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mcb 244/245 > exam 2 > Flashcards

exam 2 Flashcards

1
Q

cells

A

simplest structural & functional unit of life
-arise from other cells
-all organisms composed of cells & cell products
-organism’s structure & functions due to cellular activity
-exhibit biochemical unity
-shape & size are diverse

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2
Q

TEM

A

-views cell’s ultrastructure
-high magnification & resolution
-resolution=5 nm

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3
Q

SEM

A

-3D images but only view surface features

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4
Q

LM

A

-resolution=200 nm
-human eye resolution=70-100 um

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5
Q

cytosol/intracellular fluid

A

gel-like solution

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6
Q

extracellular fluid

A

fluid outside of cell

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7
Q

PM

A

defines boundaries of cell
-intracellular face=side that faces cytoplasm
-extracellular face=side that faces outside

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8
Q

lipid components of PM

A

-phospholipids: make up 75% of lipids; arranged in bilayer w polar heads facing outside & hydrophilic tails facing inside
-cholesterol: 20% of lipids
-glycolipids: 5%; forms glycocalyx

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9
Q

proteins of PM

A

-make up 50% of PM weight
-transmembrane proteins span bilayer (mostly glycoproteins w oligosaccharides facing extracellular side; drift about freely or anchored to cytoskeleton)
-peripheral proteins adhere to one face of PM & associated w transmembrane proteins

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10
Q

membrane protein functions

A

-receptors that messengers can attach to
-second-messenger systems (binding of signaling molecule causes release of second molecule in cytoplasm; important to hormone & neurotransmitter action)

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11
Q

enzymes

A

catalyze chemical reaction at cell surface

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12
Q

ion channels

A

allow water & dissolved ions to pass through PM
-gated=open & close to stimulus
-ligand-regulated gates respond to chemical messengers
-voltage-regulated gates respond to changes in electrical potential
-mechanically regulated gates respond to physical changes such as stretch & pressure

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13
Q

carriers

A

bind target molecules & take them across PM
-exhibit specificity for particular solute
-exhibit saturation (all carriers filled w ligands, giving transport max rate)
-pumps=carriers that use ATP

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14
Q

glycoproteins

A

cell-identity markers allowing recognition of cell as “self”
-all animal cells have glycocalyx external to PM
-human blood types determined by glycolipids

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15
Q

cell-adhesion molecules

A

hold cells to one another

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16
Q

surface extensions of cells

A

-microvilli: increase SA; dense & appear as brush border
-cilia: hairlike processes that serve sensory or motile functions; every human cell has single, nonmotile primary cilium few micrometers long
-flagella: whiplike structures longer than cilia; only on sperm cells in humans

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17
Q

filtration

A

process by which particles are driven through PM by hydrostatic pressure
-blood capillaries (materials forced through gaps by blood pressure)
-kidneys filter waste materials from blood

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18
Q

simple diffusion

A

net movement of particles from areas of high to low concentration, moving down conc gradient
-rates based on five factors: temp (high temp=faster rate); weight (more weight=slower rate); gradient (steep gradient=faster rate); SA (high SA=faster rate); permeability (high permeability=faster rate; adjust permeability by adding/removing membrane channels)

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19
Q

osmosis

A

diffusion of water down conc gradient through selectively permeable membrane
-moves from more dilute to more concentrated solution (more water to less water)
-water enters cells through aquaporins
-solution w nonpermeating molecules on one side causes water to cross towards that side (water level falls on side w permeating molecules & rises on nonpermeating side; levels become stable when osmotic pressure on both sides in balance)
-reverse osmosis, water forced through membrane under pressure against conc gradient

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20
Q

osmole

A

used to measure osmotic conc of body fluids
-osmolality=number of osmoles per kg of water
-osmolarity=number of osmoles per liter of solution
-physiological conc measured in milliosmoles per liter (mOsm/L)

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21
Q

tonicity

A

ability of solution to affect fluid volume & pressure in cell

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22
Q

hypotonic solution

A

lower conc of nonpermeating solutes than in intracellular fluid
-water moves into cell

