Nervous System

Neuron Structure

• Neurons are "similar to other cells in the body" in that they: • Have a cell membrane. • Have a nucleus that contains DNA. • Have cytoplasm

Axon

- Axons are the " long body extension" of a neuron. - The axon takes information (in the form of electricity) away from the cell body (the head end - which contains the cell nucleus) towards the terminal end (or tail) of the neuron.

Dendrite

- Dendrites (These are the head extensions) collect "information" in the form of chemical signals from other nearby neurons. - When sufficient chemical signals are received by the Dendrites an electrical signal (or impulse) is made (generated) in the cell body and axon.

Neurons

- Nerve Cells - They are specialized to carry "messages" - around the body, to and from the brain - Neurons generate and transmit Electrical signals. these electrical signals are called - impulses - Neurons connect and communicate with other neurons using chemicals called Neurotransmitters

Neurons are different from other cells

- Neurons can be very long -some are up to half a meter long ! (For example the neurons that go from your toes to your spine). Why so long? The anatomy (structure) of a neuron is related to its Physiology (function) - taking messages from one area of the body to another. - Neurons are different from other cells because they can generate (make) and transmit electricity (impulses)

Neurotransmitters

- Neurons connect and communicate with other neurons using chemicals called Neurotransmitters - Once the electrical "impulse" reaches the "Terminal end of an axon" it causes the terminal end to release special chemical substances. These are called Neurotransmitters. - The neurotransmitter chemical then causes the NEXT neuron to generate/make a new electrical signal or impulse.

Impules

- Neurons generate and transmit Electrical signals. these electrical signals are called - Electrical messages or "impulses" travel along the Axon of the neuron

How do manmade "Drugs" affect the nervous system

- Some drugs speed up the nervous system - this is called stimulation. (for example caffeine or nicotine) - Some drugs slow down the nervous system - they depress it (alcohol does this)

Sensory neurons

- are nerve cells that take information from the skin and other sensory organs (like the eye and ear) to the brain - notice that the "heads" of all of the different types of sensory neurons are slightly different in shape. - The special "head region" of a nerve cell is called the Dendrite

Sensory neurons in your body

Some areas of the body are more sensitive than others because they have sensory nerves in that specific location

synapse

These neurotransmitter chemicals Diffuse across a "tiny gap" - this tiny gap that separates the end of one neuron from the dendrite (head) of another is called a synapse.

How the Brain is linked to your organs

This system of an ELECTRICAL SIGNAL being converted to a CHEMICAL SIGNAL which is then converted to a new ELECTRICAL SIGNAL is how the brain is linked to all organs of your body