Nervous System
Nervous System
• Stimulus any change inside or outside your
body the brings about a response
• Homeostasis regulation of steady conditions
inside organism
Neurons
• Made up of a cell body and branches called dendrites and
axons
– Dendrites receive messages and send them to the cell body
– Axons carry messages away from the cell body
• Messages carried by nerve cells called impulses
• Three types
– Sensory send info to brain
– Interneurons send info from sensory to motor
– Motor conduct impulses from brain to muscles/glands
• Nerve cells do not touch
– Synapse space between nerve cells
– Chemicals flow across synapse and relay impulse to dendrite of
next neuron
Nervous System
• Central Nervous System Made up of brain
and spinal cord
• Peripheral nervous system connects your
brain and spinal cord to rest of body
Injuries
• Injuries to nervous system very serious
– Injury to spine can cause loss of muscle
movement, or paralysis
• Important to wear safety gear when playing sports,
riding in a car, or on a bike
Reflex
• An involuntary automatic response to a
stimulus controlled by the spinal cord
Drugs
• Drugs like alcohol and caffeine affect nervous
system
– Alcohol slows activities of CNS
– Caffeine speeds up activity of CNS
Senses
• 5 senses
– Vision
– Hearing
– Smell (olfactory)
– Taste
– Touch