Slides 3 Flashcards
(251 cards)
1
Q
Where does integration of sensory information typically occur?
A
Mostly in the pre-frontal cortex
2
Q
What are the 3 things the brain needs to do in order to produce behaviour?
A
- Receive info about the world
- Integrate info to create a sensory reality
- Produce commands to control the movement of muscles
3
Q
What are the brain’s 3 primary functions?
A
- Create a sensory reality
- Integrate information
- Produce behaviour
4
Q
How are white matter tracts detected in the brain?
A
Tractography
5
Q
Sensory receptors:
A
specialized cells that transduce (convert) sensory energy (like light) into neural activity
6
Q
Energy for vision
A
Light –> chemical
7
Q
Energy for audition
A
air pressure –> mechanical
8
Q
Energy for somatosensation
A
Mechanical energy and sometimes chemical energy
9
Q
Energy for taste and olfaction
A
Chemical molecules
10
Q
Is our perception an exact replication of the real world?
A
Not really, it is a subjective construction of reality that is manufactured by the brain
11
Q
How does the brain distinguish between the different senses?
A
They are processed in different parts of the brain
Learn to distinguish the senses through experience
12
Q
Which is our primary sense?
A
Vision
13
Q
3 layers of the eye
A
Cornea: clear outer covering
Lens: focuses light
Retina: where light energy initiates neural activity q
14
Q
Retina vs Fovea
A
Retina = light sensitive surface at the back of the eye consisting of neurons and photoreceptor cells Fovea = center of the retina, the receptive field at the senteer of the eye's visual field
15
Q
what is the function of the bipolar cells?
A
They connect the rods and cones to the ganglion cells
16
Q
What cells make up the optic nerve?
A
The axons of the ganglion cells
17
Q
Retinohypothalamic tract
A
Axons of ganglion cells that go to the hypothalamus and contribute to circadian rhythms and pupil size
18
Q
Characteristics of rods
A
- More numerous than cones
- Sensitive to dim light
- Used for night vision
- No colour perception
19
Q
Characteristics of cones
A
- Responsive to bright light
- Colour and high visual acuity
- Located in the fovea
- Colour vision
20
Q
2 layers of a photoreceptor
A
Outer: stacks of membranes that contain visual pigment molecules (rhodopsin)
Inner: organelles and opsin molecules
21
Q
Geniculostriate visual pathway
A
Retina –> visual cortex
Main pathway that allows you to form images
22
Q
Tectopulvinar visual pathway
A
retina –> superior colliculus
Allows you to detect motions
Visually guided movements
23
Q
Retinohypothalamic visual pathway
A
Synapse at the suprachiasmatic nucleus of the hypothalamus
Regulates circadian rhythm and pupillary reflex
24
Q
Is an image formed at V1?
A
No, thats where all of the information (colour, motion, depth, form) is integrated
Images are put together in V2, V3, and V4
25
Dorsal Visual Stream
Occipital --> parietal
| How: visually guided movements
26
Ventral Visual stream
Occipital --> temporal
| What: visual identification of objects
27
Pinna:
Funnel-like external structure of the ear designed to catch sound waves and direct them to ear canal
28
External ear canal:
Amplifies sound waves and directs them to the eardrum
29
Middle ear:
An air filled chamber with 3 bones:
- Hammer
- Anvil
- Stirrup
30
The inner ear has what 3 components?
Cochlea
Basilar membrane
Hair cells
31
Cochlea:
Fluid filled stricture that have the auditory receptor cells
32
Basilar membrane:
Receptor surface in the cochlea that transduce sound waves into neural activity
- Where the hair cells are embedded
33
Hair cells
Sensory cells that when stimulated by waves in the cochlear fluid, push up against the tectorial membrane and make action potentials in the auditory nerve
34
Fast vs slow wave sound frequencies
Fast: max displacement at base of membrane
Slow: max displacement at apex of membrane
35
Process of sound wave to NT release
- Sound makes waves in the cochlear fluid which moved the basilar membrane
- Hair cells are anchored in the basilar membrane, so they get pushed up against the tectorial membrane
- Displacement of hair cells changes the membrane potential and leads to NT release
36
Inner vs outer hair cells
Inner: afferent and make up 90% of auditory nerve
Outer: both efferent and afferent
37
What direction of movement of the hair cells causes a depolarization?
