chapter 4.1

Question 1

L-dopa

Answer 1

penetrates the blood-brain barrier and is converted to dopamine once inside the brain.

Question 2

membrane potential

Answer 2

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

Question 3

to record a neuron’s membrane potential

Answer 3

you must position the top of one electrode inside the neuron and the tip of another electrode outside the neuron in the extracellular fluid.

Question 4

microelectrodes

Answer 4

intracellular electrodes.

Question 5

resting potential

Answer 5

steady membrane potential of about -70 mV; said to be polarized.

Question 6

ions

Answer 6

positively and negatively charged particles.

Question 7

in resting neurons

Answer 7

there are more Na+ ions outside the cell than inside, and more K+ ions inside than outside.

Question 8

ions channels

Answer 8

specialized pores in neural membranes through which ions can pass. Each type is specialized for the passage of particular ions.

Question 9

electrostatic pressure

Answer 9

the -70 mV charge attracts the positively charge Na+ ions into resting neurons.

Question 10

random motion

Answer 10

pressure for Na+ ions to move down their concentration gradient.

Question 11

sodium-potassium pumps

Answer 11

Hodgkin and Huxley; mechanisms in the cell membrane continually exchange three Na+ ions inside the neuron for two K+ ions outside.

Question 12

transporters

Answer 12

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