Lecture 4 materials - Integumentary/skin

Question 1

What are the functions of the integument?

Answer 1

Protection, sensory information, storage of water and electrolytes, vitamin synthesis, thermoreglation, immunity, intraspecies communication

Question 2

What is the largest organ system of all mammals?

Answer 2

The integument (this includes but not exclusively skin)

Question 3

What does the skin consist of?

Answer 3

Epidermis and dermis

Question 4

Name accessory structures of the integument

Answer 4

Skin glands, hair, pads, claws, mammary glands

Question 5

Describe the skin

Answer 5

Made from epidermis (top) and dermis (deep)

Melanocytes produce pigment

SKin encloses the body and blends mucus membranes at orifices

Question 6

Describe the epidermis

Answer 6

Ectodermal with stratified squamous epithelium

Avascular

Thick in non-hairy skin and thin in hairy skin

Question 7

What are the 5 layers of thick skin

Answer 7

Stratum basale, stratum spinosum, stratum granulosum, stratum lucidum, stratum corneum

Question 8

Describe the dermis (corium)

Answer 8

Comes from mesoderm, formed from dense connective tissue (collagen)

Papillary and reticular layer

Well vascularized and innervated

Question 9

What part of the skin does leather come from?

Answer 9

Dermis

Question 10

What is the difference between the papillar and reticular layer of the dermis?

Answer 10

Cells are more spread out in the papillary layer

Question 11

Describe the hypodermis

Answer 11

Between skin and superficial fascia

Cutaneous muscles extend tendons in to the hypodermis for skin movement

The subcutis is thin where movement is undesirable

Question 12

What is the subcutis made of

Answer 12

Collagen, elastic fibers, white fat

Question 13

What does thickening of the subcutis lead to?

Answer 13

Skin folds

Question 14

Are there glands on nasal skin of dogs?

Answer 14

No, moisture comes from serous secretions from lateral nasal glands

Question 15

What is the nasal skin made of?

Answer 15

polygonal plaque areas form the planum nasale

Question 16

What are the 2 basic skin glands?

Answer 16

Sebaceous, Sweat

Question 17

Describe sebaceous glands

Answer 17

Produce sebum and drain directly in to hair follicles with apocrine sweat glands

Lubricates and waterproofs skin and coat

Question 18

Describe Eccrine sweat gland

Answer 18

Eccrine (no hair): found in footpads of dogs, predominantly in primates, secrete water-y sweat by exocytosis

Question 19

Describe Apocrine sweat gland

Answer 19

Apocrine (with hair): Empties in to hair follicles with sebaceous glands by pinching off part of the cell.

Odorous

Question 20

Describe ceruminous glands

Answer 20

Produces ear wax (cerumen)

By apocrine and sebaceous (pinching off, oily sebum) secretion

Located in external auditory canal

Question 21

Describe circumoral gland

Answer 21

Found only in lips of cats

Sebaceous in nature, used to mark territory

Secretion deposited by rubbing head against objects

Question 22

Describe carpal glands

Answer 22

Present in cats and pigs

Located proximal to the carpal pad and marked by a tactile hair

Question 23

Describe caudal glands

Answer 23

Sebaceous and serous glands

Located at the base of tail (cat) or around 7th to 9th caudal vertebrae (dogs)

Most active during breeding season

Question 24

What is the cause of stud tail?

Answer 24

Caudal gland hyperplasia

Question 25

Describe circumanal glands

Answer 25

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

Question 26

Describe glands of the anal sacs

Answer 26

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

Question 27

What are the 3 basic types of hair?

Answer 27

Guard hair, wool hair, tactile hair

Question 28

Describe guard hairs

Answer 28

Lie close against the skin Straight and stiff, forms top coat Comes in bristle, wavy and wavy bristle

Question 29

Describe wool hairs

Answer 29

Form soft undercoat Fine and wavy Bristled wavy, large wavy, fine wavy

Question 30

Describe tactile hairs

Answer 30

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

Question 31

Characteristics of the hair cycle

Answer 31

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

Question 32

What are the phases of the hair cycle?

Answer 32

Anagen, early catagen, late catagen, telogen, early anagen

Question 33

What is the anagen phase?

Answer 33

Fully functional hair follicle

Question 34

What is the early catagen phase?

Answer 34

Follicle begins to atrophy

Question 35

What is the late catagen phase?

Answer 35

Further atropy of hair follicle

Question 36

What is the telogen phase?

Answer 36

New hair matrix begins to form under atrophied follicle

Question 37

What is the early anagen phase?

Answer 37

New hair begins to grow

Question 38

What phases are in the transition phase?

Answer 38

Early catagen, late catagen

Question 39

What is considered the resting phase of the hair cycle?

Answer 39

Telogen

Question 40

Describe plantigrade mammals

Answer 40

Plantigrade mammals (walking on soles) Digital pads, metacarpal pads, metatarsal pads, carpal pads, tarsal pads Bears, humans

Question 41

Describe digitigrade mammals

Answer 41

Walking on toes Digital pads, metacarpal pads, metatarsal pads, carpal pads (no use) No tarsal pads Dogs, cats

Question 42

Describe the footpad

Answer 42

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)

Question 43

Describe claws

Answer 43

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

Question 44

How are claws retracted in cats?

Answer 44

Elastic ligaments retract claws back in to claw fold (vallum)

Question 45

How are mammary glands arranged in dogs?

Answer 45

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

Question 46

What is a mamma?

Answer 46

Glandular complex associated with a single papilla (nipple) that has 7-12 openings

Question 47

Describe the mammary gland

Answer 47

Modified, enlarged compound tubuloalveolar sweat gland Each opening of the papilla leads to an independent duct

Question 48

Describe the blood supply of the thoracic mammary glands

Answer 48

Perforating branches of the internal thoracic artery and vein

Question 49

Describe blood supply for cranial abdominal mammary glands

Answer 49

Cranial superifical epigastric artery and vein

Question 50

Describe blood supply for caudual abdominal mammary gland and inguinal mammary gland

Answer 50

Caudal superficial epigastric artery and vein

Question 51

Describe the lymphatic system of the mammary gland

Answer 51

Thoracic and cranial abdominal mammae drain indepenently to axillary lymph nodes Caudal abdominal and inguinal mammae drain to the superficial inguinal lymph nodes

Question 52

If one teat gets mastitis, will the other teats be more likely to get mastitis?

Answer 52

No, because they were independent from one another. Cranial abdominal and caudal thoracic may connect adjacently but not between Left and Right sides