Nervous System, Synapses, and Neurotransmitters (Unit 1) Flashcards

(57 cards)

1
Q

main divisions of nervous system

A
  1. Sensory
  2. Integrative
  3. Motor
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2
Q

Sensory Division of nervous system

A

tactile, visual, auditory, olfactory

perceiving sensation from the environment

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3
Q

Integrative Division

A

process information, creation of memory

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4
Q

Motor Division

A

respond to and move about in our environment

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5
Q

Neurons

A

The basic functional unit of the central nervous system

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6
Q

3 major anatomical/structural components of nervous system

A
  1. Soma
  2. Axon
  3. Dendrite
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7
Q

Soma

A

the main body of the neuron

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8
Q

Axon

A

extends from soma to synaptic terminal –> the effector part of neuron (the output side)

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9
Q

Dendrite

A

projections from soma; the sensory portion of neuron (the input side where information is received)

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10
Q

how many neurons in CNS?

A

over 100 billion

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11
Q

how many synaptic connections from input fibers on neuron?

A

anywhere from hundreds to as much as 200,000

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12
Q

Structure of a large neuron in the brain showing its important functional parts.

A

insert pic

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13
Q

Somatosensory axis of the NS function

A

Transmits sensory info from receptors of body surface and some deep structures through peripheral nerves to various sensory processing locations in the CNS

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14
Q

Skeletal motor nerve axis of the NS function

A

Motor functions include stimulation of

  1. Contraction of skeletal muscle
  2. Contraction of smooth muscle in organs
  3. Secretions of active chemical substances by both exocrine and endocrine glands
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15
Q

Major Types of Synapses (2)

A

chemical and electrical

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16
Q

Synapse

A

Junction point from one neuron to the next

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17
Q

Synapse Role in Info Processing

A

Play a role in info processing by performing selective action depending on input and modulation

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18
Q

Synapse determines the _____ nervous signals will spread throughout the NS

A

direction

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19
Q

most synapses in human are _____

A

chemical synapses

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20
Q

chemical synapse: mechanism

A

presynaptic neuron secretes neurotransmitter that acts on receptor proteins in the membrane of the next neuron

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21
Q

affects chemical synapse can have on the succeeding neuron (3)

A
  • excite neuron
  • inhibit neuron
  • modify neuron
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22
Q

electrical synapse: mechanism

A

pre and post neurons are physically connected via gap junctions. Gap junctions allow free movement of ions, so action potentials are directly communicated from the interior of one neuron to the interior of the next neuron

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23
Q

Transmission direction of signals is through electrical synapse

A

bidirectional – allows coordination of activities of large groups/networks of interconnected neurons

24
Q

Chemical synapses always communicate info in

A

ONE DIRECTION —allows for signals to be directed toward specific goals

25
_____ (#) presynaptic terminals about surface of dendrites (80-95%) and soma (5-20%) of motor neuron
10,000-200,000
26
% of presynaptic terminals about surface of dendrites vs. soma
80-95% and 5-20%
27
Neurons in different locations vary in (4 characteristics)
1. Size of soma 2. Length, size, # of dendrites 3. Length, size of axon 4. # of presynaptic terminals
28
Neurotransmitter binding to GPCR can induce( 4)
1. Opening specific ion channels in postsynaptic membrane —ion channel effects through this mech stay open longer than those activated directly 2. Activation of cAMP or cGMP 3. Activation of 1 or more intracellular enzymes 4. Activation of gene transcription
29
GPCR
G-protein coupled receptor
30
NTs that cause opening of cation channels in postsynaptic membrane = (excitatory vs. inhibitory)
excitatory
31
NTs that cause opening of anion channels in postsynaptic membrane = (excitatory vs. inhibitory)
inhibitory
32
G protein complex consists of:
guanosine diphosphate (GDP) alpha (α) component that is the activator portion of the G protein beta (β) and gamma (γ) components that are attached to the alpha component
33
G protein complex is found:
in the cytosol
34
G protein complex bound to GDP = active vs. inactive.
inactive
35
how does the nervous system get long-acting responses/changes in postsynaptic neurons?
activation of cell signaling 2nd messenger pathways
36
Mechanisms of excitation of postsynaptic neurons
Opening of Na+ channels Decreased Cl- or K+ conductance Changes in internal metabolism or gene expression
37
Mechanisms of inhibition of postsynaptic neurons
Opening of Cl- channels Increased K+ conductance Activation of receptor enzymes that cell metabolic fxn or gene expression
38
Concentration Differences of Ions across the Neuronal Somal Membrane.
sodium and chloride high in extracellular fluid, potassium high in intercellular fluid
39
why is there a low concentration of chloride in neurons?
negative voltage 9-65 mV) repels the negatively charged chloride ions, forcing them outward through channels until the concentration is much less inside the membrane than outside.
40
resting membrane potential of spinal motor neuron soma
-65 mV
41
diffusion potential for chloride with respect to neuron cell
-70 mV
42
Vm in neurons in the CNS is (less/more) negative than large peripheral neurons
less
43
importance of neuron have a less negative membrane potential
allows both positive and negative control of the degree of excitability of the neuron
44
EPSP
Excitatory postsynaptic potentials
45
Excitatory postsynaptic potential process
1. Stimulation of the postsynaptic neuron with excitatory NTs causing increased Na permeability 2. Na influx raises the membrane potential to a less negative (more positive) potential → EPSP (requires stimulation of multiple presynaptic terminals, not just one!) 3. If EPSP rises high enough to exceed threshold, an AP will occur
46
In EPSP, where does the AP occur?
APs are not initiated immediately adjacent to | the synapse, but at the initial segment of the axon
47
IPSP
Inhibitory postsynaptic potentials
48
Neuron in an excited state
less negative intraneuronal potential (−45 millivolts) caused by sodium influx
49
Neuron in an inhibited state
more negative intraneuronal membrane potential (−70 millivolts) caused by potassium ion efflux, chloride ion influx, or both.
50
IPSP process
Increased conductance of Cl- or K+ = hyperpolarization of the membrane potential -->decrease in membrane potential to a more negative value -- makes it harder to get to the action potential threshold
51
spatial summation
the effect of summing simultaneous postsynaptic potentials by activating multiple terminals on widely spaced areas of the neuronal membrane
52
temporal summation
when successive discharges from a single presynaptic terminal occur rapidly enough such that they add to one another in summation
53
decremental conduction
the decrease in membrane potential as it spreads electrotonically along dendrites toward the soma
54
synapses that lie (near/far away from) the soma have far more effect in causing neuron excitation or inhibition that do those that lie (near/far) from the soma
near; far
55
do thresholds of neurons vary?
tresholds are different for different populations of neurons
56
when excitatory state rises above threshold for action potential, a neuron will:
fire repeatedly as long as it stays above the threshold
57
trend for firing rate of neurons
increases as excitatory state increases (arbitrary units) but then eventually plateaus at the max firing rate (has to due with the refractory period of the ion channels)