Physio Test 2 - Histology

Front 1

Epidermis

Back 1

Mainly stratified squamous epithelium (keratinocytes)

Front 2

Types of cells in epidermis

Back 2

keratinocytes, melanocytes, merkel cells, langerhans cells

Front 3

Thick vs thin skin

Back 3

classified based on thickness of epidermis

Front 4

thick skin

Back 4

smooth, nonhairy, prominent epidermal ridges. found on palms and soles.

Front 5

thin skin

Back 5

hairy. found everywhere else.

Front 6

5 layers of epidermis

Back 6

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

Front 7

Stratum Basale

Back 7

single layer of basophilic cuboidal/columnar cells resting on basement membrane.

Front 8

Surface junctions in stratum basale

Back 8

desmosomes bind adj cells; hemidesmosomes bind cells to basal lamina

Front 9

important role of stratum basale

Back 9

stem cells located here; lots of mitotic cell activity

Front 10

types of cells in stratum basale

Back 10

melanocytes, merkel cells in addition to keratinocytes

Front 11

Stratum Spinosum

Back 11

polyhedral cells w/ central nucleus and cytokeratin bundles. can be many layers thick. also contain langerhans cells.
“prickle” cells in process of growth and early keratin synthesis

Front 12

Tonofibrils

Back 12

aggregates of cytokeratin that converge at desmosomes and help cells be cohesive. resist injury.

Front 13

Stratum granulosum

Back 13

intracellular granules contribute to keratinization process

Front 14

stratum lucidum

Back 14

very thin layer, only seen in thick skin. Thin layer, extremely flattened cells without organelles; keratin filaments present

Front 15

stratum corneum

Back 15

15-20 layers of flat, keratinized cells whose cyto is filled w/ mature keratin. cells coated w/ lipid-derived anti-wetting agents.
Flat, fused remnants of dead keratinocytes

Front 16

melanocytes derived from

Back 16

neural crest

Front 17

melanocytes

Back 17

found btw cells of stratum basale, project into dermis. round cell bodies w/ projections into spinosum that transfer melanin to keratinocytes.

Front 18

Melanin made from

Back 18

tyrosine, to dopa, to dopaquinone, to melanin.

Front 19

Role of melanin

Back 19

accumulates in keratinocytes, protects nuclei from solar radiation. Ultimately fuse w/ lysosomes to create skin pigmentation.

Front 20

Langerhans cells

Back 20

comma-shaped, in spinosum only. Macrophage of skin. Carried here in blood. look for cytoplasmic process.

Front 21

Merkel cells

Back 21

in very thick skin; have free nerve endings; found in stratum basale; have sensory mechanoreceptor function. similar appearance to melanocytes.

Front 22

Dermis

Back 22

connective tissue that supports epidermis and binds it to hypodermis

Front 23

layers of dermis

Back 23

papillary layer and reticular layer

Front 24

papillary layer

Back 24

small layer, loose CT (collagen III and elasti fibers) made by fibroblasts

Front 25

reticular layer

Back 25

dense irregular CT (collagen I and elastic fibers)

Front 26

Hair follicles

Back 26

elongated keratinized structures derived from invaginations of epidermal epithelium.

Front 27

hair root

Back 27

cells surrounding dermal papilla (blood supply); continuous w/ shaft that protrudes from skin

Front 28

layers of hair

Back 28

central medulla, cortex, cuticle. more heavily keratinized in outer layers

Front 29

arrector pili muscles

Back 29

bundles of smooth muscle around follicles; binds follicle to dermis. contraction = goosebumps

Front 30

Sebaceous glands

Back 30

complex glands embedded in dermis and associated w/ hair follicles.

cells proliferate in lower layer and are pushed up, filling gland with sebum; degenerate near follicle shaft and release sebum. holocrine secretion

Front 31

holocrine secretion

Back 31

secretion includes remnants of cell itself

Front 32

melocrine secretion

Back 32

aka eccrine. cells release secretions via exocytosis. widespread in skin

Front 33

apocrine

Back 33

secretions include small amt of cellular debris. axillary and pubic areas

Front 34

sweat glands

Back 34

simple, coiled, tubular glands that open to surface.

Front 35

myoepithelial cells

Back 35

surround secretory portion of sweat glands and contract to help discharge sweat.

Front 36

clear cells

Back 36

lack granules; salt/fluid transport

Front 37

dark cells

Back 37

pyramidal cells that are filled w/ granules and responsible for glycoprotein content of sweat.

