Post on 23-Dec-2015
Divisions of the Nervous System
The nervous system is divided into- Central Nervous System (CNS), containing the brain and spinal cord- The Peripheral Nervous System (PNS), containing the nerves and ganglia
The Peripheral Nervous System
contains… cranial nerves
which arise from the brain
Spinal nerves which arise from the spinal cord as well as many branches
Nerve Tissue
The nerve tissue is composed of two types of cells: -neurons, which conduct impulses, and…-neuroglia which support the neurons
Neurons Structural and functional
units of the nerve system Perform sensory, integrative
and motor functions-sensory: ability to sense (receive) information-Integrative: ability to process the information received and arrive at a desire to respond.-Motor: ability to initiate a response with body movement or secretion of a product.
Structure of neurons
Each contain a cell body with a nucleus
Numerous dendrites: receive and send information to the cell body
A single axon: moves impulse from dendrites and body to dendrites or body of other neurons.
2. Nucleus
The nucleus is the control center of the cell and contains the genetic information in the form of DNA
5. Axon Tip(s)
The axon tips release chemicals that enable the impulse to cross the synapse
Axon Tips
6. Synapse
The space between the axon tip and the next dendrite. It is also called the synaptic cleft.
Myelin in PNS and CNS
Axons in large peripheral nerves contain a fatty, supportive sheath called myelin sheath
Presence of myelin makes nerve tissue appear white (white matter)
In CNS spinal cord, unmyelinated nerve tissue appear gray (grey matter)
What makes up the brain, the spinal cord or your peripheral nerves?
Neurons are “the cell”
Cell body Nucleus Axon Dendrite What do you think
surrounds the cell? What other
organelles would be needed?
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
AXON
The synapse - where the action happens
The next cell’s plasma membrane
What is this in the membrane?
Transport protein
Close up look at your synapse (The Gray Matter)
How does the Synapse carry the signal?
1. impulse travels down the axon (The White Matter)2. Vesicles with neurotransmitters move toward the
membrane 3. Neurotransmitters are released and diffuse toward
the next cell’s plasma membrane4. The chemicals open up the transport proteins and
allow the signal to pass to the next cell
There are lots of proteins and chemicals in your body to do the work
Why is it important that it is an electrical current?
Alcohol damages dendrites - can repair after abstinence
Alcohol blocks receptors and slows down transmission
100 Billion or so neurons - what’s the problem with some of them dying?• Cells multiply all the time
- will your neurons?• Does everyone react the
same way to accidents, or drugs and alcohol?
• Do all organisms react the same to all stimulus?
• Which of your activities use your neurons?