Exam 3 Flashcards
(82 cards)
1
Q
structures of CNS
A
brain and spinal cord
2
Q
structures of PNS
A
spinal nerves
cranial nerves
ganglia
anything outside of CNS
3
Q
the function of the nervous system
A
integrate sensory and motor information
4
Q
spinal nerves
A
31 pairs
carry impulses to and from the spinal cord
5
Q
ventral root
A
motor only
6
Q
dorsal
A
sensory only
7
Q
cranial nerves
A
12 pairs
arise from the brain
carry impulses to and from the brain
8
Q
somatic division sense
A
skeletal muscle and skin
9
Q
general somatic afferents (GSA)
A
temperature, touch, pain, and pressure
all spinal nerves thru the dorsal root
10
Q
special somatic afferents (SSA)
A
sight, sound, equilibrium
CN 2 and 8
11
Q
general somatic efferents (GSE)
A
motor to skeletal muscle and skin
all spinal nerves thru ventral roots
some cranial nerves
12
Q
general visceral afferents (GVA)
A
stretch, visceral pain, nausea
all spinal nerve thru dorsal roots
13
Q
special visceral afferents (SVA)
A
smell and taste
cranial nerves
14
Q
general visceral efferents (GVE)
A
sympathetic
parasympathetic
15
Q
sympathetic
A
fight or flight
all spinal nerves thru ventral roots and some CN
16
Q
parasympathetic
A
rest and digest
CN 3, 7, 9, 10
S2-S4
17
Q
effector tissue for somatic motor neurons
A
skeletal muscle
18
Q
effector tissue for autonomic motor neurons
A
cardiac muscle
smooth muscle
glands
19
Q
soma/cell body
A
nucleus, nucleolus, and granular cytoplasm
ribosomes
20
Q
dendrites
A
short, thick diffusely branched process
transmit graded potentials toward the cell body
sever as a sensory input region
21
Q
neurons
A
highly specialized cells that communicate via electrical impulses
extreme longevity
amitotic (cannot reproduce)
very high metabolic rate
22
Q
axon
A
arise from the soma
transmit motor impulses away from the cell body
myelin sheath protects and electrically insulates the neuron
23
Q
nodes of Ranvier
A
gaps in the myelin sheath
where electrical impulses flow
24
Q
multipolar neurons
A
1 axon, many dendrites
most common type
major CNS neuron
25
bipolar neuron
1 axon, 1 dendrite
| rare, found in the retina and olfactory mucosa
26
unipolar (pseudounipolar)
the single process from the cell body that divides into proximal and distal fibers
sensory neurons of PNS
27
glial cells
form a scaffolding for neurons
| more numerous than neurons
28
sensory/afferent
from skin/internal organs to CNS
unipolar
cell bodies in dorsal root ganglia
29
motor/efferent
carry impulses away from CNS to effector organ (muscle/gland)
cell bodies in ventral and lateral horns
30
interneurons
in CNS between sensory and motor neurons
integration
multipolar
majority of neurons
31
astrocytes
star-shaped
most abundant glial cell
connect neurons to capillaries and transfer nutrients
blood-brain barriers
regulate ECF by taking up K+ and neurotransmitters
32
microglia
orid cells with long, thorny processes
| a specialized type of macrophages
33
ependymal cells
lines cavities within the brain and spinal cord
| squamous to columnar in shape, ciliates
34
oligodendrocytes
forms myelin sheath around numerous axons
35
satellite cells
```
surround neuron cell bodies in ganglia
function similarly to astrocytes
```
36
Schwann cells
form myelin sheath
| essential to the regeneration of peripheral nerves
37
general principles of electricity in the body
generate electrical signals when given stimuli
communication
separated charges (+ and -)
currents due to gradient
current is used to do work
Ohms law
resistance is any hindrance to the flow of charge
38
Ohm's law
V = IR
V: voltage
I: current
R: resistance
39
resting membrane potential
the voltage across the plasma membrane found in most cells
the stimulus can change membrane permeability
alter ion concentrations
40
RMP depolarization
decrease or loss in membrane potential
inside becomes less negative
K+ moves in
41
RMP hyperpolarization
increase in membrane potential
inside becomes more negative
K+ moves out
42
RMP repolarization
return to RMP
43
graded/local potentials
dendrite or cell body
incoming signals operating over short distances
input signal
Na+, Cl-, CA+2
can be summed
the entry of ions via channels
depolarization (Na+) and hyperpolarization (K+, Cl-)
44
action potentials
```
long-distance signals of axons
conduction signal
axon hillock thru axon
Na+ and K+
cannot be summed
depolarization only (Na+)
refractory period- no summation
```
45
definition of action potential
the sequence of membrane potential changes from RMP to a brief reversal of polarity
46
the sequence of events in action potential
1) graded potential reach axon hillock and hyperpolarize the membrane to the threshold (-55)
2) depolarization of membrane causes voltage-gated channels to open, permeable to Na+
3) Na+ channels closed at activation and open during inactivation, the influx of Na+
- further, depolarization causes positive feedback, inside cell reaches +30
4) K+ channels open slowly in response to voltage
- K+ moves out = repolarization
5) some K+ channels remain open causing hyperpolarization
- excessive K+ efflux
- Na+ channels reset to the original position
47
propagation of action potentials
1) graded potentials above the threshold at the axon hillock
2) voltage-gated Na+ channels open, Na+ enter the cell to depolarize the cell
3) positive charge flows into axon by current flow
4) creates a positive feedback loop, depolarization opens Na+ channels, continuous Na+ helps maintain the amplitude of AP
5) Na+ gates close, no new AP in that area, refractory period
6) K+ channels close and returns to RMP
