TALBOT Q's [Membrane Biophysics & Resting Membrane Potentials, AP, Synaptic Transmissions, Actin Filaments, Muscle Contraction, The Neuromuscular Junction, Excitable Cells, Channelopathies] Flashcards
(289 cards)
1
Q
what stains actin?
A
rhodamine phalloidin
2
Q
what stains tubulin?
A
anti-tubulin & fluorescein secondary antibody
3
Q
what stains DNA/nucleus?
A
dapi
4
Q
what’s the protein of actin filaments?
A
actin
5
Q
what’s the protein of microtubules?
A
tubulins
6
Q
what’s unpolymerized form of actin filament?
A
globular, monomer (G actin)
7
Q
what’s unpolymerized form of MT?
A
heterodimer (1alpha +1beta)
8
Q
what’s the bound nucleotide in actin filaments?
A
ATP
9
Q
what’s the bound nucleotide in MT?
A
GTP
10
Q
what’s the form of polymer in actin filaments?
A
2-stranded helix
11
Q
what’s the form of polymer in MT?
A
hollow tube, 13 protofilaments
12
Q
do actin filaments have dynamic instability?
A
yes
13
Q
do MTs have dynamic instability?
A
yes
14
Q
are actin filaments structurally polar?
A
yes
15
Q
are Mts structurally polar?
A
yes
16
Q
what’s the growing end of actin filament?
A
+ end
17
Q
what’s the growing end of MT?
A
+ end
18
Q
what’s the shrinking end of actin filament?
A
+ end
19
Q
what’s the shrinking end of MT?
A
+ end
20
Q
what are the roles of actin filaments?
A
- mircrovilli
- contractile bundles in cytoplasm
- form leading edge projections in crawling cells
- form the contractile ring in cell division
21
Q
which end of actin filament do G-actin monomers bound to ATP add to?
A
+ end
22
Q
which end of actin filament do G-acin monomers bound to ADP come off of?
A
- end
23
Q
profilin
A
actin binidn protein that binds to actin monomers and facilitates exchange for ADP for ATP
24
Q
treadmilling
A
refers to the fact that any given G-actin appears to “move along a treadmill” in that it adds on to the + end and falls off from the - end
25
TRUE or FALSE. "actin filament can grow or shrink at either end in vivo. however, they preferentially grow at their + end and shrink at their - end
True
26
ATP cap
as long as it is on the actin filament, the end in which it is located is where the actin filament grows
NOTE: if it comes off, ADP may be exposed, allowing possible shrinking at that end
27
severing proteins (aka. gelsolins)
they cut an actin in the middle, exposing ADP-actin on the plus end of the new fragment as well as on the new minus end; thus they promote rapid depolymerization and convert the gel-like structures into a more liquid solution
28
what is an example of cross-linking protein?
filamin
29
what are some examples of bundling protein?
fimbrin, villain, alpha-actin
30
what is an example of motor protein?
mysosin
31
what are some examples of capping (end-blocking) proteins?
capZ, tropomodulin
32
what is an example of side-binding/stabilizing proteins?
tropomyosin
33
what are some examples of nucleating proteins?
ARP 2/3, profilin
34
what do you call the filament growing out of ARP 2/3?
daughter filament
35
[difficult-long answer] what are the steps of cell crawling?
1) nucleating proteins promote pushing out actin filaments towards leading edge structures
2) bundling proteins in filopodia help form exploratory fibers
3) integrins form new adhesion point; severing proteins promote depolymerization of actin filaments
4) myosin's walk along actin filaments, pulling rear of cell towards new adhesion point
36
motor domain of myosin
acts with actin and hydrolyzes ATP
37
what are the 3 distinct, fibrous components of the cytoskeleton?
intermediate filaments, MT, and actin
38
what is the similarity among the 3 distinct, fibrous components of the cytoskeleton?
they each is made of 2-13 protofilaments arranged in parallel to each other and held together by non-covalent bonds
39
what is the difference among the intermediate filament, MT and actin?
they each is unique in the type of protein subunits used to form each structure and in their individual roles in the cell
40
what are the similarities between actin and tubulin?
- bind and hydrolyze a nucleotide triphosphate and its relative form influences the affinity of the protein subunit for other subunits
- exhibit dynamic instability
- structurally polar, with functionally distinct ends
- the plus end preferentially grows whereas the mini send preferentially shrinks
41
what is the intracellular Na+ concentration?
15 mM
42
what is the interstitial Na+ concentration?
