Nervous System/Heart/Lungs Flashcards
(209 cards)
1
Q
Is the autonomic nervous system motor or sensory?
A
Visceral motor system
2
Q
Interoreceptors
A
Visceral afferent fibers
3
Q
2 Functions of interoreceptors
A
24/7 monitoring of internal activity, conveying visceral pain
4
Q
2 Divisions of the autonomic nervous system
A
sympathetic and parasympathetic
5
Q
What types of neurons are involved in the ANS
A
preganglionic visceral motor neuron and postganglionic visceral motor neuron. Can also say pre and postganglionic sympathetic, and pre and postganglionic parasympathetic.
6
Q
Where are the cell bodies of preganglionic sympathetic neurons (of ANS) located?
A
Within central nervous system, ie intermediolateral area of gray matter
7
Q
Where do the axons of postganglionic parasympathetic neurons (ANS) terminate?
A
On or near the target cell/tissue/organ
8
Q
How are autonomic fibers distributed to target organs or tissues?
A
1) independent travel/distribution, 2) my travel with other nerves, 3) may form part of a plexus, 4) may travel with blood vessels
9
Q
Name some notable examples of a target tissue/organ of the ANS that does NOT receive both sympathetic and parasypathetic fibers.
A
Cutaneous blood vessels; sweat glands; hair shafts (sympathetic input only)
10
Q
What kind of ANS innervation do cutaneous blood vessels, hair shafts and sweat glands have?
A
Sympathetic input only.
11
Q
Give another name for the sympathetic ANS.
A
Thoracolumbar component
12
Q
What is the thoracolumbar component?
A
Another name for the sympathetic ANS, given because the preganglionic sympathetic cell bodies reside in the intermediolateral cell column of the gray matter in the spinal cord from T1 to L2.
13
Q
Where does ALL sympathetic outflow originate and why?
A
T1 to L2, only location in the entire nervous system where preganglionic sympathetic neurons are found.
14
Q
How do axons of preganglionic sympathetic neurons exit the spinal cord?
A
Ventral roots of spinal nerves (motor fibers only)
15
Q
What is another name for a sympathetic chain ganglion?
A
Paravertebral chain ganglion.
16
Q
Explain the structure of the sympathetic chain ganglia in the cervical spinal region.
A
Three large ganglia: superior, middle and inferior, serve as synaptic points for sympathetic fibers supplying the head, neck, heart and upper extremities.
17
Q
What is the connection between the ventral root and the sympathetic chain ganglion and what travels through it?
A
WRC, white ramus communicans, traveled by the preganglionic sympathetic neuron.
18
Q
What are the targets of postganglionic sympathetic neurons that travel to the skin?
A
1) smooth musculature of blood vessels (vasocontriction) - regulates the lumen of the blood vessels
2) smooth musculature of hair shafts of skin (make hair stand on end)
3) sweat glands - to stimulate them to secrete
19
Q
If postganglionic sympathetic neurons do not exit the spinal nerve area via either the dorsal or ventral rami, what are their other “travel options”?
A
They can join other postganglionic fibers traveling directly to viscera/organs.
20
Q
If an axon of a preganglionic sympathetic neuron does not synapse immediately, what are its “travel options”?
A
It can enter the sympathetic chain and travel either superiorly or inferiorly and exit in a different area of the body.
21
Q
What is another name for the parasympathetic component of the ANS?
A
Craniosacral component
22
Q
What is the craniosacral component?
A
Another name for the parasympathetic component of the ANS, so named because its preganglionic visceral motor neurons are located within specific nuclei of the brain OR in the gray matter of the intermediolateral cell column of the spinal cord at S2-S4.
23
Q
What is the vagus nerve?
A
Made up of preganglionic parasympathetic fibers, aka the 10th cranial nerve
24
Q
Where does the vagus nerve synapse?
A
The preganglionic fibers synapse in microscopic ganglia close to or within the organ that they innervate. The postganglionic fibers are very short.
