Physio II Lecture 1B Flashcards
(103 cards)
1
Q
The nervous system is divided into three parts. Name them
A
CNS, PNS, ANS
2
Q
The CNS consists of _____
A
Structures arising directly from the neural tube. Includes: Brain and spinal cord
3
Q
The PNS consists of ______
A
cranial nerves and spinal nerve
4
Q
The ANS consists of_______
A
sympathetic and parasympathetic
5
Q
Define CNS
A
the CNS consists of unpaired, bilaterally symmetrical structures extending along the longitudinal axis of the midsagittal plane of the body
6
Q
What is a brain?
A
Sorts through and properly routes incoming sensory info. Initiates controls and coordintes most muscular activity except simple reflexes
Site of origin of 12 cranial nerve pairs
7
Q
What 4 pairs of cranial nerves carry parasympathetic fibers?
A
III, VII, IX, X
8
Q
What are the general functional categories of the brain
A
sensory
motor
cognitive
9
Q
Define spinal cord
A
It is the first CNS structure encountered by most incoming sensory info except sensory fibers in cranial nerves. It is the last relay station for most motor information except ANS motor fibers. It is the site of coordination of most reflex arcs
10
Q
Define peripheral nervous system
A
It is made up of transmission pathways carrying info between the CNS an external/internal environment. Has afferent pathways and efferent pathways
11
Q
What carries info to the CNS
A
afferent (sensory) pathways
12
Q
What carries information FROM CNS
A
efferent (motor) pathways
13
Q
How many cranial nerves are included in the PNS?
A
12
14
Q
How many spinal nerves are included in the PNS?
A
31 of the PNS
15
Q
PNS has sensory receptors in _____
A
the skin and wall of the gut tube as well as in tendons and skeletal muscles
16
Q
PNS motor end plates are between ______
A
motor neurons and skeletal muscle fibers
17
Q
ANS may be considered a subdivion of _________
A
the PNS
18
Q
ANS is entirely _________
A
motor
19
Q
ANS innervates ______
A
smooth muscle and glands (viscera)
20
Q
ANS sympthetic system is also called the ______ and ________
A
fight or flight
also called thoracolumbar
21
Q
ANS prasympathetic is called _____ and _______
A
feed and breed
also called craniosacral
22
Q
What is the cell body of a neuron?
A
It is part of a neruon that encloses the nucleus and other organelles necessary to maintain and repair the neuron
Has a trophic unit and perikaryon
23
Q
What are dendrites of a neuron?
A
Branches off the cell body that carry information to the cell body: Receptive unit
Characteristics: -usually several to many dendrietes per neuron
-relatively short, compared to the axon
-often branched
**have receptors for neurotransmitters
**conduct local potentials
24
Q
What is the axon of a neuron?
A
The conductive unitthe neuron that carries info to another neuron or muscle cell
25
What are axon characteristics?
Usually relatively long
Single (one per neuron)
Conducts action potentials (nerve impulse)
Releases neurotransmitters
26
What are telodendria?
- Short branched processes at axon ends
| - They give off endings called terminal boutons
27
axons may have what type of branches?
collateral
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what is the cell membrane of the axon called?
axolemma
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what is the cytoplams of the axon called?
axoplasm
30
what does the axon contain?
mitochondria, neurofilaments, and neurotubules
31
axon is covered by a __________
neurolemma
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neurolemma is made up of _________ and is often________. And the ______ is formed by ___ ____
The neurolemma is made up of Schwann cells and is often myelinated. And the myelin is formed by Schwann cells
33
What is the ONLY part of the neuron that can be mylinated? Is this part always myelinated?
The Axon
| Not all axons are myelinated, even though they are covered by schwann cells
34
What is aggregation of dendrites and nerve cell bodies in CNS called?
Nucelus
35
What is aggregation of dendrites and nerve cell bodies in PNS called?
ganglion
36
What are bundle of fibers (axons) in the PNS called?
Nerve
37
What are bundle of fibers (axons) in the CNS called?
Tract
38
What is the tract in the CNS that crosses from one side to the other called?
commissure
39
What are areas of myelinated axons called?
white matter
40
What are areas of unmylenated axons, cell bodies, and dendrites called?
gray matter
41
What are two spinal nerve branches (rami)?
dorsal primary rami and ventral primary ramus
42
Each spinal nerve in the thoracolumbar region, before branching into _______ gives off two small branches called ______ and _______.What are the functions of the two small branches?