145 mM
43
what is the intracellular K+ concentration?
120 mM
44
what is the interstitial K+ concentration?
4.5 mM
45
what its the interstitial Ca2+ concentration?
1.2 mM
46
what is the intracellular Cl- concentration?
20 mM
47
what its the interstitial Cl- concentration?
116 mM
48
synaptic transmission is predominantly _____ (via NTs) but also can be _____ (via gap junctions).
chemical; electrical
49
in neurons that interact via _____ synapses, the pre-synaptic AP induces the secretion of NT, leading to a change in _____ in the postsynaptic cell.
chemical; Vm
50
in neurons that are connected by _____ synapses, the signal moves through gap junctions directly from the pre-synaptic cell to the post synaptic cell.
electrical
51
electrically coupled cells
cells that are connected by gap junctions
52
where can you find electrically coupled cells?
brain, cardiac muscle, and some smooth muscle
53
T/F in electrical transmission, there is some loss of voltage between the pre- and post-synaptic cell.
TRUE
54
T/F electrical synapses are almost always excitatory.
TRUE
55
what is responsible for the loss of voltage between the pre- and post-synaptic cell?
passive spread of a change in membrane potential
56
between electrical and chemical synapses, which one is only unidirectional?
chemical synapse
57
there are 9 steps in a chemical synapse. name all the 9 steps
1) NT synthesized and stored in vesicles in presynaptic cell
2) AP depolarizes nerve terminus
3) depolarization opens voltage-gated Ca2+ channels
4) Ca flows from ECF into cell
5) Ca acts as 2nd messenger, inducing vesicles to fuse with plasma membrane
6) NT released into synaptic cleft
7) NT binds to receptors on post-synaptic cell
8) this alters gating of ion channels in the post-synaptic cell
9) PSP (post synaptic potential )develops across post-synaptic cell dendritic membrane
58
SNARE proteins
proteins that allow the vesicle to recognize, dock and fuse to the plasma membrane; found in both vesicular membrane and palsmamembrane
59
which two synaptic toxins inhibit NT secretion?
botulism toxin
&
tetanus toxin
60
which synaptic toxin induces a massive non-specific release of NT?
alpha-latrotoxin
61
the vesicle contains a _____ and the target membrane contains a _____ and the 2 must interact to allow the vesicle to ultimately fuse and release its contents.
nSNARE; tSNARE
62
_____ allows the interaction bw the vSNARE and the tSNARE to occur, leading to secretion of NT.
calcium
63
how do botulism toxin and tetanus toxin inhibit NT secretion?
they are proteases (they cleave the SNARE proteins)
64
which synaptic toxin does black widow spider venom contain?
alpha-latrotoxin
65
how does alpha-latrotoxin induce a massive non-specific release of NT?
by by-passing the calcium regulation of NT secretion
66
what do you call complementary proteins found on both the vesicular and target membrane?
SNAREs
67
which type of SNARE is synaptobrevin?
vSNARE
68
which type of SNARE is SNAP-25 and syntaxin?
tSNARE
69
other than vSNARE, what is the other vesicular protein?
synaptotagmin
70
what does synaptotagmin bind?
calcium
71
other than tSNAREs, what is the other pre-synaptic plasma membrane protein?
neurexin
72
what are the 4 steps of docking and fusion of vesicles?
1) vesicle docks
2) SNARE complexes form, pull membranes together
3) entering Ca binds synaptotagmin
4) Ca-bound synaptotagmin catalyzes membrane fusion
73
what are the 3 major categories of classic NTs?
acetylcholine
amino acid
monoamines
74
name 3 aa NTs
GABA
glycine
glutamate
75
how are monoamines synthesized?
by replacing -COOH in aa with another functional group
76
name the monoamines (2)
catecholamines
| indolamines
77
name the subcategories of catecholamines (3)
norepinephrine
epinephrine
doapmine
78
name the indolamines (2)
seretonin
| histamine
79
which aa are indolamines formed from?
tryptophan
80
the subcategory of catecholamines are all modified _____ aa and are closely related to each other
tyrosine
81
what are the 3 characteristics of classic NTs?
1) small, clear storage vesicles
2) recycled
3) most are synthesized in nerve terminus
82
T/F non-classic NTs such as peptides are recycled
FALSE. non-classic NTs such as peptides are NOT recycled.
