Skeletal Muscle, L31 Flashcards

Flashcards to review key concepts from the muscle lecture.

An action potential in the motor nerve axon causes __ release at the neuromuscular junction (NMJ).

neurotransmitter

The neurotransmitter __ activates its receptors, which are ion channels, at the NMJ.

acetylcholine

The efflux of __ from the SR causes the myoplasmic levels to increase.

calcium

The transient contraction in response to a single action potential is known as a .

twitch

__ is consumed during muscle contraction.

ATP

In the steady state, human oxidative metabolism can only support about __ watts of muscle power output.

300

During anaerobic metabolism, ATP is supplied by the continuing metabolism of __ to lactate.

pyruvate

__ metabolism produces 6 times as much ATP per glucose as anaerobic metabolism.

Oxidative

__ contraction is a contraction where the tension developed by the muscle remains almost constant while the muscle changes length.

Isotonic

__ contraction is a contraction where the tension developed does not exceed the resistance of the object and there is no change in muscle length.

Isometric

A __ unit consists of a motor neuron and all the skeletal muscle fibres it stimulates.

motor

Skeletal muscle __ are slow fibres which have a low maximum ATPase rate and lower maximum force production.

Type 1

__ fibres are fast fibres that have a high ATPase rate and can have a high oxidative capacity, in addition to glycolytic capacity, in metabolism.

Type 2A

__ fibres are fast fibres that have a high ATPase rate, but have a low oxidative capacity and are primarily glycolytic in metabolism

Type 2B glycolytic

Small oxidative motor units are recruited __.

first

During an isometric contraction, at the level of the sarcomere the maximum active force (tension developed) is dependent on the degree of and overlap.

actin, myosin

The effects of ACh are short lasting as the enzyme __ rapidly breaks down ACh.

acetylcholine esterase

Calcium is actively pumped back into the sarcoplasmic reticulum via __ pumps.

Ca2+-ATPase

__ acts as ATP 'store', but quickly spent (<15s)

Creatine phosphate

_: Units with neurons innervating the slow efficient aerobic cells (maintaining posture, walking)

Type 1 (“slow twitch”)