Movement towards the tallest cilia
K+ entry
Causes Ca+ to enter and NT to be released
38
What direction of movement causes the hair cells to hyperpolarize?
Movement towards the shortest cilia
| Causes less NT release
39
Where do the inner hair cells synapse to?
spiral ganglion axons that make the auditory nerve (cranial nerve 8)
40
What brain region helps you detect where sounds are coming from?
Superior Olivary complex
41
What brain region mediates sound guided movements?
Inferior colliculus
42
Left vs right temporal lobe in sound processing
```
Left = language processing
Right = spatial dynamics and emotion
```
43
Humans have which two types of skin?
Hairy and glabrous
44
Nociception
Perception of pain, temperature and itch
45
Hapsis
perception of fine touch and pressure
| Identify objects through touch
46
Proprioception
Perception of the location and movement of the body
| - sensitive to the stretch of muscles and tendons and movement of joints
47
What sense to free nerve endings respond to?
Chemical signals for pain
48
Rapidly adaptive reception
responds briefly at the beginning and at the end of a stimulus
- touch, fluttering sensations and vibration
49
Slowly adapting receptor
responds as long as a sensory stimulus is on the body
| - pain, temperature, skin indentation
50
Root ganglion neurons
Axons that carry sensory information from the skin to CNS
| - May synapse with other neurons in the spinal cord or go straight to the brain
51
Proprioceptive and haptic neurons
Large, well myelinated axons --> fast
| Ipsilateral in spinal cord and cross at brain stem
52
Nociceptive neurons
Small, not well myelinated axons --> slow
| Cross in brain stem
53
Primary somatosensory cortex (Broadmans area 3-1-2)
Receives projections from the thalamus
| Begins the process to constructing perceptions from somatosensory information
54
Secondary somatosensory cortex
| Brodman's area 5 and 7
Refines the construction of perceptions
| Projects to the frontal cortex
55
Integrating vision with somatosenses
The dorsal stream projects to the secondary somatosensory cortex and then to the frontal lobe
56
Movement planning in the frontal lobe
Prefrontal: planning movements
Premotor: organizes motor sequences
Primary motor: produces specific movements
57
Axon projections of one eye
Half stay on the ipsilateral side and go to the contralateral side
58
Which receptors are furthest away from the lens?
Photoreceptors
59
What cells are the interneurons of the visual system?
Amacrine and horizontal cells
60
Which cells does light reach first in the eye?
Ganglion cells
61
Which eye cells produce action potentials?
Ganglion and amarine cells
62
What eye cells produce graded potential
Photoreceptors, horizontal cells and bipolar cells
63
What NT do photoreceptors release?
Glutamate
64
How are pigments arranged in rods and cones?
Rods: in disks that do not contact the membrane
Cones: comb-like structures that are continuous with the membrane
65
How many disks are replaced each hour?
3, it requires a lot of energy
66
What is rhodopsin made of?
A complex of a large opsin protein and a light absorbing retinal
67
What does the opsin protein look like?
A large protein with 7 hydrophobic trans-membrane helices
68
What happens to retinal when it absorbs light?
It changes shape = photoisomerization
| It goes from 11-cis retinal to all trans retianl
69
What happens to rhodopsin when retinal changes shape?
The whole protein changes shape
70
What molecule is crucial for phototransduction?
Metarhodopin II
71
All-trans retinal is the precursor for what?
