Anatomy Exam 3

Front 1

muscle cells

Back 1

are essentially a device for converting the chemical energy of ATP into the mechanical energy of movement

Front 2

excitability

Back 2

responsiveness; when stimulated by chemical signals, stretch, and other stimuli; muscle cells respond w/ electrical changes across plasma membrane

Front 3

conductivity

Back 3

local electrical change triggers wave of excitation that travels rapidly along cell and initiates processes leading to contraction

Front 4

contractility

Back 4

ability to shorten substantially when stimulated, enabling them to pull on bones/other organs to create movement

Front 5

extensibility

Back 5

ability to stretch b/w contractions-skeletal muscle cells can stretch 3x their contracted length (other cells would rupture)

Front 6

elasticity

Back 6

when muscle cell is stretched and then released it recoils to shorter length (elastic recoil); prevents resting muscles from being too slack

Front 7

skeletal muscles

Back 7

voluntary, striated muscle usually attached to one or more bones

Front 8

striations

Back 8

alternate light and dark transverse bands; reflect overlapping arrangement of their internal contractile proteins

Front 9

myofibers/muscle fibers

Back 9

because of their extraordinary length

Front 10

muscle fibers

Back 10

have a complex, tightly organized internal structure in which even the special arrangement of protein molecules is closely tied to its contractile function

Front 11

sarcolemma

Back 11

plasma membrane of muscle fiber

Front 12

sarcoplasm

Back 12

cytoplasm of a muscle fiber; occupied by myofibirls; contains glycogen and myoglobin

Front 13

myofibrils

Back 13

long protein cords

Front 14

glycogen

Back 14

starchlike carb that provides energy for cell during heightened levels of exercise

Front 15

myoglobin

Back 15

red oxygen-binding pigment which provides some of oxygen needed for muscular activity

Front 16

myoblasts

Back 16

stem cells

Front 17

multinuclear muscle fibers

Back 17

myoblasts fuse to produce each fiber with each myoblast contributing one nucleus

Front 18

satellite cells

Back 18

unspecialized myoblasts; between the muscle fiber and endomysiym; important in regeneration of damaged skeletal muscles

Front 19

sacroplasmic recticulum

Back 19

aka smooth ER; forms network around each myofibril; periodically exhibiting terminal cisternae

Front 20

terminal cisternae

Back 20

dilated end-sacs; that cross the muscle fiber from one side to the other

Front 21

transverse (T) tubules

Back 21

sarcolemma tubular infoldings; penetrate through the cell and emerge on the other side

Front 22

triad

Back 22

T-tubule +2 terminal cisternae

Front 23

muscle contraction process

Back 23

t-tubule signals SR when to release calcium into cytosol to active the contraction

Front 24

myofilaments

Back 24

a bundle of parallel protein microfilaments in a myofibril

Front 25

thick filaments

Back 25

made of 100s of myosin

Front 26

myosin

Back 26

shaft-like tail; double globular head projecting from it at an angle (like a golf club) in a helical array around the bundle

Front 27

bare zone

Back 27

in the middle, no heads

Front 28

thin filaments

Back 28

composed primarily of two intertwined strands of a fibrous (F) actin protein

Front 29

globular (G) actin

Back 29

protein made up string of subnits (beaded necklace) F actin& beads = G actin

Front 30

active site

Back 30

each G actin has one that can bind to a myosin head

Front 31

tropomyosin

Back 31

blocks active sites of 6-7 G actin- prevents mysoin from binding when relaxed

Front 32

troponin

Back 32

smaller Ca binding protein of each tropomyosin molecule

Front 33

elastic filaments

Back 33

made of titin; run through the core of each thick filament and anchor it to a Z disc at one end and M line at other

Front 34

titin

Back 34

huge springy protein; stabilizes thick filament; centers it b/w thin fliaments, prevents overstretching and recoils like spring after muscle is stretched

Front 35

contractile proteins

Back 35

mysoin and actin; shorten the muscle fiber

Front 36

regulatory proteins

Back 36

troponin and tropomyosin; act like switch to determine when fiber can contract and when it cant

Front 37

dystrophin

Back 37

enormous protein b/w sarcolemma and outermost myofilaments; links actin filaments to peripheral protein

Front 38

muscular dystrophy

Back 38

genetic defect of dystrophin

Front 39

striated muscles

Back 39

dark A bands alternating with lighter I bands

Front 40

A Bands

Back 40

anisotropic; thick filaments lying side by side; each thick filament is surrounded by hexagonal array of thin filaments where they overlap(very dark)

Front 41

I Band

Back 41

isotropic

Front 42

H Band

Back 42

middle/lighter region of A Band

Front 43

M-line

Back 43

the thick filaments of the middle of H-Band links through dark, transverse protein complex

Front 44

Z disc/Z line

Back 44

a dark narrow line that bisects I Band; provides anchorage for thin and elastic filaments

