3. Transmission of Excitation from Cell to Cell

[ chapter 2 ]

3.1 Chemical Synaptic Transmission
Chemical synapses & Motor End Plate of the Muscle
Synaptic Inhibition & Equilibrium potential for inhibition
Synaptic Transmission & Receptor

3.2 Interactions of Synapses

3.3 Microphysiology of chemical synaptic transmission

Nerve cells: differ from other cells in the body
communicate rapidly with one another, over great distance with great precesion
this is possible by two signalling mechanisms (axonal conduction and synaptic transmission)

Synapse: 20세기 초에 Charles Sherington이 사용: Ramon Cajal이 보고한 neuron간의 special contact zone을 기술하기 위해
Two schools: 1930년대 controversy
1) electrical (physiologists, John Eccles)
2) chemical (pharmacologist, Henry Dale)

1950, 1960년대: the issue was resolved
both exist, but chemical synapse is predominant in the brain

Electrical synapses: (Fig. 9-1)
1) 3.5 nm between presynaptic & postsynaptic cell membranes
2) Gap junction, 3) cytoplasmic continuity,
4) synaptic delay virtually absent, 5) ionic current flow
6) direction of transmission: usually bidirectional

not unique to nerve cells
present in other cells: heart, smooth muscle, epithelial liver cells
in the brain electrical synapse is less common
electrical synapses do not readily allow inhibitory actions or
long-lasting changes in effectiveness.