Front 38

pacinian corpuscle

Back 38

found in deep dermis/hypodermis. responds to deep pressure, high-freq vibration. single unmyelinated ending encapsulated. myelinated fiber for rapid transport

Front 39

meissner corpuscle

Back 39

dermal papillae; light touch, single unmyelinated nerve ending wrapped in CT.

Front 40

Parakeratosis

Back 40

Nucleated cells in the stratum corneum
Psoriasis; Dandruff; Increased rate of cell turnover and
division

Front 41

osteoblasts

Back 41

secrete organic and some inorganic components of bone, aka responsible for appositional growth

Front 42

where are osteoblasts found

Back 42

synthesize osteoid (uncalcified bone matrix) and are found on surfaces of bone tissues

Front 43

active osteoblasts

Back 43

cuboidal shape; produce alkaline phosphatase

Front 44

osteocytes

Back 44

Form from osteoblasts that are surrounded by matrix. maintain bony matrix

Front 45

osteocyte communication

Back 45

via cytoplasmic processes and gap junctions housed in canaliculi

Front 46

osteoclasts

Back 46

dissolve collagen and calcium phosphate crystals.

Front 47

active osteoclast

Back 47

large, multinucleate, ruffled border, cytoplasmic clear zone

Front 48

bone matrix

Back 48

ECM composed of collagen I, glycoproteins, proteoglycans, Ca++, phosphorus, bicarb, citrate, Mg, K, Na

Front 49

hydroxyapatite crystals

Back 49

calcium and phosphorus

Front 50

periosteum

Back 50

covers external surface of bone; has an outer collagen/fibroblast layer and inner osteoprogenitor cell layer

Front 51

sharpey's fibers

Back 51

bind periosteum to bone

Front 52

osteoprogenitor cells

Back 52

mitotically active, can divide and differentiate into osteoblasts. single layer in endosteum and periosteum

Front 53

endosteum

Back 53

lines internal cavities w/in bone. single layer of flat osteoprogenitor cells

Front 54

Role of Periosteum and Endosteum

Back 54

provide osteoblasts and nutrition to bone tissue

Front 55

primary bone

Back 55

woven/immature; seen in embryonic dev and fracture repair. irregular array of collagen; less mineral content and more osteocytes than mature bone

Front 56

secondary bone

Back 56

lamellar/mature bone. organized collagen; osteons

Front 57

osteons

Back 57

units w/ concentric layers of collagen and mineraliezd matrix. grow from outside in; have haversian canal at center for vessels and nerves. communicate via volkmann's canals

Front 58

compact bone

Back 58

dense, without cavities. mainly seen in diaphyses of long bones, coating of short bones, 2 layers of calvaria.

Front 59

spongy bone

Back 59

cavities interconnected w/ trabeculae; seen in epiphyses of long bones, core of short bones, diploe between skull bones.

Front 60

intramembranous ossification

Back 60

direct mineralization of matrix secreted by osteoblasts. multiple ossification centers fuse. bones of skull.

Front 61

endochondral ossification

Back 61

depositionof bone matrix onto pre-existing hyaline cartilage. primary and secondary centers fuse. long and short bones.

Front 62

ossification process

Back 62

osteoblasts secrete matrix, chondrocytes die, osteoclasts etch holes to allow for vascularization; matrix put down onto calcified cartilage.

Front 63

epiphyseal plate

Back 63

resting zone, proliferative zone, hypertrophic cartilage zone; calcified cartilage zone, ossification zone

Front 64

resting zone

Back 64

hyaline cartilage

Front 65

proliferative zone

Back 65

chondrocytes divide rapidly, form columns of stacked cells.

Front 66

hypertrophic cartilage zone

Back 66

chondrocytes enlarge, less matrix btw them

Front 67

calcified cartilage zone

Back 67

chondrocytes die, thin septa of matrix is calcified

Front 68

ossification zone

Back 68

capillaries, osteoprogenitor cells from periosteum invate cavities of dead chondrocytes, bone matrix deposited over calcified cartilage

Front 69

appositional growth

Back 69

expands girth. bone deposition at periosteum; resorption at endosteum

Front 70

fracture

Back 70

matrix destroyed, adj cells die, clot forms

Front 71

fracture repair

Back 71

macrophages remove debris, periosteum and endosteum proliferate, hyaline cartilage forms, primary bone forms, remodeled to 2.

Front 72

Bone calcium mobilized by

Back 72

transfer of ions btw hydroxyapatite crystals to interstitial fluid to blood and also PTH inhibits osteoblasts, makes them secrete factors to activate osteoclasts

Front 73

calcitonin

Back 73

secreted by thyroid, inhibits osteoclasts.

Front 74

hyperparathyroidism

Back 74

excessive PTH leads to fractures, hypercalcemia