Nervous System

Question 1

Information processing steps

Answer 1

1. Sensory input
2. Integration
3. Motor output

Question 2

Sensory neurons

Answer 2

Function in transmitting information from external stimuli

Afferent: bringing in info

Question 3

Interneurons

Answer 3

Function in integration of sensory information

Question 4

Motor neurons

Answer 4

Function in triggering muscle or gland activity

Efferent: sending out info

Question 5

Central nervous system

Answer 5

Portion of nervous system where signal processing and integration takes place
Includes brain and nerve cord

Question 6

Peripheral nervous system

Answer 6

Portion of nervous system that carries information in and out of the CNS

Question 7

Nerves

Answer 7

Neurons of PNS bundled together
Information transfer
Afferent (signals into CNS) and efferent (signals out of CNS)

Question 8

Cell body (soma)

Answer 8

Location of most of neuron’s organelles

Question 9

Dendrites

Answer 9

Highly branched extensions that receive signals from other neurons

Question 10

Axon

Answer 10

Long extension that transmits signals to other cells at synapses

Question 11

Axon hillock

Answer 11

Cone-shaped base of axon (place where axon is attached to cell body)

Question 12

Synaptic terminal

Answer 12

End of axon

Passes information across the synapse

Question 13

Neurotransmitters

Answer 13

Chemical messengers

Information that is transmitted across synapse

Question 14

Synapse

Answer 14

Junction between an axon and another cell

Question 15

Flow of information transfer

Answer 15

Info is transmitted from presynaptic cell (neuron) to postsynaptic cell (neuron, muscle, or gland cell)

Question 16

Glial cells

Answer 16

Nourish or insulate neurons

Question 17

Membrane potential

Answer 17

Cell’s voltage difference across its membrane

Changes in this act as signals

Question 18

Resting potential definition

Answer 18

Membrane potential of a neuron not sending signals

Question 19

Resting potential of a mammalian neuron

Answer 19

K+ is highest inside cell
Na+ is highest outside cell
Many open K+ channels, but fewer open Na+ channels: K+ diffuses outside of cell (resulting buildup of negative charge is major source of membrane potential)

Question 20

Sodium-potassium pumps

Answer 20

Use energy of ATP to maintain K+ and Na+ gradients across plasma membrane (chemical potential energy)

Question 21

Opening of ion channels in plasma membrane

Answer 21

Conversion of chemical potential to electrical potential

Question 22

Gated ion channels

Answer 22

Open or close in response to stimuli, causing changes in membrane potential

Question 23

Hyperpolarization

Answer 23

Increase in magnitude of membrane potential (increase in negative charge)
Caused by opening of gated K+ channels: K+ diffuses out of cell, making inside of cell more negative

Question 24

Depolarization

Answer 24

Reduction in magnitude of membrane potential

Opening other types of ion channels (ex: Na+) counteracts hyperpolarization

Question 25

Graded potential

Answer 25

Changes in polarization where the magnitude of the change varies with the strength of the stimulus

Question 26

Action potential

Answer 26

Massive change in membrane voltage caused by a large shift in membrane potential by depolarization
Constant magnitude, all-or-none, transmit signals over long distances

Question 27

Voltage-gated ion channels

Answer 27

Open or close when the membrane potential passes a certain level

Question 28

Action potential steps

Answer 28

1. Resting potential (voltage-gated Na+ and K+ channels are closed)
2. Voltage-gated Na+ channels open: Na+ flows into cell
3. Rising phase: threshold is crossed and membrane potential increases
4. Falling phase: voltage-gated Na+ channels become deactivated and voltage-gated K+ channels open, causing K+ to flow out of cell
5. Undershoot: membrane permeability to K+ is higher than normal, and then voltage-gated K+ channels close and resting potential is restored
6. Refractory period: second action potential cannot be initiated (temporary inactivation of Na+ channels)