25
Why is the parasympathetic fiber of the vagus nerve unique?
The parasympathetic fibers associated with other cranial nerves synapse in specific, named, macroscopic ganglia, while the vagus nerve (Cr. X) synapses in microscopic ganglia.
26
What other nerve collection behaves in the same way as the vagus nerve, in that it synapses on microscopic ganglia close to or within the area of innervation?
Pelvic splanchnic nerves - a collection of preganglionic parasympathetic fibers whose cell bodies are located at S2-S4.
27
Name the 2 types of sensory fibers serving the viscera.
1) Those that provide 24/7 internal monitoring for homeostasis, "monitoring and integration," (parasympathetic fiber distribution), 2) Those that transmit what we perceive as pain (sympathetic fiber distribution).
28
Where are the cell bodies of interoreceptors that provide monitoring and integration of visceral activities?
The cell bodies of these sensory fibers are located in special nuclei and ganglia within the brain.
29
How do the processes of the "monitoring" interoreceptors travel?
Peripherally directed processes travel:
1) with cranial nerves
2) within specific tracts within the spinal cord
30
Give 2 examples of what activate the interoreceptors which detect visceral "pain."
1) stretching of the GI tract wall, 2) lack of oxygen or nutrients to cardiac muscle
31
Where are the cell bodies of "visceral pain" interoreceptors located?
The cell bodies of "visceral pain" afferent fibers are located in the dorsal root ganglia (with the cell bodies of the somatic afferent fibers****).
32
What is referred pain?
Referred pain is a phenomenon whereby visceral stress from an area of the body that the brain is not accustomed to receiving pain signals from, causes "confusion" in the brain, and is interpreted as pain arising from whatever extremities whose somatic sensory nerve cell bodies share the DRG with the cell bodies of the actual source (visceral) of the pain.
33
If someone is having a heart attack, in what areas might that person experience pain?
Chest and down left arm, the extremities and skin served by T1-T5.
34
Walk me through a heart attack from the point of view of the nervous system
Deprivation of blood to myocardium -->
Visceral afferent fibers are stimulated -->
Centrally directed processes of visceral afferent fibers transmit the stimulus to the gray matter of the spinal cord in the areas at T1-T5 -->
The afferent somatic nerve cell bodies that share this DRG and gray matter area serve the skin of dermatomes T1-T5 --> Brain receives information and cannot discern the true source of the painful stimulus, so the pain is interpreted and felt to be coming from the skin and extremity areas, in this case the chest and radiating down the arm.
35
What parts of the body comprise the CNS?
Brain and spinal cord.
36
What parts of the body comprise the PNS?
Associated nerves, processes, and ganglia, including spinal nerves (originate in spinal cord) and cranial nerves (originate in the brain)
37
Name three places where you might find the cell body of a nerve fiber, generally speaking.
1) brain
2) spinal cord (gray matter)
3) peripheral ganglion
38
Define a nerve.
A collection of the processes of individual cells (neurons); the structural and functional unit of the nervous system.
39
What is an axon?
An axon is the process of a motor neuron that carries information from the cell body to the area of synapse with another neuron.
40
What is a dendrite?
A dendrite is the area of a motor neuron where information is first received from a synapse with another neuron.
41
How many processes are contained within a sensory neuron, generally speaking?
In general, sensory neurons have a single process.
42
How are cell bodies of sensory neurons involved in afferent communication?
They're NOT, UNLESS they are part of the ANS afferent sensory fiber system (referred pain guys). Cell bodies of afferent sensory neurons are not involved in information transmission.
43
In dissection, you identify a peripheral nerve. Of what is this nerve typically comprised?
Peripheral nerves will generally be made up up groups of axons of motor neurons and processes of sensory neurons that run in parallel to their specific destination.
44
What are the 2 STRUCTURAL components of the PNS?
1) Bundles of axons and processes = "nerves"
| 2) Collections of nerve cell bodies called ganglia
45
Why are ganglia unique among nervous structures?
