10.6 Muscle tension in skeletal muscle

Question 1

Define wave summation

Answer 1

When a muscle is excited in faster and faster intervals, the muscle is not given time to relax completely, and so the force of the contraction becomes greater as the interval between contractions shortens.

Question 2

tetany

Answer 2

when contractions fuse and there is no muscle relaxation between contractions.

Question 3

muscle tension

Answer 3

The resting tension in a skeletal muscle generated by involuntary somatic nervous system stimulation. Motor units stimulated change constantly while the muscle is at rest so no muscle is fatigued. The tension caused by tone stabilized the bone and joints. Tone also primes a muscle for contraction so it can respond more quickly to stimuli.

Question 4

isometric contraction

Answer 4

when a muscle is flexed to try to move something, but the force against movement is too great, so no movement is produced.

Question 5

isotonice

Answer 5

muscle tension is greater than the resistance and so movement is produced.

Question 6

Concentric

Answer 6

when muscle is shortened

Question 7

Eccentric

Answer 7

when muscle is lengthened

Question 8

define length tension relationship

Answer 8

Muscles at their normal resting length general the most force when stimulated because it has an optimal amount of myosin heads ready to attach to the actin which creates the force for contraction. Those that are already shortened or extended produce less force.

Question 9

What is the primary cause of muscle fatigue?

Answer 9

• Decrease in glycogen stores.
• Excitation of neuromuscular junction- not enough Ca2+ to enter knob or not enough vesicles of Each to stimulate contraction.
• Excitation-contraction coupling- ion concentration change which stops the muscle from generation the needed action potential.
• Cross-bridge cycling- increase in phosphate ion concentration- this could stop myosin from detaching from actin. Decreased amounts of Ca2+ might also effect this as the Ca2+ might be bonding with the phosphate ions.

Question 10

How does muscle adapt to regular stress?

Answer 10

• Increase in the number of mitochondria and the number of enzymes inside mitochondria.
• Increase in the enzymes used for the breakdown of fatty acids in aerobic cellular respiration
• increased amount of lactate dehydrogenase enzyme- for converting lactate back to pyruvate.

Question 11

What does the heart do in response to regular exercise?

Answer 11

The ventricle walls can thicken to beat harder. Additional blood vessels can form.

Question 12

What does resistance exercise do?

Answer 12

Causes the skeletal muscle to increase the number of actin and myosin. This is hypertrophy which also causes increased amounts of mitochondria, myoglobin, and larger glycogen reserves. Slight increase in creatine phosphate and ATP occurs too. There may also be an increase in the number of muscle fibers.

Question 13

Hyperplasia

Answer 13

Increase in the number of muscle fibers.

Question 14

Caveolae

Answer 14

Invaginations on the surface of smooth muscle cells.

Question 15

Function of dense plaques

Answer 15

Anchor intermediate filaments to the sarcoplasm

Question 16

Function of dense body

Answer 16

spot welds that anchor intermediate filaments to each other.

Question 17

What is the cytoskeleton of smooth muscle made of?

Answer 17

Intermediate filaments.

Question 18

Where are contractile proteins located?

Answer 18

Between dense bodies and dense plaques.