Muscle Contraction

Reorder the following

• The stimulus arrives at the axon terminal or end of the nerve

• calcium enters the terminal and causes the release of acetylcholine into the synaptic cleft

• receptors on the motor end plate receive the acetylcholine

• the impulse spreads through the sarcolemma and down the T-tubules to the sarcoplasmic reticulum

• calcium stored in the sarcoplasmic reticulum is released into the sarcoplasm

Calcium in the sarcoplasm acts with the proteins ​ (a)   , which causes the ​ (b)   to contract and pull on the ​ (c)   .

• troponin and tropomyosin
• myosin
• actin

Which of these is the neurotransmitter responsible for muscle contraction?

• sarcolemma

• calcium

• sarcoplasm

• acetylcholine

Left over ​ (a)   in the ​ (b)   is broken down by the enzyme ​ (c)   .

• acetylcholine
• synaptic cleft
• acetylcholinesterase

​ (a)   then detaches from troponin and tropomyosin and is returned to the ​ (b)   by ​ (c)   .

• Calcium
• sarcoplasmic reticulum
• active transport

A motor neuron causes all fibers in that motor unit to contract simultaneously.

• True

• False

A single motor neuron acts on many muscle fibers.

• True

• False

Muscles will not respond to a stimulus, unless the signal is strong enough to reach the ​ (a)   .

• threshold stimulus
• high frequency stimulus

Match the following

• a by product that builds up in the muscles when there's insufficient oxygen in the muscle

• lactic acid

• the red blood cells that bring oxygen to the body

• Myoglobin

• the primary source of energy for muscle contraction; must be regenerated often

• ATP

• a pigment that helps store oxygen in muscle tissue

• Hemoglobin

Muscle ​ (a)   occurs when an ​ (b)   deficit cause the build up of ​ (c)   which interferes with muscle ​ (d)   .

• fatigue
• oxygen
• lactic acid
• contraction