Exam 2 Flashcards
What receptors participate in CICR?
Ryanodine receptors
Name a calcium buffering protein
calretinin
Mitochondria soak up excess Ca++ via the ______ and utilize it through ______ to stimulate Ca++ dependent citric acid cycle enzymes to make more ATP
Ca++ uniporter
Na+/Ca++ exchanger
____ and _____ can be ligands for nucleotide gated channels
cGMP and cAMP
When PLC acts on PIP2 and DAG, PIP2 goes on to activate _______, while IP3 goes on to activate ______
PKC
IP3 gated Ca++ channels
Which 4 receptors allow Ca++ into the cytosol?
Which 2 take it back out?
IP3 receptor, Ligand gated Ca++ channel, voltage gated Ca++ channel, ryanodine receptor
Na+/Ca++ exchanger, Ca++ pump. (Also Ca++ binding buffer proteins)
PKA is activated by:
CaMKII is activated by:
PKC is activated by:
cAMP
Ca++/Calmodulin
DAG, Ca++, and phosphatidyl serine. (Need all 3)
Arginine + _____ = ______ and ______
NO synthase
NO and Citrullene
NO synthase (NOS) is activated by:
Ca++/Calmodulin complex
How is NO degraded?
NO spontaneously oxidizes into a number of inactive metabolites
NO can directly modify proteins via
nitrosylation
Example of NO modifying a protein
it activated Guanylyl cyclase
Which two sites can CREB bind to?
CRE (cyclic AMP response element) and CaRE (Ca++ Response element)
Which 3 proteins can activate CREB?
MAPKinase, PKA, and CamKinase IV
What is NGF?
nerve growth factor
NGF is important for:
neuron survival, differentiation, and axon outgrowth
what 3 pathways can NGF stimulate?
PI 3 kinase, ras, or PLC
What kind of receptor is NGF?
RTK, receptor tyrosine kinase. Therefore it dimerizes upon ligand binding and autophosphorylates
Finish this pathway: NGF–>PI 3 kinase –>_______–>______
—>Akt kinase—> cell survival
stops programmed cell death
Finish this pathway–> NGF–>GEF–>_____–>_____–>____–>
Ras–>MAPK–>neuron growth and differentiation
Synaptic Plasticity –
experience-dependent changes in synaptic strength (increases or decreases in synaptic strength
as time between action potentials increases, facilitation _______
decreases
Synaptic depression is thought to arise from ________
synaptic vesicle depletion
Who worked with Aplysia?
Eric Kandel
Snail response decreasing over time is:
habituation
Which neuron contributes to sensitization in the snail?
modulatory/facilitatory interneuron
where does the modulatory neuron synapse?
the terminal of the siphon sensory neuron
Explain how short term sensitization works.
Serotonin release from facilitatory interneuron–> serotonin receptor–> G protein–> Adenylyl cyclase–>cAMP–>PKA–>closes K+ delayed rectifier channel–> increase AP duration–> increase Ca++ influx–> releases more NT to Motor neuron
Explain how LT sensitization works:
Trains of shocks lead to lots of serotonin release–> lots of free PKA–>CREB gets phosphorylated–> CREB increases Ubiquitin hydrolase production–> ubiquitin hydrolase degrades PKA reg. sub.–> PKA persistent activity.
Also, CREB enhances C/EBP production, which grows synapse
what is the chain of neurons in the hippocampus?
CA3 pyramidal, schaffer collaterals, CA1 pyramidal
When you stimulate tetanus in 1 pathway to elevate EPSP, what happens to EPSP in a second pathway?
nothing unless it was simultaneously stimulated
Who thought that memory might be formed by synapses that have coincidental activity
Donal Hebb. ‘Hebbian Synapse’
To achieve LTP, you must have pre synaptic activity paired with:
postsynaptic depolarization
Associativity:
a proposed way of linking information from two signals together. A big stimulus on one and a small stimulus will result in the strengthening of both synapses
Comes from the fact that on the second receptor, glutamate is released and since the NMDA receptors are open, glutamate is able to bind and get calcium influx and ultimately synaptic strengthening
How does LTP occur. For example, What must happen for a post synaptic membrane to become enhanced?
Glutamate must be released, opening AMPA receptors. AMPA receptors must depot. mem. enough to dislodge Mg+ from NMDA to allow Ca++ in to phosphorylate PKC and CaMKII, eventually leading to more AMPA
Evidence of the need for changes in gene expression for LTP comes from the fact that if you stimulate a synapse while protein synthesis inhibitors are present in the PS membrane, ________
EPSP will not persist above control
Finish this chain: NMDA opens–> Ca++ flows in–> ……
Ca++/calmodulin forms and activates AC–> cAMP–> PKA–>CREB–>MORE AMPA and other stuff!