83
where are non-classic NTs synthesized?
in cell body
84
4 characteristics of peptide NTs
1) much larger variety
2) may be co-localized to the same nerve terminal as classic NTs
3) most are synthesized in cell body, usually as prohormones
3) most are enzymatically inactivated in the synapse
85
_____, _____ _____ vesicles often contain "classic" NTs
small, clear round vesicles
86
_____, _____ vesicles typically contain peptide NTs or, in some cases, _____
large, dense-core; biogenic amines
87
3 main mechanisms to eliminate NT from cleft
1) reuptake of NT into axon terminus or transport into neighboring glial cell
2) inactivate NT using enzymes present with in synaptic cleft
3) allow NT to diffuse from cleft into surrounding ECF or blood stream
88
SSRI's
selective serotonin reuptake inhibitors; antidepressive
89
Glutamate synthesis and cycling between neurons and glia: The action of glutamate released into the synaptic cleft is terminated by uptake into surrounding glial cells (and neurons) via _____. Within glial cells, glutamate is converted to _____ by _____ and released by glial cells by a different transporter. _____ is taken up into nerve terminals via _____ and converted back to glutamate by _____. Glutamate is then loaded into synaptic vesicles via _____ to complete the cycle.
excitatory amino acid transporters (EAATs)
glutamine
glutamine synthetase
glutamine
SAT2 transporters
glutaminase
vesicular glutamine transporters
90
acetyl choline esterase (AChE)
cleaves ACh back into choline and acetate
91
ACh binds to one of several types of _____ receptors on the post-synaptic membrane
cholinergic
92
AChE inhibitors include _____ (a nerve gas) and many _____
sarin; many organophosphate pesticides
93
fast chemical synapses contain _____ receptors (_____ channels)
ionotropic; ligand-gated
94
slow chemical synapses contain _____ receptors (_____ receptors)
metabotropic; G-protein coupled
95
within fast chemical synapses, there are 2 subcategories based on how quickly a PSP develops in the postsynaptic cell. the speed with which the response is induced is due to differences in the __________.
type of receptor found in the dendritic membrane
96
how fast are the fast chemical synapses?
~1 msec
97
how slow are the slow chemical synapses?
secs-mins
98
in the slow chemical synapses, receptor _____ leads to a change in membrane potential in post-synaptic cell
indirectly
99
bw fast and slow chemical synapses, which one allows for amplification of the signal, leading to a larger response?
slow chemical synapse
100
ECF [K+]
4 mM
101
T/F ions can passively move up their concentration gradient if it brings the membrane potential closer to that ions equilibrium potential
TRUE
102
the membrane potential of a cell is -20mV, E of Cl- is -45 mV. the net flux of Cl- will be:
inward directed
103
the axonal membrane domain is non-conducting with regards to Na+ when the voltage-gated Na+ channel is
both closed and inactivated
104
which vesicular membrane-associated protein is involved in vesicular fusion to the axon terminal membrane?
synaptobrevin
105
the end-plate potential is the result of which of the following ionic events occurring at the nicotinic AchR?
influx of Na+ and efflux of K+
106
function of ARP 2/3
nucleation
107
function of myosin
motor protein
108
function of CapZ
plus end cap
109
function of gelsolin
severing
110
during the cross bridge cycle in a sarcomere, when does the "power stroke" of the myosin head occur?
during the rigor phase
111
the depolarization phase of an AP is carried by Ca2+ in which cells?
cardiac pacemaker cells and some smooth muscle cells
112
excitation-contraction coupling refers to:
how a muscle membrane AP leads to an increase in cytoplasmic [Ca2+]
113
malignant hypothermia can occur when _____ is mutated
RyR1 of skeletal muscle
114
according to the chemiosmotic hypothesis, which of the following contributes to the proton-motive force across the inner mitochondrial membrane (IMM)?