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23
Q

hypertonic solution

A

higher conc of nonpermeating solutes than in intracellular fluid
-water moves out of cell

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24
Q

isotonic solution

A

total conc of nonpermeating solutes equal to that of intracellular fluid
-equal amounts of water flows into & out of cell

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25
Q

uniports

A

carry one solute at a time

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26
Q

symports/co-transport

A

carry two or more solutes in same direction

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27
Q

antiports/counter-transport

A

carry two or more solutes in opposite directions

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28
Q

facilitated diffusion

A

carrier-mediated transport that moves solute down conc gradient
-no ATP

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29
Q

primary active transport

A

carrier-mediated transport that moves solute against conc gradient
-ATP
-Na+/K+ pump (each cycle of pump hydrolyzes one ATP & exchanges 3 Na for 2 K)

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30
Q

vesicular transport

A

moves large particles, droplets of fluid, or numerous molecules through PM in vesicles

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31
Q

endocytosis

A

brings materials into cell
-employ motor proteins powered by ATP

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32
Q

exocytosis

A

process of discharging material from cell, occurs in many cells that secrete hormones or enzymes
-vesicle containing material to be discharged merges w cell membrane, releasing it to extracellular space
-employ motor proteins powered by ATP

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33
Q

receptor-mediated endocytosis

A

selective process by which cells take in specific molecules w minimum of unnecessary fluid
-receptors bind to particles from ECF & cluster together
-membrane sinks in & pit becomes coated inside cell w protein clathrin which buds off into cells as vesicle
-LDL (cholesterol)

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34
Q

phagocytosis

A

process by which cells engulf particles
-neutrophils=WBCs that phagocytize bacteria by extending pseudopods & trapping bacteria in phagosome which is merged w lysosome that contain enzymes to destroy invader

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35
Q

pinocytosis

A

process of taking in droplets of ECF containing useful molecules
-pits form in cell membrane & separate from membrane, forming membrane-bound pinocytotic vesicles inside cell

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36
Q

cytoskeleton

A

collection of protein filaments & cylinders that structurally support cell, determine its shape, organize its content, move substance through cell, & contribute to movement of entire cell

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37
Q

microfilaments

A

thin (6 nm); made of actin, forming network on inside of PM called membrane skeleton

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38
Q

intermediate filaments

A

8-10 nm; resist stress & participate in cell junctions
-composed of keratin in epidermal cells

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39
Q

microtubules

A

25 nm; made of tubulin
-radiate from centrosome & hold organelles in place, form structural bundles, guide organelles & molecules, & form axonemes of cilia & flagella
-forms mitotic spindle that guides chromosomes during cell division

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40
Q

organelles

A

internal structures in cells that carry out specialized metabolic tasks

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41
Q

nucleus

A

largest organelle; control center (contains genetic info)
-most cells = one nucleus (RBCs = none & skeletal muscle = multiple)
-enclosed by nuclear envelope that’s perforated w nuclear pores
-nuceloplasm=material in nucleus including chromatin & nucleolus

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42
Q

ER

A

system of interconnected cisternae enclosed by single membrane

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43
Q

rough ER

A

flattened sac covered w ribosomes
-synthesizes phospholipids & proteins of PM & proteins that are packaged in other organelles or secreted from cell

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44
Q

smooth ER

A

more tubular cisternae & lacks ribosomes
-alcohol & drug detoxification
-manufactures steroid hormones
-stores calcium in muscle cells

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45
Q

ribosomes

A

small granules of protein & RNA that translate mRNA into protein

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46
Q

Golgi apparatus

A

system of cisternae
-synthesizes & adds carb moieties to proteins prior to packaging
-receives completed proteins from rough ER, sorts them, & packages them into Golgi vesicles
-secretory vesicles that store cell product

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47
Q

lysosomes

A

packages of enzymes surrounded by membrane
-hydrolyze proteins & nucleic acids
-aid in digestion of phagocytized bacteria, nonvital organelles, & surplus cells

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48
Q

peroxisomes

A

resemble lysosomes; produced in ER
-use oxygen to oxidize organic molecules, producing hydrogen peroxide that’s used to oxidize other molecules

