Question

1.) Single muscle cells have an electrical all or none response similar to action potentials of neurons.

	True
	False

2.)

Acetylcholine released from a motor neuron onto a skeletal muscle cell is an example of __________ signaling.

	endocrine
	exocrine
	autocrine
	paracrine

3.)

Multiple, closely spaced depolarizations of skeletal muscle can sum together to produce a more powerful contraction because of accumulation of __________.

	ATP in the cytosol
	ATP in the sarcoplasmic reticulum
	Ca2+ in the sarcoplasmic reticulum
	Ca2+ in the cytosol

4.)

Isometric contraction involves the muscle generating greater force than the load leading to sarcomere shortening.

	True
	False

Answer 1

1) True,simple,a muscle fibre (not a whole muscle) either contracts fully of doesn't contact at all, it's like a falling ball,it either falls fully or doesn't at all.

2) Ach from a neuron associated with a muscle is released to the muscle, this is called paracrine signalling (means near signalling).

3) The contraction is because of Ca2+ ions in the cytosol,so more the cytosolic Ca2+,powerful the contraction.

4) True, because in isometric contraction , though the sarcomere contracts, the total length of the muscle remains the same and much more force is generated.