- the proton concentration gradient across the IMM
- the electrical potential gradient across the IMM
- the difference in oxygen concentration across the IMM
115
which ionotropic receptor? heteromeric, 5 subunits; number of different subunits varies between muscles and neuronal types; permeable to Na and K
nAChR
116
most serotonin receptors are G-protein coupled (metabotropic) receptors, but the _____ type is an ionotropic receptor food mostly in CNS; clinical significance as antagonists acts as anti emetics (anti-nausea), anxiolytics (anti-anxiety) and antipsychotics; permeable to Na and K
5-HT3R
117
which rionotropic eceptor? fx primarily in synaptic inhibition, selective for Cl-
GABA-A receptors
118
which ionotropic receptor? major inhibitory NT in spinal cord and brain; selective for Cl-
glycine receptor
119
which ionotropic receptor? several types, widespread in CNSD, primarily excitatory; receptor subtypes named for the agonists that stimulate them
glutamate receptors
120
name the 5 ionotropic receptors discussed in class
```
nicotinic AChR
5-HT3R
GABA-A receptor
glycine receptor
glutamate receptor
```
121
name the 5 metabotropic/GPCR receptors found on the post-synaptic membrane
- muscarinic AChR
- g-aminobutyric acid (GABA) receptor
- metabotropic glutamate -receptors (mGluR)
- a and b adrenergic receptors
- dopamine receptor (DaR)
122
most of the _____ are localized to the corpus striatum and take part in coordinating motor fx
dopamine receptor (DaR)
123
T/R a and b adrenergic receptors can be activated by either Nor or Epi (with vary affinities). these receptors are found in the brain as well as throughout the body
TRUE
124
_____ are one of the more unique GPCR family members and have only minimal sequence homology
metabotropic glutamate receptors (mGluR)
125
_____ are found in the brain, leading to either excitation or inhibition, depending on the receptor subtype activated
muscarinic acetylcholine receptor
126
_____ receptors indirectly activate their effector protein
G-protein coupled receptors
127
metabotropic receptors indirectly lead to the opening of _____
ion channels
128
what are the 2 ways in which a NT binding got a GPCR/metabotropic receptor can lead to the opening of ion channels
1) the activated G-protein can directly bind and change the gating of an ion channel
2) the activated G-protein can activate an enzyme that leads to the production of 2nd messenger in the cell. the 2nd messenger then binds to and opens specific ion channels
129
cardiac pacemaker cells are innervated by the _____ nerve of the (sympathetic/parasympathetic) nervous system; _____ is the NT.
vagus; parasympathetic; ACh
130
cardiac pacemaker cells are innervated by the vagus nerve of the parasympathetic nervous system; ACh is the NT. ACh binds to the (nicotinic/muscarinic) AChR GPCR and _____ the G-protein; here the G_____ subunit is the active unit.
muscarinic; activates; beta-gama
131
cardiac pacemaker cells are innervated by the vagus nerve of the parasympathetic nervous system; ACh is the NT. ACh binds to the muscarinic AChR GPCR and activates the G-protein; here the Gbeta-gamma subunit is the active unit. Gbeta-gama binds to a _____ channel in the _____ membrane, opening it and allowing _____ to flow (in/out) of the cell
K+; plasma; K+; out
132
K+ (influx/efflux) (hyper/hypo)polarizes the membrane of the pacemaker cells, which leads to a (increase/decrease) in the heart rate
efflux; hyper; decrease
133
T/F an example of a postsynaptic cell with a metabotropic receptor where the G-protein directly affects the gating of the ion channel can be seen in cardiac pacemaker cells.
TRUE
134
binding of NT to receptors in the postsynaptic membrane leads to changes in Vm --> _____ potentials
graded
135
what do you call ion flow across a membrane?
current
136
_____ influx always produces an EPSP (excitatory postsynpatic potentials)
Na+
137
_____ efflux always produces an IPSP (inhibitory postsynaptic potentials)
K+
138
_____ flux (in or out) typically produces an IPSP (inhibitory postsynaptic potentials)
Cl-
139
T/F the somatodendritic domain cannot produce APs, but an EPSP can increase the likelihood of developing an AP at the axon hillock
TRUE
140
T/F the somatodendritic domain cannot produce APs, but an EPSP can decrease the chance of an Ap forming at the axon hillock
TRUE
141
how do you increase the chance of developing an AP? (3)
1) produce EPSP closer to axon hillock
2) decrease threshold voltage
3) summation=larger EPSP
142
you often see (excitatory/inhibitory) synapses closer to axon hillock
inhibitory
143
spatial summation of PSP
several different presynaptic neurons firing (at same time) at different synapses
144
temporal summation of PSP
- same or nearby presynaptic neuron firing multiple times in close succession
- stimulation may occur if multiple EPSPs occur within a short duration
145
summation can occur over both _____ and _____
time, space
146
_____ the time constant, the longer the Vm stays above rest from each incoming PSP in temporal summation. thus the more likely summation can occur
greater
147
spatial summation of PSP: _____ the length constant, the further the change in Vm will travel before it decays back to rest, thus increasing the likelihood that it can interact, sum, with a PSP received at a different part of the membrane.