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49
Q

proteasomes

A

protein complexes responsible for degrading proteins tagged for destruction

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50
Q

mitochondria

A

specialized to synthesize ATP (powerhouse of cell)
-double membrane (inner membrane=cristae)
-matrix (between cristae) contains ribosomes, enzymes, & mtDNA

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51
Q

centriole

A

short cylindrical assembly of microtubules arranged in 9 groups of 3
-2 centrioles lie perpendicular to each other in centrosome
-plays role in cell division

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52
Q

inclusions

A

-stored cellular products: glycogen granules
-foreign bodies: viruses, intracellular bacteria, dust particles
-never enclosed by membrane

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53
Q

pyrimidines

A

C, T, U

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54
Q

purines

A

A, G

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55
Q

complementary base pairing

A

A&T forms 2 H-bonds; C&G forms 3 H-bonds

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56
Q

DNA function

A

code for proteins a cell makes

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57
Q

chromatin

A

DNA complexed w proteins
-46 chromosomes
-2 m in length if fully unwound
-stored in nucleus
-nucleosomes (consists of core particle that’s disc-shaped of 8 proteins called histones wrapped around DNA & linker DNA)
-chromosome territory: chromosome packed into its own region of nucleus permeated w channels

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58
Q

RNA vs DNA

A

-RNA smaller than DNA (tRNA=70-90 bases; mRNA=10,000 bases; DNA=100 million bases)
-single-stranded
-ribose sugar not deoxyribose
-uracil not thymine
-RNA function=interpret code in DNA & direct synthesis of proteins

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59
Q

gene

A

information-containing segment of DNA that codes for production of RNA molecule

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60
Q

genome

A

all the DNA in one 23-chromosome set

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61
Q

genetic code

A

system that enables 4 nucleotides to code for AA sequences of all proteins
-3 nucleotides per AA makes codon contained by mRNA
-max of 64 codons (some AA specified by more than one codon)
-start codon (Met) & stop codon

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62
Q

transcription

A

process by which DNA is made into RNA
-RNA polymerase: binds to DNA & assembles RNA strand
-promoters=start
-enzyme opens DNA helix, reads bases in one strand, & forms complementary bases
-terminator=stop
-produces pre-mRNA that contains exons & introns (enzymes remove introns & splice exons together; modified at 5’ end by adding G-cap that protects from degradation & helps ribosome recognize start site on mRNA; polyA tail added to 3’ end)

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63
Q

translation

A

process by which mRNA is made into proteins
-protein cap=start
-tRNA w anticodon on one end & binding site for AA on other side
-ribosomes w two subunits composed of rRNA & enzymes (two subunits come together; A, P, & E sites where tRNAs bind)

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64
Q

DNA replication

A

accomplished through complementary base pairing
-unwind double helix from histones
-DNA polymerase matches exposed bases w complementary free nucleotides (two strands copied by separate DNA polymerases moving in opposite directions; two new daughter strands made w each daughter DNA consisting of one old & new strand- semiconservative replication)

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65
Q

G1 phase

A

-synthesize proteins, grows, & carries out its tasks in support of body
-accumulate materials needed to replicate DNA

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66
Q

S phase/DNA replication

A

makes duplicate copy of centrioles & nuclear DNA

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67
Q

G2 phase

A

finishes replicating centrioles & synthesizes enzymes that control cell division
-checks for error

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68
Q

cell cycle length

A

-skin cells=rapid
-bone cells=slow
-skeletal muscle & nerve cells=no time

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69
Q

G0 phase

A

cells that cease to divide
-inability to stop cycling & enter G0 common in cancer cells

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70
Q

prophase

A

period where chromosome shorten & thicken, becoming compact rods that align in middle of cell
-nuclear envelope disintegrates & chromosomes released into cytosol
-centrioles sprout spindle fibers that push centrioles apart
-spindle fibers attach to kinetochore on each side of centromere

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71
Q

metaphase

A

period where chromosomes, anchored by mitotic spindle, wait for signal to split apart

