Lecture 4 materials - Integumentary/skin Flashcards
What are the functions of the integument?
Protection, sensory information, storage of water and electrolytes, vitamin synthesis, thermoreglation, immunity, intraspecies communication
What is the largest organ system of all mammals?
The integument (this includes but not exclusively skin)
What does the skin consist of?
Epidermis and dermis
Name accessory structures of the integument
Skin glands, hair, pads, claws, mammary glands
Describe the skin
Made from epidermis (top) and dermis (deep)
Melanocytes produce pigment
SKin encloses the body and blends mucus membranes at orifices
Describe the epidermis
Ectodermal with stratified squamous epithelium
Avascular
Thick in non-hairy skin and thin in hairy skin
What are the 5 layers of thick skin
Stratum basale, stratum spinosum, stratum granulosum, stratum lucidum, stratum corneum
Describe the dermis (corium)
Comes from mesoderm, formed from dense connective tissue (collagen)
Papillary and reticular layer
Well vascularized and innervated
What part of the skin does leather come from?
Dermis
What is the difference between the papillar and reticular layer of the dermis?
Cells are more spread out in the papillary layer
Describe the hypodermis
Between skin and superficial fascia
Cutaneous muscles extend tendons in to the hypodermis for skin movement
The subcutis is thin where movement is undesirable
What is the subcutis made of
Collagen, elastic fibers, white fat
What does thickening of the subcutis lead to?
Skin folds
Are there glands on nasal skin of dogs?
No, moisture comes from serous secretions from lateral nasal glands
What is the nasal skin made of?
polygonal plaque areas form the planum nasale
What are the 2 basic skin glands?
Sebaceous, Sweat
Describe sebaceous glands
Produce sebum and drain directly in to hair follicles with apocrine sweat glands
Lubricates and waterproofs skin and coat
Describe Eccrine sweat gland
Eccrine (no hair): found in footpads of dogs, predominantly in primates, secrete water-y sweat by exocytosis
Describe Apocrine sweat gland
Apocrine (with hair): Empties in to hair follicles with sebaceous glands by pinching off part of the cell.
Odorous
Describe ceruminous glands
Produces ear wax (cerumen)
By apocrine and sebaceous (pinching off, oily sebum) secretion
Located in external auditory canal
Describe circumoral gland
Found only in lips of cats
Sebaceous in nature, used to mark territory
Secretion deposited by rubbing head against objects
Describe carpal glands
Present in cats and pigs
Located proximal to the carpal pad and marked by a tactile hair
Describe caudal glands
Sebaceous and serous glands
Located at the base of tail (cat) or around 7th to 9th caudal vertebrae (dogs)
Most active during breeding season
What is the cause of stud tail?
Caudal gland hyperplasia
Describe circumanal glands
Sebaceous in nature (only dogs)
Around anal area of the dog
No excretory duct, empty by bursting
Play a role in steroid synthesis, intraspecies communication and is a common tumor site
Describe glands of the anal sacs
Found within the walls of the anal sacs of dogs and cats
Sebaceous and serous in nature, serves as a marker
Foul and expressed during defecation
What are the 3 basic types of hair?
Guard hair, wool hair, tactile hair
Describe guard hairs
Lie close against the skin
Straight and stiff, forms top coat
Comes in bristle, wavy and wavy bristle
Describe wool hairs
Form soft undercoat
Fine and wavy
Bristled wavy, large wavy, fine wavy
Describe tactile hairs
Modification of guard hairs
Found on head of dogs and cats, and on the carpus of cat and pigs
Tactile hairs are thicker and extend past guard hairs
Characteristics of the hair cycle
All hair has a finite life span
All dogs shed
Not all hair is shed at one time, shedding can be seasonal or year-round
What are the phases of the hair cycle?
Anagen, early catagen, late catagen, telogen, early anagen
What is the anagen phase?
Fully functional hair follicle
What is the early catagen phase?
Follicle begins to atrophy
What is the late catagen phase?
Further atropy of hair follicle
What is the telogen phase?
New hair matrix begins to form under atrophied follicle
What is the early anagen phase?
New hair begins to grow
What phases are in the transition phase?
Early catagen, late catagen
What is considered the resting phase of the hair cycle?
Telogen
Describe plantigrade mammals
Plantigrade mammals (walking on soles)
Digital pads, metacarpal pads, metatarsal pads, carpal pads, tarsal pads
Bears, humans
Describe digitigrade mammals
Walking on toes
Digital pads, metacarpal pads, metatarsal pads, carpal pads (no use)
No tarsal pads
Dogs, cats
Describe the footpad
Heavily keratinzied epidermis
Made with rough conical papillae in the dog (smoother in cat)
Digital cushion is made of subcutis (hypodermis)
Footpads contain eccrine sweat glands (no hair)
Describe claws
Extend apically from pad
Made from modified superficial layers of epidermis
Encloses distal phalanx (quick) and consists of a sole, two walls and a central dorsal ridge
How are claws retracted in cats?
Elastic ligaments retract claws back in to claw fold (vallum)
How are mammary glands arranged in dogs?
Two bilaterally symmetric rows suspended from ventral abdominal wall
5 pairs in dogs, 4 pairs in cats
2 pair thoracic, 2 pair abdominal (1 in cats), 1 pair inguinal
What is a mamma?
Glandular complex associated with a single papilla (nipple) that has 7-12 openings
Describe the mammary gland
Modified, enlarged compound tubuloalveolar sweat gland
Each opening of the papilla leads to an independent duct
Describe the blood supply of the thoracic mammary glands
Perforating branches of the internal thoracic artery and vein
Describe blood supply for cranial abdominal mammary glands
Cranial superifical epigastric artery and vein
Describe blood supply for caudual abdominal mammary gland and inguinal mammary gland
Caudal superficial epigastric artery and vein
Describe the lymphatic system of the mammary gland
Thoracic and cranial abdominal mammae drain indepenently to axillary lymph nodes
Caudal abdominal and inguinal mammae drain to the superficial inguinal lymph nodes
If one teat gets mastitis, will the other teats be more likely to get mastitis?
No, because they were independent from one another.
Cranial abdominal and caudal thoracic may connect adjacently but not between Left and Right sides
