The+Nervous+System

The Nervous System

1. The Nervous System consists of the central nervous system and the peripheral nervous system.

2. Three types of neurons include sensory neurons, interneurons and motor neurons.

3. The three main parts of the neuron include; the cell body, which holds the nucleus, the dendritie, which receives signals, and the axon, which conducts nerve impulses.

4. A nerve impulse is the way in which the nervous system conveys information. When a nerve impulse is not occuring in the axon of a neuron, there is resting potential. This term means that there is a difference in ion distribution on varying sides of the axon's membrane, and the difference is caused by a sodium-potassium pump. It pumps sodium out and potassium into the axon. When a stimulus causes the difference between sodium and potassium levels to fluctuate to a threshold level, action potential occurs. The sodium gate opens and sodium floods the axon, depolarizing it. Then, the potassium gate opens, and potassium rushes to the outside of the axon. Repolarization occurs as the axon regains a negative charge and potassium leaves.

5. Neurons are able to transmit impulses across to one another due to neurotransmitter molecules. These molecules are released when signaled, and they bind to receptor proteins on each side of the synapse.

6. The central nervous system is mainly composed of the spinal cord and the brain.

7. The spinal cord holds many reflex arcs, and it provides communication between nerves leaving it and the brain. It also controls pain messages and how and when they are received by the brain.

8. The four main parts of the brain include the cerebrum, the diencephalon, the cerebellum and the brain stem. The cerebrum is divided into hemispheres, and controls activities such as learning, memory, reasoning and speech. The diencephalon regulates homeostasis in the body. The cerebellum maintains posture and balance and tells body parts where they should be located after receiving sensory input. Finally, the brain stem controls visual, auditory and tactile responses. It is in charge of breathing and the body's heartbeat.