The Neuron 31.1

Functions of the nervous system Two parts to the nervous system: Peripheral nervous system – nerves and supporting cells that collects information. Central nervous system –consists of the brain and spinal column. The function of the nervous system is to collect information, process it, and then respond to it.

Neurons Neurons are the basic unit of the nervous system. Types of neurons – Sensory neurons carry impulses from the sensory organs to the spinal cord and brain. Motor neurons carry impulses from the brain and spinal column to the muscles and glands. Interneurons process information from sensory neurons and send commands to other interneurons.

Structure of the neuron

The Nerve Impulse A Nerve Impulse  Neurons at rest: inside is negatively charged, outside is positively charged  Sodium ions (Na + ) outside and K + inside

33.1 Structure of the Nervous System During an action potential (AP): Na + moves into the axon, K + rushes out. After the AP, the Na/K pump restores the membrane (3 Na + move out for every 2 K + moving inside). Inside becomes positive and outside becomes negatively charged.

Graph and steps of an action potential

Transfer of signal between neurons At the end of the neuron is the synapse. This is where the electrical impulse is changed into a chemical signal. These chemicals are called neurotransmitters.