Integumentary intro Flashcards
list the 6 functions of the skin
- physical barrier
- temp regulation
- blood pressure
- secretory
- sensory
- protection
what are the 3 layers of the skin?
- epidermis
- dermis
- hypodermis/subcutis
what is the function of the epidermis?
primary protection/physical barrier against microbes, chemicals, toxins, and impact via formation of cornified envelope, production of antimicrobial substances, and permanent shedding of corneocytes
what skin layer is the primary envelope to contain water, electrolytes, and macromolecules?
epidermis
what are the 5 layers of the epidermis?
from deep to superficial:
1. stratum basale/germinativum
2. stratum spinosum
3. stratum granulosum
4. stratum lucidum
5. stratum corneum
what is found in the stratum basale? give tissue type
stem cells to produce all following layers, rests upon dermis; single layer of columnar or cuboidal epithelium; EUCHROMATIC
describe the stratum spinosum give tissue type
maturing keratinocytes are found here; keratinocytes produce keratin filaments that will kill the cell when enough are produced; cells shrink when plated but are held together by desmosomes so you can see their spines! polyhedral or squamous prickle cells
where is the stratum spinosum thick? where is it thin?
thick in regions where there is not hair, thin in regions with hair
describe the stratum granulosum; give tissue type
keratohyalin granules (clumped keratin filaments; soft keratin) are seen; cells also secrete lipids (lamellar bodies) to make skin waterproof and act like mortar between bricks for added protection; flat, squamous cells
describe the stratum lucidum; where is it found? give tissue type
only present in very thick tissue! will look clear since no like stain; found in foot pads or highly keratinized tissue; homogenous squamous cell layer
describe the stratum corneum; give tissue type
dried, horny cells in the process of being desquamated (turned into dander); layers of flat cornified cells lacking a nucleus
give what epidermal layers keratinocytes are proliferative, maturing, and inactive
proliferative: stratum basale
maturation: stratum spinosum and stratum granulosum (keratin filament and keratohyalin formation)
inactive: stratum lucidum and stratum corneum (lose nucleus, cell contents comapcted)
what are internal impacts to the epidermis? what is the result?
malnutrition or lack of essential fatty acids leads to epidermal lipid deficiency/disturbance which leads to scaling or poor barrier function
what are external impacts to the epidermis? what is the result?
excessive washing, chemical, and wet/dry environments weaken the epidermal barrier, leading to increased scaling and increased transepidermal water loss
what is the most numerous cell type in the integument?
keratinocytes
what do keratinocytes produce?
keratin
where are melanocytes located?
in the stratum basale and project into the stratum spinosum
what do melanocytes possess? how does this aid their function?
possess cytoplasmic processes of considerable length; these cells secrete pigment that their cytoplasmic processes inject into adjacent cells
describe the cytoplasm of melanocytes
clear and scant; usually mixed with pigment granules
what two pigments do melanocytes produce?
- eumelanin (black/brown)
- pheomelanin (orange/yellow)
responsible for skin and hair color
what are intraepidermal macrophages/Langerhan’s cells? describe their cytoplasm and where they are found
an immunologic link between outside environment and individual immune system; found in the strata basale and spinosum, but mainly spinosum; have clear cytoplasm with a round to irregular shaped nucleus
what are tactile epitheliod/Merkel cells? give function and describe cytoplasm and location
function not confirmed, but believed to be mechanoreceptors; clear cytoplasm with a pyramidal to flat nucleus parallel to epidermal surface; FOUND ONLY IN BASALE
what are the 2 layers of the dermis?
- papillary layer
- reticular layer
describe the papillary layer of the dermis; give cell types (5)
interdigitates with and increases cells on basement membrane; contains
1. fibroblasts
2. macrophages
3. plasma cells
4. mast cells
5. fat
describe the reticular layer of the dermis
a network of collagen, elastic fibers, and reticular fibers
what does the reticular layer of the dermis contain? (5)
- hair follicles
- sweat and sebaceous glands
- blood vessels
- lymphatic vessels
- nerves
what are the 3 functions of the reticular layer of the dermis?
- blood supply
- immune protection
- anchor epidermis
what are epidermal pegs/ridges?
epidermal projections into the dermis
what are dermal papillae?
projections where the dermis conforms to the contour of the basale
what do dermal papillae and epidermal ridges do?
increase surface area and thickness
what are the 3 main physiologic functions of the dermis?
