Muscle Contraction

Question 1

what are the three types of muscle contraction?

Answer 1

concentric (shortening), eccentric (lengthening), isometric (static) contraction

Question 2

what is a motor unit?

Answer 2

the motor neurone, the axon (pathway), and the muscle fibres combined together

Question 3

what is the anatomy of skeletal muscle?

Answer 3

1. muscle fibre (sarcolemma and sarcoplasmic reticulum, myofibril)
2. thick filament (myosin) - sarcomere
3. thin filament (actin) - sarcomere

Question 4

what is the all or none principal?

Answer 4

when a motor unit is stimulated to contract, all muscle fibres that is connected with contract

Question 5

what is the neuromuscular junction?

Answer 5

electrical impulse travels along nerve pathways to come into contact with the muscle at the neuromuscular junction

Question 6

what happens after the electrical impulse reaches the neuromuscular junction?

Answer 6

1. ACh is released from the axon terminal (neurotransmitter molecules)
2. They bind to receptors which depolarizes the membrane of muscle fibre
3. electrical impulse travels the t tubercles and opens calcium stores
4. Ca++ ions are released from the sarcoplasmic reticulum

Question 7

what is the sliding filament theory?

Answer 7

when the muscle contracts, the myosin and actin filaments overlap each other

Question 8

what is a cross bridge?

Answer 8

a cross bridge is when the myosin filament attaches tot he actin bind sites, rotates, detaches, and re attach

Question 9

what does a cross bridge result in?

Answer 9

this results in shortening of the sarcomere (muscle contraction)

Question 10

when does the sliding filament action continue?

Answer 10

1. the signal from CNS continues
2. calcium is present
3. ATP is present