Ganglia are the ONLY structures that house cell bodies of nerves outside the CNS.
46
What are the 2 functional components of the PNS?
1) Efferent/motor fibers that produce an effect in their target organ/tissue
2) Afferent/sensory fibers, which take in information FROM the periphery and relay it to the CNS.
47
What are the 2 destinations for the nerves found in the PNS?
1) Somatic nerves control voluntary muscle movements, ie skeletal muscle and skin
2) Visceral nerves control involuntary muscle movements and viscera, ie smooth muscle and internal organs
48
How many pairs of spinal nerves are there? What sections are they divided into?
```
31 pairs of spinal nerves:
8 pairs of cervical
12 pairs of thoracic
5 pairs of lumbar
5 pairs of sacral
1 pair of coccygeal
```
49
What are the 2 destinations of spinal nerves?
Skeletal muscles and skin, therefore all spinal nerves are referred to as somatic nerves.
50
What are the 3 main structural components of a spinal nerve?
Ventral root, dorsal root, dorsal root (or spinal) ganglion
51
What does a ventral root consist of?
A ventral root is made up by axons of MOTOR neurons, whose cell bodies are in the gray matter of the spinal cord. The direction of transmission is outward to the target muscle/area.
52
What does a dorsal root consist of?
A dorsal root is made up by processes of SENSORY neurons, whose cell bodies are housed in the dorsal root ganglion.
53
Where are dorsal root ganglia typically found?
DRG's are located just outisde the spinal cord in spaces between the vertebrae called intervertebral foraminae.
54
What is an intervertebral foramina and what can be found there?
The intervertebral foramina is a space between the vertebrae where dorsal root ganglia can be found (and in turn, the sensory neuron cell bodies they house)
55
Why are PREvertebral ganglia unique?
Prevertebral ganglia are locations of sympathetic preganglionic neuron cell bodies, but this is NOT part of the sympathetic (PARAverterbal) chain ganglia. PREvertebral ganglia are located in the abdominal cavity in association with the major branches of the abdominal aorta.
56
What basic components make up every spinal nerve?
Ventral root (for motor efferent), dorsal root (for sensory afferent), and the dorsal root ganglion (for cell bodies of sensory afferents)
57
Dorsal root me. What is there?
Groups of centrally directed sensory processes, exteroreceptors at the periphery, sending info to the CNS, specifically temperature, touch, pain and pressure sensations
58
The dorsal ramus is part of what kind of nerve, and what extremity areas does it supply?
The dorsal ramus is a component of the spinal nerve, and supplies the muscles bones and skin of the posterior neck and truck. This explains why it's kind of thinner than the ventral ramus.
59
The ventral ramus is part of what kind of nerve, and what extremity areas does it supply?
The ventral ramus is a component of the spinal nerve, and supplies the muscles, bones and skin of the anterior thoracic and abdominal walls and corresponding extremities.
60
What is another term for the ventral rami, when they are specifically located in the thoracic region of the spinal cord?
Intercostal nerves, run parallel to each rib.
61
What is the main DIFFERENCE between the ventral rami of the cervical, lumbar and sacral spinal nerves and the intercostal nerves of the thoracic region?
The intercostal nerves are regular and segmented, whereas the other ventral rami form large plexi that intermingle and network with one another.
62
Why are there 31 pairs of spinal nerves but only 30 dermatomes?
The spinal nerve serving the spinal cord at C1 has no corresponding skin neuron access (no cutaneous innervation.)
63
What is the cause of Herpes zoster?
Herpes virus lives in the DRG and is dormant in general, but can become active again if the patient becomes very stressed or immunosuppressed (or being old or having bad luck).
64
Are sensory ganglia associated with all spinal nerves?
No, because C1 has no cutaneous terminus, therefore it has no sensory information transmission taking place.
65
If a highway was the spinal cord, and the cars on the highway were neuronal pulses or stimuli traveling along it, what structures would be the on and off ramps at a particular exit?