1. primary rami
2. White ramus communicans: Carries myelinated preganglionic fibers
3. Gray ramus communicans: Carries unmyelinated postganglionic fibers back to spinal nerve
43
What is linked together into a long chain on either side of the vertebral column in the thoracolumbar region.Is the site of cell bodies of postganglionic sympathetic nervesAnd is the site of synapes between preganglionic myelinated sympathetic neurons and postganglionic non myelinated sympathetic neurons?
paravertebral ganglia
44
What is a nerve supplying viscera called
splanchnic nerve
45
What is typically found anterior to abdonminal aortaAnd is the site of synapses btw preganglionic myelinated sympathetic neurons and postganglionic non myelinated neurons?
prevertebral ganglion
46
What is a reflex arc?
a pathway that leaves form and returns to the CNS. It consists minimally of a sensory pathway and a motor pathway
Extra: can't override consciously, can't fake it
47
what carries sensations from non-visceral structures such as the skin and skeletal muscle?
Somatic afferent pathways (Sensory)
48
What carries sensation from viscera?
Visceral (splanchnic) afferent pathways(sensory)
49
What carries motor signals to skeletal muscles?
somatic efferent pathways
50
What carries motor signals to smooth or cardiac muscles?
visceral (splanchnic) motor pathway
51
What are association neurons (interneurons)
-some reflex arcs consist only of an efferent neuron and an afferent neuron but most have intervening neurons, called association neurons or interneurons, in the central nervous system that modulate the interactions btw the afferent and the efferent neurons
52
What is associated with synaptics vesicles filled with neurotransmitters
presynaptic membrane
53
What is the synaptic cleft a part of?
part of a synapse
54
What is associated with receptors for neurotransmitters?
postsynaptic membrane
55
What are pathways consisting only of afferent neurons and efferent neurons and each pathway has a single synapse
monosynaptic pathways
56
What pathways include interneurons as well as afferent and efferent neurons and each pathway has multiple synapses?
polysynaptic pathways
57
Depending on synaptic activity, a neuron may be in one of three physiologic states.What are the three states and explains what is happening in each state?
1. Resting- cell body potential is about -65 mv
2. Excited- cell body potential is more positive; about -45. Typically due to influx of Na ion
3. Inhibited- cell body potential is more negative than at rest;about -70. Typically due to influx of Cl ion or efflux of K ion
58
What refers to the sequence of structures invloved in the transmission of a sensory signal from the peripheral receptors to higher brain centers
somatosensory axis
59
What are components of the somatosensory axis pathway?
```
peripheral receptors
afferent neurons
spinal cord or brainstem
reticular substance- medulla, pons, mesencephalon
cerebellum
thalamus
somesthetic areas of cerebral cortex
```
60
How are afferent neurons arranged?
In a series of three:
primary afferent neurons- synapse in the posterior horns of spinal cord or sensory nuclei in the brain
secondary afferent neurons- synapse in the thalamus
tertiary afferent neurons- synapse in the somesthetic areas of cerebral cortex
61
the skeletal motor nerve axis refers to _____
the sequence of structures involved in the transmission of an action potential from the higher brain centers to skeletal muscles
62
skeletal motor nerve axis includes ________
motor cortex of cerebrum
| Efferent pathways effectors- skeletal muscles
63
What is made up of upper motor neurons extending form cortical areas to the anterior horns of the spinal cord and its alpha motor neurons (lower motor neruons) are extending to the skeletal muscles?
Skeletal motor nerve axis efferent pathways
64
What are smooth muscles and glands supplied by?
ANS and have a somewhat different pathway compared to skeletal motor nerve axis
65
What are the processing areas of the skeletal motor nerve axis?
```
basal ganglia(nuclei) in telencephalon
thalmus in the diencephalonspinal cord reflexes
```
66
Acetylcholine is secreted by what neurons?And are they excitatory, inhibitory, or both?
pyramidal cells (cerebral cortex)
some neurons in the basal nuclei
alpha motor neurons
preganglionic nuerons of ANS
postganglionic neurons of the parasympathetic system
some postgaglionic neurons of the sympathetic system
They are usually excitatory
67
norepinephrine is secreted by what neurons?And are they excitatory, inhibitory, or both?
many neurons located in brain stem and hypothalamussome neurons located in the pons (i.e., locus ceruleus)
most postgaglionic nuerons of the sympathetic system.
