Module 8 Quiz Questions

Question 1

What is the latent period of a muscle twitch?

Answer 1

The period of time between the stimulus and a muscle fibre contraction.

Question 2

Distinguish between isotonic and isometric contractions.

Answer 2

Isotonic: the muscle shortens but muscle tension remains relatively constant.
Isometric: the muscle length stays the same but the tension on the muscle increases.

Question 3

What is a motor unit?

Answer 3

A single motor neuron and all the fibres it stimulates.

Question 4

What is the sarcoplasmic reticulum and what is its function?

Answer 4

Is modified endoplasmic reticulum and its function is to contain calcium ions and release them upon stimulation into the sarcoplasm to trigger muscle contraction.

Question 5

Describe the events that occur at a neuromuscular junction and which result in the contraction of skeletal muscle.

Answer 5

A nerve impulse causes a release of acetylcholine that diffuses across the synaptic cleft. Acetylcholine receptors on muscle fibre bind acetylcholine and generate a muscle action potential.

Question 6

What proteins make up the thin myofilaments of muscle?

Answer 6

Actin
Troponin
Tropomyosin

Question 7

2hat 2 molecules are stored by muscles for use in ATP synthesis?

Answer 7

Glycogen
Creatine phosphate (phosphocreatine)

Question 8

What is meant by the term oxygen debt?

Answer 8

When muscles are forced to generate ATP under anaerobic conditions, they produce lactic acid as a waste product. At rest the body must consume extra oxygen to metabolize this lactic acid. The extra oxygen required is termed the oxygen debt (oxygen recovery consumption).

Question 9

The entire muscle is wrapped in the __.

Answer 9

Epimysium

Question 10

Identify 4 properties of muscle tissue that enable it to function:

Answer 10

Excitability
Contractility
Extensibility
Elasticity

Question 11

Identify the 3 types of muscle tissue and characterize each in terms of striated/non and voluntary/in.

Answer 11

Skeletal; striated, voluntary
Cardiac; striated, involuntary
Smooth; nonstriated, involuntary

Question 12

What is the role of gap junctions between the cardiac muscle fibres?

Answer 12

Allow the rapid passage of the stimulus for contraction from one cardiac muscle fibre to the next.

Question 13

Name the specific connective tissue that divides muscles into bundles of fibres called fascicles.

Answer 13

Perimysium

Question 14

What is the role of acetylcholinesterase?

Answer 14

Destroys the acetylcholine in the synaptic cleft to allow for the transfer of a subsequent stimulus.

Question 15

Describe fast glycolytic fibres.

Answer 15

FGF have small amounts of myoglobin and mitochondria, and poor capillary supply. They get their ATP from anaerobic metabolism, contract rapidly and tire quickly.

Question 16

What is muscle tone?

Answer 16

Sustained, small contractions give a firmness to a relaxed skeletal muscle that is known as muscle tone.

Question 17

List 3 histologic differences between skeletal and smooth muscle cells:

Answer 17

Filaments not orderly arranged.
Intermediate filaments in smooth muscle.
No T tubules in smooth muscle.
Scanty SR in smooth muscle. 
(Table 8.1)

Question 18

Which type of muscle has striations, a single nucleus, intercalated discs, sarcomeres, transverse tubules, and gap junctions between fibres?

Answer 18

Cardiac muscle

Question 19

The darker area within a sarcomere which includes an H zone in the centre is called:

Answer 19

A band

Question 20

Sustained, wavering contraction is called:

Answer 20

Unfused tetanus

Question 21

Which of the following is true about smooth muscle?

Answer 21

Smooth muscle can both shorten and stretch to a greater extent that striated muscle

Question 22

Creatine phosphate provides enough energy for muscle to contract maximally for about __ seconds.

Answer 22

15

Question 23

In relaxed muscle fibre, which structure stores calcium?

Answer 23

Sarcoplasmic reticulum

Question 24

Which regulatory protein blocks the attachment of myosin cross-bridges to actin?

Answer 24

Tropomyosin

Question 25

Calcium is actively transported back into the sarcoplasmic reticulum during which period of a myograms record of a twitch (muscle) contraction?

Answer 25

Relaxation period