Dorsal root would be the on ramp (bringing information TO the CNS/afferent/sensory) and the ventral root would be the off ramp (bringing information/responses AWAY from the CNS/efferent/motor).
66
Our friend, the phrenic nerve, innervates a few destinations. Give me a few, and which KINDS of innervation is taking place.
Motor fibers of the phrenic nerve innervate the diaphragm, whereas sensory fibers innervate the pericardium, mediastinal pleura and diaphragmatic peritoneum. Wikipedia also claims there is lung innervation...
67
Intercostal nerves are made up of what kind of fibers?
Somatic motor and somatic sensory. Dr. Stearns said, "Don't you go telling me that they are autonomics!"...hopefully I heard this correctly.
68
All spinal nerves are composed of:
Somatic motor and somatic sensory nerve fibers
69
What characteristics make spinal nerves "short" in general?
They divide immediately into branches of unequal size, the dorsal and ventral rami. However both rami still have the same component fibers.
70
Which rami (dorsal or ventral) supply the intercostal nerves?
Ventral rami contain the axons of the intercostal neurons (motor).
71
A patient complains of pain in their cervical/neck region. Based on your knowledge of nerves, what could be the actual source of the pain?
A problem in the diaphragm is a good candidate for cervical pain because of innervation by the phrenic nerve, which begins at C5-C7 and contains somatic motor and somatic sensory fibers (and postganglionic sympathetic fibers that supply the vasculature).
72
What are two causes of Horner's Syndrome?
1) A physical mass putting pressure on the sympathetic chain ganglia
2) Carotid artery dissection (widening, stretches the sympathetic chain ganglia that run with it, causing the same symptoms and sympathetic disfunction)
73
What is the brachial plexus?
The brachial plexus is a large, intricate group of ventral rami controlling movements of the upper extremity.
74
What are the symptoms of Horner's syndrome?
The 3 "osises" -- hemianhydrosis (no sweating), pitosis (droopy eyelid), myosis (pupil constriction)
75
As a general rule, all visceral plexi contain:
1) postG sympathetic fibers
2) preG parasympathetic fibers
3) visceral afferent fibers (monitoring and "pain")
76
Why do visceral plexi generally NOT contain preganglionic sympathetic fibers?
Because the sympathetic fibers have typically already synapsed in the paravertebral ganglia before joining to form the plexus.
77
What is the main example of a preganglionic parasympathetic fiber in the thoracic region?
The vagus nerve.
78
Explain the five types of innervations of the lung.
1) Sympathetic, postG fibers go directly to lungs
2) PreG parasympathetic, part of the vagus nerve, synapse in microscopic ganglia in or near the lung
3) Visceral afferent monitoring
4) Visceral afferent pain, follow with sympathetics of the region (dermatomes at T1-T5)
5) Somatic afferent, from parietal pleura, transmitted by phrenic and intercostal nerves
79
What are the two functions of the parasympathetic fibers innervating the lung (Cr. X)?
1) Bronchoconstrict
| 2) Initiate secretary activity from glands
80
Neonates lack what visual cortex structure?
Ocular dominance columns
81
What was used to study the development of ocular dominance columns in neonates?
tritiated proline
82
Where is the source of the problem causing amblyopia?
Brain (not eye itself)
83
In monoclear deprivation experiments, what happened to the non-deprived eye?
The non-deprived eye columns became overly large, taking over cortical territory normally used by the other eye
84
Are their binocular-processing cells in MD?
Very few
85
What is this? A peripheral problem, involving the extraocular muscles and improper alignment of the eyes
Strabismus
86
What is this? A Central problem, abnormal development of connections in the visual cortex, must be corrected while the patient is still very young.
