► Absence of pigment in the skin due to genetic inability of melanocytes to manufacture pigment
Albinism
► superficial fascia/subcutaneous tissue
► A layer of loose (areolar) connective tissue
and interspersed fat connecting the skin to
underlying structures such as bones and
muscles
► Permits movement of the skin without tearing
► not part of skin but underlies the skin, bind
the skin to muscles, provides pathway for
vessels and nerves to reach the skin
Hypodermis
fatty and loose ( hypodermis layer )
Superficial layer
membranous and stronger ( hypodermis layer )
Deep layer
► This muscle is associated directly with hair follicles
► Erect the hairs against cold and in behavioristic displays
Arrector pili muscles
► Anchored in dermis closely affixed to superficial fascia
► Contraction of these muscles causes movement of the skin or structures associated with the skin
Cutaneous muscles
► Deepest, major blood supply to the skin ( plexus )
Subdermal plexus
► Intermediate in position, forms a network around hair follicles and glands ( plexus )
Cutaneous plexus
► Branch of cutaneous, most superficial
► Source of nutrients and oxygen for the epidermis
► Serves as the “sink” for waste products produced by the epidermal layer ( plexus )
Subpapillary plexus
► Includes the hair and associated follicle, footpads, claws, sebaceous glands and sweat glands associated with the skin
Appendages of the skin
► uniquely mammalian features
► All common domestic mammals except the pig have abundant hair
► The long, slender, filamentous appendage of the skin composed of keratinized (dead) epithelial cells.
Haircoat
Each hair consist of?
shaft and a root
is contained in a depression (hair follicle)
root
► Outmost layer (topcoat), covers most of skin surface except the sheep and pig
► Generally thick, long and stiff
► Effective in preventing water from penetrating the skin, preventing chilling
Guard hairs
► Innermost layer of hair (undercoat) over most of skin surface
► Thinner, more undulating (wavy), softer, finer and shorter than guard hairs
► Provides direct insulation and warming effect
► The hair type of the fleece of sheep
Wool hairs
► Specialized hair adapted to provide sensory information from the environment particularly the perception of touch and space
► The base resides in a blood-filled sinus that gently amplifies the motion of hair and increase its sensitivity
► Thicker than other hair in the body and usually protrude outside beyond the surrounding hair coat
► Mostly concentrated in the head; on the upper and lower lip, chin, cheek, around the eye and the carpus
Tactile hairs (Tylotrich hair /sinus hair/vibrissae)
► Determined by complicated genetic factors governing the amount of pigment (melanin) in the hair.
Color of Hair
There are only three hair pigments;
black, brown and
yellow.
result from loss of pigments ( color of hair )
Gray hairs of aging
This color of hair is due to absence of pigment and presence of air in the hair shaft
white hair
► A modification of the epidermis
► Invaginates from the surface of the skin as a double layered root sheath that surrounds the hair and terminates in a hair bulb of epidermal origin
Hair follicle
This animal has a compound hair follicles with single primary hair and a group of smaller secondary hairs
Dog
This animal has a single follicle with primary guard hair surrounded by clusters of compound follicles
Cat
This animal has a 4 digital pads, carpal pad and metacarpal/metatarsal pad
Dogs
Hairless, cushion-like, toughest skin on the dog
Pads
extremely thickened and cornified (usu. Heavily pigmented) and possess conical papillae that provide friction as the dog walks
Epidermal pad
typical dermis and markedly thickened subcutis containing abundant reticular, collagenous and elastic fibers interspersed with adipose tissue and eccrine sweat glands formed within adipose tissue of footpads
Digital cushion
function as the load-bearing, shock-absorbing pads
metacarpal, metatarsal, and digital pads
This pad helps with skid and traction on a slope or while stopping
carpal pad
► Associated or connected to hair follicles, ducts open at the base of the hair follicles
► The cells lining the glands disintegrate to form the secretion sebum
Sebaceous glands or oil glands
an oily substance consisting of a mixture of cholesterol, protein and inorganic salts which is released into the hair follicles to lubricate the skin and prevent excessive evaporation
Sebum
► Located in the skin surrounding the anus, open directly into skins surface; can become neoplastic (perianal adenoma)
Circumanal glands
► Sebaceous in nature, lies within the walls of anal sacs
Anal sac glands
► Sebaceous glands located in a diamond-shaped area on the dorsal aspect on tail at level of Cd 7-9
► Hairs in this region are larger
► The modified skin is believed to function in individual recognition and I.D.
Tail area glands/caudal gland
in all domestic species; in the wall of the external auditory canal; produce “ear wax” which protects the tympanic membrane from foreign bodies
Ceruminous glands
only in cats; in the skin around the mouth esp the lower lip; called “cleaning glands” but functional significance is probably for marking
Circumoral/perioral glands
► Predominant in man ( sweat glands )
► Restricted in the footpads of carnivores
► Function relates to territorial markings and thermoregulation
Eccrine (merocrine) sweat glands
predominates in domestic species ( sweat glands )
Apocrine sweat glands
► Thought to be a modified sweat glands that nourishes the young
Mammary Glands
This animal usually has a 10 mammae; 5 (4-6) mammary complexes on each side separated by an intermammary groove
Bitch
This animal has 8 mammae, four on each side of the ventral
adominal wall
Queen
–extra teats may or may not be connected to primary mammary gland tissue in both male and females
Accessory teats or supernumerary teats (polythelia)
extra mammae
Polymastia
► An epidermal structure composed of keratin
► Formed from modification of the superficial layers
of epidermis, often deeply pigmented
► It create traction and help a dog dig and tear at prey
Claws
most distal portion of claw
Sole
laterally compressed portion and form the axial and abaxial surfaces of the claw
Walls (2)
if claw is cut too short the dermis maybe exposed, “quicked”, causing pain and bleeding
Nail trimming
removal of the claws of cats; to prevent regrowth, the dorsal aspect of the ungual crest must be removed usu done by removing the whole distal phalanx by cutting through the distal phalangeal joint
Declaw (onychectomy)
► The accessory digits
Dewclaw
