Ch. 5 — For Exam 1 Flashcards
(172 cards)
1
Q
The brain receives ____% of cardiac output (800 ml per minute), and uses ____% of body oxygen
A
20%; 20%
2
Q
CNS vasculature must be _________ to supply oxygen and b/c CNS stores little or no ________
A
Continuous; glucose
3
Q
True or False:
CNS blood flow rates change minimally /c increases in the level of celebration (flow rates are mostly determined by vascular pressure differences)
A
True
4
Q
What are the two arterial supply systems of CNS?
A
- Vertebral arteries (aka vertebrobasilar system)
2. Internal carotid arteries
5
Q
What arteries are…
- paired
- enter skull thru foramen magnum on the ventrolateral surfaces of the spinal cord
A
Vertebral arteries
6
Q
The vertebral arteries has paired _____________ arteries, which unit to from a single midline artery and the ______________ artery.
A
Anterior spinal aa.; posterior inferior cerebellar aa.
7
Q
The union of the vertebral arteries forms the _______ a., which is a ingle midline a. That courses to the midbrain.
A
Basilar a.
8
Q
What are the 3 branches of the basilar a.?
A
- Anterior inferior cerebellar a.
- Short pontine branches
- Superior cerebellar aa.
9
Q
At the midbrain, the basilar a. Bifurcated to form the two __________ arteries
A
Posterior cerebral arteries
10
Q
What 3 areas does the posterior cerebral a. Supply?
A
- Caudal diencephalon
- Medial & lateral occipital lobes (visual cortex)
- Posterior inferior temporal lobe
11
Q
Which arteries pass thru the cavernous sinus to the base of the brain /c several branches?
A
Internal carotid arteries
12
Q
What are the two branches of the internal carotid artery that enter thru the cavernous sinus?
A
- Ophthalmic A.
2. Posterior Communicating a.
13
Q
The internal carotid a. Terminates lateral to the __________ as what two terminal branches?
A
Optic chiasm
- Middle cerebral a.
- Anterior cerebral a.
14
Q
Which artery…
- passes laterally thru the lateral fissure to supply the lateral orbital gyri and lateral parts of the frontal, parietal, and temporal lobes
A
Middle cerebral a.
15
Q
Some branches of the ________a. Pierce to supply to basal ganglia, diencephalon, and internal capsule.
A
Middle cerebral
16
Q
Which artery….
- passes anteriorly to supply the orbital and medial aspects of the frontal lobe and medial aspect of the parietal lobe
A
Anterior cerebral a.
17
Q
The R and L anterior cerebral arteries are connected in the midline by what?
A
Anterior communicating artery
18
Q
What is the Circle of Willis?
A
An arterial ring at the base of the brain
19
Q
What does the circle of Willis allow for?
A
Anastomoses btw the vertebrobasilar and carotid arteries
20
Q
The circle of Willis may act as what?
A
A safety valve if one portion of the circle becomes obstructed
21
Q
What 5 arteries/ artery pairs are included in the Circle of Willis?
A
- Posterior cerebral arteries (paired)
- Posterior communicating arteries (paired)
- Internal carotid arteries (paired)
- Anterior Cerebral arteries (paired)
- Anterior communicating arteries.
22
Q
Valveless venous channels btw two layers of the dura mater
A
Dural sinuses
23
Q
What drains into the superior sagittal sinus?
A
Upper, lateral, and medial cortex
24
Q
The superior sagittal sinus is located superiorly in the midline and flows toward the ________ region
A
Occipital
25
The superior sagittal sinus drains into the __________ sinus, which drains laterally into the ______ sinus.
Transverse; sigmoid
26
Venous blood ultimately drains into the _________ vein at the base of the skull
Internal jugular
27
Deep cerebral venous blood flows to what 4 things?
1. Great vein of Galen
2. Straight sinus
3. Transverse, sigmoid sinus
4. Internal Jugular vein
28
- connect some dural sinuses /c veins that are superficial to the skull
- can be a route for spread of infection from face or nasopharynx
Emissary veins
29
Vascular insufficiency for more than several minutes can result in __________
Infarction (necrosis)
| - ex. Stroke, CVA
30
Vascular insufficiency can be caused by what two things?