Amblyopia
87
Strabismus can often lead to:
Amblyopia, Alternating strabisbus or Diplopia
88
In MD, the reason for the dramatic reduction in cells responding to the deprived eye is not disuse, but instead:
Active competition between the two eyes for cortical territory and synaptic coverage
89
Intravitreal injections of TTX showed:
Normal activity of the retina is silenced in the presence of TTX. Showed evidence of Hebbian mechanisms of ocular dominance (cells that fire together wire together)
90
Cortical reorganization is an example of:
adult neural plasticity beyond the critical period
91
Cranial nerve IX is:
glossopharyngeal
92
Name the cranial nerves I-VI:
1. Olfactory
2. Optic
3. Oculomotor
4. Trochlear
5. Trigeminal
6. Abducens
93
Name the cranial nerves VII-XII:
7. Facial
8. Vestibulocochlear
9. Glossopharyngeal
10. Vagus
11. Accessory
12. Hypoglossal
94
What s the mneumonic for determining motor or sensory input of the cranial nerves?
Some (1) Say (2) Marry (3) Money (4) But (5) My (6) Brother (7) Says (8) Big (9) Brains (10) Matter (11) More (12)
95
Afferent information from the face, sinuses and teeth is transmitted via which of the following cranial nerves?
..
96
Cornel blink reflex is closure of the eyelids in response to blowing on the cornea or touching it with a wisp of cotton. It caused by:
bilateral contraction of the orbicularis oculi uscles. Its efferent limb is the facial nerve, its afferent limb is the nasociliary nerve (ophthalmic division of trigem)
97
_____ is a paralysis of the facial muscles on the affected side because of a lesion of the facial nerve.
Bell's palsy
98
A subarachnoid hemmorhage is due to a rupture of __1__ that cross the subarachnoid space. It may be caused by a rupture of an aneurysm on the __2__ or, less commonly, by a hemangioma.
1. cerebral arteries and veins
| 2. Circle of Willis
99
What is Willis's penis?
anterior spinal artery
100
What does the posterior communicating artery supply?
Optic chiasm
Optic tract
Hypothalamus
101
The choroid plexus of the lateral ventricles, the optic tract, optic radiations and LGN are supplied by what artery?
Anterior choroidal (and internal capsule)
102
What brain areas does the posterior cerebral artery supply?
Midbrain
Temporal lobe
Occipital lobe
103
A lesion of the optic tract produces:
contralateral homonymous hemianopia
104
White matter of the brain includes:
1. Corpus collosum
2. Fornix
3. Anterior commissure
4. Posterior commissure
5. Optic tract
6. Optic Chiasm
7. Optic Nerve
8. Corona Radiata
9. Internal Capsule
10. Crus Cerebri
105
Rising BP, falling pulse and a pupil that has become sluggish suggest:
Increased ICP
106
What is the greatest risk factor for a CVA?
Hypertension
107
What is the function of the iris?
Regulates the amount of light entering the eye
108
Where is the fovea?
It lies at the center of the macula lutea
109
What is the direct pathway for the transmission of visual information from the eye to the brain?
Photoreceptor --> bipolar cell --> ganglion cell --> brain
110
Increased activity of PDE (phosphodiesterase)
Absorption of a photon by 11-cis-retinal
A conformational change in the rhodopsin protein
Dissociation of the alpha subunit of transducin from the beta/gamma complex
--These all describe what?
Phototransduction signaling cascade
111
The main reason that rods are more sensitive to light cones is that:
The rod transduction mechanism provides greater signal amplification.
112
True or False: Cells that are inhibited by light in their center are excited by light in their surround.
True
113
True or False: Cells that are excited by light in their center are inhibited by light in their surround.
True
114
True or False: The spatial extent to which a cell can be influenced by light never extends beyond the physical extent of its dendritic field.
FALSE
115
True or False: The best stimulus for an on-center cell is light in its center and darkness in its surround.
True
116
True or False: The surround portion of the receptive field is typically an annulus (donut-shaped ring) that surrounds a circular center.
True
117
What the the effect of the pupillary light reflex?
Light falling on one eye will cause both pupils to constrict.
118
Sensitivity to edges
Preference for a specific orientation
Preference for a specific direction of motion
All these contribute to what?
