Chap Nine Muscle

Front 1

basic types of muscle tissue

Back 1

skeletal- striated, voluntairy, multinucleated
cardiac- striated, involuntary- uninucleated
smooth- nonstraited, involuntary, may be multinucleated

Front 2

4 important functions of muscle tissue

Back 2

movement
heat generation
maintaining posture
stabilizing joints

Front 3

gross atatomy

Back 3

myofibers, vv, nn, connective tissue

Front 4

connective tissue

Back 4

endomysium- covers each individual muscle fiber
perimysium- covers fasicles
epimysium covers entire muscle

Front 5

microscopic structure of myofibers

Back 5

sarcolemma- cell membrane
sarcoplasm which has gycosomes and myoglobin
myofibrils- contain the contractile elements

Front 6

a band
i band
h zone

Back 6

a band is the dark striation
the lighter stipe in the middle of the A band is the H zone and the dark line in the middle of the H Zone is the Z- Disc

Front 7

I band
m line

Back 7

I band is the light striation and the m line is a dark line through the light striation

Front 8

function role of myofibrils

Back 8

once triggered, they bind and cause contraction of sarcomere

Front 9

function role of sarcoplasmic reticulum

Back 9

storage of Calcium ion

Front 10

transverse tubules

Back 10

allows action potential to run throughout the entire fascicle

Front 11

sliding filament mechanism of skeletal muscle contraction

Back 11

myosin heads attach to the exposed actin binding site and "hook and pull" them. the result is a sliding motion of the 2 proteins

Front 12

define motor unit

Back 12

a motorneuron and the muscle fibers it supplies.

Front 13

how does the cell become polarized?

Back 13

1. nerve impulse opens Calcium channels allowing Calcium ions to flow into neurotransmitter from extracellular fluid.
The presence of calcium causes neurotransmitter to be released into synaptic cleft. once there, the aCh fuses with receptors in the motor end plate and aCh is broken down. aCh receptors allow sodium ion and potassium ions to pass, more sodium is let in than potassium is let out. interior becomes slightly less negative

Front 14

how does depolarization pass on action potential

Back 14

action potential moves along the length of the sarcolemma, opening voltage gated sodium channels. sodium diffuses into cell

Front 15

repolarization

Back 15

restores sarcolemma to polarized state. sodium channels closeing and potassium opening, potassium diffuses out of cell.

Front 16

how does action potential stimulate muscle to contract?

Back 16

action potential moves along the SR and down T Tubules. once it passes the triads, it triggers the terminal cisternae to dump an assload of calcium into sarcoplasm. Calcium ions bind to troponin, removing the blocking action of tropomyosin. the myosin heads attach to center of sarcomere. ATP hydrolysis allows the myosin to "pull"

Front 17

3 phases of muscle twitch

Back 17

latent period- when excitation-contraction coupling is occurring
period of contraction-period of contraction when cross-bridges are active
period of relaxation-initiated by calium ions going back into SR, contractile force no longer being generated

Front 18

what is muscle twitch

Back 18

the responce of a motor unit to a single action potential of its motor neuron

Front 19

what is the muscles response to changes in stimulation frequency

Back 19

the second twitch will be stronger than the first, but the refractory period is always honored. if the stimulus strength is held constant and the muscle is stimulated at a faster rate, the relaxation time becomes shorter. but if the muscle did not repolarize, nothing happens.