1. Occlusion (via thrombus or embolus)
| 2. Hemorrhage (usually more severe)
31
- temporary neurological dysfunction
| - warning sign of vascular insufficiency
Transient ischemic attack (TIA)
32
What substances do not pass from the blood into the brain?
Large proteins and penicillin
33
True or False:
Neuro damage can break down the blood-brain barrier
True
34
What part of the neuron usually receives and integrates signals?
Dendrite-soma
35
What part of the neuron functions to conduct or transmit the signal away from the cell?
Axon
36
What part of the neuron is the effector segment (where the action is passed on)?
Synapse
37
A peripheral neuron which conveys information (sensory) to the CNS about the external environment
First-order neuron
38
The peripheral process begins in sensory tissues such as what? (4 things)
1. Retina
2. Skin
3. Muscles
4. Joints
39
The charged state of a cell at rest (not conducting an impulse)
Resting potential
40
The resting potential is a comparison of the difference btw the ______ and ________ of the cell (intracellular and extra cellular fluid)
Inside; outside
41
What 3 things diffuse freely across the semipermeable plasma membrane through non-gated open channels?
1. Sodium
2. Chloride
3. Potassium
42
Sodium and Chloride are highly concentrated _______ the cell. Potassium and organic anions are highly concentrated _______ the cell.
Outside; inside
43
What does the sodium-potassium pump do?
- pumps 3 sodium’s out of the cell for every 2 potassium’s pumped in
- requires ATP
44
What establishes the electrical potential difference across the cell membrane?
The sodium potassium pump
45
What is the electrical potential difference of the cell membrane?
-60 (outside the cell) to -90 (inside the cell)
46
Allows the calculation of the magnitude of potential at which ions are in equilibrium across a membrane
Nernst equation
47
The Nernst equation only considers ______ channels, not ______ channels
Open; gated
48
The resting membrane potential is mostly due to what?
Potassium
49
Why does sodium only contribute a small amount to the cells resting potential?
B/c sodium channels are gated, so they are not open in a resting cell
50
- enables a neuron to respond to and transmit info as an electrical signal
- a stimulus may cause a change in the resting membrane potential (depolarization) by opening or closing channels (allowing passive diffusion of concentrated ions)
Excitability of a neuron
51
Always permit passage of ions; involved in maintaining resting potentials
Open channels
52
Have a molecular gap or gate which can open to permit passage of particular ions and will not allow passage of other types of ions
Gated channels
53
The process by which a channel is opened during activity
Gating
54
What are 3 types of gating?
1. Chemical channels
2. Modality-specific channels
3. Voltage-gated channels
55
Have gates which respond to chemicals or transmitters
Chemical channels
56
Have gates which open when the membrane potential changes
Voltage-gated channels
57
Respond to specific modalities such as touch
Modality-specific channels
58
What are the two types of membrane responses?
1. Hyperpolarization
| 2. Depolarization
59
Membrane becomes more negative on its inside
Hyperpolarization
60
Membrane becomes less negative on the inside, may even become positive
Depolarization
61
What are the 5 functional organizations of the neuron?
1. Receptive segment
2. Initial segment
3. Conductive segment
4. Transmissible segment
5. Tropic segment
62
The reception of a stimuli (chemically or modality gated) results in a __________
Local potential
63
The most common receptive segment is _____
Dendrite-soma unit
64
The postsynaptic receptor membrane is responsive to neurotransmitters from the _________ vesicles
Presynaptic
65
At the dendrite-soma unit, chemically gated channels open to allow ________ to flow in and ______ to flow out. The result is a ___________ potential which is _________.
Sodium; potassium
| Receptor (local); graded (short duration and short distance)
66
What is an excitatory postsynaptic potential (EPSP)?
A partial depolarization at the dendrite-soma unit, which is insufficient to generate an action potential
67
When a closely successive stimuli brings the membrane closer to depolarization after an EPSP
Temporal summation
68
When closely placed local potentials have an additive effects in overlapping margin areas after an EPSP
Spatial summation
69
What are two types of facilitation?
1. Temporal summation
| 2. Spatial summation
70
An inhibitory postsynaptic potential (IPSP) results in a degree of hyperpolarization which prevents neuron firing
Inhibition
71
The receptive segment integrates _____ synaptic inputs
All
72
EPSPs are most concentrated on the ________, while IPSPs are most concentrated on the __________. This allows IPSPs to effectively control the _______ of excitatory influences
Dendrites; cell bodies; quantity
73
Aside form the dendrite-soma unit, what is another receptive segment?
