Download Nervous System

Nervous System
NERVOUS SYSTEM
NERVOUS
SYSTEM
CENTRAL
NERVOUS
SYSTEM
BRAIN
SPINAL
CORD
PERIPHERAL
NERVOUS
SYSTEM
NERVES
SENSE
ORGANS
Two Parts
• Central (CNS)
• Peripheral (PNS)
http://inside.salve.edu/walsh/cns_pns.jpg
Central Nervous System
• Brain
• Spinal Cord
The Brain
• Coordinates body activities
• Made up of approximately 100 billion
neurons
• Divided into three major parts– the cerebrum
– the cerebellum
– the brain stem (medulla)
Cerebrum
• Largest part of the brain
• Used for:
– Thinking
– Memory is stored
– Movements are controlled
– Impulses from the senses are
interpreted.
Cerebellum
• Interprets stimuli from eyes, ears,
muscles
• Controls voluntary muscle movements
• Maintains muscle tone
• Helps maintain balance
Medulla (Brain Stem)
• Connects brain to spinal cord
• Act as pathways connecting various
parts of the brain with each other
• Controls involuntary actions
– Breathing, digestion, heart beat
http://www.cbituk.org/GRAPHICS/brain.gif
The Spinal Cord
• Extension of the brain stem
• Bundles of neurons that carry
impulses from all parts of the body to
the brain and from the brain to all
parts of your body
PERIPHERAL
NERVOUS
SYSTEM
NERVES AND SENSES
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
• Interneuron
Sensory Neurons
• Receive information
• Send impulses to the brain or spinal
cord
Interneurons
• 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
STIMULUS /RESPONSE
•
Synapse
• Small space across which an impulse
moves from an axon to the dendrites
or cell body of another neuron
Synapse
• As 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
Peripheral Nervous System
• Connects body to brain & spinal cord
• 12 pairs of nerves from your brain
(cranial nerves)
• 31 pairs from your spinal cord (spinal
nerves)
– Bundles of sensory and motor neurons
held together by connective tissue
http://www.christopherreeve.org/Research/Research.cfm?ID=178&c=21
Peripheral Nervous System
• Two divisions
– Somatic
– Autonomic
http://abdellab.sunderland.ac.uk/lectures/Parmacology/Pics/anatomy/PNS.GIF
Somatic Nervous System
• Controls voluntary actions
• Made up of the cranial and spinal
nerves that go from the central
nervous system to your skeletal
muscles
Autonomic Nervous System
• Controls involuntary actions-those not
under conscious control-such as your
heart rate, breathing, digestion, and
glandular functions
http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/A/autonomic.gif
Reflexes
• Involuntary, automatic response to a
stimulus
• Involves a simple nerve pathway
called a reflex arc