greater
148
membrane time constant represents the time it take the membrane to reach _____% of the final voltage
63%
149
membrane time constants of different neurons typically range from _____ to _____ ms
1-20ms
150
what does membrane time constant affect?
how long it takes before membrane potential returns to its resting value
151
[LIKELY HIGH YIELD] T/F the longer the time constant, the longer the membrane potential will take to return to its resting potential (implications for integration of multiple incoming signals)
TRUE
152
cholinergic receptor
binds to ACh; the 2 main subtypes of cholinergic receptors include nicotinic cholinergic receptors and muscarinic cholinergic receptors
153
adrenergic receptor
binds the 2 main catecholamines (norepinephrine and epinephrine); named after the adrenal gland (which secretes epinephrine). many different subtypes within 2 main classes (alpha and beta)
154
serotonergic receptor
binds serotonin
155
histaminergic receptor
binds histamine
156
agonist
activator; a chemical that is usually a structural analog of the natural ligand such that when it bind sot the binding site on the receptor, it induces the normal response
157
GPCR
G-protein coupled receptor
158
ICR
ion channel receptor = ligand-gated ion channel = ionotropic receptor
159
what do you call muscle plasma membrane?
sarcolemma
160
[LIKELY HIGH YIELD] what does sarcolemma contain?
- depressions with junctional folds on the post-synaptic side of the motor end plate
- transverse or T-tubules (invaginations)
- voltage-gated Na+ and K+ channels
161
what are the 2 membrane domains in the SR?
1) longitudinal elements
| 2) terminal cisterane
162
what is the calcium storage site in skeletal muscle?
SR (sarcoplasmic reticulum)
163
neuromuscular junction
a specialized chemicla synpase bw the nerve terminus of a motor neurons and a skeletal muscle
164
[LIKELY HIGH YIELD] T/F each skeletal muscle fiber is only innervated by a single neuron, but a motor neuron can synapse on multiple muscle fibers.
TRUE!
165
[LIKELY HIGH YIELD] what is a motor unit?
a single motor neuron and all the muscle fibers it innervates
166
the _____ muscle fibers in a motor unit, the finer the control
fewer
167
the greater the number of fibers in a motor unit, the _____ the force of contraction can be
stronger
168
the neuromuscular junction consists of: _____, _____, and _____
1) presynaptic nerve terminus
2) synaptic cleft
3) post-synpatic motor end plate
169
what does the presynaptic nerve terminus of the neuromuscular junction contain?
vesicles filled with ACh
170
how big is the synaptic cleft of the neuromuscular junction?
50 nm
171
what does the synaptic cleft of the neuromuscular junction contain?
ACh esterase on the cleft side of the post-synpatic membrane & proteins associated with an extracellular matrix
172
T/F the post-synaptic motor end plate of the neuromuscular junction is a skeletal muscle cell membrane.
TRUE
173
what does the post-synaptic motor end plate of the neuromuscular junction contain?
terminal folds
174
each vesicle in a neuromuscular junction contains _____ ACh molecules
1,000
175
1 vesicle in a neuromuscular junction = 1 _____
quanta
176
each vesicle in a neuromuscular junction is _____ diameter
50 nm
177
in the postsynaptic membrane of the neuromuscular junction, clusters of nicotinic ACh receptors are in the _____
junctional folds
178
the size of the synaptic cleft bw nerve and muscle cells
50-100 nm
179
how long does it take for ACh to diffuse in the synaptic cleft bw nerve and muscle cells?
0.5 ms
180
presynaptic clusters of ACh containing vesicles, arranged in orderly manner right _____ active zone (primary region of vesicular fusion)
above
181
AChR clustered just _____ active zone; mosat receptors _____ top of junctional folds
below; near
182
T/F various glycoproteins form synaptic basal lamina that help adhere presynaptic nerve terminus to junctional folds.
