Lecture 6 8/31/23

Question 1

What is the functional unit of the nervous system?

Answer 1

neuron

Question 2

What is the role of dendrites?

Answer 2

receive signals from other neurons

Question 3

What is the role of the neuron cell body?

Answer 3

manufacture proteins to keep the cell alive and functioning

Question 4

What is the role of the axon?

Answer 4

carry signals to and from the neuron body/initial segment and the pre-synaptic terminal

Question 5

What is the role of the pre-synaptic terminal?

Answer 5

release neurotransmitters in order to communicate with other neurons

Question 6

When does the pre-synaptic terminal release neurotransmitters?

Answer 6

when an action potential comes down the axon and to the terminal

Question 7

What is the charge of neurons compared to the extracellular environment?

Answer 7

negative charge

Question 8

How does the sodium-potassium pump work?

Answer 8

-powered by ATP
-pumps 3 Na+ ions out of the cell
-pumps 2 K+ ions into cell
-results in net negative charge inside cell

Question 9

What source of energy MUST neurons use?

Answer 9

glucose

Question 10

What things are able to alter the membrane potential of a neuron?

Answer 10

-synaptic messages
-responses to environmental stimuli

Question 11

What are the characteristics of Excitatory Post-Synaptic Potentials (EPSP)?

Answer 11

-makes resting potential more positive
-neuron is closer to reaching action potential
-typically associated w/ influx of Na+

Question 12

What are the characteristics of Inhibitory Post-Synaptic Potentials (IPSP)?

Answer 12

-makes resting potential more negative
-neuron less likely to reach action potential
-either Cl- influx or K+ efflux

Question 13

Why is summation important?

Answer 13

one pre-synaptic terminal discharge is not enough to initiate action potential

Question 14

What are the two types of summation?

Answer 14

-Spatial: multiple potentials arriving at the same time
-Temporal: consecutive potentials quickly, one after another

Question 15

When does an action potential occur?

Answer 15

when the stimulus reaches the threshold for an action potential

Question 16

What are the characteristics of an action potential?

Answer 16

-initiated when stimulus reaches threshold
-fixed amplitude and shape
-begins at axon’s initial segment and rapidly spreads down axon

Question 17

What are the stages of an action potential?

Answer 17

-resting
-summation
-depolarization
-repolarization
-hyper-polarization

Question 18

Why is depolarization “all or nothing?”

Answer 18

action potentials are uniform; cannot have a larger or smaller one

Question 19

What occurs during depolarization?

Answer 19

voltage-gated Na+ channels open and Na+ floods into cell

Question 20

What occurs during repolarization?

Answer 20

-Na+ channels close
-voltage-gated K+ channels open and K+ leaves the cell

Question 21

Why does hyper-polarization occur?

Answer 21

driving the cell’s resting potential lower than normal makes it less likely another action potential will occur right after the first one

Question 22

What things increase the speed of conduction down an axon?

Answer 22

-larger axon diameter
-increased myelination

Question 23

Why are nodes of Ranvier important?

Answer 23

-un-myelinated junctions between Schwann cells
-contain increased density of Na+ channels
-action potential jumps from node to node