Muscle Tissue II

Question 0

Center of A band (middle), thick filament only

Answer 0

H zone

Question 1

The – band is the middle of sarco mere, includes thick n thin filaments

Answer 1

A band

Question 2

The sliding filament mechanism pertains to

Answer 2

Contraction

Question 3

H zone (thick filament) + 2 zones of overlap (thick n thin) =

Answer 3

A band

Question 4

During muscle contraction, what happens to the A band, the I band and the H zone

Answer 4

The A band, the length of the myosin filament, stays the same
The H and I zones (thick only and thin only) go away
I = thin/actin only

Question 5

Excitation vs contraction (they are coupled)

Answer 5

Excitation - action potential propagation

Contraction - sliding filaments

Question 6

Where is Ca 2+ stored

Answer 6

Sarcoplasmic reticulum

Question 7

In contraction, an action potential propagating along the sarcolemma into t-tubule causes – release channels to open

Answer 7

Ca2+

Question 8

What does released Ca bind to

Answer 8

Troponin

Question 9

What causes the reorientation and energization of the myosin head

Answer 9

Myosin heads split ATP into ADP and P, which are bound to the myosin

Question 10

When are the phosphate and ADP released from myosin head

Answer 10

Myosin attaches to actin, releases P

Power stroke occurs as actin slides toward m line, releases ADP

Question 11

2 changes that allow for muscle relaxation

Answer 11

1. Motor impulses cease bc no more ACh, no propagation thru T tubules
2. Pumps on SR pump Ca back into the SR, so Tropomyosin covers binding sites on actin again

Question 12

What is a motor unit

Answer 12

One motor neuron and all the fibers it stimulates

Question 13

What is muscle TONE

Answer 13

Small amount of tension due to weak involuntary contractions of motor units

Question 14

Isotonic vs isometric contractions

Answer 14

Isotonic - tension/tone remains the same but muscle changes length (eccentric = lengthen)

Isometric - tension but no movement

Question 15

First source of ATP for contraction

Answer 15

Creatine phosphate

Question 16

Muscle fatigue

Answer 16

Inability to contract after prolonged activity due to

• depletion of creatine p
• insufficient oxygen
• depletion glycogen

Question 17

Skeletal m fibers are fast or slow based on what

Answer 17

Speed of ATPase (opposite of ATP synthase) in myosin head splitting ATP

Question 18

3 types of skeletal m fibers from slowest to fastest contraction

Answer 18

1. Slow oxidative - aerobic respiration
2. Fast oxidative glycolytic (FOG) - aerobic respiration and glycolysis
3. Fast glycolytic