exam 3 learning objectives Flashcards
(126 cards)
1
Q
What are the overall functions of the nervous system?
A
-stimulate muscles and glands
-action potential, producing quick responses via electrochemical mechanisms
-contribute to homeostatic feedback loops
2
Q
What are the two major nervous systems?
A
central nervous system (cns) and the peripheral nervous system (pns)
3
Q
what is in the cns?
A
the brain and the spinal cord
4
Q
what is in pns?
A
nerves and ganglia (ganglion) - contains neuron cell bodies
5
Q
Sensory division
A
“afferent”
somatic
-sensory nerves in skin, bones, skeletal muscles, joints
visceral
-detects changes in the internal body system (ex: stomach, heart, lungs)
6
Q
motor division
A
“efferent”
somatic
-voluntary muscle contractions
-involuntary somatic reflexes (ex: a hand on a hot stove)
visceral
-mainly autonomous
-cardiac and smooth muscle
-glands
7
Q
Ganglia (ganglion)
A
collection of neuron cell bodies specifically in the PNS. same as nuclei, location differ.
8
Q
Nerves
A
bundles of axons in the PNS
9
Q
Nuclei
A
collection of neuron cell bodies in the CNS
10
Q
tracts
A
bundles of cns axons that share a common origin, destination, and function
11
Q
columns
A
several tracks that are traveling together (CNS)
12
Q
properties found in all neurons
A
excitability - response to stimuli
conductivity - conduct electrical signals along the nerve fiber
secretion - the axon terminals release chemical neurotransmitters that influence other cells.
13
Q
interneurons
A
only in the cns, the neurons between the sensory and motor. integrative function
14
Q
main parts of the neuron
A
dendrites
cell body (soma)
axon
15
Q
cell body
A
aka: soma, neurosoma, cell body, perikaryon (in both CNS and PNS)
control center.
16
Q
lipofuscin granules
A
products of lysosomal activity, accumulates with age. Pushes the nucleus to one side of the cell
17
Q
dendrites
A
responsible for receiving stimuli, have tiny protrusions from the dendrites which allow contact with other neighboring dendrites (increase surface area) (dendrite spines, spikes), have chemically regulated ions gates
18
Q
trigger zone
A
axon hillock + initial segment (important in initiating nerve cell)
19
Q
Which part of the nerve fiber are there voltage regulated ion gates?
A
axon, the conducting region (only axon protentional here)
20
Q
multipolar neurons
A
multiple dendrites (only one axon), most of the neurons in the brain and spinal cord
21
Q
multipolar neurons example
A
purkinje cell of the cerebellum and the pyramidal cell
22
Q
Bipolar neurons
A
one dendrite and axon
23
Q
bipolar neuron example
A
olfactory cell and retinal cell
24
Q
unipolar neuron
A
no dendrites and one axon - peripheral process axon (which is like dendrites) and central process axon
25
unipolar neuron example
dorsal root ganglion cell
26
anaxonic neuron
no axon, only dendrites, can't transmit action potential, only is able to communicate locally.
27
retrograde
organelle transport towards the soma in the axon (inward transport)
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anterograde
down the axon, away from the soma (outward transport)
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anterograde fast transport
organelles, enzymes, synaptic vesicles, small molecules
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anterograde slow
enzymes, cytoskeletal components, new axoplasm
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retrograde fast
recycles materials (pathogens & toxins)
32
neuroglia/glial cells
non-neuron cells, out numbers neurons 10:1
-binds neurons together
-in fetus, guide neurons to where they need to be
-cover neurons (except for synapses) to aid in precise conduction
-provide physical and metabolic support
33
Olygodendrocytes
glial cell in the CNS, forms myelin sheaths around nerve fibers
-covers different ones at the same time, branches out
34
ependymal cells
glial cell in the CNS, lines the cavities and produces CSF
35
Astrocytes
glial cells in the CNS, regulate chemical environment (extracellular) for neurons.
-converts glucose to lactate (which is supplied)
-forms the blood-brain barrier
36
microglial cells
glial cells in the CNS, specialized population of macrophages, defensive cells
-remove damaged neurons and infections
37
Schwann cell
glial cells in the PNS, myelinate sheath certain axons and assist in regeneration of damaged fibers
wraps the axon entirely, forms one internode
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satellite cell
glial cells in the PNS, surrounds and supports the cell bodies, provides electrical insulation and regulates the chemical environment, attached to the cell body
39
myelin sheath
made of 20% protein and 80% lipids.
- made by oligodendrocytes in cns, schwann cells in pns
-increase action potential conduction velocity.
40
internode
myelin-covered segments
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mode of ranvier
gaps between internodes
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neurilemma
the outermost nucleated cytoplasmic layer of Schwann cells
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to regenerate damaged pns nerve fiber
soma is intact and some of the neurilemma remains
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unmyelinated peripheral axon
schwann cells folds it's plasma membrane around several axons. Instead of the nucleus sitting on top of the membrane, it is in the middle and the axons surround the nucleus.
