Bio Lecture Test 7

Front 1

muscle fibers

Back 1

long smooth and skeletal muscle cells

Front 2

myofilaments

Back 2

the muscle equivalents of the actin or myosin-containing filaments

Front 3

skeletal muscle

Back 3

organs that attach to and cover the bony skeleton

Front 4

smooth muscle

Back 4

muscle in the walls of hollow, visceral organs

Front 5

cardiac muscle

Back 5

muscle in the walls of the heart

Front 6

excitability

Back 6

ability to receive and respond to a stimulus

Front 7

contractibility

Back 7

ability to shorten forcibly

Front 8

extensibility

Back 8

ability to be stretched or extended

Front 9

elasticity

Back 9

ability of a muscle fiber to recoil and resume its length after being stretched

Front 10

endomysium

Back 10

fine sheath of connective tissue consisting of reticular fibers which surrounds each muscle fiber

Front 11

fascicles

Back 11

bundles of endomysium-wrapped muscle fibers

Front 12

perimysium

Back 12

layer of fibrous connective tissue surrounding each fascicle

Front 13

epimysium

Back 13

layer of dense irregular connective tissue surrounding the entire muscle

Front 14

deep fascia

Back 14

connective tissue which lies between neighboring muscles or the superficial fascia deep to the skin

Front 15

sarcolemma

Back 15

plasma membrane surface of a muscle fiber

Front 16

sarcoplasm

Back 16

nonfibular cytoplasm of a muscle fiber which contains large amounts of glycosomes and substatial amounts of myoglobin

Front 17

myoglobin

Back 17

red pigment that stores oxygen

Front 18

myofibrils

Back 18

rodlike bundle of contractile filaments found in muscle cells

Front 19

A bands

Back 19

the darker bands which represent thick filaments and never shorten

Front 20

I bands

Back 20

light bands which represent thin filaments

Front 21

H zone

Back 21

Lighter stripe in the A band's midsection which represents a place with no actin and are visible only in relaxed muscle fibers

Front 22

M line

Back 22

dark line bisecting H zone vertically and contains fine protein strands which hold the adjacent thick filaments together

Front 23

Z disc

Back 23

darker area interrupting I band composed of the protein nebulin which anchors the thin filaments and connets each myofibril to the next and is a network of titin

Front 24

sarcomere

Back 24

region of a myofibril between two z discs which contains an A band flanked by half and I band at each end and is the smallest contractile unit of a muscle fiber and the functional unit of skeletal muscle

Front 25

thick filament

Back 25

filament exteding the entire length of the A band composed primarily of myosin

Front 26

thin filament

Back 26

filament extending across the I band and partway into the A band composed chiefly of actin

Front 27

sarcoplasmic reticulum

Back 27

elaborate smooth endoplasmic reticulum whose interconnecting tubules surround each myofibril and it regulates intracellular levels of ionic calcium

Front 28

terminal cisternae

Back 28

channels formed by perpendicular tubules crossing normal tubules at the A-I band junctions that always occur in pairs in the sarcoplasmic reticulum

Front 29

T tubules

Back 29

elongated tube formed by the penetration fo the sarcolemma into the cell interior at the A-I band junction

Front 30

triads

Back 30

successive groupings of the 3 membranous structures- terminal cisternae, t tubule, terminal cisternae

Front 31

muscle tension

Back 31

force exerted by a contracting muscle on an object

Front 32

muscle load

Back 32

opposing force exerted by the weight of an object on a muscle

Front 33

motor unit

Back 33

motor neuron and all the muscle fibers it supplies

Front 34

myogram

Back 34

a graphic recording of contractile activity

Front 35

muscle twitch

Back 35

response of a motor unit to a single action potential of its motor neuron

Front 36

latent period

Back 36

first few milliseconds following contraction coupling is ocurring when muscle tension is beginning to increase but there is no myogram response

Front 37

period of contraction

Back 37

when cross-bridges are active from the onset to the peak of tension develoopment and myogram rises to a peak

Front 38

period of relaxation

Back 38

initiated by the reentry of calciurm into the sarcoplasmic reticulum, muscle tension decreases to zero and the tracing ends

Front 39

graded response

Back 39

variations in the degree of muscle contraction by changing either the frequency or strength of the stimulus

Front 40

wave summation

Back 40

when the second twitch appears to ride on the first on the myogram

Front 41

incomplete tetanus

Back 41

sustained but quivering contraction caused by shortening twitches, rise of clacium, and greater degree of summation

Front 42

complete tetanus

Back 42

smooth, sustained contraction as muscle contractions disappear

Front 43

multiple motor unit summation

Back 43

increasing voltage to the muscle which causes more and more muscle fibers into play and controls force of contraction precisely

Front 44

threshold stimulus

Back 44

stimulus at which the first observable contraction occurs

Front 45

maximal stimulus

Back 45

strongest stimullus that produces increased contractile force

Front 46

treppe

Back 46

staircase pattern caused by muscle contractions half as strong as those that occur later

Front 47

muscle tone

Back 47

relaxed muscles are almost always slightly contracted due to alternalte stimulating of motor units

Front 48

isotonic contraction

Back 48

muscle length changes and moves the load

Front 49

isometric contraction

Back 49

tension builds to the muscle's peak tension-producing capacity, but the muscle neither shortens nor lengthens

Front 50

aerobic enducance

Back 50

length of time a muscle can continue to contract using aerobic pathways

Front 51

anaerobic endurance

Back 51

point at which muscle metabolism converts to anaerobic glycolysis

Front 52

muscle fatigue

Back 52

state of physilogical inability to contract even while still receiving stimuli

Front 53

contracture

Back 53

states of continuous contraction which result because cross-bridges are unable to detach

Front 54

myoblasts

Back 54

embryonic mesoderm cells which develop all muscle tissues