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
Q

refractory period (2)

A
  • 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
Q

What are the 2 phases of the refractory period?

A

absolute & relative

3
Q

absolute refractory period (2)

A
  • no stimulate of any strength will trigger an action potential
  • Na gates are open
4
Q

relative refractory period (2)

A
  • only especially strong stimulus will trigger an action potential
  • K gates are open
5
Q

For communication, the nerve signal must ______

A

travel to the end of the axon

6
Q

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

A

unmyelinated fibers

7
Q

saltatory conduction in PNS

A

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

8
Q

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

A

Node of Ranvier

9
Q

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

A

triggers the release of neurotransmitters via exocytosis

10
Q

Neurotransmitters stimulate what?

A

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

11
Q

axodendritic synapse

A

presynaptic neuron synapse with a dendrite

12
Q

axosomatic synapse

A

presynaptic neuron synapse with a soma

13
Q

axoaxonic synapse

A

presynaptic neuron synapse with an axon of postsynaptic neuron

14
Q

Where does typical synapse occur?

A

dendrites

15
Q

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

A

gap junctions that join adjacent cells

advantages: quick transmission no delay for release & binding
disadvantages: cannot integrate info & make decisions

16
Q

Why is it possible to integrate info?

A

because of the transfer of electrical to chemical signals

17
Q

What are the 4 categories of neurotransmitters?

A
  1. acetylcholine
  2. amino acid neurotransmitters
  3. monoamines
  4. neuropeptides
18
Q

Characteristics of neuropeptides? (5)

A
  • 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
Q

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

A

FALSE

20
Q

What are the actions of neurotransmitters? (4)

A
  • excitatory
  • inhibitory
  • open ligand-regulated ion gates
  • depend on receptor of post synaptic cell
21
Q

3 Kinds of synapse

A
  • excitatory cholinergic
  • inhibitory GABA-ergic
  • excitatory adrenergic
22
Q

excitatory cholinergic synapse

A

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

23
Q

inhibitory GABA-ergic synapse (3)

A
  • employs gamma-aminobutyric acid as its neurotransmitter
  • receptors are chloride channels
  • postsynaptic neurons are inhibited
24
Q

excitatory adrenergic synapse

A
  • 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
Q

What advantage does excitatory adrenergic synapse have over other synapses?

A

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

26
Q

neuromodulators

A

hormones, neuropeptides, and other messengers that modify synaptic transmission

27
Q

How do neuromodulators modify synaptic transmission? (2)

A
  • stimulate neuron to install more receptors in the postsynaptic membrane adjusting its sensitivity to the neurotransmitter
  • alter the rate of the neurotransmitter synthesis
28
Q

enkephalins

A

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

29
Q

nitric oxide

A

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

30
Q

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

A

more; longer; origin

31
Q

Why do we have synapses? (3)

A
  • to process info & make decisions
  • chemical synapses are the decision making devices
  • more synapse the greater the decision capabilities
32
Q

What is neural integration based on?

A

the postsynaptic potentials produced by neurotransmitters

33
Q

excitatory postsynaptic potential? examples?

A

EPSP
any voltage change in the direction of threshold that makes a neuron more likely to fire
-ex. glutamate & aspartate

34
Q

inhibitory postsynaptic potential?examples?

A

IPSP
any voltage change away from threshold that makes a neuron less like to fire
-ex. glycine & GABA

35
Q

Which neurotransmitters can be excitatory or inhibitory?

A

ACh & norepinephrine

36
Q

summation

A

the process of adding up postsynaptic potentials & responding to their net effects that occurs in the trigger zone

37
Q

temporal summation

A
  • occurs when a single synapse generates EPSPs so quickly that each is generated before the previous one fades
  • 1 neuron
38
Q

spatial summation

A

occurs when EPSPs from several different synapses add up to threshold at an axon hillock
-multiple neurons

39
Q

facilitation

A

a process in which one neuron enhances the effect of another one

40
Q

neural coding

A

the way in which the nervous system converts info to a meaningful pattern of action potentials

41
Q

What does qualitative information depend on?

A

which neuron fires (labeled line code)

42
Q

What does quantitative information depend on?

A

information about the intensity of a stimulus is encoded in 2 ways (different neurons have dif thresholds of excitation; more strongly a neuron is stimulated, the more frequently it fires)

43
Q

neural pools

A

neurons function in large groups

44
Q

diverging circuit

A

one nerve fiber branches & synapses with several postsynaptic cells

45
Q

converging circuit

A

input from many dif nerve fibers can be funneled to one neuron (opposite of diverging)

46
Q

reverberating circuit

A

neurons stimulate each other in linear sequence but one cell restimulates the first cell to start the process all over

47
Q

parallel after discharge circuit

A

input neuron diverges to stimulate several chains of neurons

48
Q

memory trace (engram)

A

physical basis of memory is a pathway through the brain

49
Q

synaptic plasticity

A

the ability of synapses to change

50
Q

synaptic potential

A

the process of making transmission easier

51
Q

What are the 3 types of memory?

A

immediate
short
long

52
Q

immediate memory (3)

A
  • the ability to hold something in your thoughts for just a few seconds
  • essential for reading
  • our memory “echoes” in our minds for a few seconds (reverberating circuit)
53
Q

short term memory (3)

A
  • lasts from a few seconds to several hours
  • quickly forgotten if distracted
  • reverberating circuits
54
Q

What causes memory to last longer?

A

facilitation

55
Q

tetanic stimulation

A

rapid arrival of repetitive signals at a synapse (accumulation of Ca2+)

56
Q

posttetanic potentiation

A

to jog a memory (Ca2+ level in synaptic knob stays elevated)

57
Q

types of long term memory (2)

A

declarative

procedural

58
Q

declarative long term memory

A

retention of events that you can put into words

59
Q

procedural long term memory

A

retention of motor skills

60
Q

alzheimer disease

A

deficency in ACh and nerve growth factors

61
Q

parkinson disease

A
  • progressive loss of motor function beginning in 50s or 60s- NO RECOVERY
  • degeneration of dopamine releasing neurons
  • involuntary muscle contractions