Chapter 12: Nervous Tissue (Part 2) Flashcards Preview

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Flashcards in Chapter 12: Nervous Tissue (Part 2) Deck (61)
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1

refractory period (2)

-the period of resistance to stimulation when an action potential can not be fired again
-only refers to a small patch of the neurons membrane

2

What are the 2 phases of the refractory period?

absolute & relative

3

absolute refractory period (2)

-no stimulate of any strength will trigger an action potential
-Na gates are open

4

relative refractory period (2)

-only especially strong stimulus will trigger an action potential
-K gates are open

5

For communication, the nerve signal must ______

travel to the end of the axon

6

Which fibers have voltage regulated ion gates along its entire length?

unmyelinated fibers

7

saltatory conduction in PNS

in myelinated fibers the signal seems to jump from node to node

8

What part of the myelinated fiber contains voltage gated ion channels?

Node of Ranvier

9

When a nerve signal reaches the end of the axon what happens?

triggers the release of neurotransmitters via exocytosis

10

Neurotransmitters stimulate what?

dendrites or directly onto a soma that triggers a local potential to the axon hillock

11

axodendritic synapse

presynaptic neuron synapse with a dendrite

12

axosomatic synapse

presynaptic neuron synapse with a soma

13

axoaxonic synapse

presynaptic neuron synapse with an axon of postsynaptic neuron

14

Where does typical synapse occur?

dendrites

15

What type of junctions are in electrical synapse?advantages & disadvantages?

gap junctions that join adjacent cells
advantages:quick transmission no delay for release & binding
disadvantages:cannot integrate info & make decisions

16

Why is it possible to integrate info?

because of the transfer of electrical to chemical signals

17

What are the 4 categories of neurotransmitters?

1. acetylcholine
2. amino acid neurotransmitters
3. monoamines
4. neuropeptides

18

Characteristics of neuropeptides? (5)

-chains of 2 to 40 amino acids
-act at lower concentrations
-longer lasting effects
-some function as hormones or neuromodulators
-stored in secretory granules

19

T/F Do neurotransmitters have the same effect everywhere in the body

FALSE

20

What are the actions of neurotransmitters? (4)

-excitatory
-inhibitory
-open ligand-regulated ion gates
-depend on receptor of post synaptic cell

21

3 Kinds of synapse

-excitatory cholinergic
-inhibitory GABA-ergic
-excitatory adrenergic

22

excitatory cholinergic synapse

employs ACh as its neurotransmitter (excites some postsynaptic cells & inhibits others)

23

inhibitory GABA-ergic synapse (3)

-employs gamma-aminobutyric acid as its neurotransmitter
-receptors are chloride channels
-postsynaptic neurons are inhibited

24

excitatory adrenergic synapse

-employs norepinephrine as its neurotransmitter
-act through second messenger system
-receptor is not an ion gate, but a transmembrane protein associated with a G protein
-slower to respond

25

What advantage does excitatory adrenergic synapse have over other synapses?

enzyme amplification:single molecule of NE can produce vast #s of product molecules in the cell

26

neuromodulators

hormones, neuropeptides, and other messengers that modify synaptic transmission

27

How do neuromodulators modify synaptic transmission? (2)

-stimulate neuron to install more receptors in the postsynaptic membrane adjusting its sensitivity to the neurotransmitter
-alter the rate of the neurotransmitter synthesis

28

enkephalins

a neuromodulator family the inhibit spinal interneurons from transmitting pain signals to the brain

29

nitric oxide

a neuromodulator (simple) gas released by postsynaptic neurons in some areas of the brain concerned with learning & memory

30

The ____ synapse in a neural pathway, the _____ it takes for info to get from its ____ to its destination

more; longer; origin