Lab 13

Question 0

? describes the events that occur when skeletal muscles are activated by ?.

Answer 0

• Excitation contraction coupling

- somatic motor neurons

Question 1

? is composed of numerous multinucleated cells (fibers) with a characteristic arrangement of ? proteins that gives the cells a striated appearance under light microscopy.

Answer 1

• Skeletal muscle

- actin and myosin

Question 2

The ? of the brain initiates action potentials that travel along the ? of the CNS.

Answer 2

• primary motor cortex

- corticospinal tract

Question 3

A ? consists of a somatic motor neuron and all the muscle cells controlled by that neuron.

Answer 3

motor unit

Question 4

When the action potential along the motor unit neuron reaches the muscle cells it innervates, the neuron axon terminals release the neurotransmitter ?.

Answer 4

acetylcholine (ACh)

Question 5

The ? is an ion channel, that when activated by two ACh molecules open to allow sodium ions to diffuse in and potassium ions to diffuse out.

Answer 5

nicotinic receptor

Question 6

Once achieving threshold, ? along the sarcolemma are triggered to open thus causing a greater depolarization spike as sodium enters the cell.

Answer 6

sodium voltage gated channels

Question 7

Repolarization of the membrane is achieved by the opening of ?.

Answer 7

potassium voltage gated channels

Question 8

As action potentials are conducted along the membrane and into the t-tubules, ? (dihydropyridine (DHP) receptor) in the t-tubules are activated.

Answer 8

calcium voltage gated channels

Question 9

The calcium voltage gated channels in the t-tubules interact with ? (ryanodine (RyR) receptors) of the sarcoplasmic reticulum and lead to the release of calcium into the sarcoplasm of the muscle cell.

Answer 9

calcium release channels

Question 10

Increased calcium in the muscle cell binds with the protein ? to trigger muscle contraction.

Answer 10

troponin