TRUE
183
calcium channels are concentrated at the NMJ in regions of the _____ nerve terminal opposite clusters of AChRs on the _____ membrane
presynaptic; postsynpatic
184
each polypeptide subunit shares significant homology and spans the membrane 4x with the _____ exposed to the _____ of the synaptic cleft
N-temrinus; extracellular fluid
185
nicotinic AChR is a mixed cation channel with permeability to both Na and K but the driving force for _____ entry is greater, leading to a net _____
Na; depolarization
186
[LIKELY HIGH YEILD] whereas the skeletal muscle nicotinic receptor is composed of _____ different subunits, the neuronal nicotinic AChR is composed of only ____ subunit types
4; 2
187
[LIKELY HIGH YIELD] the subunits of the NMJ nAChR contain recognition sites for agonists such as..
nicotine
188
[LIKELY HIGH YIELD] the subunits of the NMJ nAChR contain recognition sites for reversible antagonists such as..
curare
189
[LIKELY HIGH YIELD] the subunits of the NMJ nAChR contain recognition sites for alpha-toxins such as..
cobra alpha-toxin & alpha-bungarotoxin
190
cobra alpha toxin and alpha-bungarotoxin are both from _____ venoms
snake
191
neostigmine
a reversible ACh esterase inhibitor
192
in the following findings in a clinical case, "muscle response with reposted direct stimulation of the muscle is normal," what is implied by direct stimulation of the muscle?
an external electrical stimulus such as shock that non-specifically depolarizes the membrane potential
193
end plate potentials: when the AChR ion channel on post-synaptic membrane opens, both Na and K flow (up/down) their electrochemical gradient
down
194
[LIKELY HIGH YIELD] at resting potential, net driving force for _____ is much greater than _____, when ACh triggers opening of these channels more _____ moves inwards than _____ outwards, depolarizing the endplate. this potential change is called _____.
```
Na
K
Na
K
end plate potential (EPP)
```
195
T/F EPP (end plate potential) is an AP
FALSE. EPP is not an action potential
196
T/F EPP (end plate potential) is simply depolarization of specialized motor end plate, analogous to an EPSP in a postsynaptic neuron
TRUE
197
[LIKELY HIGH YIELD[]each EPP produces a _____ that _____ the production of an _____ along the sarcolemma
suprathreshold depolarization; triggers; AP
198
the resting Vm of most skeletal muscle is close to _____mV
-90mV
199
in both adult and fetal AChR, the _____ is 0 mV. this is because the AChR ion channel is equally permeable to both Na and K, and since they have similar (but opposite) chemical gradients, in the absence of an _____, there will be no net flux (current = 0)
reverse potential; electrical gradient
200
the number of ACh molecules in each vesicle is called a _____
quantum
201
_____ specifically refers to non-stimulated events due to the random fusing of vesicles to the active zone of the nerve terminus
miniature EPPs
202
myasthenia gravis
an autoimmune disease in which patients develop antibodies against nicotinic ACh receptors
203
myasthenia gravis is an autoimmune disease in which patients develop antibodies against nicotinic ACh receptors. thus, the amplitudes of MEPPs and EPPs are reduced (why?) and the muscle membrane may not be depolarized sufficiently to fire an AP
since there will be less depolarization for the same ant of released ACh
204
how do you treat myasthenia gravis?
give an acetylcholinesterase inhibitor to prolong and increase the AP of ACh at the available receptors and to restore the muscle AP
205
what are the symptoms of myasthenia gravis?
- eye muscle weakness
- eyelid drooping
- blurry/double vision
- unstable gait
- change in facial expression
- difficulty in swallowing
- shortness of breath
- impaired speech
- weakness in the arms, hands, fingers, legs and neck
206
curare
-non-depolarizing muscle relaxant/paralytic
207
T/F curare is an anesthetic
FALSE. curare is a relaxant/paralytic
208
what does curare block?
nicotinic receptors
209
what do you need to be careful about curare?
patients may feel pain but cannot show it
210
what does neostigmine block?
cholinesterases
211
neostigmine is a component of _____ and _____
nerve gases & insecticides
212
what results from defects in the ClC-1 Cl- channel?
myotonia congenita (myopathy)
213
in skeletal muscle, why isn't there an "after hyper polarization" after an AP?
because the resting Vm in skeletal muscle is closer to Ek
214
[LIKELY HIGH YIELD] what are the differences bw skeletal muscle and neuronal membrane potentials?
