Nervous System Flashcards Preview

Bio 121 > Nervous System > Flashcards

Flashcards in Nervous System Deck (28):
1

Information processing steps

1. Sensory input
2. Integration
3. Motor output

2

Sensory neurons

Function in transmitting information from external stimuli
Afferent: bringing in info

3

Interneurons

Function in integration of sensory information

4

Motor neurons

Function in triggering muscle or gland activity
Efferent: sending out info

5

Central nervous system

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

6

Peripheral nervous system

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

7

Nerves

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

8

Cell body (soma)

Location of most of neuron's organelles

9

Dendrites

Highly branched extensions that receive signals from other neurons

10

Axon

Long extension that transmits signals to other cells at synapses

11

Axon hillock

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

12

Synaptic terminal

End of axon
Passes information across the synapse

13

Neurotransmitters

Chemical messengers
Information that is transmitted across synapse

14

Synapse

Junction between an axon and another cell

15

Flow of information transfer

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

16

Glial cells

Nourish or insulate neurons

17

Membrane potential

Cell's voltage difference across its membrane
Changes in this act as signals

18

Resting potential definition

Membrane potential of a neuron not sending signals

19

Resting potential of a mammalian neuron

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)

20

Sodium-potassium pumps

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

21

Opening of ion channels in plasma membrane

Conversion of chemical potential to electrical potential

22

Gated ion channels

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

23

Hyperpolarization

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

24

Depolarization

Reduction in magnitude of membrane potential
Opening other types of ion channels (ex: Na+) counteracts hyperpolarization

25

Graded potential

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

26

Action potential

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

27

Voltage-gated ion channels

Open or close when the membrane potential passes a certain level

28

Action potential steps

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)