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72
Q

anaphase

A

cleaving of centromere of each chromatid pair, forming sister chromatids
-daughter chromosomes migrate to opposite poles by motor proteins in kinetochore crawling on spindle fiber
-sister chromatids=genetically identical

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73
Q

telophase

A

sister chromatids clustered on each side of cell
-new nuclear envelope forms & chromosome uncoil while mitotic spindle vanishes

74
Q

cytokinesis

A

overlaps telophase; cytoplasmic division into two new cells
-myosin pulls on actin microfilaments, creating cleavage furrow
-parent cell pinches in two as furrow is deepened
-daughter cells enter interphase

75
Q

tissues

A

group of similar cells that arise from same region of embryo & work together to perform specific role

76
Q

human development

A

begins w fertilized egg which divides to produce identical, smaller cells
-first tissues organized into 3 strata called primary germ layers

77
Q

ectoderm

A

outer layer that gives rise to epidermis & nervous system

78
Q

endoderm

A

inner layer that gives rise to mucous membranes of digestive & respiratory tracts & to digestive glands

79
Q

mesoderm

A

middle layer that becomes mesenchyme, giving rise to muscle, bone, & blood

80
Q

epithelium

A

covers body surface, lines body cavities, forms external & internal linings of organs, & constitutes most gland tissue
-lies on layer of loose CT & dependent of tissue’s blood supply for nutrients & waste removal

81
Q

simple epithelium

A

one cell layer where every cell touches basement membrane
-squamous (thin, scaly)
-cuboidal (squarish, round)
-columnar (tall, narrow; produce mucus that’s secreted by goblet cells)
-pseudostratified columnar (all cells contact basement membrane but not all reach apical surface; produce mucus that’s secreted by goblet cells)

82
Q

stratified epithelium

A

two or more layers where only basal layer contacts basement membrane
-squamous, cuboidal, columnar (rare)
-transitional (transitional stage between squamous & columnar)

83
Q

stratified squamous epithelium

A

-deepest layers=cuboidal to columnar & undergo continual mitosis
-daughter cells pushed toward surface & become flatter (scalier)
-cells migrate to surface where they die & flake off (exfoliation/desquamation)

84
Q

keratinized stratified squamous epithelium

A

found on skin surface; covered w layer of compact, dead squamous cells packed w keratin & coated w water repellant glycolipid

85
Q

nonkeratinized stratified squamous epithelium

A

lacks surface layer of dead cells; found on tongue, esophagus, vagina, & other internal membranes

86
Q

transitional epithelium

A

limited to urinary tract; umbrella cells w thick outer phospholipid layer w dense patches of lipid rafts (uroplakins that are impermeable to urine embedded in rafts)

87
Q

cell junctions

A

connections between cells
-enable cells to resist mechanical stress, communicate, & control movement of substances through gaps between cells

88
Q

tight junction

A

completely encircles epithelial cell near apical surface & joins it tightly to neighboring cells
-transmembrane cell-adhesion proteins link adjacent cells & seal off intercellular space preventing substances from passing between cells

89
Q

desmosome

A

patch that holds cells together
-keep cells from pulling apart but don’t prevent substances from passing between cells
-common in epidermis & cardiac muscle

90
Q

hemidesmosome

A

links basal cells of epithelium to basement membrane

91
Q

gap junction

A

formed by connexon
-each connexon consists of ring of 6 transmembrane proteins surrounded central water-filled channel (allow ions, glucose, & solutes to pass from cell to another)
-found in intercalated discs of cardiac muscle & smooth muscle

92
Q

glands

A

cells or organs that secrete substances for use elsewhere or for elimination
-product=secretion if useful to body OR excretion if waste product

93
Q

exocrine glands

A

maintain contact w surface through ducts
-enclosed in fibrous capsule w septa/trabeculae that divide gland into lobes
-simple=single unbranched duct
-compound=branched ducts
-tubular=duct & secretory portions of uniform diameter
-acinar=secretory cells that form dilated sac
-tubuloacinar=tubules & acini
-sweat, mammary, lacrimal, salivary, liver & pancreas