45
What is local potential produced by?
ligand-gated Na+ channels on the dendrites and soma
46
What is action potential produced by?
produced by voltage-gated ion channels (when there is an increase density in these channels) (opens and closes depending on membrane potential) on the trigger zone and axon.
47
what can start local potential?
excitatory (depolarizing, more + voltage)
inhibitory (hyperpolarizing, more - voltage)
48
what can start action potential?
always starts with depolarization
49
strength of local potential stimuli?
graded, the amount of change in membrane potential is determined by the size of the stimulus that causes it. (stronger stimuli opens more na+ channels)
50
strength of action potential stimuli?
All or none law - if stimulus depolarizes the neuron to threshold, the neuron fires at it's maximum voltage, if it isn't reached - there is no action potential
51
is local potential reversible or irreversible?
reversible
52
is action potential reversible or irreversible?
irreversible
53
how far does local potential go?
local, has effects for only a short distance from point of origin
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how far does action potential go?
far, it triggers neighboring membrane areas into producing action potential
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Decremental
local potential signal grows weaker with distance
56
non decremental
signal maintains same strength regardless of distance in action potential
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how are local potential and action related?
local potential starts in the dendrites and if the signal is strong enough, it starts action potential, which release neuro transmitters to dendrites
58
What affects conduction velocity of nerve signals?
diameter, larger axons have more surface area and conduct signals more rapidly (conduction velocity is proportional to fiber diameter)
presence or absence of myelin (and thickness) increases signal conduction
59
continuous conduction
happens in nonmyelinated axons
as the action potential moves, the ion channels open, causing positive ions to enter into the membrane, depolarizing it. which make the action potential to move. (like a domino effect)
60
saltatory conduction
happens in myelinated axons
the myelin sheath doesn't allow for depolarization. but it can happen at the nodes. so it moves form node to node. giving a skipping like effect.
61
four main functions of the spinal cord
conduction - nerve fibers conduct sensory/motor information
Neural integration
locomotion - simple repetitive muscle contractions (coordinated by central pattern generators)
reflexes
62
where does the spine start
starts bellow the foramen magnum
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where does the spinal cord end
at the medullary cone/conus medullaris
64
filum terminale
the portion of the pia matter that supports the cauda equina
65
cauda equina
a bundle of spinal nerves
66
enlargements of the spine? (top to bottom)
cervical and lumbosacral
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What are the three meninges
pia mater, arachnoid mater, dura mater (in this order)
68
grey matter
cell bodies of neurons, with dendrites (inside spine, outside brain)
69
white matter
myelinated axons, lipids, (outside the spine, inside the brain)
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how is the white matter organized in the spine?
3 columns/funiculi (top to bottom)
posterior white column
lateral
anterior
71
posterior
back end of the body
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anterior
front end of the body
73
lateral
towards the side of the body from the midline
74
how is the gray matter arranged in the spine?
divided into three horns
-posterior gray horn
-lateral
-anterior
75
Lateral grey horn, how far does it go?
extends only through t1-l2, related to autonomic motor nervous system
76
what is in the posterior gray horn?
somatic and visceral,
sensory nuclei
interneuron cell bodies, this is where the soma of the interneuron cell bodies will be,
the ganglion is where the sensory cell soma is.
77
where is the motor nuclei located?
in lateral and anterior gray horn
visceral and somatic
motor neuron cell bodies are located in the grey matter of the spine, because there is no ganglion like sensory
78
describe the flow direction in the spine
sensory
skin-> ganglion -> dorsal horn -> brain (goes up the track)
motor
(goes down the track)
brain -> lateral/ventral horn -> motor neuron -> muscle fibers
79
ipsilateral
when the track, in the spine, is on the same side of the body
80
contralateral
when the track, in the spine, crosses over to the opposite side of the body
81
decussation
the point int which some track cross over to the other side of the body
82
types of ascending pathways
spinothalamic (anterolateral) pathway
spinocerebellar pathway
dorsal column-medial lemniscus pathway
83
spinothalamic (anterolateral) pathway
spine cord to the thalamus to cortex
crosses to the other side (decussate)
has two separate tracts
-lateral (temperature & pain)
-anterior (crude touch (gentle touching) & pressure)
first order ends at substantia gelatinosa
second order starts at the tip of dorsal horn (aka substantia gelatinosa) - ends at thalamus
third order neurons starts at thalamus and ends at cortex
84
spinothalamic (anterolateral) pathway
spine cord to the thalamus to cortex
crosses to the other side (decussate)
has two separate tracts
-lateral (temperature & pain)
-anterior (crude touch (gentle touching) & pressure)
first order ends at substantia gelatinosa
second order starts at the tip of dorsal horn (aka substantia gelatinosa) - ends at thalamus
third order neurons starts at thalamus and ends at cortex
85
spinocerebellar pathway
start in spinal cord, through the pons and goes up to the cerebellum, won't be conscious of this
controls balance and posture
there is an anterior and posterior tract
take proprioceptive input
86
spinocerebellar pathway
start in spinal cord, through the pons and goes up to the cerebellum, won't be conscious of this
controls balance and posture
there is an anterior and posterior tract
take proprioceptive input
87
dorsal column-medial lemniscus pathway (DCML)
carries fine touch and proprioception (movement and joint position)
from spine -> medulla -> cortex
88
fasciculus cuneatus
from DCML, t6 and above, brings sensations from upper limb and chest. goes up to the medulla then at the nucleus cuneatus, (becomes 2nd order) and crosses the midline
89
fasciculus gracilis
from DCML, below t6, brings sensations from lower limb and lower trunk. goes up the medulla and to the nucleus gracilis (2nd order) and crosses the midline.
