Muscle Contraction physiology

Question 1

The interaction of myofibrils during contraction is known as:

Answer 1

Sliding filament theory of contraction

Question 2

What is the first step to muscle contraction?

Answer 2

Motor neuron releases its neurotransmitter (usually acetylcholine)

Question 3

Once the motorneuron is released

Answer 3

Acetylcholine diffuses across the synapse and touches the sarcolemma

Question 4

What two things happen once the neurotransmitter has touch the sarcolemma?

Answer 4

1) Sodium channels along sarcolemma open and sodium ions rush in
2) acetylcholine is broken down by acetylcholinesterase

Question 5

Once sodium ions have entered the interior of the muscle cell:

Answer 5

Transverse-tubules allow the sodium to travel throughout

Question 6

T-tubule

Answer 6

Structures that act as passageways for material in the sarcoplasm

Question 7

The presence of Sodium ions in the sarcoplasm causes:

Answer 7

Calcium ions to be released by sarcoplasmic reticulum

Question 8

What do calcium ions do?

Answer 8

Flood the sarcomere and bind to troponin

Troponin fall away from tropomyosin

Question 9

Once troponin falls away:

Answer 9

Tropmyosin slides off actin’s binding sites and cross-bridges form between actin and myosin

Question 10

Once cross-bridges have formed

Answer 10

Myosin heads pivot and pull actin to shorten sarcomere

Question 11

Once the sarcomere has shortened slightly

Answer 11

ATP is used to break present crossbridges and new ones form until desired contraction has occured

Question 12

After desired contraction has occured:

Answer 12

Calcium ions are pumped back into the sarcoplasmic reticulum

Question 13

Once calcium has returned to the sarcoplasmic reticulum

Answer 13

Troponin and tropomyosin return to their original position and block unwanted actin-binding sites