WEEK 3 INFO
peptides
-cell body
Amino acids and monoamine
-axon terminal
synaptic transmission and neurotransmitter release
-Ca2+ is higher in concentration outside the cell, and opening of voltage-gated Ca2+ channels by
depolarization allows Ca2+ to flow into the cell.
-Not all of the vesicles of neurotransmitter are triggered to fuse by a single action potential.
-
ionotropic receptors
-The receptor itself is an ion channel that directly opens or closes and allows ions to flow into or out
of the cell.
-They do not require G proteins in order to open or close ion channels.
-They are ligand-gated ion channels.
-They produce effects that are typically faster but shorter lived
Classical neurotransmission
-associated with ionotropic receptors.
-typically produces a more rapid and shorter electrical response
-amino acids and monoamines
neuromodulation
-It produces a slower and more longer-lived electrical response
-Monotaboic receptors
-neuropetides and monoamine
IPSPs
- During an IPSP, the cell becomes less likely to fire an action potential.
-membrane becomes more negative
-hyperpolarization
-Closing a Na+ channel
-Opening a K+ channel
EPSP- Closing a K+ channel. Opening a Ca2+ channel. Closing a Cl- channel
-membrane becomes less negative -depolarization -the cell becomes more likely to fire an action
potential.
,Temporal summation
-It is the process by which EPSPs from a single pre-synaptic neuron are added or summed to reach
threshold potential
spatial summation
-It is the process by which EPSPs from two or more pre-synaptic neurons are added to reach
threshold potential.
-Spatial summation of two excitatory postsynaptic potentials or EPSPs will bring a neuron closer to
threshold potential and make it more likely to fire an action potential.
-two or more inhibitory postsynaptic potentials or IPSPs will bring a neuron farther from
threshold potential and make it less likely to fire an action potential
Coincidence detection
-summation and coincidence detection of converging inputs single neurons to build complexity
- allows each neuron to be a decision-maker as well as a communicator.
-"Coincidence detection" and the need for summation decreases the "noise" of sending on false
signals.
antagonist
-It would bind to the dopamine receptor and block tdopamine from binding to the receptor and thus
reduces or eliminates the effects of dopamine.
-It would bind to the dopamine receptor but would not induce the normal dopamine response.
Agonist
-It would bind to the dopamine receptor and mimics the effect of dopamine by inducing the normal
response.
WEEK 4 INFO
PUMPS
-move ions against their concentration gradient
- require energy
-pumps can move ions into OR out of the cell
Na+ higher outside the cell, lower inside
K+ higher inside , lower outside
Na/K+ pump
-moves 3 Na+ for every 2 K+ it moves.
-moves Na+ out of the cell and K+ into the cell.
-pumps both against concentration gradient
Non-gated ion channels
,- open at rest
-at rest their are more K+ than Na
-move ions down their concentration gradient
-dont require energy
voltage-gated ion channels
- closed at rest
-move ions down their concentration gradient
Nongated K+ channels
-allows K+ to move in whatever direction its gradient is facing, although usually flows OUT OF
the cell
-does not require energy
-move down concentraion gradient
-At rest, K+ flows out of the cell through the non-gated K+ channel
Nongated Na+ channel
-allows Na+ to move down its concentration gradient.
-at rest, Na+ flows into the cell through the non-gated Na+ channel.
-does NOT requires energy to move
voltage-gated Na+ channel
-The voltage-gated Na+ channel allows Na+ to move into the cell down its concentration gradient.
-It opens in response to small increases in positive charge inside the cell, i.e., when the inside of the
cell gets a little bit less negative.
-voltage-gated Na+ channel is opened by small increases in depolarization,
Voltage gated K+ channel
-the voltage-gated K+ channel is opened by large changes in depolarization or positive charge inside
the cell.
-allows K+ to move out of the cell down its concentration gradient.
-it can be closed and opened or activated but not inactivate
Happens first during action potential
-Opening of voltage-gated Na+ channels
Hyperpolarization
-Overshoot, more negative than at rest
-Pumping of Na+ back out of the cell and K+ into the call by the Na+/K+ pump
-Closing of voltage-gated K+ channels
-De-inactivation of voltage-gated Na+ channels
Repolarization
-inactivation of voltage-gated Na+ channels
, -opening of voltage-gated K+ channels
repolarization refers to the stage of the action potential in which the inside of the cell rapidly
becomes less positive/more negative,
depolarization refers to the phase of the action potential in which the inside of the cell rapidly
becomes less negative/more positive
hyperpolarization refers to the phase of the action potential in which there is an overshoot of
resting membrane potential and the inside of the cell becomes even more negative than at rest.
Plasma membrane
-pumps, non-gated, and voltage-gated ion channels are all proteins found in it
Resting membrane potential
-Large, negatively charged intracellular molecules
-The non-gated K+ channel
-Na/K+ pump main contributor
-It is the charge or voltage difference at rest across the plasma membrane
-the inside of the neuron is more NEGATIVE inside compared to outside
Saltatory conduction
-"jumping" from Node to Node greatly speeds up action potential propagation down the axon
-The myelin sheath surrounds the axon except at bare patches known as Nodes of Ranvier
-The action potential occurs in the unmyelinated part of the axon.
action potential propagation
-during the refractory period, the previous membrane patch can't reform the action potential
because the voltage-gated Na+ channels are inactivated.
-The influx of Na+ from an action potential flows into adjacent membrane areas in both directions.
-The action potential only moves in one direction, down the axon toward the synapse.
Termination of synaptic signaling
Neuropeptides
-diffusion away from the synapse
amino acid and monoamine
-Reuptake by the presynaptic neuron
-Uptake by glial cell
•Degradation—breakdown of NTs by enzymes in the synapse—neuropeptides
-•Reuptake—transporter proteins move NT back into presynaptic neuron axon terminal
—amino acids and monoamines
•Diffusion—passive movement of NT away from synapse--neuropeptides