Giant Nerve Cells of Squid

Ion distribution across cell membrane

A. Effect of concentration difference

B. Electrical potential difference affecting negative ions

C. Pressure difference

Transport of solutes across the Neuronal membrane

Ion movement across cell

Resting membrane Potential

Action Potential

Propagation of AP

Saltatory conduction

The Refractory Period

Synapse

Electrical synapse

Chemical Synapse

Chemical Synapse at Neuromuscular Junction

Neurotransmitter release

Post synaptic receptor

Excitatory and Inhibitory Post Synaptic Potential

Excitatory and Inhibitory signals

Excitatory and inhibitory currents have competitive effects in a single nerve cell. (Adapted from Eckert et al., 1988.)

Inhibition

Neurotransmitters

1. The substance must be present within the presynaptic neuron

2. The substance must be released in response to presynaptic depolarization, and the release must be Ca2+-dependent.

3. Specific receptors for the substance must be present on the postsynaptic cell

Major classes of NT

Acetyl Choline

Cholinergic Receptors in Normal Brain

Serotonin System

Dopamine System

Norepinephric System

Glutamate System

GABA System

•Widespread in the brain and spinal cord•Inhibitory by increasing permeability to Cl

Second Messenger