- skeletal muscle maintains a more negative resting membrane potential usually closer to -90mV
- the T-tubule membranes contains a chloride channel (ClC-1) that contributes to the resting Vm
215
the more negative Vm of the skeletal muscle is due to: (2)
1) increased K gradient
| 2) increased Cl- gradient and Cl- permeability
216
[LIEKLY HIGH YIELD] excitation-contraction (EC) coupling
the muscle membrane AP indirectly induces the release of calcium from the SR, leading to contraction
217
excitable cells
- cells that are capable of developing APs across their plasma membranes
- maintain a resting Vm
- contain voltage-gated ion channels
218
[LIKELY HIGH YIELD] the T-tubule membranes contains a _____ that contributes to the resting Vm along the K leak channel
chloride channel (ClC-1)
219
what are the similarities bw skeletal muscles APs and neuronal APs? (4)
1) resting potential maintained in absence of incoming stimulus
2) voltage-gated Na channels open 1st, induce initial rapid depolarization
3) Na channels inactivate as voltage-gated K channels open (delay)
4) K channels allow depolarization of membrane potential
220
[LIKELY HIGH YIELD]when K channels allow depolarization of membrane potential, what happens to neuron and skeletal muscle?
neuron hyper polarize BUT skeletal muscle does not
221
in addition to the voltage-gated Na and K channels in the sarcolemmal T-tubules, there is also a member of the voltage-gated Ca channel family --> the _____ receptor
DHP Receptor
222
a triad is 1 _____ and the _____ of 2 _____ regions
T-tubule; terminal cisternae; SR
223
the T-tubule contains the voltage-sensitive DHP _____ channels
calcium
224
the SR terminal cistern contain calcium release channels known as ____ receptors
Ryanodine
225
depolarization of the T-tubule membrane indirectly induces _____ release: this is known as _____
calcium; excitation-contraction coupling
226
intercalated disks contain:
1) gap junctions
| 2) desmosomes
227
gap junctions allow direct electrical coupling of _____
myocytes
228
_____ conduction of APs between cells through the gap junctions
rapid
229
desmosomes
- cell-to-cell junctions
| - allow force transfer bw cells
230
what are the 3 kinds of cardiac muscle cells?
autorhythmic
conducting cells
contractile cells
231
which of the cardiac muscle cells are pacemaker (nodal) cells?
autorhythmic
232
which of the cardiac muscle cells are Purkinje fibers?
conducting cells
233
which 2 types of cardiac muscle cells have little actin and myosin?
autorhythmic and conducting
234
[LIKELY HIGH YIELD] myogenic muscle cells _____ depolarize, initiating contraction when the threshold potential is reached
spontaneously
235
"pacemaker" refers to the fact that the time bw contractile events is set by the _____ rate of depolarization and not an external signal
intrinsic
236
[LIKELY HIGH YIELD] DHP receptor
L-type Ca2+ channel
237
Ryanodine receptor
the SR calcium release channel
238
tetanus
greater and prolonged contraction
239
what is the predominant smooth muscle type in wall of visceral organs and blood vessels?
single-unit smooth muscle
240
where can you find multi-unit smooth muscle?
- trachea
- iris and ciliary body of the eye
- piloerector muscles of the skin
- some blood vessels
241
in most cases, the depolarization phase of the smooth muscle action potentials is carried by _____ via voltage-gated _____ channels
calcium; calcium
242
neurogenic smooth muscle requires the binding of a _____ to a receptor to initiate the depolarization phase of the AP
NT
243
bw neurogenic and myogenic smooth muscles, which can spontaneously depolarize?
myogenic smooth muscle
244
does multi-unit smooth muscle have gap junctions?
no
245
does single-unit smooth muscle have gap junctions?
yes
246
is initiation of contraction for multi-unit smooth muscle neurogenic or myogenic?
neurogenic
247
is initiation of contraction for single-unit smooth muscle neurogenic or myogenic?
myogenic
248
does multi-unit smooth muscle have T-tubules?
no
249
does single-unit smooth muscle have T-tubules?
no
250
how much SR does multi-unit smooth muscles have?
very little
251
how much SR does single-unit smooth muscles have?
very little
252
multi-unit source of calcium for contraction
ECF/SR
253
single-unit source of calcium for contraction
ECF/SR
254
muscle AP in multi-unit smooth muscles?
no
255
muscle AP in single-unit smooth muscles?
yes
256
is multi-unit smooth muscle responsive to stretch?
no
257
is single-unit smooth muscle responsive to stretch?
yes
258
[LIKELY HIGH YIELD] how is multi-unit smooth muscle similar to skeletal muscle?
- doesn't have gap junctions
- neurogenic initiation of contraction
- SR as source of calcium for contraction
- doesn't respond to stretch
259
[LIKELY HIGH YIELD] how is multi-unit smooth muscle different from skeletal muscle?
- doesn't have T-tubules
- very little SR
- ECF as one of the sources of calcium for contraction
- no muscle AP
260
[LIKELY HIGH YIELD] how is single-unit smooth muscle smilier to skeletal muscle?