V1 firing of neurons in primary visual cortex
119
T or F: Higher order orientation-selective cells have preference for line length.
True
120
T or F: Within a vertical column in the PVC, one finds cells with the same orientation.
True
121
T or F: An oblique penetration through PVC would show cells with continuously varying orientations.
True
122
T or F: Orientation-selective cells were discovered by Hubel and Wiesel by accident.
True
123
T or F: The first orientation-selective cells are found in alternating layers within the LGN.
FALSE
124
T or F: Each of the six layers has distinct cell types that send projections both within cortical columns and to structures outside of the cortex.
FALSE
125
T or F: Layer 4C is dominated by spiny stellate cells.
True
126
Pyramidal cells are the principal projections neurons through the:
visual cortex
127
The upper layers of the PVC, 2 and 3, project to layer:
5
128
The lower layers, ______, of the PVC, project to the brainstem and thalamus.
5 and 6
129
What is the structure where a visuotopically organized, alternating (L/R) pattern of monoclear responsiveness is found?
Layer 4
130
In relation oth other retinal cells, what cells have particular fine spatial resolution and better color sensitivity?
P ganglion cells
131
Visual area V4 is most specialized for the processing of:
color information
132
Area MT is a brain region that has:
Large, motion-sensitive cells that respond selectively to oriented moving edges, but lack responsiveness to fine structural details.
133
Optic tract damage or cortical damage often lead to:
Contralateral visual field deficit
134
Long term storage of nondeclarative memory is in the:
cerebellum
135
_______ leads to a contralateral homonymous inferior quadrantanopia/hemianopia.
Parietal lobe damage
136
Where is LTP observed?
Throughout the brain, is cerebral cortex, cerebellar cortex
137
T or F: LTP requires NMDA receptor activation.
True
138
T or F: LTP is a model for declarative memory.
True
139
T or F: LTP enhances synaptic transmission.
True
140
T or F: LTP involves a long-lasting increase in synaptic strength.
True
141
What cells provide support as stem cells for the olfactory epithelium?
Basal cells
142
T or F: CT enhances visualization of soft tissue.
False. CT has less contrast difference between soft tissues compared to MRI. Elements with a higher atomic number, like Ca, show up better.
143
In a CT, what color is bone?
White
144
T or F: MRI can be used to diagnose epilepsy.
True
145
T or F: MRI can be used to diagnose inflammatory disease.
True
146
T or F: MRI enhances visualization of soft tissues.
True.
147
What kind of waves does MRI use?
Radio waves
148
What is the best technique for imaging cortical degeneration?
MRI
149
Why is MRI good at studying cortical atrophy?
Because it visualizes chemical structure and fiber tracts well
150
What are the primary taste qualities?
Sweet, salty, sour, bitter and umami
151
Salt and sour stimuli are transduced through:
ion-coupled transduction
152
Each sensory axon contains information from _____ taste cells.
~ 2-10
153
T or F: Taste information is relayed from sensory axons to the nucleus of the solitary tract and then to the VPM nucleus of the thalamus.
True
154
LTD in hippocampal area __1__ is induced by low frequency stimulation for __2__.
1. CA1
| 2. long periods of time
155
The LTD pattern of stimulation activates __1__ and permits Ca2+ entry through the receptor-channel such that __2__ are preferentially activated.
1. NMDA receptors
| 2. phosphatases
156
In LTD, activation of protein phosphatases has what effect?
The internalization of AMPA receptors
157
The long-term effect of the internalization of AMPA receptors in LTD is:
decrease in synaptic efficacy.
158
In neural development, Shh mediated __1__ patterning by expressing in the __2__-plate.
1. dorsal-ventral
| 2. floor
159
Besides the floor plate, where is Shh highly expressed during dorsal-ventral patterning?