11-cis retinal
72
What nutrient is needed from our diet to make all-trans retinal
Vitamin A
73
What is the confirmation of retinal at rest>
11-cis retinal
74
Because all-trans retinal is more straightened out, what happens to the rhodopsin protein when activated by light
The opsin gets pushed open
75
What is different between photoreceptors that capture different colour wave lengths
the amino acid sequences are slightly different
76
How do invertebrates' photoreceptors respond to light?
Depolarization
77
How to photoreceptors in vertebrates respond to light?
Hyperpolarization
78
What does photoactivated rhodopsin (meta II) do when stimulated?
It activates the G-protein transducin, initiating the phototransduction cascade
79
What is the activity of photoreceptors in the dark?
Na+ and Ca++ enter ion channels and cause depolarization and glutamate is released
80
What happens to the activity of the photoreceptor when stimulated by light?
The sodium channels close due to reduced levels of cGMP
| Rod becomes hyperpolarized and reduces glutamate release
81
Levels of cGMP and sodium channels
```
High = channel open
Low = channel closed
```
82
The g-protein transducin has 3 subunits. What happens to the alpha subunit during transduction?
Alpha exchanges GDP for GTP
| It break off and activates the membrane bound phosphodiesterase. It hydrolyzes cGMP to GMP --> reducing levels of cGMP
83
What happens when there is decreased cGMP?
It is less able to bind to Na channels, so they close and the rod hyperpolarizes
84
What dictates the specific wave length that will stimulate a rod?
The amino acid sequence of the opsin molecule
85
The amount of of NT released from the rods is related to what?
The amount of light
86
Is there a blood brain barrier on the nose?
No
87
Sequence of olfactory cells
Receptors to Glomerulus to Mitral cells (which make up the olfactory projection)
88
What are the inhibitory cells in olfaction
Periglomerular cells (connest the glomerulus together)
Tufted cells
Granule cells
89
Odour applied to the soma makes what type of response?
A short rapid response
90
Odour applies to the dendrites of cilia produce what type of response
A large, long lasting response
| >> Due to second messengers
91
What receptors are involved in smell and where are they located?
Golf receptors
| In the cilia
92
What happens to the Golf receptor when an odour binds?
1. Alpha subunit dissociates
2a. Activates adenylyl cyclase and increases cAMP
3a. Opens Na and Ca channels influx
2b. Also a activates phospholipase 3
3b. Converts PIP2 to IP3
4b. Opens Ca channels
93
What happens when the olfactory cilia become depolarized (influx of Na and Ca)
Ca causes the chloride channels to open, and Cl effluxes, causing further depolarization
94
What happens when the olfactory cilia become depolarized (influx of Na and Ca)
Ca causes the calcium-activated chloride channels to open, and Cl effluxes, causing further depolarization
95
What does it mean to say that odour receptors are more general?
More than one odourant type can bind to each receptor
96
Why do odour receptors need to be constantly replenished?
Because they are constantly being killed off, maybe from all the calcium
97
Are receptor types evenly spaced in the nose/
No, particular odourant receptors are found in restricted areas of the olfactory epithelium
98
Where do olfactory receptors project to?
To the olfactory bulb
| Which mainly projects to the amygdala
99
What is the significance of lots of olfactory projections to the amygdala
It makes unconscious emotional assessment of odour
100
What other sense enhances taste?
Smell
101
Which flavours have g-protein receptors?
Umami
Salty
Bitter
Sweet
102
Where are taste buds located?
Mainly within small bumps on the tongue called papillae
| But they are all throughout the mouth
103
Do taste cells have axons?
No, they form chemical synapses with afferent neurites
104
What is the signal transduction pathway for all G-coupled taste receptors
1. Alpha subunit activate phospholipase 3
2. Phospholipase 3 make PIP2 into IP3 and DAG
3. IP3 release calcium from ER 4. Increased calcium levels make NT release
105
What is the scala media?
It is the fluid in the cochlea that has a high concentration of potassium and low concentration of sodium that the hair cells are in
106
Fast waves = ______ pitch
High pitch/frequency
107
The scala media has a high concentration of K and low Na, so what ion rushes in when the hair cell channels open?
