INTEGUMENT AND BONE TISSUE Flashcards
Epidermis
-made up of epithelial tissue
-constantly shedding and regenerating
-composed of keratinized stratified squamous epithelium
Keratinized stratified squamous epithelium
4 main cell types:
-Keratinocytes
-Melanocyte
-Merkel cells (tactile cells)
Keratinocytes
-producing keratin
-tough fibrous protein
-provides protection
Melanocytes
-produce melanin
-important for protection from UV
-melanin is a pigment that protects against damage from UV radiation
Merkel cells (tactile cells)
-touch receptor cells
-in stratum basale
-when compressed, send signals to nerves
Stratum basale
-deepest, single layer of cuboidal to low columnar keratinocytes in contact with basement membrane
-cell division occurs here
-also contains melanocytes and tactile cells
-continuous cell division
-produces all other layers
-as cell divides, new cell is pushed toward external surface
Stratum spinosum
-layer of 8-10 keratinocytes and some dendritic cells
-several layers of keratinocytes attached to neighbours by desmosomes
-epidermal dendritic cells present
Stratum granulosum
-3-5 layers of keratinocytes with distinct granules in cytoplasm
-keratinization begins in this layer
-non dividing cells
-filled with granules of keratin
-as keratin is produced causes nucleus and organelles to disintegrate
Stratum lucidum
-only present in thick skin
-fingers tips, palms, soles
-2-3 layers of anucleate, dead keratinocytes
-seen only in thick skin (i.e., palms of hands, soles of feet)
Stratum corneum
-most superficial layer of epidermis
-20-30 layers of dead, flattened, anucleate, keratin-filled keratinocytes
-~20 layers of flat cell remnants
-continuously shed and replaced
Dermis
-dermis has extensive nerve fibers
-sensory nerve fibers
-tactile corpuscles
-detect pressure, vibration and cold
-motor nerve fibers
-control blood flow and gland secretion
-dermal blood flow
-supply nutrients to epidermis and dermis
-important role in body temperature and blood pressure regulation
Papillary region (dermis)
-consists of areolar connective tissue with capillaries, tactile receptors and free nerve endings
-superficial layer of dermis
-composed of areolar connective tissue
-forms dermal papillae
-houses capillaries and tactile receptors
Reticular region (dermis)
-deeper layer of dermis
-composed of dense irregular connective tissue
-surrounds and supports hair follicles
-sebaceous glands and sweat glands, nerves and blood cells
-consists of dense irregular connective tissue with adipose cells, hair follicles, nerves and glands
Subcutaneous
-attaches the skin to underlying tissues and organs
-acts as an energy reserve
-provides thermal insulation
-drugs often injected here
-not considered part of the integument
-deep to dermis
-composed of areolar and adipose connective tissue
Hair
-pilus ( single hair )
-composed of dead, keratinized epidermis cells
-functions:
-protection
-heat retention
-sensory reception
-main components:
-shaft: above the surface of the skin
-root: deep to the skin surface
-bulb: made of epithelial cells, where the hair originates
Nails
-composed of keratinized epidermal cells
-found on the dorsal surfaces of the ends of the fingers and toes
-functions:
-protection
-assist in grasping objects
Sebaceous glands
-connected to hair follicles
-secretes oily substance into hair follicle
Sebum:
-prevents dehydration of hair and skin
-inhibits growth of certain bacteria
-oil glands are stimulated by androgens
Eccrine sweat glands
-occur over most of the body and open directly into the skins surface
-cools the body as sweat evaporates from the skin
-secretes a watery substance
-sweat while exercising ( no order )
-secretes a watery substance that helps to cool the body and eliminates small amounts of waste
Apocrine sweat glands
-located in the skin of the axilla, groin, areolar, and bearded facial regions of adult males
-released during sexual activity
-produce waxy substance
-found in ear canal
-secrete a water substance with proteins and lipids
-susceptible for bacteria growth leading to odor
-emotional or stressful sweating
Know the 4 steps involved in wound healing
- cut blood vessels bleed into the wound
- blood clot (scab) forms
- blood vessels regeneration
- epithelial regeneration
- cut blood vessels bleed into the wound
-brings clotting proteins leukocytes and antibodies
-inflammation
- blood clot (scab) forms
-temporary barrier
-prevents the entry of pathogens
-macrophages and neutrophils clean the wound of cellular debris
-proliferation
- blood vessels regeneration
-also creates granulation tissue
-vascular connective tissue
-macrophages begin to remove clotted blood
-fibroblasts produce new collagen fibres
-remodelling
- epithelial regeneration
-due to cell division at the edge of the wound
-scar tissue
-more thick and tough
-fibrosis
Regeneration
-replacement of damaged cells with cells of the same type
Fibrosis
-replacement of damaged cells with different cells
-produces scar tissue
-composed primarily of collagen fibres produces by fibroblasts
First degree burn
-only involves the epidermis
-mild pain and redness
-no blistering or loss of function
-ex. mild sunburn
Second degree burn
-involves the epidermis and dermis
-redness, blister formation, edema and pain
-some skin functions are lost
-ex. severe sunburn or scalding from hot liquid