2 .) In the laboratory, a skeletal muscle is extracted from an animal and placed

Question

2.) In the laboratory, a skeletal muscle is extracted from an animal and placed in a solution that contains no calcium ions.

a.) You add a neuron to the solution that synapses on the muscle. Will the isolated muscle contract when the added nerve is stimulated? (1 point)

b.) Explain your reasoning with the physiology you have learned (include mechanisms). At least four correct aspects to the mechanisms involved must be included for credit (3 point per)

c.) What type of neuron is synapsing on the skeletal muscle? (1 point)an image to help you visualize this scenario:

Explanation / Answer

2.a) No, the muscle will not contract as calcium ions are not present.

b) The physiology of muscle contraction includes:

i) excitation signal: Excitation of a neuron causes the release of neurotransmitters into the synaptic cleft which bind to receptors on the muscle cell and triggers excitation of muscle cell.

ii) calcium ion: The excitation of muscle cell causes the release of calcium ions into the cytoplasm of the muscle cell.

iii) troponin: The calcium ion binds to troponin found in muscle cells which activates actin receptors.

iv) sliding filament theory: Myosin hydrolise ATP (adenosine triphosphate) causing it to bind to actin receptors. When the phosphate molecule from myosin detaches, the actin and myosin filaments to slide over each other. The distance between the filaments shorten and the muscle is said to contract.

c) A somatic motor neuron is synapsing on the skeletal muscle.

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