Neurons are specialized cells that send chemical and electrical signals to/through the brain. There are 3 different kinds of neurons: Motor neurons, Sensory neurons, and Interneurons. Motor neurons are neurons that are located in the Central Nervous System. They join with muscle fibers in order to make the muscle contract. They also join with muscle spindles which are stress receptors that are typically used in reflex testing. They are sensitive and when they are stimulated they send an impulse directly to the spinal cord and create a muscle contraction. They directly and indirectly control muscles. Sensory neurons are responsible for sending stimuli signals to the brain. For example, if I hit my elbow, the sensory neurons are responsible for telling my brain that it hurt, and the amount of pain I am in. Sensory neurons respond to a particular stimulus which affect the senses and converts it into electrical signal via transduction, which is sent to the spinal cord or brain. The brain then decides on what to do based on the signal sent by a sensor neuron. Interneurons connect neurons to other neurons within the same region of the spinal cord or brain in networks. It is basically a telephone line between neurons. It enables communication between sensory or motor neurons and the central nervous system. The interaction between interneurons allow the brain to perform complex functions such as learning, and decision making. An action potential occurs when a neuron sends information down an axon (nerve fiber that is long slender projection of a nerve cell that sends messages away from nerve cell body). It is caused when different ions cross the neuron membrane. Part of the neuron membrane opens to allow positively charged ions inside the cell and negatively charged ions out.

The synapse is the point of connection between two neurons or between a neuron and a muscle or gland. Electrochemical communication between neurons takes place in synapses. They consists of three elements: presynaptic membrane, the postsynaptic membrane and synaptic cleft. The presynaptic membrane is formed by the terminal button of an axon while the postsynaptic is composed of dendrite or cell body. The space between the two structures is called the synaptic cleft. When a nerve impulse reaches the end of an axon, the axon releases chemicals which are known as neurotransmitters. They then travel across the synapse which then bind to the membrane of the receiving dendrite. This binding allows the nerve impulse to travel through the neuron. When the brain gets really excited , it fires off a lot of signals. The faster and more excited the brain is , the higher frequency of action potentials are. However, at rest the action potential would not be sent down as the channels are deactivated and closed for ions to come through.