Terminals distal to the first node of Ranvier in the peripheral sensory neurons
74
True or False:
Peripheral sensory ends have long receptive segments
False; they have short receptive segments
75
Some peripheral sensory neurons are associated /c special sensory receptors. Name 3 examples.
1. Rods & cones
2. Organ of Corti
3. Muscle spindles
76
Terminals distal to the first node of Ranvier in the peripheral sensory neurons are ________ gated channels and produce ________ potentials
Modality-specific; graded receptor
77
Modality-specific gated channels are opened by what 4 things?
1. Light
2. Vibration
3. Stretch
4. Touch
78
At the initial segment of the neuron, the sum effects from the receptive zone generate an ________ potential
Integrated
79
The initial segment of the neuron is the region of the _________ in most neurons, or the ___________ in peripheral sensory neurons
Axon hillock; first node of Ranvier
80
What region has the lowest threshold (-45 mv) to generate an action potential?
Initial segment
81
Once threshold is reached, a _________ potential is generated.
Action
82
What segment of the neuron conducts “all-or-none” action potentials to the synaptic segment?
Conductile segment
83
A rapidly propagated wave of electrical impulse passing “all-or-none” w/o decrement down the axon
Action potential
84
What is an action potential due to?
Voltage-gated sodium and potassium channels being opened differentially
85
Action Potential
1. ________ channels open first and inside of the cell becomes more ________
2. the more positive the potential voltage becomes, the more sodium channels open (________________)
3. sudden opening of all __________ channels causes the depolarization seen at initiation of the AP
4. Gated ________ channels open 0.2 ms after the sodium channels open, which along /c the action of the _________ results in depolarization of the membrane
5. The AP impulse is __________ along the length of the nerve fiber
1. Sodium; positive
2. Positive feedback
3. Sodium
4. Potassium; Na/K pump
5. Propagated
86
AP propagation
1. The AP is propagated constantly along the full length of __________ axons, /c the initial depolarization triggering depolarization of the adjacent resting membrane and so forth on down the fiber
2. AP in a ________ fiber is propagated in a “skipping or jumping” fashion from one node of Ranvier to the next node of Ranvier.
1. Unmyelinated
| 2. Myelinated
87
What is saltatory conduction?
The depolarization skips from one node of Ranvier to the next in myelinated axons
88
What is saltatory conduction due to?
The inability of the current to flow transversely thru the myelin d/t its increased resistance
89
Nerve conduction velocity increases /c what 4 things?
1. Myelin
2. Increased thickness of myelin
3. Increased fiber thickness
4. Increased length of internodes
90
What segment of the neuron is the presynaptic vesicles releasing the neurotransmitter?
Transmissive/synaptic segment
91
At the transmissive/synaptic segment, the AP upon arrival at the presynaptic membrane opens voltage-gated _________ channels. Calcium moves ______ the cell, which prompts vesicles to fuse /c the terminal plasma membrane. The neurotransmitter is then released into the __________ and diffuses across it. The transmitter binds to ________ receptors to effect the postsynaptic neuron, muscle cell, or gland cell.
Calcium; into; synaptic cleft; protein
92
Once a neurotransmitter binds to a protein receptor on the postsynaptic cell…
- a new vesicle is then formed by __________ and filled /c neurotransmitter
- synapses at the ____________
- the post-synaptic response is initiated and determined by the transmitter-receptor interaction followed by the generation of a ________ potential
- pinocytosis
- motor end plate
- graded
93
At the motor end plate
- ___________ is the neurotransmitter
- large quantities of the neurotransmitter result in end plate potential which releases __________ from the sarcoplasmic reticulum to initiate fiber contraction
- acetylcholine (ACh)
| - calcium
94
Acetylcholine is excitatory in ___________ and inhibitory in __________
Voluntary muscle; cardiac muscle
95
True or False:
| Specific molecule-receptor combinations exist in dynamic steady state of binding and unbinding
True
96
How are transmitters removed from the synaptic cleft?
