SMT 2 again

Question 1

what happen when the calcium binds to troponin C in the muscle fiber cytosol?

Answer 1

the troponin complex undergoes a conformational change and Troponin T “pulls” tropomyosin and Troponin I off the myosin-binding site of G-actin subunits

Question 2

what are the steps of cross-bridge cycle

Answer 2

1. ATP hydrolysis
2. cross-bridge formation
3. power stroke
4. detachment of myosin from actin

Question 3

prior to myosin being able to bind to actin, it must be ?

Answer 3

“energized”

Question 4

what happens when myosin is bound to ATP

Answer 4

it lowers it’s affinity for actin and there is no cross-bridge formation

Question 5

what hydrolyses ATP -> ADP + Pi in the myosin head?

Answer 5

intrinsic ATPase activity

Question 6

hydrolysis causes what change in the mysoin head?

Answer 6

causes the myosin head to pivot, moving down the actin filament so that it lines up with a new actin monomer

Question 7

calcium binding to troponin, has uncovered what?

Answer 7

the mysoin-binding site on actin

Question 8

the energized myosin head attached to the mysoin-binding site on actin and what is released?

Answer 8

Pi

Question 9

when the myosin head is attached to the myosin-binding site, this creates what?

Answer 9

a myosin-actin cross bridge

Question 10

the cross bridge generates force as what?

Answer 10

as myosin neck rotates toward center or sarcomere

Question 11

what is getting closer together, shortening the sarcomere and generating force?

Answer 11

Z lines

Question 12

what dissociates from myosin and the actin-myosin complex is left in a rigid, “attached” state?

Answer 12

ADP

Question 13

what binds to myosin and myosin detaches from actin

Answer 13

ATP

Question 14

what is isometric contractions?

Answer 14

muscle contracts against force transducer without decreasing muscle length

Question 15

when does isometric contractions occur?

Answer 15

occurs when the load is greater than the force of muscle contraction

Question 16

what is isotonic contractions?

Answer 16

muscle shortens against a fixed load

Question 17

when does isotonic contractions occur?

Answer 17

occurs when the force fo the muscle contraction is greater than the load and the tension on the muscle remains constant

Question 18

what binds to free calcium within the SR

Answer 18

calsequestrin and calreticulin

Question 19

there are 2 main types of muscle fiber types which are?

Answer 19

type 1 (slow fibers)
type II (fast fibers)

Question 20

which fiber type is generally smaller and innervated by smaller nerve fibers?

Answer 20

type 1 or slow fibers

Question 21

which fiber type is larger in size and innervated by large nerve fibers

Answer 21

type 2 or fast fibers

Question 22

what are the two subtypes of type II fast fibers

Answer 22

Type IIA - fast oxidative glycolytic fibers
type IIB - fast glycolytic fibers

Question 23

which type of muscle fiber has more capillaries to supply higher amounts of oxygen

Answer 23

type I/ slow fibers

Question 24

which type of muscle fiber has lots of SR for rapid Ca2+ release

Answer 24

type II/ fast fibers

Question 25

which type of muscle fiber has lots of myoglobin, giving a reddish appearance

Answer 25

type I/slow fibers

Question 26

which type of muscle fiber has lots of mitochondria to support high levels of oxidative metabolism

Answer 26

type I/slow fibers

Question 27

proportions of type I and II fibers seems to be partially determined by ?

Answer 27

genetic inheritance

Question 28

there are 3 different metabolic systems responsible for recycling AMP and ADP back into ATP to provide a continuous supply of ATP in muscle fibers. what are the 3 metabolic systems?

Answer 28

1. phosphagen system 2. glycogen lactic acid system 3. aerobic system

Question 29

T or F: phosphorylated creatine molecule has a low energy phosphate bond

Answer 29

false, phosphorylated creatine molecule has a high energy phosphate bond

Question 30

T or F: high energy phosphate bond of phosphocreatine has more energy than the bond of ATP

Answer 30

true

Question 31

Both phosphocreatine and ATP together constitute the ?

Answer 31

phosphagen system

Question 32

the phosphagen system provide how long of maximal power?

Answer 32

8-10 seconds of maximal power

Question 33

what is the initial stage of the glycogen-lactic acid system

Answer 33

glycolysis

Question 34

in the case of insufficient oxygen, pyruvate will be converted into what?

Answer 34

lactate

Question 35

what happens after the pyruvate converting into lactate

Answer 35

it diffuses out of the muscle cells into the interstitial fluid and blood

Question 36

glycogen lactic acid system can sustain maximal muscle contraction for ?

Answer 36

1.3-1.6 minutes

Question 37

what is the name of the process of glucose -> pyruvate -> lactate -> glucose

Answer 37

cori cycle

Question 38

what is the overall net loss or gain of ATP in the Cori cycle?

Answer 38

overall loss of 4 ATP

Question 39

What is the purpose of the cori cycle?

Answer 39

providing muscle fibers with 2 ATP, replenishing NAD+ for glycolysis, prevents build-up of lactic acid in skeletal muscle

Question 40

in presence of oxygen, what happens to pyruvate?

Answer 40

pyruvate is broken down into carbon dioxide, water, and energy via citric acid cycle and ETC

Question 41

as long as nutrients in the body last, the aerobic system can be used for ?

Answer 41

unlimited duration

Question 42

muscle strength is determined mainly by what?

Answer 42

its overall size

Question 43

what is muscle power?

Answer 43

the measure of the amount of work that the muscle can perform in a given period of time

Question 44

the endurance of muscle depends on

Answer 44

the amount of glycogen that has been stored in the muscle prior to the period of exercise and depends on the type and size of muscle fibre

Question 45

what is muscle atrophy

Answer 45

muscle no longer receives contractile signals required to maintain normal muscle size

Question 46

what is muscle hypertrophy

Answer 46

results from an increase in the number of actin and myosin filaments in each muscle fiber = enlarges individual muscle fibers

Question 47

what is hyperplasia

Answer 47

formation of new muscle fibers

Question 48

what is muscle lengthening

Answer 48

occurs when muscles are stretched to a greater than normal length which causes new sarcomeres to be added at the ends of the muscle fibers where they attach to the tendons