Nerves Flashcards
1
Q
Millions of sensory receptors monitor changes
A
sensory input
2
Q
processes and interprets sensory input and decides what should be done
A
integration
3
Q
Nervous system activates effector organs—the muscles and glands—to cause a response
A
motor output
4
Q
what are affector organs?
A
muscles and glands
5
Q
brain and spinal cord (ends just below ribs)
A
central nervous system (cns)
6
Q
CNS or PNS: integration and control center
A
cns
7
Q
CNS or PNS: receives sensory input; dictates motor output
A
CNS
8
Q
CNS or PNS:
communication lines link entire body to CNS
cranial nerves, spinal nerves, and ganglia
A
PNS
9
Q
carry impulses to/from brain
A
cranial nerves
10
Q
carry impulses to/from spinal cord
A
spinal nerves
11
Q
collections of neuron cell bodies
A
ganglia
12
Q
nerve fibers
A
axons
13
Q
voluntary nervous system (impulses from skin, skeletal muscles, and joints)
A
somatic sensory nerve fibers
14
Q
involuntary nervous system (transmit impulses from visceral organs in ventral body cavity)
A
autonomic sensory nerve fibers
15
Q
review chart on slide 4
A
yes
16
Q
transmit impulses from CNS to effector organs (muscles and glands)
A
motor nerve fibers
17
Q
what do motor nerve fibers cause when they transmit an impulse?
A
muscles contract
glands secrete
18
Q
Excitable (responsive to stimuli)
Dendrites transmit messages toward the cell body
Axons transmit messages away from the cell body
A
neurons
19
Q
Supporting cells
Surround and wrap delicate neurons
A
neuroglia
20
Q
how many types of cells make up nervous tissue
A
only 2
21
Q
“Nerve glue,”
A
neuroglia (glial cells)
22
Q
Four kinds in CNS; two in PNS
A
neuroglia (glial cells)
23
Q
Like neurons, they have branching processes and central cell bodies; smaller than neurons
A
neuroglia (glial cells)
24
Q
In CNS, Outnumber neurons 10 to 1!
Make up half of brain’s mass
A
neuroglia (glial cells)
25
Most abundant and versatile
astrocytes "star cells"
26
Support and anchor neurons to capillaries (nutrient supply lines)
astrocytes "star cells"
27
information processing
astrocytes "star cells"
28
Control chemical environment around neurons:
“Mop up” leaked K+ ions
Recycle released neurotransmitters
astrocytes "star cells"
29
Phagocytize microorganisms and dead neurons
microglial cells
30
Important because regular immune cells have limited access to CNS
microglial cells
31
Line cerebrospinal fluid (CSF)-filled cavities
Form permeable barrier between CSF and nerve tissue
Many have cilia, which help circulate CSF
ependymal cells
32
Cover thick nerve fibers in CNS with a myelin sheath
ogliodendrocytes
33
sympathetic nervous system associated with...
autonomic (visceral) nervous system
34
Neuroglia in PNS:
like astrocytes in CNS
Support neurons
control chemical environment around neurons
satellite cells
35
```
Neuroglia in PNS:
like oligodendrocytes of CNS
Surround all nerve fibers in PNS
Form myelin sheath around thicker nerve fibers
Help regenerate PNS fibers
```
schwann cells
36
Which one set neurons apart?
(1) Excitability: Respond to stimuli transmit nerve impulses
(2) Extreme longevity: They can operate optimally for a lifetime
(3) Amitotic: Neurons cannot divide and cannot be replaced (some exceptions)
(4) Exceptionally high metabolic rate: Neurons constantly need glucose and oxygen and will die within minutes if deprived of oxygen
extreme longevity
amitotic
exceptionally high metabolic rate
37
all neurons contain at least:
cell body and at least one extension (process)
38
also called soma
cell body;
| most protected by skull and vertebral column
39
cell bodies tend to...
cluster together
40
Cluster of cell bodies in CNS
nucleus
41
Cluster of cell bodies in PNS
ganglion
42
nerve fibers
extension of a neuron (axons)
43
CNS contains both neuron process and
cell bodies
44
clusters of cell bodies in CNS=nuclei
clusters of cell bodies in PNS=ganglia
45
bundles of cell processes in CNS=tracts
bundles of cell processes in PNS=nerves
46
mostly contain processes, not cell bodies
PNS
47
2 types of processes?
dendrites and axons
48
Short, highly branched extensions off of cell body
| large surface area so neuron can receive messages
dendrites
49
Synapses (point of contact) with other neurons are called...
dendritic spines
50
Convey electrical impulses toward the cell body
| graded potentials, not action potentials
dendrites
51
most neurons have how many axons?
1
52
Axons transmit electrical impulses (action potentials) (blank) from cell body
away
53
Proteins are made in cell body and shipped to axons
axons can be absent, short, or very long
54
occur at the end of the axon
terminal branches
55
knobby end points of terminal branches
In motor neurons, axon terminals part of neuromuscular junction,
electrical impulse arrives, neurotransmitters released
axon terminals
56
whitish, fatty (protein-lipoid), and segmented
| Protects and electrically insulates nerve fibers
myelin sheath
57
Increases the transmission speed of nerve impulses
myelin sheath
58
myelin sheaths are found only on...
axons, never dendrites
59
do all axons have myelin sheaths?
no
60
receptive region of axon
receives stimulus (near "head")
61
conducting region of axon
generates/transmit action potentials (axon length area)
62
secretory region of axon
release neurotransmitters (near "foot")
63
proteins can move about 15 inches per...
day
64
white matter is white because...
of the myelin sheath
| bundles of cell processes in CNS
65
PNS, Schwann cells wrap around axon
multiple times
66
schwann cell plasma membrane is unique
many common proteins (ex: channels) protein
| "Velcro" proteins present
67
outer collar of perinuclear cytoplasm
cytoplasm and nucleus squeezed out into outer wrapping layer
68
smallest diameter axons myelinated yes or no
no
69
What makes myelins sheaths in the CNS?
ogliodendrocytes
70
what is gray matter?
where neuron cell bodies are where connections occur
71
multipolar neurons most common in...
