Midterm 1

Need: ID, Pen, Pencil25 multiple-choice (50%) –Ch 1,3

2/3 essays (50%) – SQ 1-12

Axon Hillock

Biophysics of Neural Impulse:

Action Potential

Saltatory Conduction: from one node to the next & so on

Nodes of Ranvier

Membrane- selectively permeable to ions

Ions: 1. Electrostatic pressure2. Diffusion3. Na – K “Pumps”

Neuron polarized

Neuron depolarized

Neuron hyperpolarized

Proteins--

IPSP - inhibitory postsynaptic potential

in Cl - (Chloride) or

out K+ (Potassium)

The terminals of this axon have inhibitory effects - axosomatic synapse

SYNAPSE: The terminals of this axon have excitatory effects

Axodendritic synapse

EPSP - Na+ excitatory postsynaptic potential

P+

P

IN

OUT

Excitation: EPSP axodendritic - Na+

Inhibition: IPSP axosomatic - Cl- in

- K+ out

EPSP

Ionotropic receptor

Ion channel

Ca++channels open

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).

1. Re-uptake or2.Breakdown Enzyme

3. Autoreceptors

Terminating transmission at the synapse:

1. Post-synaptic competition blocking e.g., Thorazin blocks DA receptors

3. Post-synaptic agonist e.g., morphine - Enkephalin, Endorphin valium - GABA

2. Pre-synaptic Reuptake block e.g., Prozac - Serotonin (5-HT)

4. Pre-synaptic agonist e.g., Amphetamine - Norepinephrine

No molecule in binding site.

Channel closed

Transmitter molecule in binding site.

Channel is open

Drug molecule blocking the binding site.

Channel is closeda. Agonistsb. Antagonists

1 1

Drugs:

Drug

(Receptor)