90
pyramidal tracts
starts in cerebral motor cortex, goes down the upper motor neuron and directly innervate (via spinal cord) down the lower motor neuron and to the muscle
91
corticobulbar tract
a pyramidal tract, muscles of the head and the neck
92
corticospinal tract
a pyramidal tract, muscles of the limbs and trunk
93
extrapyramidal tracts (EPTs)
starts from the brain stem, down the upper motor neuron, indirectly by innervate via spinal cord, responsible for involuntary and automatic control of muscle
94
vestibulospinal tract
ept, helps maintain balance
95
reticulospinal tract
ept, transmission in pain signals, analgesic pathways
96
tectospinal tract
ept, head-turning reflex, toward a visual/auditory stimuli
97
rubrospinal tract
ept, regulation of muscle tone
98
corticospinal pathway
controls contralateral muscles
have two motor neurons,
brain to spinal cord, in the middle of spinal cord, 90% of the fibers cross and 10% does not
99
lateral corticospinal tract
the 90% fibers that cross over
100
anterior corticospinal tract
the 10% of fibers that stay on the same side
101
what are the major group of nerves
12 pairs of cranial nerves (some sensory/motor- most mixed)
31 pairs of spinal nerves (all mixed)
102
epineurium
covers pns, has a lot of fascicle inside and some blood vessels
103
perineurium
around one fascicle, in the spinal nerve
104
endoneurium
covers a single axon, which is in a fascicle, which is in a spinal nerve
105
dermatome map
diagram of the cutaneous regions innervated by each spinal nerve
106
cervical nerves
c1-c8
107
order of spinal nerves
top to bottom
cervical
thoracic
lumbar
sacral
108
thoracic nerves
t1-t12
109
lumbar nerves
L1-L5
110
sacral nerves
s1-s5
111
nerve plexus
a branching network of intersecting nerves
cervical plexus
brachial
lumbar
sacral
coccygeal
112
what forms the sciatic nerve
largest branch of sacral plexus
L4, L5, s1, s2, s3
113
sciatica
refers t the compression of the sciatic nerve
-herniated disc
-muscle spasm
-produces pain that radiates from the lower back along the leg
114
reflex
quick, involuntary, stereotyped (occur the same way every time)
happens in glands and muscles
115
visceral reflexes
glandular or non-skeletal muscular response carried out in the internal structure
116
somatic reflexes
in somatic nervous system, skeletal muscle
117
steps in a reflex
-stimulus activates receptor
-nerve impulse travels to spine
-processed in the integration center by interneurons (simplest ones don't involve interneurons)
-motor neuron transmits impulse to effector
-effector responds to impulse from motor neuron (response is to counteract or remove the stimulus)
118
monosynaptic reflex
very minor synaptic delay, no interneuron
direct communication between sensory and motor neuron
119
polysynaptic reflex
has a interneuron facilitates sensory-motor communication
120
stretch reflex (myotatic reflex)
regulates skeletal muscle length, monitored by a receptor called a muscle spindle.
so in response to the stretching of the muscle,
the muscle contracts
(ex: knee jerk - patellar)
121
extrafusal muscle fibers
the normal muscle fibers that are found in skeletal muscles. controlled via alpha motor neuron
122
muscle spindles
stretch receptors, primarily used to detect changes in the length in the muscle.
inside the extrafusal muscle fibers
inside the capsule of connective tissue are the intrafusal muscle fibers, which receive sensory info in the middle, controlled via gamma motor neuron
123
intrafusal muscle fibers
specialized fibers that make up the muscle spindle
124
golgi tendon reflex
when the muscle contraction pulls on the tendon, the collagen fibers come together and squeeze the nerve (sensory) endings between
basically muscle relaxation
protects the muscle from excessively heavy loads
125
flexor (withdraw) reflex
the quick contraction of flexor muscles, which results in withdraw of a limb from an injurious stimulus
extensors- relaxed
flexors - contracted, stimulated
126
cross extension reflex
extends and stiffens the limb and enables to help you keep your balance.
extensors - stimulated
flexors - relaxed