Potassium
108
After K rushes into the hair cell, what happens?
There is a calcium influx which causes NT release
109
What is another name for the hair cells?
Stereocilium
110
What connects the stereocilium?
Tip links - a coiled protein
111
How do the tip links open ion channels on hair cells?
When the hair cells move, they tension in the tip links increase and this promotes the opening of K channels
112
What protein opens the gates of the ion channels when there is tension in the coil between hair cells
myosin
113
How do hair cells adapt to sound?
The myosin protein slides down the kinocilium, which reduces tension in the coil and closes the gates
114
What type of calcium channel is in hair cells?
Potassium gated calcium channel
115
What important function does calcium play in hair cells?
Stimulates the release of NT
116
How are nocioceptive, hapsis, and proprioceptive receptors stimulated?
Nociception : free nerve endings activated by chemicals
Hapsis : activated by mechanical stimulation of the hair or tissue
Proprioception: sensitive to stretch and tension of muscles
117
Rapidly adapting receptor
responds breifly to the beginning and the end of a stimulus on the body
118
Slowly adapting receptor
responds as long as sensory stimulus in on the body
119
Stretch receptor (weak vs strong)
sense the stretch of the muscle
Weak: produces grated potential
Strong: produces action potential
120
Fast vs Slow adapting stretch receptor
Slow adapting = persisting firing
| Fast adapting = declining firing
121
What is the muscle spindle made of?
small intrafusal fibers that are embedded in the bulk of the muscle
122
What two types of neurons innervate the muscle spindle?
1. Large muscle fibers are supplied by alpha-motorneurons
| 2. Intrafusal fibers are supplied by gamma efferent fibers
123
Group 1A of the afferent neurons of the muscle spindles
Large diameter, fast conducting that from the primary nerve ending
124
Group 2 of the afferent neurons of the muscle spindles
Smaller and conduct more slowly, that form the secondary nerve endings
125
Primary nerve endings of the muscle spindle
Sensitive to the rate of change of the stretch (rapidly adapting)
> connected to group 1A axons
126
Secondary nerve endings of the muscle spindle
Sensitive to the level of static tension (slow adapting)
| > connected to the smaller group 2 axons
127
What are 3 ways that mechanoreceptor channels can be opened?
1. Through forces conveyed through tension in the membrane
2. Forces affecting coiled proteins linked to the channel gate
3. Indirectly activated by a second messenger
128
What ion enters the muscle when it contracts
Sodium
129
What are the two main receptors involved in pain perception?
G protein coupled receptors (GPRC) - metabotropic
| Transient receptor potential (TRP) - ionotropic
130
TRPs have different thermal activation ranges, what does that mean?
Different chemicals produce sensations of temperature that are not necessarily painful (menthol)
131
How do GPCR affect TRP?
The activation of GPCR can increase the sensitivity of TRPs
132
GPCR - TRP axis
When the GPCR and stimulated, they can lead to the activation of different kinases which phosphorylate the TRP and activate them --> TRP gets sensitized to pain
133
What is the mechanism of the GPCR - TRP axis
1. GPRC stimulates phospholipase C (PLC)
2 PLC stimulates PKC
3 PKC activated TRP
There are many different mechanisms, but the important component is that a Kinase phosphorylates TRP
134
What part of the spinal cord are the pain receptors located?
Dorsal horn
135
What can make nociceptors hyper-reactive
- more transducers
- more GPCR
- more signalling
- more Na channels
136
What role does inflammation play in pain sensitivity
Inflammation can phosphorylate TRPs and alter the thresholds of activation
137
What causes the delay between stimulation of a pre-synaptic neuron and a post synaptic response?
The time it takes the NT to travel across the cleft
138
What causes the delay to increase and decrease
Temperature
| Warmer = less delay
139
What is required for an action potential to occur?
A depolarization of the cell
140
Do depolarizations always result in action potentials?
No
| but action potentials are the strongest depolarization
141
What causes the delay between the end of an action potential and the release of NT?