1. Enzymes break down the remaining transmitters
OR
2. Molecular pumps remove the transmitters from the cleft
97
What segment of the neuron is…
- the cell body
- the metabolic center to maintain neuron viability
- usually located in the receptive segment (the conductile segment of the sensory neuron)
Tropic segment
98
_______ must integrate all the excitatory and inhibitory inputs, to determine if AP occurs or not
Neurons
99
CNS neurons may be _______ neurons projecting to distant regions, or _______ neurons
Projection; local circuit
100
__________ can allow one neuron to influence another or even itself
Interneurons
101
An interneuron btw a motor neuron axon collateral and the dendrite-soma of the same motor neuron or other motor neurons
Renshaw cell
102
The axon collateral is _________ on the Renshaw cell and the Renshaw axon is _________ on the original motor neuron
Excitatory; inhibitory
103
The _______ synapse may allow one neuron to influence the presynaptic terminal of another neuron
Axoaxonic
104
Presynaptic excitation: great ________ influx causes greater releases of _________
Calcium; neurotransmitter
105
Presynaptic inhibition: less ________ influx results in less __________
Calcium; transmitter
106
Why is presynaptic inhibition important? Provide an example
- keeps neural expressions under proper control, thus preventing excess and unnecessary movements
- ex. Learning to write, excess movements are gradually eliminated
107
Where are most first order neurons located?
In spinal nerves (dorsal root ganglia) and most cranial nerves (sensory ganglia)
108
Are first order neurons mostly unipolar, bipolar, or multipolar?
Unipolar
109
Have a single process which divides into at distal process to the sensory nerve endings and a proximal process extending toward the CNS
Unipolar
110
Some first order neurons are bipolar. What are 3 examples?
1. Olfactory (in nasal mucosa)
2. Optic (in retina)
3. Vestibulocochlear (in vestibular system)
111
Two process from cell body
Bipolar
112
Series of actions or operations among neurons in a processing center
Neural processing
113
Sequential neural connections, each acting upon the next (ex. Patellar reflex)
Serial processing
114
- A receptor has synaptic connections /c several different sequences of neurons
- These different channels then convey the information in parallel fashion
- The impulses may be compared to each other to help interpret the environment
Parallel processing
115
Various levels have specific ranks. Each successive levels processes at a more complex level
Ex. Visual system —> rods/cones —> bipolar cells —> ganglia
Hierarchical organization (of CNS)
116
When neurons of a pathway are excited, those neurons stimulate inhibitory neurons in adjacent areas to suppress the circuits conveying superfluous information. The result is that the signal is emphasized and the background is suppressed/filtered.
Lateral inhibition
117
The CNS ability to regulate and alter the resting level of excitability and responsiveness of a neuron or circuit. This level can be raised to make the input more effective or lowered to make the input less effective.
Modulation
118
- A cylinder of an inner core of gray matter surrounded by columns of white matter
- encased in the upper 2/3 of the bony vertebral column
Spinal cord
119
The spinal cord functions as a central _______ and _______ station
Processing; relay
120
The spinal cord extends from the foramen magnum to the cone shaped end, ___________, at L1
Conus medullaris
121
Non-neural _________ extends caudally from the tip to attach at the coccyx
Film Terminale
122
Meningeal coverings are continuous /c the _______ meninges (pia, arachnoid, and dura)
Brain
123
What 3 things is the pia attached to?
1. Spinal cord
2. Spinal roots
3. Film terminale
124
The spinal cord is suspended along its length by ~20 paired ____________ which extend from the pia of the lateral surface outward to the dura
Denticulate ligaments
125
What does a lumbar puncture do?
Remove CSF from the subarachnoid space of the lumbar cistern
126
Where are anesthetics frequently injected?
