Module 8 Quiz Questions Flashcards
What is the latent period of a muscle twitch?
The period of time between the stimulus and a muscle fibre contraction.
Distinguish between isotonic and isometric contractions.
Isotonic: the muscle shortens but muscle tension remains relatively constant.
Isometric: the muscle length stays the same but the tension on the muscle increases.
What is a motor unit?
A single motor neuron and all the fibres it stimulates.
What is the sarcoplasmic reticulum and what is its function?
Is modified endoplasmic reticulum and its function is to contain calcium ions and release them upon stimulation into the sarcoplasm to trigger muscle contraction.
Describe the events that occur at a neuromuscular junction and which result in the contraction of skeletal muscle.
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.
What proteins make up the thin myofilaments of muscle?
Actin
Troponin
Tropomyosin
2hat 2 molecules are stored by muscles for use in ATP synthesis?
Glycogen Creatine phosphate (phosphocreatine)
What is meant by the term oxygen debt?
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).
The entire muscle is wrapped in the __.
Epimysium
Identify 4 properties of muscle tissue that enable it to function:
Excitability
Contractility
Extensibility
Elasticity
Identify the 3 types of muscle tissue and characterize each in terms of striated/non and voluntary/in.
Skeletal; striated, voluntary
Cardiac; striated, involuntary
Smooth; nonstriated, involuntary
What is the role of gap junctions between the cardiac muscle fibres?
Allow the rapid passage of the stimulus for contraction from one cardiac muscle fibre to the next.
Name the specific connective tissue that divides muscles into bundles of fibres called fascicles.
Perimysium
What is the role of acetylcholinesterase?
Destroys the acetylcholine in the synaptic cleft to allow for the transfer of a subsequent stimulus.
Describe fast glycolytic fibres.
FGF have small amounts of myoglobin and mitochondria, and poor capillary supply. They get their ATP from anaerobic metabolism, contract rapidly and tire quickly.
What is muscle tone?
Sustained, small contractions give a firmness to a relaxed skeletal muscle that is known as muscle tone.
List 3 histologic differences between skeletal and smooth muscle cells:
Filaments not orderly arranged. Intermediate filaments in smooth muscle. No T tubules in smooth muscle. Scanty SR in smooth muscle. (Table 8.1)
Which type of muscle has striations, a single nucleus, intercalated discs, sarcomeres, transverse tubules, and gap junctions between fibres?
Cardiac muscle
The darker area within a sarcomere which includes an H zone in the centre is called:
A band
Sustained, wavering contraction is called:
Unfused tetanus
Which of the following is true about smooth muscle?
Smooth muscle can both shorten and stretch to a greater extent that striated muscle
Creatine phosphate provides enough energy for muscle to contract maximally for about __ seconds.
15
In relaxed muscle fibre, which structure stores calcium?
Sarcoplasmic reticulum
Which regulatory protein blocks the attachment of myosin cross-bridges to actin?
Tropomyosin
Calcium is actively transported back into the sarcoplasmic reticulum during which period of a myograms record of a twitch (muscle) contraction?
Relaxation period
