A&p I - Lecture - Week Of 11/23

Front 1

Steps of a Muscle’s Excitation-Contraction Reaction - 1

Back 1

Acetylcholine triggers an AP in the muscle fibers (excitation of the muscle)

Front 2

Steps of a Muscle’s Excitation-Contraction Reaction - 2

Back 2

Excitation causes calcium to be released from the sarcoplasmic reticulum.. Calcium is only allowed in temporarily, it’s pumped back into the SR

Front 3

Steps of a Muscle’s Excitation-Contraction Reaction - 3

Back 3

Calcium released by the SR binds to troponin and causes the tropomyosin to shift away from the actin binding sites. Allows myosin to bind to actin.

Front 4

Steps of a Muscle’s Excitation-Contraction Reaction - 4

Back 4

Contraction: Myosin heads attach and detach, pulling it myosin towards the center of the sarcomere.

Front 5

Steps of a Muscle’s Excitation-Contraction Reaction - 5

Back 5

Contraction ends when Calcium is pumped back into SR

Front 6

Each Muscle fiber has ____ neuromuscular junction

Back 6

one

Front 7

Depolarization leads to the _________ of each sarcomere in the muscle fiber

Back 7

contraction

Front 8

At rest, myosin binding is blocked by __________

Back 8

tropomyosin

Front 9

Tropomyosin fits into the binding spots on the _________

Back 9

actin

Front 10

Calcium binds to _______, which releases ________ from actin

Back 10

troponin…tropomyosin

Front 11

Stronger _________s lead to a greater number of motor units being recruited

Back 11

stimulations

Front 12

Summation –

Back 12

When two AP come close together, the second contraction is stronger.

Front 13

Sustained muscle contraction –

Back 13

When acetylcholine builds up in the synaptic cleft and is called “tetanus”

Front 14

Muscle fatigue –

Back 14

When the muscle can no longer continue the contraction, despite nervous impulses.

Front 15

Treppe –

Back 15

“The Staircase Effect”. After contracting with some frequency (warming up) contractions become stronger with the same level of stimulation. More calcium is available. Head generated increases activity of involved enzymes.

Front 16

Muscle Tone –

Back 16

Spinal nerve reflexes that alternately contract motor units throughout the day to maintain muscle health.

Front 17

Concentric –

Back 17

Muscles that work by shortening.

Front 18

Eccentric –

Back 18

Muscle does work by lengthening.

Front 19

Isometric contractions –

Back 19

Muscle length remains the same.

Front 20

Cross Bridge Cycle

Back 20

• Calcium binds troponin, troponin causes tropomyosin to shift and let Myosin-ADP attach to actin.//•Power stroke: Myosin rackets forward as ADP is released.//•ATP binds to myosin and causes myosin to fall off actin. // •Hydrolysis of ATP to ADP cocks the head into ready position and the cycle repeats until calcium concentrations fall.