Block 2 Skeletal Muscle Function

Front 1

myosin head has what? what catalyzes it

Back 1

an ATPase that is catalyzed by binding to actin

Front 2

tropomyosin

Back 2

long thin fibrous molecule follows around the thin filament near the channel formed by the two F-actin strands

Front 3

troponin subunits

Back 3

C (binds calcium which controls On/Off of contracting process)

T(binds to tropomyosin)

I (prevent the interaction of the actin and myosin molecules)

Front 4

calcium sequestration

Back 4

active transport process of Ca2+ removal from the area of the filament area back to the sarcoplasmic reticulum. very rapid!

Front 5

isotonic contraction

2 subtypes?

Back 5

muscle shortens, work is done. (lifting an object)

concentric is when contracile force is sufficient to cause muscle-shortening contraction

eccentric-when muscle tension is less than the external load=muscle will progressively lengthen during contraction

(negative pull up)

Front 6

isometric contraction

Back 6

muscle doesn't shorten (opposing the force of gravity/posture) no work is done=no shortening occurs

Front 7

twitch response. what accounts for the slow relaxation time?

Back 7

the elastic component (calcium sequestration requires time to gradually relax the muscle fiber)

the shape of the twitch is characteristic to skeletal muscle, although contraction/relaxation times vary from muscle to muscle

Front 8

summation and tetanus

Back 8

increasing the rate of motor neuron firing (more APs->>>more muscle contractions)

not like neurons, you can add a second stimulus before first has subsided=super/max tension=summation

is MECHANICAL, not electrical. measuring tension

Front 9

the frequency required to produce tetanus depends on what?

Back 9

the contraction time of the certain type of muscle

15-30/sec capable of smooth maintained contraction

Front 10

tetanus=?

Back 10

maximum muscle tension in response to repetitive stimulus=increased force

fused=no relaxation allowed btw responses=constant

unfused=individ twitch response are discernible-can see where it relaxes

Front 11

ATP is supplied for short periods of activity in the first few seconds of exertion via what pathway?

what are the other 2 pathways? what durations do they have

Back 11

creatine phosphate->creatine. produces ATP

other 2 pathways are glycolytic (anaerobic-several minutes of exertion) and oxidative metabolism (long-term exertion)

Front 12

name the 2 (technically 3) types of muscle fibers. their contraction speed and resistance to fatigue

Back 12

Type I=slow, very resistance to fatigue

Type IIA=fast, fairly resistance to fatigue

Type IIB=fast, fatigue rapidly

Front 13

what is the ATPase activity of each of the different muscle fibers?

Back 13

ATPase is slow for the "slow" fibers=Type I

ATPase activity is fast for fast twitch

Front 14

muscles are composed of a ______ of these 3 fiber types

Back 14

mixture

Front 15

fast fiber contract speed

slow fiber contract speed

Back 15

20-40msec

50-70msec