Neurons

Messages, in the form of electrical impulses, constantly travel back and forth between the brain and other parts of the

body.

A special cell called a neuron is responsible for carrying these messages.

There are about 100 billion neurons in the human brain.

Three main parts of a neuron:

1. The cell body contains the nucleus and directs all activities of the neuron.

Label, color, and describe the cell body…(yellow)

and the nucleus … (green)!

(The cell body or soma contains the nucleus)

2. Dendrites extend out

from the cell body like

branches and receive

messages from other nerve

cells.

Label and describe the

job of the dendrites.

(Receives Messages)

3. An axon is a long single fiber that

transmits messages from the cell body to:

a. the dendrites of other neurons b. other body tissues, such as muscles.

Label, color, and describe the job of the

axon…(orange)

(Transfers Message)

Myelin sheath, covers most neurons. Made of lipoproteins (fat)

1. insulates the axon2. helps nerve signals

travel faster and farther.

Damage can leadMultiple sclerosisFibromyalgia

Label, color and describe the job of the

myelin sheath…(blue)!

(Protects and helps messages send faster and farther)

Label, color, and describe

the axon terminals…

(red)!

(Sends Neurotransmitters)

Messages travel along a single neuron as electrical impulses, but messages between

neurons travel differently. The transfer of information from neuron to

neuron takes place through the release of chemical substances called neurotransmitters

into the space between the axon and the dendrites.

The process is called neurotransmission. The space between the axon and the

dendrites is called the synapse.

• Impulse triggers the release of neurotransmitters from the axon terminal into the synapse.

• Neurotransmitters cross the gap between neurons and bind to receptors.

• Synapse is the minute gap between neurons.

• Receptors are located on dendrites. Receive and process msgs.

A

C

B

F

DA. Cell body B. Nucleus C. DendritesD. AxonE. Myelin SheathF. Synapse

E

Three Types of Neurons1.Sensory (or afferent) neurons: send information

from sensory receptors (e.g., in skin, eyes, nose, tongue, ears) TOWARD the central nervous system.

2.Motor (or efferent) neurons: send information AWAY from the central nervous system to muscles or glands.

3.Interneurons: send information between sensory neurons and motor neurons. Most interneurons are located in the central nervous system.

Review

1. The __________________ protects the axon and helps messages travel faster.

2. The __________________ receives messages from other neurons.

3. The __________________ contains the nucleus and directs the activities of the cells.

4. Messages travel through a space called the __________________ between neurons.

myelin sheath

dendrites

cell body

synapse

Review

1. An__________________ is a long single fiber that transmits messages from the cell body

2. Chemicals called _____________________ allow for the transfer of information from one neuron to another neuron.

3. Dendrites have tiny__________________ which receive and process the information from a neruon.

4. _______________ neurons send signals to muscles or glands.

Axon

Neurotransmitters

Receptors

Motor

http://images.google.com/imgres?imgurl=http://www.drugabuse.gov/JSP/MOD3/images/NEURON2.gif&imgrefurl=http://www.drugabuse.gov/JSP/MOD3/page3.html&usg=__rzbUKVLZ-

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RESOURCES

http://www.biotechlearn.org.nz/var/biotechlearn/storage/images/focus_stories/transgenic_cows/images/a_nerve_cell/219060-1-eng-AU/a_nerve_cell_large.jpg

http://upload.wikimedia.org/wikipedia/commons/thumb/b/bc/Neuron_Hand-tuned.svg/400px-Neuron_Hand-tuned.svg.png