Bio 146 Lab 5 Muscle Contractions

Front 1

subthreshold stimulus:



wave summation: stimuli of same intensity of increasing frequency that sums to create stronger response in tension until tetanus reached (measured in volts of millivolts)
tetanus: full, constant contraction of fiber from wave summation.

Back 1

stimulus without change in tension of fiber.

Front 2

threshold/minimal stimulus:

Back 2

first change in tension, shows up as peak on graph

Front 3

maximal stimulus:

Back 3

weakest stimulus where all cells are contracting.

Front 4

supramaximal stimulus:

Back 4

increase in stimulus does not increase reaction as max has been reached, shown by repeated blips of same size.

Front 5

treppe:

Back 5

repeated simulations immediately after relaxation phase cause series of contractions with INCREASING TENSION. or increasing tension as a reaction to a repeated stimuli of the same intensity, relaxation is complete between stimuli (warming up example) (see graph)

Front 6

subthreshold stimulus:

Back 6

stimulus without change in tension of fiber.

Front 7

threshold/minimal stimulus:

Back 7

first change in tension, shows up as peak on graph

Front 8

maximal stimulus:

Back 8

weakest stimulus where all cells are contracting.

Front 9

supramaximal stimulus:

Back 9

increase in stimulus does not increase reaction as max has been reached, shown by repeated blips of same size.

Front 10

treppe:

Back 10

repeated simulations immediately after relaxation phase cause series of contractions with INCREASING TENSION. or increasing tension as a reaction to a repeated stimuli of the same intensity, relaxation is complete between stimuli (warming up example) (see graph)

Front 11

wave summation:

Back 11

stimuli of same intensity of increasing frequency that sums to create stronger response in tension until tetanus reached (measured in volts of millivolts)

Front 12

tetanus:

Back 12

full, constant contraction of fiber from wave summation.

Front 13

All or none principle of contraction:

Back 13

fiber tension change as a response to stimuli is all or none. A fiber will contract fully or not at all. Not to be confused with multiple motor unit summation, where MORE fibers are recruited (but they all contract fully after threshold).

Front 14

muscle fatige:

Back 14

muscle loses some or all ability to contract, oxygen deficit, possible lack of ATP or increased lactic acid byproduct. physiological in nature, [of note] neuromuscular junctions fatigue faster than muscles, as well as psychological fatigue, so physiological fatigue is rare.

Front 15

muscle twitch:

Back 15

contraction of skeletal muscle

Front 16

latent phase:

Back 16

lag after stimulus, before activity, chemical/electrical changes are occurring (flatline)

Front 17

contraction phase:

Back 17

fibers shorten (rising peak on graph)

Front 18

relaxation phase:

Back 18

fibers relax and lengthen (declining wave on graph)

Front 19

depolarization:

Back 19

Na floods into cell (polarity change shown by up wave)

Front 20

repolarization:

Back 20

K floods out of cell (polarity resetting shown by down wave)

Front 21

action potential:

Back 21

signal made of rapid de and repolarization down the nerve

Front 22

absolute refractory period:

Back 22

no reaction allowed

Front 23

relative refractory period:

Back 23

some Na/K balance restored, possible reaction from strong stimuli

Front 24

Why does all or none work in a fiber but not a whole muscle?

Back 24

Why does all or none work in a fiber but not a whole muscle?

Front 25

Why low stimulus not produce reaction?

Back 25

threshold not reached, no ca released

Front 26

At high stimulus voltages, why supramaximal reached?

Back 26

No more fibers to recruit. All fibers are ON in the all or none principle.

Front 27

Tetanus requires high frequency stimulus, what tells us about calcium reuptake by sarcoplasmic reticulum?

Back 27

Ca reuptake is generally fast so fast stimuli needed to defeat ca reuptake.