Front 45

sarcomere

Back 45

segment of myofibril b/w z discs; functional contractile unit of muscle fibers

Front 46

denervation atrophy

Back 46

severed connection of muscle is never restored; paralyzed muscle wastes away in a shrinkage

Front 47

somatic motor cells

Back 47

nerve cells; cell bodies are found in brainstem and spinal cord; serve skeletal system

Front 48

somatic motor fibers

Back 48

axons of the somatic motor cells

Front 49

motor unit

Back 49

one nerve fiber+ all muscle fibers innervated by it; dispersed through muscle; weak contraction

Front 50

small motor units

Back 50

used where fine control is needed; provide fine degree of control; subtle change;

1000muscle fibers may be innervated by 200 neurons

Front 51

large motor units

Back 51

used in areas where strength is needed; greater change;

1000 muscle fibers may be innervated by only 1-2neurons

Front 52

motor units in work shifts

Back 52

when muscle fibers are subjected to constantstimulation, some become fatigued – other motor neurons take over whilefatigued ones recover so muscle can sustain long-term contraction

Front 53

synapse

Back 53

point where a nerve fiber meets any target cell; fingerlike projections

Front 54

neuromuscular junction/motor end plate

Back 54

when the target cell(synapse) is a muscle fiber

Front 55

synaptic knob

Back 55

the bulbous swelling at end of nerve fiber;

Front 56

synaptic cleft

Back 56

separates synaptic knob from muscle fiber

Front 57

schwann cells

Back 57

envelops entire junction, isolating it from surrounding tissue fluid

Front 58

synaptic vessicles

Back 58

organelles filled with neurotransmitter ACh

Front 59

ACh

Back 59

functions as a chemical messenger from the nerve cells to the muscle cells

Front 60

electrical signal

Back 60

aka nerve impulse; cannot cross synaptic cleft, instead causes synaptic vesicles to undergo exocytosis and release ACh into cleft

Front 61

ACh receptors

Back 61

transmembrane proteins incorporated into its plasma membrane across from synaptic knobs; binds to ACh

Front 62

junctional folds

Back 62

infoldings in sarcolemma; increase surface area of ACh

Front 63

myasthenia gravis

Back 63

a disease of a deficiency of ACh receptors that leads to muscle paralysis

Front 64

basal lamina

Back 64

made of collagen and glycoproteins; surrounds entire muscle fiber and schwann cell of NMJ; separates them from surrounding connective tissue; fills synaptic cleft

Front 65

acetylcholinesterase(AChE)

Back 65

found in sarcolemma and part of basal lamina; enzyme breaks down ACh after the ACh has stimulated the muscle cell

Front 66

electrophysiology

Back 66

study of electrical activity of cells; key to learning nervous activity, muscle contractions

Front 67

ICF

Back 67

intracellular fluid; greater concentration of negative ions than ECF; net negative charge inside cell; membrane polarized, K+

Front 68

ECF

Back 68

extracellular fluid; Na+; adjacent to plasma membrane

Front 69

electrical potential/voltage

Back 69

difference in electrical charge from 1 point to another; -90 mV for sarcolemma of muscle cell

Front 70

resting potential membrane (RMP)

Back 70

the voltage; maintained by the sodium-potassium pump

Front 71

action potential

Back 71

quick up and down voltage shift from negative RMP to positive value then back to RMP

Front 72

RMP vs. Action Potential

Back 72

stable voltage in waiting cell vs. quickly fluctuating voltage in active, stimulated cell

Front 73

nerve impulses

Back 73

wave of action potentials; one causes another to happen immediately in front of it; travel along the sarcolemma along nerve fibers

Front 74

Excitation

Back 74

the process by which action potentials in the nerve fiber lead to action potentials in the muscle fibers

Front 75

end-plate potential (EPP)

Back 75

rapid fluctuation in voltage at the motor end plate

Front 76

Excitation- contraction coupling

Back 76

refers to events that link action potentials on the sarcolemma to activation of the myofilaments; preparing them to contract

Front 77

contraction

Back 77

the step in which the muscle fiber develops tension and may shorten

Front 78

sliding filament theory

Back 78

mechanism of contraction; like pulling a boat anchor hand over hand

Front 79

myosin ATPase

Back 79

an enzyme in the head, hydrolyzes this ATP into ADP and phosphate

Front 80

cross-bridge

Back 80

between myosin and actin; formed when myosin binds to the active site

Front 81

power stroke

Back 81

myosin releases the ADP and phosphate and flexes into a bent, low-energy position; tugging the thin filament along

Front 82

recovery stroke

Back 82

recock; hydorlyze the new ATP; repeat the whole process

Front 83

Relaxation

Back 83

when the nerve fiber stops stimulating it, a muscle fiber relaxes and returns to its resting length