NS

Question 1

Neurons

Answer 1

-specialized cells that transmit E signal nad translate into chemical

Question 2

General structure of neuron

Answer 2

• soma: cell bosy w/ nuclei, ER, ribosomes
• dendrites
• axon hillock: initial part of axon that integrated incoming signals; responsible for summation
• axon: terminates at the receiving cell
• meylin sheath: maintains E signal within one neuron, increases speed of conduction
• nodes of Ranvier: critical for rapid signal transmission
• nerve terminal: release of neurotransmitters

Question 3

meylin sheath is produced

Answer 3

• oligodendrocytes in CNS

- Schwann cell in PNS

Question 4

Synaptic cleft

Answer 4

connects nerve terminals w/ dendrites of another cells

Question 5

synapse

Answer 5

include nerve terminal +synaptic cleft+postsynaptic neuron

Question 6

nerve

Answer 6

collection of neurons in PNS

Question 7

Ganglia

Answer 7

collection of cell bodies in PNS

Question 8

tract

Answer 8

collections of axons in CNS

Question 9

nuclei

Answer 9

collection of cell bodies in CNS

Question 10

astrocyte

Answer 10

• CNS ganglia
• nourishment
• blood-brain barrier

Question 11

ependymal cells

Answer 11

• CNS
• line ventricles
• produce CSF (physical support and shock absorber)

Question 12

microglia

Answer 12

• CNS

- phagocytes

Question 13

AP

Answer 13

• all-or-nothing
• relay E impulse down the axon
• causes the release of neurotransmitters

Question 14

Resting potential in NS

Answer 14

• 70mV (inside is negative)

- maintained via use of Na/K ATPase (3 Na comes out, 2 K in; primary active transport)

Question 15

Depolarization

Answer 15

• increase in membrane potential

- caused by excitatory input

Question 16

Hyperpolarization

Answer 16

• decrease in membrane potential below resting

- caused by inhibitory input

Question 17

Threshold in NS

Answer 17

• 55mV

- will cause propagation of the AP

Question 18

Types of summation

Answer 18

• addictive effect of multiple signals
  1. Temporal: add frequent input from one source
  2. Spatial: add input from one source

Question 19

Changes in the membrane potential after threshold

Answer 19

1. Na influx until +35 via V-gated NA channels; causes depolarization
2. V-gated Na channels are inactivated
3. V-gated K channels open - repolarization due to K efflux
4. V-gated K channels slowly start to close - hyperpolarization
5. refractory period

Question 20

when can Na gated channels be deactivated

Answer 20

when membrane potential approaches -70mV

Question 21

types of refractory periods

Answer 21

1. Absolute - no stimulus can cause another AP to occur (when NA channels are inactivated)
2. Relative - stronger than usual stimulus can cause AP, but only when Na channels are deactivated

Question 22

Impulse propagation

Answer 22

when AP travels down the axon to cause release of naurotransmit
- allows unidirectional flow of info (b/c of refractory periods)

Question 23

saltatory conduction

Answer 23

signal hops from node to node

Question 24

describe steps of neurotransmit release

Answer 24

1. stored in vesicles in the cleft
2. AP arrives
3. Ca influx
4. fusion of the vesicles with the membrane and release of neurotransmitters
5. diffuse across cleft to be bound to the postsyn. neuron

Question 25

types of neurotransmitter receptors and its effect on postsynapt neuron

Answer 25

1. ligand-gated (depolar or hyprepolar)

2. G protein-coupled receptor (cause changes in cAMP or influx Ca)

Question 26

ways to remove neurotransmitters

Answer 26

1. broken down by enzyme
   2 brought back to presyn. neuron via reuptake carriers (common for serotonin, dopamine, NE)
2. diffuse out of synaptic cleft (ex. nitric oxide)