Chapter 1

Question 1

The strongest force in a muscle can be produced when the muscle is?

Answer 1

Partially flexed meaning many myosin heads are posed above the actin filaments so all of these heads can bind and cause the muscle to contract.

Question 2

Excitation-Contraction Coupling Phase

Answer 2

The sarcoplasmic reticulum is stimulated to release calcium ions, calcium binds to troponin which causes tropomyosin to move exposing the myosin binding site on actin. The cross-bridge binds to actin allowing cross-bridge flexion to occur. At any time the amount of cross-bridges bound to actin dictates how much force the muscle can produce

Question 3

Contraction Phase

Answer 3

ATP attached to the crossbridge and is broken down to ADP which causes flexion. Then another ATP molecule must replace the ADP by binding to the crossbridge allowing it to detach from the actin site and recock. Calcium and ATP are required for cross-bridge cycling

Question 4

Relaxation Phase

Answer 4

Calcium is pumped back into the SR which prevents the link between actin and myosin

Question 5

Slow Twitch fiber

Answer 5

Type 1, develop force and relax slowly and have longer twitch times. Are fatigue resistant and use aerobic energy but cannot develop force quickly

Question 6

Fast Twitch fiber

Answer 6

Type 2, develop force quickly and relax quickly resulting in a short twitch time. Fatigue easily, develop force rapidly and have high anerobic power.

Question 7

2 ways that a muscle increases its force output.

Answer 7

1. Increasing the frequency at which motor units are stimulated.
2. By motor unit recruitment

Question 8

Golgi Tendon Organ

Answer 8

Proprioceptors (sensory receptors sensitive to pressure and tension in joints, muscles, and tendons, which communicate with the nervous system to perform coordinated movements) in tendonsthat inhibits a motor neuron if a tendon is overstretched, causing the muscle to relax

Question 9

Exergonic reactions

Answer 9

release energy and are generally catabolic

Question 10

endergonic reactions

Answer 10

require energy and are usually anabolic and involve muscle contraction

Question 11

What system is present at the start of all activity regardless of intensity?

Answer 11

Phosphagen

Question 12

Creatine Kinase

Answer 12

enzyme that satalyzed the synthesis of ATP from CP and ADP so that ADP + CP (with the help of Creatine Kinase) can turn into ATP and creatine. So obviously type 2 fast twitch fibers contain higher concentrations of CP than Type 1.

Question 13

Sarcoplasmic Reticulum Function

Answer 13

Store and release calcium ions to regulate muscle contraction

Question 14

Tetanus

Answer 14

a convergence of smaller contractions in order to create a steay contraction

Question 15

Sliding Filament Theory

Answer 15

The actin dilaments at each end of the sarcomere slide inward on myosin filaments, pulling the z-lines toward the center of the sarcomere and thus shorteing the muscle fiber. As actin filaments slide over myosin filaments, bothe the H zone and I band shrink.

Question 16

Type 2a fibers

Answer 16

have greater capacity for aerobic metabolism and more capillaries surronding them than type 2x

Question 17

Type 2x fibers

Answer 17

show greater ressistnace to fatigue than type 2a

Question 18

Which of the following structures do the cross-bridges attach during muscle action?

Answer 18

Actin

Question 19

When throwing a baseball, an athlete’s arm is rapidly stretched just prior to throwing the ball. Which of the following structres detects and reponds to that stretch by feflexively increasing muscle activiy?

Answer 19

Muscle spindle

Question 20

Muscle Spindle

Answer 20

are sensory receptors within the belly of a muscle, which primarily detect changes in the length of this muslce. The convey length information to the CNS via sensory neurons.