LTP is measured by _______________, but it is initated experimentally by ____________
post synaptic response to single action potentials
high frequency stimulation
Normal vision-
nearsighted-
farsighted-
emmetropia
myopia
hyperopia
What is accommodation?
ciliary muscles contract to focus on closer objects
The ____ is the point of highest acuity. it is located in the middle of the ______
fovea
macula lutea
Retina in cross-section. Starting from deepest part of retina in relation to aqueous humor 1. 2. 3. 4. 5. 6.
- Pigment epithelium (like melanin in skin)
- Layer of cells (rods and cones)
- Synaptic layer – outer plexiform layer
- Interneurons
- Synaptic layer – inner plexiform layer
- Ganglion Cells
plexiform refers to ____ layers
synaptic
nuclear refers to _____ layers
cell body
retinal pigment epithelium is important to the health of photoreceptors in 3 ways
absorbs excess photons, assists in disc removal, and recycles retinoid
Photosensitive GPCR:
opsin
which opsin is in rods?
rhodopsin
When light changes the retinal conformation, opsin can then:
bind to G proteins
Which protein recycles all trans retinol back into 11 cis retinal?
Where is it found?
IRBP
pigment epithelium
more intense light flashes lead to ________ hyper polarization in photoreceptors
higher amplitude/longer lasting
Finish this path: Light–>Rhodopsin changes conformation–> _______–> ______–>etc….
–>Transducin (G protein) binds to rhodopsin–> Transducin alpha subunit activates PDE–> PDE converts cGMP into GMP–> nonspecific Na+/Ca++/K+ channels close–> hyperpolarization (K+ still leaking out)
To stop the light response (hyperpolarization) in photoreceptors, what chain of events must happen?
Rhodopsin kinase phos. Meta Rhodopsin II (the conformation that is activating transducer)—> arresting binds Meta Rhodopsin II—> Arrestin blocks transducin
What is the light range of Rods?
Cones?
Scotopic through mesopic
Mesopic through photopic
which range of light do both rods and cones activate?
mesopic
Rods have high ____ and low ____
sensitivity spacial resolution (acuity)
Cones have high ____ and low _____
spacial resolution
sensitivity
what are the ratios of rods and cones to bipolar cells?
Rods: 15-30:1
cones: 1:1
How many opsins are expressed in cones?
3, but an individual cone will only have 1
The 3 cone opsins are:
Short (blue)
medium (green)
long (red)
Off center bipolar cells are ____tropic
On center bipolar cells are ____tropic
iono
metabo
describe the pathway for an on center bipolar cell when the center of the receptive field is lit up.
cone struck by photons–> hyper polarizes–> stops sending glutamate to the mGluR6 receptor of on center bipolar cell–> mGluR6 is no longer stimulated, so it is no longer activating the GPCR cascade that closes cGMP gated Na+ channels that were keeping the cell hyper polarized—> now the bipolar cell depolarizes because cGMP channels are allowed to reopen—-> they start transmitting glutamate to the AMPA/Kainate receptors of on center ganglion cell—> this ganglion depolarizes and sends signal to retina
describe the pathway for an off center ganglion when light strikes center of receptive field.
cone hyper polarizes from light—> quits sending glutamate to AMPA/Kainate receptors on off center bipolar cell (so the bipolar cell now hyper polarizes)—> bipolar cell now quits sending glutamate to off center ganglion cell—> off center ganglion cell hyper polarizes and stops sending signals to retina.
what controls circadian rhythms?
SCN- super chasmatic nucleus
what photosensitive cells are needed for circadian rhythms?
photosensitive retinal ganglion cells pRGCs
what pigment do pRGCs use?
melanopsin
P class pumps get their name from:
phosphate from ATP hydrolysis being used to activate pump
PMCA stands for
plasma membrane Ca++ ATPase
PMCA is sensitive to
Ca++/calmodulin
SERCA recovers calcium released from:
ER or SR
Are PMCAs and SERCAs electrogenic?
No
is the Na+/Ca++ exchanger electrogenic?
Yes, 3 Na+/Ca++
Na+/Ca++ exchanger is high capacity, meaning
it doesn’t require ATP phosphorylation and can function quickly
Na+/Ca++ excanger has _______ affinity
low