1. The time required to open calcium channels
| 2. The time it takes Ca entry to trigger NT release
142
Depolarization leads to the increase of what ion in the cell?
Calcium
143
High levels of Ca trigger the release of NT. Where are Ca channels mostly located?
Concentrated in the active zones of the terminal membrane
144
In terms of the active zone and calcium channels, what increased the chance that NT will be released
If there is a bigger active zone with more calcium channels
145
What is the readily releasable pool?
The collection of vesicles that are bound to the pre-synaptic membrane at the active zone that are able to be rapidly released
146
What is the reserve pool?
Vesicles in the middle of the terminal button that are bound to each other by actin filaments that are ready to be put into the readily releasable poo;
147
What is the quantum of transmitter?
The amount of NT contained in one vesicle = there is a set number of NT per vesicle
148
What are the names of the 3 steps of vesicle NT release?
1. Docking
2. Priming
3. Exocytosis
149
What does HVA stand for in terms of calcium channels?
High voltage activated
150
Which subunit in calcium channels forms the pore?
The alpha-1B subunit
151
Which subunit in calcium channels forms the pore?
The alpha subunit
152
Which type of calcium channel do we focus on in this course?
N-type
153
What is the composition of the calcium channel protein?
Alpha in the middle, flanked by beta and gamma subunits
- beta in intracellular
- gamma has 4 transmambrane segments
- alpha2 is extracellular
154
Is there just one type of each subunit in the calcium pore?
No, there are many different isoforms
155
In calcium channels, the alpha subunit is the largest, and it incorporates (4):
1. Conduction pore
2. Voltage sensors
3. Gating apparatus
4. Ligand binding sites
156
How many segments are there in the alpha subunit of the calcium channel? What do they do
6
S1-S4 are the voltage sensor molecules
S5&6 form the pore
157
How does the calcium channel open?
As the S5 and S6 subunits are activated, they twist and open the pore
158
What are the 3 different stages of voltage gated ion channels?
```
Activation = pore open
Deactivation = pore closed
Inactivation = pore closed and unable to open
```
159
There are two types of SNARE proteins embedded in membranes that form a complex:
V(esicle) SNARE
| T(plasma membrane) SNARE
160
What is the name of the v-SNARE?
Synaptobrevin
161
What are the names of the two t-SNAREs
SNAP-25
| Syntaxin-1
162
What is the function of synaptotagmin?
A Ca binding protein in the synaptic vesicle membrane
163
What happens to synaptotagmin when there is a calcium influx due to a depolarization?
Calcium will bind to synaptotagmin and will change the conformation from a trans to a cis state
164
What happens when synaptotagmin goes from a trans to a cis state?
It binds to the plasma membrane and pulls the vesicle closer to it, which allows it to dock and fuse
165
Primed vs non-primed excitosome
Primed: a docked vesicle-SNARE complex that is ready to be released
Non-Primed: a docked vesicle-SNARE complex that is not ready to be released because it is not close enough to the membrane
166
What does the non-primed excitosome complex unit consist of?
- A calcium channel
- Syntaxin 1
- SNAP 25
- trans synaptotagmin
167
What keeps the non-primed complex away from the membrane?
The electrostatic repulsion of the negative charge of trans synaptotagmin
168
What happens to the non-primed complex when there is a depolarization?
Ca concentration increases and binds to synaptotagmin which inserts itself into the membrane
169
Once the excitosome is primed, it is ready for what?
Fusion
170
What is the process of fusion?
Calcium binds to synaptotagmin which binds to the SNARE complex. Complexin leaves and an omega figure is formed
171
In the docking phase, what protein is holding syntaxin in its native conformation?
Munc
172
The SNARE complex that is formed by the tangling of synaptobrevin, syntaxin and SNAP 25 is stabilized by what during priming?
A protein called complexin
173
Once the NT are released, the synaptic vesicle is recycled by ______
Endocytosis = a bubble comes off the plasma membrane
174
Neurotransmitter release is regulated by what two things?
