4.1-4.3

Question 1

Membrane potential

Answer 1

The difference in electrical charge between the inside and outside of a cell.

Question 2

Microelectrodes

Answer 2

Records a neuron’s membrane potential by positioning the tip of one electrode inside the neuron and the tip of another electrode outside the neuron in the extracellular fluid.

Intercellular electrodes fine enough to pierce a neural membrane without severely damaging it. The tips are less than one-thousandth of a millimeter in diameter.

Question 3

Resting potential

Answer 3

The steady membrane potential of about -70 mV.

With the -70 mV charge built up across its membrane, a neuron is said to be polarized.

Question 4

Ions

Answer 4

Positively or negatively charged particles.

Na+ = sodium ion

K = potassium ion

Question 5

Ion channels

Answer 5

Pores in neural membranes through which specific ions pass.

Question 6

Sodium-potassium pumps

Answer 6

Active transport mechanisms that pump Na+ ions out of neurons and K+ ions in.

Question 7

Transporters

Answer 7

Mechanisms in the membrane of a cell that actively transport ions or molecules across a membrane.

Question 8

Depolarize

Answer 8

When neurotransmitter molecules bind to postsynaptic receptors, they typically have one of two effects, depending on the neurotransmitter, receptor, and postsynaptic nerve in question.

1) depolarize
2) hyperpolarize

Depolarize: Decreasing the resting membrane potential, from -70 to -67 mV, for example.

Question 9

Hyperpolarize

Answer 9

When neurotransmitter molecules bind to postsynaptic receptors, they typically have one of two effects, depending on the neurotransmitter, receptor, and postsynaptic nerve in question.

1) depolarize
2) hyperpolarize

Hyperpolarize: Increasing the resting membrane potential, from -70 to -72 mV, for example.