CNS
72
bipolar neurons are extremely rare...found only in...
sensory organs (eyes, ears, etc.)
73
unipolar
Peripheral process = Distal end associated with sensory receptor.
Central process = Enters CNS
found mostly in PNS ganglia as sensory neurons. (Receptive endings are sensory terminals.)
74
Most are unipolar
| Cell bodies are in sensory ganglia outside CNS
sensory (afferent neurons)--towards CNS
75
```
Multipolar
Cell bodies (nuclei) cluster in CNS
```
motor (efferent neurons)--away from CNS
76
Mostly CNS
integration
99% of all neurons!
Almost all multipolar
interneurons between sensory and motor neurons
77
what are most neurons in your body like?
multipolar
interneurons
usually one axon
several thousand dendrites
78
resting membrane potential
approximately -70 mv
79
resting membrane potential determined by 2 factors:
differences in:
ionic composition of ICF and ECF fluids
differences in membrane permeability to ions
80
most important ion for driving voltage
potassium
81
3 sodium ions out, how many potassium in?
2
82
why is resting membrane potential negative?
25x easier for K ions in than for Na ions to come out
83
depolarization
membrane potential more positive
| nerve impulse more likely
84
hyperpolarization
membrane potential more negative
| nerve impulse less likely
85
chemically gated ion channels
open in response to binding of certain neurotransmitter
86
voltage gated ion channels
open in response to changes in membrane potential
87
sodium voltage channels gated how many times?
two gates,
| three alternate states
88
activation gate
responds to voltage change
89
inactivation gate
slams shut after a few seconds
| prevents too much sodium into cell
90
K voltage channels gated how many times?
one gate
| two alternate states
91
Only cells with excitable membranes can generate action potentials
only muscle and nerve cells
92
threshold
"point of no return"
| will occur if membrane depolarizes to about -55 mv
93
in neurons, action potentials only activated in
axons
94
AP is brief reversal of membrane potential
nerve impulse in a neuron
95
True or False?
All AP’s are alike
a weak stimulus and a strong stimulus both generate the same AP
True
96
Weak vs strong
number of action potentials and frequency
97
subthreshold stimulus
not generate an AP
98
Na+ channels are all open and the neuron cannot respond to another stimulus
absolute refractory period
99
most of the Na+ channels return to resting state.
only really strong stimulus can open the Na+ channels. Strong stimuli generate multiple AP’s by intruding into this period
relative refractory period
100
2 things determine AP speed
axon diameter
| myelination
101
larger axon diameter
faster AP
102
myelination
faster AP (myelin insulates current)
103
Non myelinated axons: continuous conduction
AP's constantly regenerated along axon
| slow
104
Myelinated axons: saltatory conduction
AP’s regenerated only at myelin sheath gaps
| 30x faster than continuous conduction
105
junction neuron-neuron/neuron-effector cell (muscle/gland cell)--neuromusclular junction
synapse
106
conducts impulses toward the synapse
presynaptic neuron
107
conducts impulses away from synapse
postsynaptic neuron
108
2 kinds of synapses:
electrical (uncommon)
| chemical (common)
109
electrical synapse
direct connections
- -ions flow directly
- -neurons electrically coupled
- -very fast
110
3 parts of chemical synapse
1) Knob-like axon terminal of presynaptic neuron has synaptic vesicles that contain neurotransmitters
2) Synaptic cleft
3) Receptor region of postsynaptic neuron responds to neurotransmitters
111
0.3-5.0 ms; it is rate-limiting step in neural transmission
synaptic delay
112
neurotransmitter which cause depolarization
excitatory
113
neurotransmitter which cause hyperpolarization
inhibitory
114
Bind to and open ion channels
| elicit rapid response
direct neurotransmitter
115
Act via second-messenger molecules for long-lasting effects (act like hormones)
indirect neurotransmitter
116
One neuron stimulates the next in a chain causing a specific response
serial processing
117
examples of serial processing
Spinal reflexes and some sensory pathways
118
Generates automatic response to stimuli
reflex arc
119
5 parts of reflex arc
```
receptor
sensory neuron
integration center
motor neuron
effector (muscle/gland)
```
120
```
Inputs segregated into multiple pathways
pathway different function
unique to individual
Not repetitious (like reflexes)
Needed for higher level mental functioning
```
parallel processing
| --result of what happened, ex: why am I such a bad soccer player?
121
diverging circuit
one input, many outputs
| ex: tasting something
122
converging circuit
many inputs, one output
| ex: combo of sight, smell, sound of something reminding you of a certain place
123
reverberating circuit
regular occurrence in body
| ex: sleep/wake cycle, walking, breathing
124
parallel after discharge circuits
one input--many neurons process--one output
| complex mental processes
125
Sympathetic
Mobilizes body systems during activity (autonomic nervous system)
126
Most sensory neurons are...blankpolar
Unipolar