- SR as source of calcium for contraction
| - muscle AP
261
[LIEKLY HIGH YIELD] how is single-unit smooth muscle different from skeletal muscle?
- has gap junctions
- myogenic initiation of contraction
- doesn't have T-tubules
- very little SR
- ECF as one of the sources for calcium for contraction
- responds to stretch
262
bw multi-unit and single-unit smooth muscles, which is more similar to skeletal muscle?
multi-unit smooth muscle
263
the striations in skeletal and cardiac muscles are due to...
regular arrangements of the contractile unit of muscle, the sarcomere
264
why isn't smooth muscle striated?
because it lacks regularly arranged sarcomeres
265
[LIKELY HIGH YIELD] whats special about cardiac muscle that is different from skeletal and smooth muscles?
individual cardiac muscle cells may branch
266
which muscle cell is electrically coupled via gap junctions?
cardiac and some smooth
267
in cardiac muscle, gap junctions and _____ (which act to hold the cells together) are localized to structures called _____
desmosomes; intercalated disks
268
T/F some types of smooth muscles are electrically coupled via gap junctions.
TRUE
269
T/F only cardiac muscles cells are electrically coupled via gap junctions
FALSE
270
there are other cell types that contain voltage-gated ion channels, allowing the membrane to respond to depolarizations but not necessarily produce an AP. For example, _____ contain voltage-gated calcium channels that open in response to a depolarization induced by the closing of a specific type of potassium channel in their membrane
beta cells of the pancreas
271
[LIKELY HIGH YIELD] channelopathies
diseases caused by mutations in genes that encode ion channel subunits or regulatory proteins
272
ion channels are not open continuously but open and close in a _____ or _____ fashion
stochastic; random
273
what affects ion channel function?
1) changing the pen time
2) changing the closed time
3) changing the single channel current amplitude
4) changing the number of functional channels
274
ion channel function may be affected by chaining the open time, closed time, single channel current amplitude, or number of functional channels. changes in any of these can change the relative _____ of an ion.
conductance
275
defects that act to produce channel protein and traffic it to/from the membrane impact _____
the number of open functional channels available in a membrane
276
defects that impact ion conduction, gating and inactivation typically are impacting the _____ or _____
open probability OR current amplitude
277
[LIKELY HIGH YIELD] general characteristics of channelopathies
- although mutation is continuous, the disease may be episodic or progressive
- abnormalities in same channel may present with different disease states
- lesions in different channels may lead to same disease
278
[LIKELY HIGH YIELD] is periodic paralysis (channelopathy) episodic or progressive?
episodic
279
[LIKELY HIGH YIELD] is spinocerebellar ataxia episodic or progressive?
progressive
280
[LIKELY HIGH YIELD] which 2 channelopathies present with different disease states even though they are results of abnormalities in the same channel (SCN4A)?
hyperkalemic periodic paralysis & paramyotonia congenita
281
[LIKELY HIGH YIELD] which 2 channelopathies present with different disease states even though they are results of abnormalities in the same channel (CACNA1A)?
episodic ataxia & familial hemiplegic migraine
282
[LIKELY HIGH YIELD] SCN4A is a (Na/Ca) channel
Na
283
[LIKELY HIGH YIELD] CACNA1A is a (Na/Ca) channel
Ca
284
[LIKELY HIGH YIELD] lesions in which channels lead to periodic paralysis?
SCN4A, CACNA1S, Kir2.6
285
[LIKELY HIGH YIELD] lesions in which channels lead to long QT syndrome?
KVLQT1, SCN5A, CACNA1A
286
myotonia
characterized by delayed relaxation (or maintained contraction) of muscle following a sudden forceful contraction; it is associated with repetitive AP generation, a manifestation or sarcolemmal hyperexcitability
287
[LIKELY HIGH YIELD] periodic paralysis
- characterized by episodic weakness or paralysis of voluntary muscles (occurring with normal neuromuscular transmission and in the absence of motor neuron disease)
- it represents a transient state of hypo excitability or unexcitability in which APs cannot be generated or propagated
288
what are the 2 symptoms that are characteristic of muscle membrane (sarcolemma) NavCh dysfunction?
myotonia and periodic paralysis
289
T/F malignant hyperthermia occurs more often in adults than in children.
FALSE. malignant hyperthermia occurs more often in children than in adults because by the time the pts become adults, they would have ben treated.