94
Q

endocrine glands

A

lack ducts & secrete products into blood via capillaries
-secretions=hormones that function as chemical messengers that act on cells elsewhere in body
-pituitary, thyroid, adrenal glands

95
Q

unicellular glands

A

secretory cells found in epithelium that lack ducts
-goblet cells of respiratory system that secrete mucus

96
Q

mucous glands

A

secrete glycoprotein, mucin, which absorbs water once secreted to form mucus
-goblet cells

97
Q

merocrine (eccrine) glands

A

release products by exocytosis
-lacrimal
-sweat glands

98
Q

apocrine glands

A

lipid droplets combine in cytosol & bud from cell surface

99
Q

holocrine glands

A

accumulate product in their cells & then disintegrate to release product
-sebaceous

100
Q

functions of connective tissue

A

-binding of organs (tendons=muscle to bone & ligaments=bone to bone)
-support
-physical protection
-immune protection
-movement
-storage
-heat production
-transport

101
Q

fibroblasts

A

large flat cells that produce fibers & ground substance of tissue

102
Q

macrophages

A

large phagocytic cells that engulf & destroy bacteria, foreign particles, & dead/dying cells & respond to antigens

103
Q

leukocytes

A

enter CT from bloodstream & wander in search of bacteria

104
Q

plasma

A

synthesize antibodies

105
Q

mast cells

A

located near blood vessels & secrete heparin & histamine

106
Q

adipocytes

A

fat cells that occur in small clusters
-main cell type in adipose tissue

107
Q

collagen fibers

A

made of collagen
-tough, flexible, & resist stretching
-white fibers

108
Q

reticular fibers

A

thin collagen fibers coated w glycoprotein, forming spongelike framework in some organs

109
Q

elastic fibers

A

made of elastin which recoil from stretching

110
Q

ground substance

A

occupies space between cells & fibers
-Glycosaminoglycan (GAGs): long polysaccharide made of amino sugars & uronic acid that’s able to absorb & hold water (chondroitin sulfate, heparin, & hyaluronic acid)
-proteoglycans: central core of protein & bristle-like outgrowths of GAGs that form thick colloids & create strong structural bonds between cells & extracellular macromolecules
-glycoproteins: bind PM proteins to collagen & proteoglycans outside of cell, holding tissues together

111
Q

cell body/neurosoma

A

contains nucleus & other organelles
-center of genetic control & protein synthesis

112
Q

dendrites

A

short, branched processes extending from cell body that receive signals from other cells

113
Q

axon/nerve fiber

A

conducts outgoing signals from cell body to nerve cells

114
Q

neurons

A

detect stimuli, respond, & transmit information rapidly

115
Q

glial cells

A

outnumber neurons & make up most of volume of nervous tissue, providing support, protection, & maintenance of neurons

116
Q

cutaneous membrane/skin

A

consist of keratinized stratified squamous epithelium resting on underlying CT

117
Q

mucous membrane/mucosa

A

lines passageways open to external environment
-digestive, respiratory, urinary, & reproductive tracts
-consist of epithelium, areolar CT called lamina propria, & smooth muscle called muscularis mucosae
-covered w mucus that traps bacteria & foreign particles, preventing them from invading body

118
Q

serous membrane/serosa

A

lines insides of body cavities
-pleura, pericardium, peritoneum
-simple squamous epithelium resting on thin layer of CT
-produce watery serous fluid similar to blood serum
-epithelial content=mesothelium

119
Q

synovial membrane

A

lines some joints
-made of areolar CT & squamous epithelium w no basement membrane
-produce synovial fluid that reduces friction

120
Q

hyperplasia

A

tissue growth through cell multiplication

121
Q

hypertrophy

A

enlargement of preexisting cells

122
Q

neoplasia

A

development of tumor composed of abnormal, nonfunctional tissue

123
Q

differentiation

A

process of change from unspecialized tissue to more specialized mature tissues

124
Q

metaplasia

A

change from one type of mature epithelium into another
-during puberty, vaginal lining changes from simple cuboidal to stratified squamous

125
Q

stem cells

A

undifferentiated cells that have potential to change into one or more types of mature functional cells

