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