NEURONS Functions of the nervous system The functions

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NEURONS!

NEURONS!

Functions of the nervous system • The functions of the nervous system are 1.

Functions of the nervous system • The functions of the nervous system are 1. 2. • Control functions in the body Respond to internal and external stimuli To accomplish these functions, the cells of the nervous system must be able to send messages!

Parts of a neuron • Dendrites – Carry messages from the environment to the

Parts of a neuron • Dendrites – Carry messages from the environment to the cell body • Cell body • Axon – Carries the impulse away from the cell body • Axonal terminal – Message is sent to the next neuron • Myelin – Fatty covering around axon that makes impulse travel faster

The cells of the nervous system • The cells in the nervous system that

The cells of the nervous system • The cells in the nervous system that send the messages are neurons • Neurons send ELECTRICAL impulses! • Your brain, spinal cord, and nerves are made of hundreds of billions of neurons!

• There are three main types of neurons Types – Sensory neurons •

• There are three main types of neurons Types – Sensory neurons • They bring messages from sensory organs to the brain and spinal cord – Motor neurons • They carry messages from the brain to muscles and glands – Interneurons • They connect sensory neurons to the motor neurons • Found in brain and spinal cord of neurons

Nerve impulse (Action Potential) • A neuron is stimulated by the environment OR by

Nerve impulse (Action Potential) • A neuron is stimulated by the environment OR by another neuron • The electrical impulse starts at the dendrites • It travels through the cell body • It travels down the axon away from the cell body • The impulse reaches the axonal terminals

Nerve impulse • The message is at the axonal terminal • The message needs

Nerve impulse • The message is at the axonal terminal • The message needs to be passed to the next neuron • The two neurons DO NOT TOUCH EACH OTHER • There is a gap called a synapse

Nerve impulse • When the impulse reaches the end of the first neuron, chemicals

Nerve impulse • When the impulse reaches the end of the first neuron, chemicals called neurotransmitters (NT) are released! • The NT move across the synapse • The second neuron catches the NT • The second neuron is stimulated when it catches the NT • The electrical impulse then starts in the second neuron

Nerve impulses • The sending of messages along neurons is happening ALL OF THE

Nerve impulses • The sending of messages along neurons is happening ALL OF THE TIME in your brain, spinal cord, and nerves! • It is VERY FAST!

Neurotransmitters

Neurotransmitters

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