They can be both
68
Dopamine is secreted by what neurons?And are they excitatory, inhibitory, or both?
neurons originating in substantia nigra
| Usually Inhibitory
69
Glycine is secreted by what?And are they excitatory, inhibitory, or both?
synapses in the spinal cord
| ALWAYS inhibitory
70
GABA secreted by ____?And are they excitatory, inhibitory, or both?
many areas in the spinal cord and cerebral cortex
| Always inhibitory
71
Glutamate secreted by ______?And are they excitatory, inhibitory, or both?
many sensory pathways entering the CNS
many areas of cerebral cortex
ALWAYS Excitatory
72
READ pg 557
READ IT!
73
what may extend out for a considerable distance?
dendrites... they can receive signals from a large spatial area around a motor neuron
74
What cannot transmit action potentials?
Dendrites... they use electronic conduction instead
75
What are long and membranes are thin?
Dendrites... partially permeable to K and Cl ionssome potential lost due to leakage
76
What occurs in a dendrite due to gradual loss of the potential as the depolarization spread from the site of initiation?
decremental conduction
The signal becomes weaker as it gets farther away from site of initiation
This is in opposition to action potentials which are constantly renewed along the length of the axon and therefore do not decrease in strength
77
What is direct spread of electrical currect by ion conduction in the dendritic fluids without generating action potential?
electrontonic conduction
78
What results from electrotonic conduction?
few voltage gated Na channels in dendritic membranes
| thresholds too high for action potentials to occur
79
What is defined as the summated degree of excitatory drive to the neuron?
excitatory state
80
When does the excitatory state occur?
When there is a higher degree of excitation compared to inhibition.
81
When does the inhibitory state occur?
When there is a higher degree of inhibition compared to excitation.
82
What is firing rate
as long as the excitatory rate of a neuron remains above the threshold for excitation, the neuron will fire repetitively
83
The firing rate depends on the
normal excitatory rate and on the changes in the excitatory rate due to superimposition of additional excitatory or inhibitory signals
84
What refers to the time it takes to transmit a signal form a presynaptic neuron to a postsynaptic neuron?
synaptic delay
85
What does a synaptic delay depend on?
- time it takes to release the neurotransmitter from the presynaptic neuron
- time it takes for the neurotransmitter to diffuse across the synaptic cleft
- how the neurotransmitter acts on the postsynaptic membrane
- the time it takes for the receptor to increase membran permeability
- time it takes for the inward diffusion of Na ions
86
What are the parts of a neuron?
Cell body, dendrites, and axon
87
What do terminal boutons contain?
Synaptic vesicles filled with neurotransmitters
88
What will not summate to produce an action potential on a postsynaptic neuron?
Simultaneous firing of only a few synapses
89
What can cause superimposed action potential on the postsynaptic neuron?
Can be caused by the simultaneous firing of many synapses
90
What structures are processing areas of the skeletal motor nerve axis?
The basal ganglia (nuclei) in the telencephalon
Thalamus in the diencephalon
Spinal cord reflexes
91
What are dendritic membranes partially permeable to?
Potassium and chloride ions
92
what is main cause of lost in dendrite potential?
Leakage
93
What are the two sources of blood supply to the brain?
Vertebral arteries and internal carotids
94
What is the pathway of vertebral arteries?
First branches of the subclavian arteries
Ascend through the transverse foramina of CV 1-6
Pass through foramen magnum
Unite at caudal border of pons to form basilar artery
The basilar artery gives off cerebellar arteries and then divides into two posterior cerebral arteries
95
What is the pathway of internal carotids?
Terminal branches of the common carotids
| Enter cranial cavity through carotid canal in temporal bone
96
What is the Circle of Willis?
A pentagonal-shaped circle of arteries on the ventral surface of the brain that unites the two vertebral and the the two internal carotid arteries
97
What is an important anastomosis between the two vertebral and two internal carotid arteries?
Circle of Willis
98
What are the components of the Circle of Willis?
```
Posterior cerebral arteries
Posterior communicating arteries
Internal carotids
Anterior cerebral arteries
Anterior communicating artery (unpaired)
```
99
What are the terminal branches of the basilar artery?
Posterior cerebral arteries
100
What connects the posterior cerebral arteries to the internal carotids?
Posterior communicating arteries
101
What gives off anterior and middle cerebral arteries?
Internal carotids
102
What branches off internal carotids?
Anterior cerebral arteries
103
What connects the two anterior cerebral arteries?
Anterior communicating artery (unpaired)
