Tension Production Energy Use and Muscular Activity

Question 1

For sustained contractions you need

Answer 1

Asynchronous motor unit summation

Question 2

Describe small motor units

Answer 2

precise control

One motor neuron innervates a small number of muscle fibers

Question 3

Describe large motor units

Answer 3

Gross movement control

One motor neuron innervates a large number of muscle fibers

Question 4

If you want precise control over a specific part of your body you don’t want to be contracting tons of cells at the same time. What type of motor unit will produce precise control?

Answer 4

Small motor units

Found in hands eyes and speech muscles

Question 5

Define muscle tone

Answer 5

Resting tension in a skeletal muscle

Question 6

True or false, in any muscle some motor units are always active

Answer 6

True

Question 7

Greater resting muscle tone causes

Answer 7

higher resting rate of metabolism

Question 8

Why is it difficult to contract a muscle that has been overstretched?

Answer 8

Few, if any, myosin-actin cross bridges can form when sarcomeres are overextended

Question 9

Define isotonic contractions

Answer 9

Tension rises, length of muscle changes

Question 10

Define concentric

Answer 10

muscle tension exceeds resistance and muscle shortens

Question 11

Define eccentric

Answer 11

Peak tension developed is less than the resistance, muscle elongates

Question 12

Define isometric

Answer 12

tension rises, length of muscle remains

Question 13

In isometric contractions

Answer 13

Tension produced never exceeds resistance
Indiidual muscle fibers shorten until internal connective tissues are taut
Cannot shorten further

Question 14

True or false: there is an active mechanism for muscle fiber elongation

Answer 14

False

Question 15

Why does a muscle return to resting length?

Answer 15

recoil in elastic components in connective tissue
contraction of opposing muscle groups
gravity

Question 16

Muscle contraction requires large amounts of

Answer 16

ATP

Question 17

Muscle cells store only enough high energy molecules to sustain contraction until

Answer 17

additional ATP can be generated

Question 18

How long do ATP and Creatine phosphate reserves last during a contraction?

Answer 18

15 seconds

Question 19

Muscle cells must generate ATP at approximately the same rate as its

Answer 19

used for remainder of contraction

Question 20

CP reserves release stored energy in order to

Answer 20

Convert ADP to ATP when ATP is needed at start of contraction

Question 21

______ pathway provides most ATP needed for resting muscle and moderate levels of muscle activity

Answer 21

Aerobic cellular respiration

Question 22

At peak activity you need ______ pathway to generate additional ATP

Answer 22

Anaerobic glycolysis

Question 23

Describe aerobic metabolism

Answer 23

Used at rest to moderate activity
Uses O2
Releases CO2
Occurs in mitochondria

Question 24

CO2 is produced in the

Answer 24

Citric acid cycle

Question 25

What occurs during the Electron Transport Chain?

Answer 25

ATP synthesis

O2 is used

Question 26

Resting muscle fibers rely on aerobic metabolism of ___ to generate ATP

Answer 26

fatty acids

Question 27

Contracting muscle fibers rely on what type of metabolism of glucose?

Answer 27

BOTH aerobic and anaerobic

Question 28

Pyruvate metabolism is

Answer 28

Anaerobic

Question 29

Why do you use pyruvate metabolism?

Answer 29

If oxygen levels are insufficient to allow all of pyruvate to be metabolized aerobically, the rest of pyruvate is converted to lactic acid and recycles cofactors needed by glycolysis enzymes

Question 30

What are the advantages of anaerobic metabolism?

Answer 30

Produces ATP rapidly

Question 31

What are the disadvantages of anaerobic metabolism?

Answer 31

Insufficient use of glucose

Lactic acid lowers intracellular pH

Question 32

When does the recovery period begin?

Answer 32

Immediately after activity ends

Question 33

What is oxygen debt?

Answer 33

Amount of oxygen required during resting period to make enough ATP to restore muscle to normal conditions

Question 34

During the recovery period, what happens?

Answer 34

Rebuild ATP and CP levels
Recycle lactic acid to make pyruvate
Rebuild glycogen reserves

Question 35

Define fatigued muscle

Answer 35

muscle that can no longer perform at required level of activity

Question 36

What are the causes of muscle fatigue?

Answer 36

Exhaustion of energy resources
Build up of lactic acid and lower of pH
Psychological fatigue