Question

How would you descrive the transmission of a nerve impulse across a synapse?

Answer 1

Nerve impulse transmission across synapse takes place by
1. Neurosecretion and
2. Chemoreception.

Synaptic transmission is achieved by use of neurochemicals.

Explanation:

Synapse has three structural entities:

1. presynaptic axonic terminal/knob,
2. synaptic cleft and
3. postsynaptic dendritic terminal/membrane.

Synaptic impulse transmission takes place from presynaptic to postsynaptic neuron.

• When nerve impulse reaches presynaptic terminal, calcium ions flow in. This prompts secretory vesicles stored inside axonic terminal to burst and release neurohumor substances in synaptic cleft.
• Neurohumor molecules act as neurotransmitters, and are of different types: acetylcholine, serotonin, etc. Neurotransmitter molecules diffuse through synaptic cleft and reach dendritic terminal.
• Postsynaptic dendritic membrane ramains associated with specific receptors for specific neurohumor. Attachment of neurohumor to receptor causes depolarisation and a new action potential is formed in the postsynaptic neuron.