126
Q

embryonic stem cells

A

compose early human embryo
-totipotent: develops into any type of human cell
-after 4 days of fertilization (embryonic blastocyst stage) cells are pluripotent where they can develop into any cell in embryo except placenta or amniotic sac cells

127
Q

adult stem cells

A

occur in small numbers in mature organs & tissue
-multipotent: develop into 2 or more different cell types
-unipotent: develop into one mature cell type

128
Q

regeneration

A

replacement of dead/damaged cells w same type of cell as before, restoring organ’s normal function

129
Q

fibrosis

A

replacement of damaged tissue w scar tissue composed mainly of collagen produced by fibroblasts
-doesn’t restore normal function

130
Q

healing of injury

A

-bleeding occurs & mast & damaged cells release histamine, increasing blood flow & capillary permeability
-blood clot forms in tissue, knitting edges of cut together & inhibiting spread of pathogens from site of injury; surface of clot forms scab while macrophages underneath begin to clean up tissue debris
-new blood capillaries grow into wound, transforming deeper portions of clot into granulation tissue; macrophages remove blood clot & fibroblasts deposit new collagen in its place
-surface epithelial cells around wound multiply & migrate into wounded area under scab; scab loosens & falls off; epithelium grown thicker
-epithelium undergoes regeneration while CT undergoes fibrosis (scarring)

131
Q

atrophy

A

shrinkage of tissue through loss in cell size or number

132
Q

senile atrophy

A

result of normal aging

133
Q

disuse atrophy

A

results from lack of use

134
Q

necrosis

A

premature, pathological death of tissue due to trauma, toxins, or infection

135
Q

infarction

A

sudden tissue death that occurs in cardiac muscle or brain tissue when blood supply is cut off

136
Q

gangrene

A

tissue necrosis resulting from insufficient blood supply, usually involving infection
-dry: diabetes complication due to arterial & nerve damage (usually in feet)
-decubitus ulcer: form of dry gangrene caused by continual pressure on skin
-wet: occurs in internal organs that become infected
-gas: necrosis of wound resulting from infection w Clostridium species (deadly; may require amputation)

137
Q

apoptosis

A

programmed cell death
-dissolves webbing between fingers & toes during embryonic development & causes shrinkage of breasts after lactation

138
Q

skin

A

largest organ of body that consists of outer epidermis & deeper dermis
-hypodermis lies dermis but not true part of skin

139
Q

thick skin

A

covers palms, soles of feet, & surfaces of fingers & toes
-contains sweat glands

140
Q

thin skin

A

covers rest of body & contains hair follicles & sebaceous & sweat glands

141
Q

functions of skin

A

-resistance to trauma & infection
-barrier (absorbing/losing excess water; blocks UV radiation; harmful chemicals- selectively permeable)
-vitamin D synthesis
-sensation
-thermoregulation
-nonverbal communication

142
Q

keratinocytes

A

synthesize keratin

143
Q

melanocytes

A

occur only in stratum basale like stem cells & synthesize melanin
-shed melanin-containing fragments from tips of branching processes
-keratinocytes phagocytize these fragments & accumulate melanin on nucleus; melaning shield DNA from UV radiation

144
Q

tactile cells

A

receptors for sense of touch found in stratum basale
-associated w underlying dermal nerve fiber

145
Q

dendritic cells

A

immune cells that migrate from bone marrow found in stratum spinosum & granulosum

146
Q

friction ridges

A

markings on fingertips responsible for fingerprints

147
Q

flexion lines

A

mark sites where skin folds during flexion of joints

148
Q

freckles

A

flat melanized patches that vary w heredity & exposure to sun

149
Q

mole/nevus

A

elevated patch of melanized skin, often w hair

150
Q

birthmarks/hemangiomas

A

patches of discolored skin caused by benign tumors of blood capillaries

151
Q

nails

A

hard derivatives of stratum corneum composed of very thin, dead, scaly cells, densely packed together & filled w parallel fibers of hard keratin

152
Q

nail plate

A

hard part of nail including:
-free edge: overhanging tip of finger/toe
-nail body: visible attached part of nail
-nail root: extends underneath overlying skin