The epidural space distal to S2, /c venous plexuses
127
Dorsal root lets join in each vertebral level to form the ___________, which has a dorsal root _________
Dorsal root; ganglion
128
Ventral rootlets join in each vertebral level to form the ___________
Ventral root
129
The dorsal and ventral roots of each segment join to form the __________, which is covered by a dural sheath just before the interventricular foramen
Spinal nerve
130
The 8 cervical nerves exit _______ their respective vertebral bodies (except c8 which exits between the _____ and ______ vertebral bodies)
Above; C7; T1
131
The 12 thoracic, 5 lumbar, 5 sacral, and 1 coccygeal nerves exit ______ the corresponding vertebral body
Below
132
The lumbar and sacral nerves have long roots which comprise the ________
Cauda equina (“horse’s tail”)
133
The cervical enlargement of the spinal cord, due to widened gray matter (C5 - T1), provides innervation to the ____________ via the _____________
Upper extremities; brachial plexus
134
The lumbosacral enlargement of the spinal cord, due to widened gray matter (L3 - S2), provides innervation to the ____________ via the _____________
Lower extremities; lumbosacral plexus
135
Afferent (sensory) fibers carrying input to the spinal cord from the sensory receptors
Dorsal roots
136
Contains all the cell bodies of dorsal root fibers which supply sensory innervation to a particular dermatome
Dorsal root ganglion
137
General _________ afferents which convey sensory info from the extremities and the body wall, and general ________ afferent which convey sensory info from the viscera
Somatic; visceral
138
Motor efferent fibers that convey output from the spinal cord
Ventral roots
139
Convey impulses to the motor end-plates of voluntary muscle fibers
Alpha motor neurons
140
What is a motor unit?
The alpha motor neuron and the muscle fibers it innervates
141
One neuron innervates _______ ocular muscle fibers for fine motor control. One neuron innervates up to ______ muscle fibers in the soleus muscle for gross motor control.
3-8; 2000
142
Convey to intrafusal fibers of the muscle spindles
Gamma motor neurons
143
Synapse in the paravertebral sympathetic ganglion /c postganglionic neurons
Preganglionic autonomic neurons
144
General somatic efferent stimulate what?
Voluntary muscles
145
General visceral efferent stimulate what?
Involuntary smooth muscle, cardiac muscle, and glands
146
Cell bodies and transverse fibers are located centrally in a “butterfly shape” in the ________ matter
Gray
147
Gray Matter
1. Each half has a thin _________ horn extending toward the dorsal root
2. Each half has a widened ________ horn containing the motor neurons
1. Posterior
| 2. Anterior
148
The gray matter is also subdivided into layers of Reed _________ I - X
Laminae
149
Lamina I - VI are located in the ________ horn, including the ____________ (lamina II)
Posterior; substantia gelatinosa
150
Laminae VII is located in the _____________
Intermediate zone
151
Laminae VIII and IX are located in the _______ horn
Anterior
152
Laminae X is located in the midline, surrounding the ____________
Central canal
153
White matter of the spinal cord is __________ and ___________ fibers running longitudinally through the cord along /c glial cells
Myelinated; unmyelinated
154
A deep cleft containing connective tissue and anterior artery branches
Ventral median fissure
155
The white matter of the spinal cord is divided into what 3 paired columns?
1. Posterior funiculi
2. Lateral funiculi
3. Anterior funiculi
156
Groups of sensory fibers from _________ tracts of the white matter
Ascending
157
Ascending tract:
| That lateral half of each posterior funiculi is called the ___________
Fasciculus cuneatus (uncrossed)
158
Ascending tract:
| The medial half of each posterior funiculi is called the _____________
Fasciculus gracilis (uncrossed)
159
The crossed ___________ tract which origininates from the dorsal horn
Spinothalamic
160
Groups of motor fibers run in _________ tracts of the white matter
Descending
161
Descending tract:
1. uncrossed __________ tract
2. Crossed ____________ tract
1. Vestibulospinal
| 2. Lateral corticospinal
162
Autonomic responses due to neural connections within the spinal cord
Spinal reflexes
163
The ________ reflex is basis for the “tendon jerk reflex”
Stretch
164
The gamma reflex loop controls ___________
Muscle tension
165
The flexor reflex is a protective withdrawal of a limb from a _________ stimulus
Painful
166
The _____________ artery originates by the joining of two branches of the vertebral arteries
Anterior spinal
167
What does the anterior spinal artery supply?
The anterior 2/3rds of the spinal cord
168
The posterior spinal arteries run along the line of attachment of the ______ roots
Dorsal
169
Reinforcing arterial supply enters through the ________ foramen and divides into an _________ and ________ spinal root which participates in an anastomotic plexus on the cord surface
Intervertebral; anterior; posterior
170
What is the largest reinforcing radicular artery?
Spinal artery of Adamkiewicz
171
Where does the spinal artery of Adamkiewicz originate?
In the upper lumbar region
172
True or False:
A venous plexus drains roughly parallel to the spinal arteries
True
