Do Now
http://www.youtube.com/watch?v=i-NgGKSNiNw
• How do you communicate messages to
friends?
• What are the purposes of these messages?
What are the functions of the
nervous system?
The main functions of nervous system
are communication and coordination of
body activities. This is done by
transmitting signals between the brain
and the rest of body.
Q: What are the functions of the
nervous system?
1. Collect information about the body’s
environment
– Internally and externally
2. Process the information
3. Create a response
– The brain or spinal cord creates
and sends a response to the body
There are two functioning parts of the
nervous system:
1. Central Nervous System
– Brain and spinal cord
– Processes information and creates response
2. Peripheral Nervous System
– Nerves that connect the body to the central
nervous system. They carry signals between
the central nervous system and body.
Central vs. Peripheral
Nervous System
Peripheral Nervous System
Consists of different types of cells;
• Nerves that carry information from the
sensory organs, ( skin, ear, eye, tongue, nose),
• Nerves that control the voluntary muscles,
• Nerves that regulate involuntary functions
such as breathing, digestion, and heartbeat.
• Nerves are made of bundles of
neurons , each surrounded by
connective tissue.
Central Nervous System Protection
• Skull protects the brain.
• Spine protects the spinal cord.
• Cerebrospinal fluid surrounds and cushions
the brain and the spinal cord. It transports
chemicals and removes waste from the central
nervous system.
Which diagram is showing
the nervous system?
Nerve tissue
• Is found in the brain, the spinal
cord and in the nerves.
• It is mainly made up of
neurons.
How is the information collected by the nervous
system carried through the body?
• Messages carrying information through the nervous system are
ELECTRICAL SIGNALS called IMPULSES
• NEURONS are cells that carry and pass along these signals
– Neurons are the main cells of the nervous system
“The functional units of the nervous system”
Structure of Neuron
• Cell Body – contains nucleus and much of
cytoplasm
• Dendrites – receive impulses (messages)
from other neurons
• Axon – long fiber carrying impulses away to
the next neuron
Quick Check…
• What are each letters?
• Are there more dendrites or axons in a
neuron?
How do electrical cords ensure the
electricity stays within the wire?
Lets make sure the message doesn’t
get lost…
• The axon is surrounded by a MYELIN SHEATH
– Keeps electric signal within the axon
– Causes the signal to move faster
Repair of Neurons
• Injured neurons in the central nervous
system don’t regenerate easily.
• Some neurons in peripheral nervous
system can regrow and repair a small
gap.
Start an impulse
• Stimuli cause electric signals
– A stimulus is a detectable
change in the environment.
• Impulses begin when neurons
Are stimulated by another neuron or
by the environment.
Sensory Receptors
• Sensory receptors are structures in the skin and
other tissues that detect changes in the internal
or external environment. These receptors consist
of specialized neuron endings or specialized cells
in close contact with neurons that convert the
energy of the stimulus (sound, color, odor, etc.) to
electrical signals within the nervous system.
Sensory receptors, together with other cells,
compose the major sense organs, including eyes,
ears, nose, and taste buds. Information from
different sensory receptors go to specific parts of
the brain.
• Read 3.10
• Bionic Arm, Diseases and disorders
• H.W. page 107 #1-7
How are messages passed between
neurons and other cells?
• The space between two neurons is called a SYNAPSE
Moving the signal between cells
• Once the signal reaches the end of the axon:
1. NEUROTRANSMITTERS are released into the
synapse
2. The neurotransmitters travel across synapse
and bind to CELL RECEPTORS (shape!!) on
the next neuron
3. The target cell takes message from
receptors and continues moving the signal
Regents Review
• The diagram represents the functional unit of
a nervous system. Which structure secretes a
neurotransmitter? Which structure contains
cell receptors that bind neurotransmitters?
• structure A
• structure B
• structure C
• structure D
Synapse and Neurotransmitters
1http://www.youtube.com/watch?v=FR4S1BqdFG4&safety_mode=true&persist_safety_mode=
1&safe=active
2http://www.youtube.com/watch?v=FR4S1BqdFG4&safety_mode=true&persist_safety_mode=
1&safe=active
3http://www.youtube.com/watch?feature=endscreen&v=qMsWtP3VS3Q&NR=1