physiology

Question 1

Ion channels are made of

Answer 1

protein

Question 2

In general, the action potential is first initiated at the

Answer 2

axon hillock.

Question 3

The sodium-potassium pump is responsible for

Answer 3

pushing three sodium ions out of the cell for every two potassium ions pumped in.

Question 4

At the K+ equilibrium potential, the electrostatic pressure pulling K+ ions into the neuron is balanced by the concentration gradient pushing them out; at this point, the

Answer 4

–65 mV

Question 5

An afterpotential is

Answer 5

a brief hyperpolarization that follows an action potential (“undershoot”).

Question 6

Action potentials generally are not transmitted along dendrites because they have

Answer 6

few voltage-gated Na+ channels.

Question 7

When applying hyperpolarizing or depolarizing stimulus to the membrane of a neuron, the beginning and end of the neuron’s response become distorted. This is due to

Answer 7

capacitance of the membrane.

Question 8

Myelin increases the speed of conduction because it

Answer 8

resists the flow of current across the membrane.

Question 9

The overall amplitude of the action potential is about

Answer 9

100 mV.

Question 10

Whether a synapse is excitatory or inhibitory is determined by the

Answer 10

type of transmitter released by the presynaptic neuron and the receptor to which that transmitter binds on the postsynaptic neuron.

Question 11

_______ receptors recognize the synaptic transmitter, but they do not themselves contain any ion channels

Answer 11

Metabotropic

Question 12

Which process is not involved in chemical synaptic transmission?

Answer 12

Electrical conduction across the synaptic cleft

Question 13

Most ACh receptors in the brain are

Answer 13

muscarinic

Question 14

The lock-and-key analogy is used to describe the

Answer 14

action of transmitter molecules on receptor proteins.

Question 15

Acetylcholine receptors are thought to be in the same family as GABA, glycine, and glutamate receptors because they

Answer 15

have a similar structure.

Question 16

The neurotransmitter acetylcholine acts on at least _______ different types of receptors

Answer 16

four

Question 17

Neurons process information by integrating (summing algebraically) the postsynaptic potentials through both _______ summation (summing potentials from different locations) and _______ summation (summing potentials across time).

Answer 17

spatial; temporal

Question 18

During the action potential, the neuron cannot be excited by a second stimulus; it is _______. For a few milliseconds afterward, the hyperpolarized neuron is _______, requiring a stronger stimulation than usual in order to fire.

Answer 18

absolutely refractory; relatively refractory

Question 19

A ligand is a

Answer 19

molecule that binds to receptor proteins.

Question 20

The phenomenon of divergence is illustrated by the visual system, in which 1 million axons of the optic nerve communicate with _______ neurons in the cerebral cortex.

Answer 20

over a billion