The receptor, now receiving a message, transmits it from the surface of the cell deep into the interior and a chain reaction occurs—biochemical events—and tiny machines directed by the ligands, make any number of activities happen, such as manufacturing new proteins, making decisions about cell division, opening or closing ion channels, and adding or subtracting energetic chemical groups.
The human brain contains billions of nerve cells or neurons, the information processing system.
A neuron has:
- Dendrites (inputs)
- Cell body
- Axon (output)
A synapse is the place where two neurons join in such a way that a signal can be transmitted from one to the other. Basically, the axon of one neuron activates a second neuron and like a chain reaction, makes a synapse with one of its dendrites or within the cell body. The two types of synapse reactions are: electrical or chemical.
A neuron receives input from other neurons and the neuron discharges an electrical pulse that travels from the body, down the axon, to the next neuron or other receptors. The axon endings are close to the dendrites or cell body of the next neuron. Transmission of an electrical signal from one neuron to the next is effected by neurotransmitters, chemicals which are released from the first neuron which bind to receptors in the second. This link is called a synapse.