Chemicals that are released at the synaptic junction are called

Explanation

A nerve impulse is transmitted from one neuron to another through junction called synapses.
There are two types of synapses. 1) Electrical synapses 2) Chemical synapses.
Electrical synapses : These synapses are electrically conductive links between two neurons and are also called :gap unctions". Impulses transmission across an electrical synapses is always faster than that across a chemical synapses.
Chemical synapses : Chemicals called neuro transmitters are involved in the transmission of impulses at those synapses. When an impulse arrives at the axon terminal, it depolarizes the membrane opening voltage gated calcium channels. Calcium ions stimulate the release of neurotransmitters in the cleft by exocytosis. The released neurotransmitters bind to their specific receptors, present on the post synaptic membrane.
The post synapticmembrane has ligand gated channels. They are ion channels which respond to chemical signals, rather than to changes in the membrane potential. The entry of ions can generate a new potential in the post synaptic neuron. The new potential developed may be either excitatory (or) inhibitory. Excitatory post synaptic potentials cause depolarisation, where as inhibitory post synaptic potentials cause hyper polarisation of post synaptic membrane.