Chapter 6 - Integument Flashcards
list and describe the phases of healing
Starts with injury
Inflammation
-initial response
- goal - limit further damage and get rid of harmful agents
Organization
- granulation tissue
Regeneration
- epithelialization and more scar tissue
List the cell types that comprise the epidermis
keratinocytes, melanocytes, Merkel cells and Langerhans cell
Keratinocytes
Cells that synthesize keratin. They have 3 distinct stages in the epidermis- basal, prickle and granular. They travel superficially from basal layer they lose their organelles to make room from keratin. As a result they die.
List the 5 layers of the epidermis
Stratum corneum - horny layer (most superficial)
Stratum lucidum - clear layer
Stratum granulosum - granular layer
Stratum spinosum - spiny layer
Stratum basale/stratum germinvatum - basal layer
Stratum basale
A single row of keratinocytes, attached to basement membrane. Engaged in cell division
Describe the unique features of paw pads
tough thick layers of fat and connective tissue
- exocrine sweat glands and lamellar corpuscles
cornical papillae cover entire pad
all 5 epidermal layers
pigmented
multiple paw pads- carpal, metacarpal/metatarsal, digital
Describe the unique features of planum nasale
Tip of nose in dogs, cats, pigs and sheep
usually pigmented
A-glandular (except in sheep, pigs and cows)
3 epidermal layers
- thin stratum corneum divided by deep surface grooves
Describe the parts of the hair follicle
Hair bulb (invagination of epidermis)
Papilla (base of bulb) (Dermal layer, attachment for the hair)
Matrix - rapidly dividing cells that cover the papilla
Internal root sheath
External root sheath
Connective tissue root sheath
Describe how hair grows
Anagen phase - follicle is longest (growth phase)
Catagen phase - thick glassy membrane (transition)
Telogen- hair very short (rest). Hair is called club hair
New cells are constantly forming in the hair bulb. These cells stick together and harden. The full strand of hair develops from this group of hardened hair cells. Because new hardened cells keep on attaching to the hair from below, it is gradually pushed up out of the skin.
List and describe the three types of hair
Primary/guard hairs - thicker and longer
Dominant hair in hair follicle
Secondary/wool-type hair - softer and shorter
And tactile/sinus hair
- whiskers
- also might be intermittently through coat
Describe the structure and location of sebaceious glands
Sebaceous glands are found all over the body except in specialized regions (like planum nasale and paw pads)
- located in dermis but came from epidermis
-simple or complex alveolar structures
-duct empties into hair follicle or directly onto skin (lips, labia, vulva, prepuce, eyelid, etc)
- manufacture and stores oily substance sebum or lanolin - for skin/hair
Differentiate between the eccrine and apocrine sweat glands
Eccrine sweat glands occur over most of the body and open directly onto the skin’s surface. Apocrine glands open into the hair follicle, leading to the surface of the skin.
Functions of the integument system
covers and protects
Prevents desiccation
Reduces threat of injury
Assists in maintenance of body temperature
Excretes water, salts and organic wastes
Receives and conveys sensory info
stores nutrients
3 layers of skin
Epidermis
Dermis/corium
Hypodermis/subcutaneous layer
Epidermis
Very thin, made of rapidly dividing epithelia cells The principle cells in the epidermis are keratinocytes, melanocytes, Merkel cells and Langerhans cells. Most are keratinocytes which produce tough, fibrous, waterproof protein called keratin
Dermis
Also called the corium.
Greatest portion of the integument - the hide
Highly fibrous, dense irregular connective tissues (most of it)
- collagen, elastic and reticular fibers
hypodermis
subcutaneous
thick layer, resides below dermis
Allows skin to move freely over underlying layers
loose layer of aerolar tissue
-fibers continuous with dermis
-adipose, blood and lymphatic vessels, nerves
-pancinian corpuscles (nerves)
Melanocytes
A cell located within lower epidermis that processes tyrosinaes and melanin.