1. Rate of neuron firing
| 2. Probability that vessicles will undergo exocytosis
175
What NT is used in all neuromuscular synapses?
Acetylcholine
176
What other synapse is ACh used in?
Parasympathetic terminals
177
How is the precursor to ACh, Acetyl CoA made?
During glycolysis when pyruvate is broken down, acetyl groups are transferred to the coenzyme A
178
Where does choline come from?
Our diets
179
What are the two components that make up ACh?
Acetyl CoA and Choline
180
How are Acetyl CoA and Choline combined to make ACh?
the enzyme Choline Acetyltransferase
181
What puts NT into vessicles and what else does it determine?
Vesicular Neurotransmitter Transporters
| they determine how many NT are in each vesicle
182
What energy source drives the vesicular neurotransmitter transporters?
the proton electrochemical driving force gradient
183
What happens to the concentration of receptors as you move away from the post-synaptic density?
There are fewer receptors
184
How many subunits are in the nicotinic ACh receptor?
5 subunits around a central pore
185
Which subunit has the binding site in ACh receptors
Alpha
186
How many alpha subunits are there in ACH receptors?
At least 2 `
187
What ion rushes in when ACh receptors open?
Sodium
188
Different subunit combinations of the ACh receptor dictate what?
The different functional properties of that receptor
189
How many trans membrane domanes does each subunit have in the ACh receptor and what are they labeled?
4
| M1-M4
190
In which ACh subunit domain is the binding site located?
The larger M1 amino terminal domain
191
What does the ACh M2 domain do?
determines the ionic selectivity of the receptor and faces the inside of the channel pore
192
What is the secondary structure of the ACh subunits that span the membrane?
Non-polar (hydrophobic) alpha helixes
193
Where specifically on the ACh receptor does ACh bind?
To the cys-loops on the beta pleated sheets on the extracellular side
194
What happens to the ACh receptor when ACh binds?
1. The beta sheets rotate
2. This causes M2 to move outward
3. This opens the pore
195
What is the precursor molecule to GABA?
Glutamate
196
What are the two main Glutamate receptors?
AMPA and NMDA
197
How do the AMPA and NMDA receptors work together?
When AMPA is stimulated it lets sodium in.
| The sodium will activate NMDA and calcium will enter
198
How many subunits are there in the AMPA receptors and what are they called?
4
| GluA1 to GluA4 (or Glur1-4 or GluR-A - D)
199
Each AMPA subunit can exist in what two forms? Caused by what?
"Flip" and "flop"
| Caused by alternative splicing
200
What is different about the flop GluA2-GluA4 AMPA subunits?
They desensitize faster but recover slower
201
AMPA receptors usually only allow sodium to flow in, but in what case does to allow Calcium in as well?
If the GluA2 receptor is (Q) instead of (R)
| > (R) is due to a post-transcriptional modification
202
Is GluA2 (R) or (Q) caused by a modification?
(R)
203
How many subunits in the GABA receptor?
5
204
GABA binds to which sub unit and how many of these subunits are there?
Alpha
| There are 2
205
When the GABA pore is open, which ion rushes in?
Chloride
206
Barbituates, ethanol etc have their ___ binding sites on the GABA receptor
Own
207
What is the function of tonic inhibition?
It is baseline inhibition that makes sure there is not random excess excitation
208
Desensitization of the GABA receptor
Even when GABA is bound the pore will not open, it is in a constant in between state
> caused by over use (alcoholism)
209
What is the difference between the GABA(A) receptor and the GABA(B) receptor?
GABA(A): direct acting - has a pore
| GABA(B): indirect acting - opens a channel through second messengers
210
What receptors are direct acting and which are indirect acting
```
Direct = ionotropic
Indirect = metabotropic
```
211
What are the 4 main G-proteins?
Gs
Gq
Gi
Go
212
What is the effector of the Gs protein?
More adenylyl cyclase --> more cAMP --> more PKA
213
What is the effector of the Gq protein?