Notochord
160
______ are diffusible axon guidance molecules that can be both attractive and repellant.
Netrins
161
CAMs, ECM molecules such as collagen/hyaluronan/fibronectin, and Ephrins and Semapphorins are all examples of:
Non-diffusible axon guidance molecules
162
__1__ proliferate in the presence of neurotrophins and degenerate in their absence.
Neurons
163
Neurotrophins are produced and secreted by:
target cells
164
What are the purposes of the patch-clamp technique?
To record microscopic current
To record macroscopic current
To detect current flow through a single membrane channel
165
Potassium ____ produces a hyperpolarization.
efflux
166
As the time constant of a neuron is increased, the probability of integration of converging synaptic signals is:
increased, because such signals will be more likely to overlap in time (temporal summation)
167
Ion flux through channels is considered to be:
Passive
168
Associate hemineglect with a lesion of the:
supramarginal area
169
Where does CN 7 come out of the cranium?
Stylomastoid foramen
170
What kind of lesion is Bell's Palsy?
LMN
171
CN's 5,6,7 (8) come out at what level of the brain?
Pons
172
CNs 3 and 4 come out at what level of the brain?
Midbrain
173
Does the facial nerve affect taste?
Yes, it is responsible for 2/3 anterior portion of tongue sensation
174
Broca's area is near what CN tracts?
7 and 12, motor to the face
175
What is the Nernst equation?
Ex = (58/z)log([X2]/[X1]) in mV
176
log 100
2
177
log 10
1
178
log 1
0
179
log 0.1
-1
180
log 0.01
-2
181
Why is there more K+ inside the neuron than out?
Na+/K+ pump
182
What causes neuronal selective permeability to K+?
K+ permeable channels that are open all the time
183
The Na+/K+ ATPase pump pumps:
3 Na+ out for 2 K+ in
184
If Vm is changing, can you use the Goldman equation?
No
185
The Vm at the height of an AP =
E-Na, -58mV
186
How do we know that K is the major ion that contributes to the resting potential of a neuron?
When [K+]out =[K+]in, Vm = 0
187
The Goldman equation measures:
a steady state potential (not an equilibrium potential)
188
What does a steady state potential mean?
There is no net flow of current and the membrane acts as a charged capacitor.
189
The rate of change of Vm after a change in the membrane current is set by:
the magnitude of the membrane capacitance
190
Lowered Na+ outside the neuron results in:
Slower and smaller APs
191
The absolute refractory period is when?
Rising and falling
192
The relative refractory period is when?
Undershoot
193
What is the effect of TEA?
Tetraethylammonium bromide, blocks K+ channels without affecting Na channels (is also an ACh blocker)
194
True or False: AP conduction requires both active and passive current flow.
True
195
How does passive current flow effect an AP?
Depolarization wave that precedes AP. Passive current flow leads to discharge of membrane capacitance ehich leads to Na+ channel activation.
196
When does the relative refractory period end?
When K+ channels close
197
What are some types of neurons that rely on passive signaling properties to relay signals?
Photoreceptors (signal travels a short distance)
198
How do you reduce the Cm?
Insulate axons bc no room to increase radius (myelination)
199
What are two effects of refractory periods?
1. Directional signaling
| 2. Limit frequency of APs
200
Name a K+ channel blocker.
Cesium, TEA
201
What is the defining property of the Kv4.1 channel?
Inactivate rapidly to depolarization
202
T or F: Ligand-gated ion channels can allow more than one type of ion to pass through the channel.
True
203
What is a function of inward rectifier cells?
Allow more current flow during hyperpolarization than depolarization.
204
What is a channelopathy?
Genetic disease resulting from mutations in channel genes
205
What channeloptahies result from defects in voltage-gated Ca2+ channels?
1. Congenital stationary night blindness
2. Familial hemiplegic migraine
3. Episodic ataxia type 2
206
Benign familial neonatal convulsion is what kind of channelopathy?
K+ channel defect
207
What toxin is a homolog of TTX?
Red tide, saxitoxin
208
Give an example of a co-transporter.
Na+/GABA, K+/Cl-
209
Ion translocation is _____ in transporters than in channels.
Slower
