AP BIOLOGY

Detailed explanation-1: -The nervous system uses tiny cells called neurons (NEW-ronz) to send messages back and forth from the brain, through the spinal cord, to the nerves throughout the body. Billions of neurons work together to create a communication network. Different neurons have different jobs.

Detailed explanation-2: -There are basically two major types of nerves: sensory and motor. Sensory nerves send information such as touch, temperature, and pain to the brain and spinal cord. Motor nerves send signals from the brain back into the muscles, causing them to contract either voluntarily or reflexively.

Detailed explanation-3: -The neuron has branches (like a tree) called dendrites, which receive signals, and a longer, simpler projection (like a tree trunk), called an axon, which sends signals. Synapses are found at the end of axons.

Detailed explanation-4: -Neurons carry messages from the brain via the spinal cord. The neurons that carry these messages to the muscles are called motor neurons. Each motor neuron ending sits very close to a muscle fibre. Where they sit together is called a neuromuscular junction.