Merkel cells
Located in small numbers in the epidermal-dermal junction. Aids in tactile functions
Langerhans cell
The macrophages of the epdiermis that phagocytize invading microorganisms and serve as antigen-presenting cells
Epidermis of hair skin
3 epidermal layers rather than 5: stratum corneum, stratum spinosum and stratum basale
Scale-like folds on skin
Tactile elevations- Epidermal papillae
Tactile hairs (whiskers)- tylotrich hairs
Epidermis gives rise to the following structures
Hair, feathers, glands, paw pads, nails/horns/beak
Additional components of Dermis (beside connective tissue)
hair follicles, nerve endings, glands, smooth muscle, blood vessels, lymphatic channels, fibroblasts, adipocytes, macrophages
Papillary layer
Thin, superficial layer
Just below epidermis
Dermal papillae
Looping blood vessels and nerve endings
Meissners corpuscles (nerve endings)
Reticular layer
80% of dermis
indistinct layer between papillary layer
Parallel bundles of collagen fibers
-tension lines
- dermal folds
Skin Pigmentation
Caused by the presence or absence of melanin granules in the extensions of melanocytes
Dispersion of granules
- no pigment if granules near nucleus
- Pigment if granules near cellular arms and surround tissue
controlled by hypophysis
- melanocyte stimulating hormone- MSH
- melanosomes absorbed by keratinocytes
Carpal pad
paw pad up near wrist
Chestnuts
Dark horny structures on the legs of hooved animals. thought to be vestiges of digits
Inside each leg at carpus and tarsus
Ergots
Dark horny structures on the legs of hooved animals. thought to be vestiges of digits
Buried in caudal hairs of fetlock
Cutaneous pouches
infoldings of skin of sheep
- contain fine hair, sebaceous and oil glands
3 locations- infraorbital, interdigital, inguinal
Functions of hair
Essential for survival
Maintenance of body temperature, protection via camouflage
Arrector Pili Muscles
Small, smooth muscle attached to each hair follicle
stimulated by the sympathetic nervous system
- contraction pulls the hair erect
Composition of hair
Medulla (middle), cortex, cuticle (outside)
Hair color
Pigment in cortex and medulla of hair strand
- melanin produced in base of hair strand
- melanin transferred to cortical and medullary cells of hair strand
Different colors
-Quantity of melanin and type
- Melanin production decreases with age
Sebum
Oily, lipid substance manufactured through sebaceous gland
Sebum is forced through hair follicle
Arrector pili muscle contracts and compresses gland
Sebum coats base of hair and skin
(first line of defense)
sweat glands
sudoriferous glands
produces water, transparent liquid
Only man and horse sweat profusely
help cool body
eccrine and apocrine
Eccrine
Watery sweat
empty onto surface of skin
found on footpads of cats
Apocrine
Stinky
Empty into hair follicles (armpits)
thicker, smellier secretions
Stratum spinosum
Spiny layer
Named because when cells removed they contract into spiculaed masses (called prickle cells). Naturally smooth
Tail glands
Oval region at base of tail, especially dogs and cats.
Especially large apocrine and sebaceous glands
For scent recognition
Stratum Granulosum
Middle layer of skin.
Two to four layers of flattened diamond-shaped keratinocytes.
These cells begin to die, cytoplasm dying
Stratum lucidum
Clear Layer found only in very thick skin
A few rows of flattened, dead cells
Anal glands
Reservoir for malodorous secretions, similar to musk glands
lined with sebaceous and apocrine glands
Contents expressed during defecation and when the animal is frightened
Location in cats and dogs
- connected by a single duct to the lateral margin of the anus. (Located at 5 and 7 time)
- can become impacted and infected
Stratum corneum
Horny layer
Outermost layer and constitutes about three quarters of the epidermis
twenty to 30 rows of keratinocytes
Claws and dew claws
Hard outer covering of distal digits (non-retractable except cats)
Functions - traction and catching prey
Dew claws - evolutionary remnants of digits
- first digit of dogs
- second and fifth digit of cows, pigs and sheep
Claws in cats
Attached at terminal phalanx - P3
The hoof
Ungula
Horny outer covering of some animals
Each hoof covers a digit
Hooves rest on the corium
- inner layer modified dermis
- outer layer modified epidermis
Corium
both claws and hooves rest on this underlying sensitive tissue
highly innervated
Corium types in horse
Laminar corium - between hoof wall and third phalanx
Pericolic corium - supplies nutrients to overlaying periople
Coronary corium - provides nutrients to the stratum externum and stratum medium
Sole corium is located superior to the sole and provides nutrients to the sole
Frog corium is located superior to frog and provides nutrients to frog
Horns
grow continuously
Mass of horny keratin
Not sex related
Structurally similar to hair
Horns versus antlers
Horns not sex specific, antlers are
Horns epidermal in origin, antlers dermal
Horns grown continuously, antlers shed
Horns are hollow, Antlers lack central core (velvet skin supply blood)
Inflammation
Nonspecific response
Edema\
Clot formation
Phagocytosis
Release of histamine and heparin
Step 2 of healing
Organization - the formation of granulation tissue
Wound repair begins soon after injury
-Phagocytosis
-granulation tissue formed
Step 3 of healing
Regeneration
Epithelization covers granulation tissue
Scab is pushed off
Granulation tissue becomes fibrous scar adhesions
1st intention healing
Surgery to heal wound
Wounds close in apposition
No granulation of tissue
2nd intention healing
Wound edges separated from each other
Scarring results
No surgery
Ist stage of healing after injury
Inflammation - the body’s way of limiting damage to the tissue, isolating the injured area, and ridding the tissue of harmful agents.
An initial vasoconstriction of the vessels to control hemorrhage is followed by vasodilation of the vessels to increase the supply of oxygen and nutrients to the injured tissue.
Plasma leaks into the tissue from the blood vessels, causing
swelling of the tissue and the animal may show signs of pain at the injured area.
Clot formation begins to slow the bleeding.
Macrophages and neutrophils are brought to the site via the
blood vessels to help eliminate debris and harmful
2nd stage of healing after injury
Organization
As neutrophils and macrophages work to rid the area of harmful agents and debris, fibroblasts begin to lay down collagen fibers and form granulation tissue (beneath the scab that develops on the surface).
The granulation tissue has many small capillaries that
provide the injured area with nutrients and oxygen.
3rd stage of healing after injury
Epithelialization occurs as new epithelial tissue is laid down over the granulation tissue. As the epithelial layer thickens, the scab will be pushed off the surface of the skin. The granulation tissue is replaced by fibrous scar tissue, which contracts and apposes the wound edges