48
all-or-none phenomenon
weakest stimulus capable of generating an AP, if the stimulus is not at or above the threshold then AP will not be generated
-strong stimuli depolarize faster, weak stimuli depolarize slower
49
absolute refractory period
the membrane is completely insensitive to further stimulation
the period between the opening of Na+ channels until they reset
ensures all-or-none
50
relative refractory period
AP can be fired with a greater than normal stimulus
most of Na+ channels reset and activation gates closed, inactivation gates are open, K+ channels open
threshold elevated due to efflux of K+
51
how to increase conduction velocity
the large diameter of axons
| myelinated axons
52
pre-synaptic membrane
cell membrane that transmits impulses to a synapse contains neurotransmitters
53
post-synaptic membrane
cell membrane that transmits impulses away from the synapse, contains receptors for neurotransmitters
54
synaptic cleft
space between pre-synaptic and post-synaptic membranes contains ESF/ISF
55
electrical synapse
gap junctions
low resistance between cells, easy to pass signal by moving ions
good for synchronizing cells
heart, smooth muscle, parts of the brain
56
chemical synapse
specialized for the release and reception of neurotransmitters
junctions of cells
57
mechanism of synaptic transmission
1) AP arrives at the axon terminal
2) voltage-gated Ca+2 channels open and Ca enters the cell
3) Ca+2 causes the vesicle containing neurotransmitters to be exocytosed into the synaptic cleft
4) neurotransmitters diffuse across the synaptic cleft, and bind to receptors on the postsynaptic membrane
5) binding of neurotransmitters to the receptor, causes the protein to undergo a conformation change and opens ion channels
- graded potentials along the postsynaptic membrane
6) reuptake by astrocytes or the presynaptic terminal
- neurotransmitters stored or destroyed
- degradation by enzymes
7) diffusion away from synapse
58
excitatory postsynaptic potentials (EPSP)
1) neurotransmitter binds to a receptor and causes a depolarization
2) chemically gated Na+ channels open and Na enters the cell and K+ leaves the cell
3) Na+ gradient is larger and is a net depolarization
59
inhibitory postsynaptic potentials (IPSP)
1) neurotransmitters bind to receptor and causes hyperpolarization
2) chemically gated K+ or Cl- channels open
- allows K+ efflux or Cl- influx
3) charge on the inside becomes more negative, less likely to fire an AP
4) large depolarizing currents are required to create an AP
60
summation
adding together many EPSP to meet the threshold
61
temporal summation
EPSPs added together over time
EPSP must be close together
causes waves of neurotransmitters to be released
62
spatial summation
EPSP and IPSP added together over space
postsynaptic membrane stimulated by many presynaptic neurons
many receptors binding neurotransmitters causing simultaneously EPSP and IPSP at the axon hillock
63
synaptic potentiation
larger than expected EPSP due to repeated use of synapse
increase in Ca+2 in
increase neurotransmitters released
64
presynaptic inhibition
axoaxonic synapse
smaller than expected EPSP because 2nd axon reduces excitatory stimulus of 1st
fewer neurotransmitters are released
65
neuromodulation
chemicals other than neurotransmitters that modify the action of neurons
drugs
66
divergent pathways
one incoming fiber triggers a response in increasing numbers of neuron along the circuit
amplifying circuits
67
convergent pathways
multiple neurons synapse with a single neuron
| concentration of signal
68
characteristics of neurotransmitters
considered neurocrines because they are transported thru the blood
created or transported to the presynaptic terminal
capable of producing an EPSP or IPSP
natural means of removal
69
acetylcholine
released in the neuromuscular junction
broken down by acetylcholine esterase and recycles
too much or too little causes a problem
Alzheimer's and Myasthenia Gravis
70
biogenic amines
catecholamines
| indoleamines
71
neurotransmitters characterized by catecholamines
norepinephrine
epinephrine
dopamine
made from amino acid tyrosine
72
neurotransmitters characterized by indoleamine
serotonin
| histamine
73
serotonin
```
sleep induction, appetite, nausea, mood
made from tryptophan
depression: too little
schizophrenia: too much
activity blocked by LSD and enhanced by ecstasy
```
74
histamine
made from histidine
| involved in wakefulness, appetite control, learning, and memory
75
amino acid as a neurotransmitter
found only in CNS
| strychnine-inhibited glycine receptors result in uncontrolled convulsions and respiratory arrest
76
neuropeptides
beta-endorphins
enkephalins
substance P
longer-acting than the rest of the hormones
77
other neurotransmitters
ATP
NO
CO
78
excitatory neurotransmitter
causes a depolarization (EPSP)
79
inhibitory neurotransmitter
causes repolarization (IPSP)
80
direct/ionotrophic neurotransmitter
neurotransmitters that open chemically gated channels
| ACh and amino acids
81
indirect/metabotrophic
second messenger systems (cyclic AMP)
82
indirect mechanism
1) neurotransmitter (1st messenger) binds to the receptor
2) receptor undergoes a conformation change and binds to nearby G-protein and G-protein activated when GTP replaces GDP
3) activated G-protein binds to adenylate cyclase
4) adenylate cyclase generates cAMP (2nd messenger) from ATP
- cAMP is broken down by phosphodiesterase
5) cAMP opens/closes channels, activated enzymes, or activated genes which causes a response