More PLC --> IP3 --> Ca Diacylglycerol --> PKC
214
What is the effector of the Gi protein?
Less adelylyl cyclase --> less cAMP --> more K channels open --> inhibition
215
What is the effector of Go protein?
less Ca channels shut --> less NT release
216
What is the composition of G-protein coupled receptors
7 transmembrane domains
Extracellular amino terminals
Intracellular carboxy terminals
217
Which intracellular loops are the binding cites?
2nd and 3rd
218
What can lead to the desensitization of the G-protein?
Phosphorylation
219
Which domains do ligands bind to in G-proteins?
TM3,5,6,7
220
What happens when a ligand binds to the G-protein?
The subunits twist and the alpha and beta/gamma subunits break off
221
When the G-protein is stimulated, what happens to the alpha subunit?
It exchanges GTP for GDP and the alpha subunits becomes activated
222
What on the receptor determines what G-protein configuration will bind?
C-terminus
223
Once the alpha and beta/gamma subunits are freed from the G-protein, what do they do?
They modulate the activity of target proteins
224
What protein turns GTP back into GDP
GTPase-activating proteins
225
Once GTP is turned back into GDP, what can happen?
The trimer can reassemble and attach back to the G-protein
226
Is the beta/gamma subunit complex membrane bound?
yes
227
What does the G-protein beta/gamma subunit do once activated?
It can interact directly with an ion channel to open or close it
228
What does the G-protein alpha subunit do once activated?
It can activate one or more enzymes that can alter ion channel activity through second messengers
229
How to the Gi beta/gamma subunit open a potassium channel?
Directly
| Induces a post-synaptic hyperpolarization
230
How do the Gi beta/gamma subunits open channels
Possibly by causing a rotation in the sub units
231
Which NT can bind to autoreceptors?
Norepinephrine
232
What happens what Go protein autorecepots are stimulated?
It causes the a,b,g subunits to release and bund to N-type calcium channels, inhibiting calcium influx and reducing NT release
233
Gs pathway
Alpha subunit is activated --> activates adenylyl cyclase --> turns ATP into cAMP --> activates PKA --> phosphorylates CREB --> initiates transcription
234
What does the Gq protein do when stimulated?
Phospholipase C --> turn PIP2 into IP3 --> Activate ER to release Ca++ --> Ca++ does many things
235
Why does intracellular calcium need to be very well regulates?
Because it is very cytotoxic
236
A neuron can make how many connections?
50 000
237
EPSPs are associated with the opening of what channels?
Sodium: influx
238
IPSPs are associates with the opening of what channels?
Potassium: efflux
Chloride: influx
239
Within the plane of the membrane, what forms a selective filter for cations/anions?
Negative and positive charges
240
What is the main difference between sodium and potassium channels?
the 4 subunits of the sodium channel are all linked up
| the 4 subunits of the potassium channel are all separate
241
In a voltage gated sodium channel, there are __ domains each with ___ transmembrane segments
4
| 6 (S1-S6)
242
Which segment in the voltage gated sodium channel is responsible for voltage sensing?
S4
243
Which segments in the voltage gated sodium channel form the pore that ions flow through?
S5 and S6
244
In a voltage gated potassium channel, there are __ domains each with ___ transmembrane segments
4
| 6
245
How many subunits form the pore in a voltage gated potassium channel?Expressed with accessory ___ subunits
4
| Beta
246
What makes the sodium channels selective
the ring of 4 glutamic acids that line the insides of the pore
247
What makes the potassium channels selective?
backbone carbonyl oxygens
248
How many binding sites are there within the potassium pore and what binds to the,?
4 (s1-s4)
| Two water molecules and two potassium molecules
249
Potassium channels are often ____ at rest
open
250
Sodium channels are often ____ at rest
closed
251
How do the voltage gated potassium channels open once stimulated?
It causes a rotation of the S4 domain, which intereacts with S6 segments to open the gate
