What is the function of the
nervous system?
 Sensory Input: action of getting information from the
surrounding environment. Things are being sent to
the brain by way of the senses (touch, smell, see, etc.)
 Integration: the interpretation or translation of
things that have been touched, smelled, seen, etc.
Takes place in the brain.
What is the function of the
nervous system?
 Motor Output: After your brain has interpreted all
that has been by using your senses, then your brain
sends a message through neurons to muscles or other
cells which work to perform the response.
The Nervous System
*The nervous system is divided into 2 parts:
*Central Nervous System: the brain,
spinal cord, and association
neurons
*Peripheral Nervous System: all the
nerves outside the CNS
Central Nervous System
 The body’s most rapid means of maintaining
homeostasis.
 Regulates bodily functions by sensing changes within
the body and from the environment.
 Makes adjustments by delivering impulses which
results in muscular contractions and/or glandular
secretions.
Central Nervous System
 Association neurons:
make up most of the
spinal cord.
 Change input impulses
to output impulses and
cause the body to
respond.
Peripheral Nervous System
Peripheral Nervous System
 There are two types of neurons in this system, sensory
neurons and motor neurons

Sensory Neurons: sends information to
CNS from internal organs and from
environment and motor neurons.

The motor neurons send impulses to
voluntary and involuntary muscles.
Peripheral Nervous System
 Motor Neurons: divided into somatic and
autonomic nervous system
 Somatic nervous system: controls skeletal
muscles and external sensory organs such as the
skin. System is voluntary, except for reflex
reactions of skeletal muscles.
Somatic Nervous System
Peripheral Nervous System
 Autonomic Nervous System: Controls
involuntary muscles such as the smooth and
cardiac muscle.
 Also called the involuntary nervous system.
Autonomic Nervous System
Nerve Cells
 Neurons
 Basic functioning units of the
nervous system
http://ilearn.senecac.on.ca/aahs/health/IHP/ottawa/anatomy/neuron/map/neuron.html
http://35.9.122.184/images/40-AnimalStructureAndFunction/
Neurons
 Made up of a cell body and branches
called dendrites and axons
 Dendrites receive messages from other
neurons and send them to the cell body
 Axons carry messages away from the cell
body
Any message carried by a neuron is called an impulse
Neurons
A message carried by a neuron is called
an impulse
Types of Neurons
 Sensory
 Motor
 Association
Sensory Neurons
 Receive information
 Send impulses to the brain or spinal cord
Association Neurons
 Send impulses from sensory neurons to motor neurons
Motor Neurons
 Conduct impulses from the brain or spinal cord to
muscles or glands throughout your body
Synapse
 Small space across which an impulse
moves from an axon to the dendrites or
cell body of another neuron
Synapse
 An impulse reaches the end of an axon
 Axon releases a chemical
 Flows across the synapse
 Stimulates the impulse in the dendrite of the
next neuron
 Impulse moves from neuron to neuron
http://www.med.harvard.edu/publications/On_The_Brain/Volume7/Number1/images/Neuron.jpg
An impulse moves in only one direction across a
synapse - from an axon to the dendrites or cell body of
another neuron.
http://mhln.com
http://inside.salve.edu/walsh/cns_pns.jpg
Reflexes
 Involuntary, automatic response to a stimulus
 Involves a simple nerve pathway called a reflex arc