Chapter 1 Introduction

Question 0

Inhibits acetylcholinesterase

Prolongs and enhances action of ACh at muscle end plate

Answer 0

Neostigmine

Question 1

Competes with ACh for receptors on motor
end plate
Decreases size of EPP; maximal doses produce paralysis of respiratory muscles and death

Answer 1

Curare

Question 2

occurs when the cell membrane is held at a depolarized level such that the thresholdpotential is passed without firing an action potential.
■ occurs because depolarization closes inactivation gates on the Na+ channels.
■ is demonstrated in hyperkalemia, in which skeletal muscle membranes are depolarizedby the high serum K+ concentration. Although the membrane potential is closer tothreshold, action potentials do not occur because inactivation gates on Na+ channelsare closed by depolarization, causing muscle weakness.

Answer 2

Accomodation

Question 3

are inputs that depolarize the postsynaptic cell, bringing it closer to threshold andcloser to firing an action potential

Answer 3

EPSPs

Question 4

Excitatory neurotransmitters include

Answer 4

ACh, norepinephrine, epinephrine, dopamine,glutamate, and serotonin

Question 5

involves degeneration of dopaminergic neurons that usethe D2 receptors.

Answer 5

Parkinson’s

Question 6

the most prevalent excitatory neurotransmitter in the brain.

Answer 6

Glutamate

Question 7

From tryptophan

Answer 7

Serotonin

Question 8

are present in the A band in the center of the sarcomere.■ contain myosin

Answer 8

Thick filaments

Question 9

single action potential causes the release of a standard amount ofCa2+ from the SR and produces a single twitch. However, if the muscle is stimulated repeat-edly, more Ca2+ is released from the SR and there is a cumulative increase in intracellular[Ca2+], extending the time for cross-bridge cycling. The muscle does not relax

Answer 9

tetanus

Question 10

measured when length is held constant. Muscle length (preload)is fixed, the muscle is stimulated to contract, and the developed tension is measured.There is no shortening.

Answer 10

Isometric contraction

Question 11

measured when load is held constant. The load against which themuscle contracts (afterload) is fixed, the muscle is stimulated to contract, and shorten-ing is measured.

Answer 11

isotonic contraction

Question 12

present in the iris, ciliary muscle of the lens, and vas deferens.■ behaves as separate motor units.

Answer 12

multiunit smooth muscle