Transcript Neurophysiol

Midterm 1
Need: ID, Pen, Pencil
25 multiple-choice (50%) –Ch 1,3
2/3 essays (50%) – SQ 1-12
Axon Hillock
Membrane- selectively permeable
to ions
Nodes of Ranvier
Saltatory Conduction:
from one node to the
next & so on
Biophysics of Neural Impulse:
Action Potential
Ions:
Neuron polarized
1.
2.
3.
Electrostatic pressure
Diffusion
Na – K “Pumps”
Proteins-Neuron depolarized
Neuron hyperpolarized
SYNAPSE:
The terminals of this axon have excitatory effects
Axodendritic
synapse
EPSP - Na+
excitatory
postsynaptic
potential
IPSP - inhibitory
postsynaptic potential
in Cl - (Chloride) or
out K+ (Potassium)
The terminals of this axon have inhibitory
effects - axosomatic synapse
Excitation: EPSP
axodendritic - Na+
Inhibition: IPSP
axosomatic - Cl- in
- K+ out
P
+
P
IN
OUT
EPSP
Ca++channels
open
Ionotropic receptor
Ion channel
Types of Receptors:
• 1. Ionotropic receptor— coupled to ion
channel and directly opens it (fast acting).
• 2. Metabotropic receptor– indirectly opens
ion channel (slow acting).
It activates G-protein in post-synaptic
neuron which (a) opens ion channel, or (b)
activates 2nd messenger (e.g., cyclic AMP)
which then opens ion channel (b is more
common).
Terminating transmission at the synapse:
1. Re-uptake or
2.Breakdown Enzyme
3. Autoreceptors
1. Post-synaptic competition blocking
e.g., Thorazin blocks DA receptors
3. Post-synaptic agonist e.g.,
morphine - Enkephalin, Endorphin
valium - GABA
1
2. Pre-synaptic Reuptake block
e.g., Prozac - Serotonin (5-HT)
4. Pre-synaptic agonist
e.g., Amphetamine - Norepinephrine
1
Drug
(Receptor)
Drugs:
a. Agonists
b. Antagonists
No molecule in
binding site.
Channel closed
Transmitter molecule
in binding site.
Channel is open
Drug molecule
blocking the
binding site.
Channel is closed