Question

which type of neurone carry impulses towards synaptic cleft​

Answer 1

Answer:

For nerve impulses to be generated and carried, nerve cells should be in contact with each other. The nerve impulse is transmitted in the following sequence: 

Axon end- synapse- dendrites- dendron- cyton- axon body- axon end. A nerve impulse travels in a form of electrical charge from axon end to the synapse. Here, the electrical impulse is converted to the chemical impulse in the synaptic cleft. Further this nerve impulse flows from synaptic cleft to dendritic tips, converting the chemical impulse to electrical impulse. Thus, the flow of impulse always flows from one axonal end of a neuron to another dendronal head of a neuron. So, the correct answer is option D.

Answer 2

The action potential can't jump from one neuron to the next. So the message(nerve impulse) is transmitted across synapse in the form of chemical messenger called neurotransmitters.

These neurotransmitters are present in synaptic vesicles. When synaptic vesicles fuse with the presynaptic membrane then these neurotransmitters are relesed into the synaptic cleft.

The neurotransmitters then attach to the protein receptors of postsynaptic membrane, changing its permeability for certain ions i.e Na+ IONS and thus start an action potential in the postsynaptic neuron.

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