153
Q

nail fold

A

surrounding skin of nail, separated from margin of nail plate by nail groove
-nail groove & space under free edge collect dirt & bacteria

154
Q

nail bed

A

skin underlying nail plate
-epidermis=hyponychium
-stratum basale thickens to constitute nail matrix at nail’s proximal end
-mitosis accounts for growth of nail
-thickness of nail matrix obscures dermal blood vessels, creating lunule
-eponychium (cuticle- zone of dead skin) overhangs at proximal end of nail

155
Q

hair/pilus

A

slender filament of keratinized cells that grows from hair follicle
-found almost everywhere on body

156
Q

lanugo hair

A

fine, downy, unpigmented hair found on fetus in last 3 months of development

157
Q

vellus hair

A

fine, pale hair that replaces lanugo by time of birth
-body hair of children
-comprises 2/3 of body hair of women & 1/10 of body hair on men

158
Q

terminal hair

A

longer, coarser, & unpigmented hair that forms eyebrows & eyelashes covers scalp, axillary & pubic hair, male facial hair, & some hair on trunk & limbs

159
Q

hair bulb

A

swelling at base where hair originates in dermis/hypodermis
-living cells of hair found only here, which grows around dermal papilla (provides nutrition to hair)

160
Q

hair root

A

remainder of hair within hair follicle

161
Q

hair shaft

A

portion of hair above skin surface

162
Q

hair matrix

A

hair’s growth center

163
Q

hair medulla

A

innermost layer; core of loosely arranged cells & air spaces
-prominent in thick hairs

164
Q

hair cortex

A

external to medulla; constitutes most of hair; several layers of elongated keratinized cells

165
Q

hair cuticle

A

outermost layer of hair composed of very thin, scaly cell layers that overlap w free edges directed upward

166
Q

hair follicle

A

diagonal tube that extends into dermis/hypodermis; associated w nerve & muscle fibers
-2 principal layers
-CT root sheath derived from dermis
-epithelial root sheath derived from epidermis
-entwined by hair receptors that respond to hair movements

167
Q

arrector pili

A

bundles of smooth muscle cells extending from dermal collagen fibers to CT root sheath
-contraction of muscles in response to cold, fear, or stimuli
-cause goosebumps

168
Q

hair color

A

-eumelanin=brown/black hair
-eumelanin & more pheomelanin=red hair
-some pheomelanin & very little eumelanin=blond hair
-absence of melanin=gray & white hair

169
Q

anagen

A

active phase of growth

170
Q

catagen

A

regression period where cell division stop

171
Q

telogen

A

resting phase where hair is shed

172
Q

alopecia areata

A

autoimmune disorder where hair follicles attacked
-spots of baldness on scalp & body

173
Q

diffuse hair loss

A

hair shed from all parts of scalp due to hormones, drugs, iron deficiency

174
Q

male pattern baldness

A

loss of hair first from only crown region of scalp due to genetic & hormonal factors

175
Q

hirsutism

A

excessive hairiness

176
Q

apocrine sweat glands

A

-produce secretions by exocytosis (large lumen)
-ducts lead into nearby hair follicles & not skin surface
-thicker & more milky due to fatty acids
-scent glands that respond to stress & sexual stimulation; don’t develop until sexual maturity

177
Q

merocine (eccrine) sweat glands

A

most numerous glands of skin that produce sweat
-simple tubular gland w twisted coil in dermis/hypodermis
-lined by stratified cuboidal epithelium in dermis & keratinocytes in epidermis

178
Q

sebaceous glands

A

produce sebum; flask-shaped w short ducts that usually open into hair follicle
-holocrine glands
-sebum keeps skin & hair from becoming dry, brittle, & cracked

179
Q

ceruminous glands

A

found only in external ear canal where secretion combines w sebum & dead epidermal cells to form earwax (cerumen)

180
Q

mammary glands

A

milk-producing glands that develop within female breast only during pregnancy & lactation
-modified aprocrine sweat glands that channel rich secretion through ducts to nipple

mcb 244/245 (8 decks)

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