Physiology: muscle

Question 1

Physiology: muscle

muscular fascia from deep to superficial

Answer 1

• Endomysium (covers individual fiber)
• Perimysium (covers individual bundles)
• Epimysium (surrounds entire muscle)

Question 2

Physiology: muscle

Skeletal muscle fibers have a cell membrane and many organelles.

• Cytoplasm = sarcoplasm
• Endoplasmic reticulum = sarcoplasmic reticulum
• Cell membrane = _______

Answer 2

sarcolemma

Question 3

Physiology: muscle

Protein filaments within each sarcomere are called

Answer 3

actin (thin; attached to Z-lines) and myosin (thick; heads)

Question 4

Physiology: muscle

Which part of muscle fiber contraction requires ATP?
Does relaxation require ATP?

Answer 4

• The release of myosin heads from actin requires ATP binding.
• Energy from ATP is required for the power stroke.
• Relaxation does not directly require ATP, but relaxation cannot occur unless Ca++ is pumped back into the sarcoplasmic reticulum using a Ca++ATPase

Question 5

Physiology: muscle

energy for sliding filament theory comes from

Answer 5

1. Stored ATP in muscles
2. Regeneration of ATP from stored creatine phosphate (FAST! 1st 15 seconds, 100-meter run; from phosphocreatine stored in muscle cells)
3. Regeneration of ATP from anaerobic breakdown of glucose: anaerobic glycolysis (50% slower; 30-40 second of muscle contraction; from carbohydrates only; lactic acid)
4. Regeneration of ATP from aerobic breakdown of glucose (long duration exercise; yields most ATP; requires fats, carbs, and glucose)

Question 6

Physiology: muscle

One motor neuron and all the muscle fibers that it controls

Answer 6

motor unit

• Small motor units produce fine movements
• Large motor units produce gross movements

Question 7

Physiology: muscle

Each actin molecule is a binding site to which a ______ ______ _______ can attach

Answer 7

myosin cross bridge

Question 8

Physiology: muscle

types of muscle fibers

Answer 8

• Slow fibers: type I, low glycolytic, high oxidative (oxidative phosphorylation)
• Fast fatigue-resistance: type IIa, high glycolytic, high oxidative.
• Fast fatigable: type IIb, high glycolytic, low oxidative

More info here

Question 9

Physiology: muscle

the golden rule in types of muscle fibers

Answer 9

Type I muscle fibers have more mitochondria

• Type I: aerobic, red, high oxidative, slow twitch, long contraction
• Type II: anaerobic, white, high glycolytic, fast twitch, short contraction

Question 10

Physiology: muscle

active insufficiency

Answer 10

• due to a muscle being too short or too long
• both result in decreased mm contraction

Question 11

Physiology: muscle

Concentric muscle force _______ proportional to velocity muscle shortening

Answer 11

inversely

Question 12

Physiology: muscle

Eccentric muscle force _____ proportional to velocity muscle lengthening

Answer 12

directly

Question 13

Physiology: muscle

muscle spindles are sensitive to

Answer 13

amount and speed of lengthening (stretching of a muscle)

Question 14

Physiology: muscle

Since a muscle can be overstretched and torn impulse from the muscle spindle causes the spinal cord to initiate a reflex contraction. Called…

Answer 14

muscle spindle stretch reflex

Question 15

Physiology: muscle

the gamma motor system

Answer 15

sets the sensitivity of the muscle spindle

• Gamma LMN travels from the SC to the intrafusal fiber of the muscle spindle
• Gamma LMN can contract the muscle spindle making it tauter and more sensitive to stretch

Question 16

Physiology: muscle

the alpha motor system…

Answer 16

directs actual muscle contraction by directing the extrafusal fibers of the muscle to contract

Question 17

Physiology: muscle

Resting tone of muscle set by

Answer 17

the gamma motor system

When the gamma motor systems tightens
the muscle spindles within the muscles the
muscle spindles more readily trigger
stretch reflex

Question 18

Physiology: muscle

Golgi tendon organs are sensitive to

Answer 18

• tension: pulling forces on the tendon
• If there is too much muscle tension the golgi tendon organ will inhibit the muscle from creating any force (via a reflex arc), thus protecting you from injuring itself.