- absorb stress from movement (push and pull of skin)
- maintain skin shape
- water storage
what part of the dermis resists pull/tensile forces?
fibers (mainly collagen)
what part of the dermis resists push/compression forces?
polymers (proteoglycans and hyaluronan/hyaluronic acid)
give 3 additional functions of the dermis
- immunologic surveillance
- thermoregulation/cooling
- cutaneous sensation
what does the hypodermis/subcutis do?
anchors the dermis to the underlying muscle and bone
what are 3 physiologic functions of the subcutis/hypodermis?
- energy reserve
- thermoinsulation
- protective padding
what are the 2 layers of the hypodermis/subcutis? describe
- panniculus adiposus: large deposits of fat that function as absorbant cushions or pads
- panniculus carnosus: cutaneous muscle for voluntary skin movement
what type of keratin is hair?
hard keratin
list and describe the 3 parts of hair
- shaft: free end that protrudes from the surface of the epidermis
- root: embedded within the skin
- hair bulb: terminal hollow bulb attached to a dermal papilla (is alive)
although they vary by animal, give the 3 general layers of hair
- cuticle
- cortex
- medulla
describe the cuticle of hair
the outermost of the hair layers in any animal; an overlapping (shingle-like) single layer of flat keratinized cells whose pattern makes it hard to pull hair from the root
describe the cortex of hair
densely packed keratinized cells that contain pigment granules acquired from the follicle
describe the medulla of hair
loosely arranged cuboidal to flattened cells at the proximal end; air-filled spaces at distal end of the shaft
what is the hair follicle?
the anatomical region of the hair where growth occurs
what are the 3 layers of the hair follicle? describe
- inner root sheath: innermost layer
- outer root sheath: continuous with stratum basale and granulosum
- dermal root sheath: inner and outer layers of collagen
describe the hair bulb
a bulbous region at the terminal end of the hair follicle that defines the outer limits of the dermal papilla (which projects into the underside of the bulb); growth occurs at the interface of the epidermal cells and dermal papilla matrix cells
how is pigmentation of hair accomplished?
epidermal melanocytes located along the epidermal cells donate their pigment to the surrounding cells
give the 3 phases of the hair growth cycle
- anagen: cell mitotically active
- catagen: regressive phase; mitotic activity decreases then ceases
- telogen: resting phase; follicle eventually cycles back to mitotically active and a new hair is formed (hair is not shed until new hair starts to grow out)
what is keratinization?
a highly orchestrated, genetically programmed process resulting in structural and metabolic changes whose endpoint is a terminally differentiated keratinocyte (dead)
give the 5 steps of keratinization
- proliferation/adhesion: firm adhesion by desmosomes, hemidesmosomes, production of keratin filaments
- production of additional keratin filament types; beginning of synthesis of lipid-containing lamellar bodies
- cornified enveloped are firmly connected via corneodesmosomes and light junctions
- progressive flattening of cells, keratin filaments get progressively packed into large, insoluble polymers, forming the cornified envelope with the help of filaggrin
- keratinocytes are terminally differentiated, coated by lipids, separated by proteases, and constantly shed
what are the 4 classifications of exocrine glands based on mode of secretion
- merocrine
- apocrine
- holocrine
- cytocrine
describe merocrine mode of secretion; give an example
secretory product discharged without any loss of cytoplasm; sweat glands
describe apocrine mode of secretion; give example
small portions of the cytoplasm lost (Pinch one off); sweat glands
describe holocrine mode of secretion; give example
entire cell and its contents are discharged (cell dies and is sloughed as product); sebaceous glands
describe cytocrine mode of secretion; give an example
secretory product is transferred from one cell to another cell; melanocytes
what do sebaceous glands empty their products into? what is the result?
into hair follicles; make hair shiny and protect hole from bacteria when hair sheds
what mode of secretion do sebaceous glands utilize?
holocrine
what is the oily secretion of sebaceous glands called?
sebum
what are the 2 functions of sweat glands?
cooling and excretory function
what two modes of secretion do sweat glands utilize?
- merocrine
- apocrine
when utilizing merocrine secretion, where do sweat glands empty their product?
directly onto the surface of the skin
when utilizing apocrine secretion, where do sweat glands empty their product?
empties into the hair follicle just before it contacts the epidermal surface
what are sweat glands that utilize merocrine secretion called/look like? where are they found? give the tissue type of the secretory portion and the duct
coiled simple tubular glands; found in specialized areas of the skin like foot pads; secretory portion is simple cuboidal and duct is bistratified cuboidal
what do sweat glands that utilize apocrine secretion look like? give the tissue types of the secretory portion and the straight duct region
look like simple tubular glands; coiled secretory region is simple cuboidal and the straight duct region is bistratified cuboidal or columnar
