Transcript Chapter 35 “The Nervous System

Chapter 35 “The Nervous
System”
• 35.1 “The Human Nervous
System”
• Objective:
– List the 3 main structures of a neuron
– Describe a Nerve Impulse
Neurons
• Basic unit of the N.S.
• Carry messages in the form of
electrical impulses
• Made up of:
– cell body - largest part
– dendrites - carry impulses toward the cell
body
– axon - carries impulse away from cell body
– axon terminal – sends impulse to next
neuron
Three Types of Neurons
1. Sensory : body to brain
2. Motor : brain to body
3. Interneurons : connect sensory
& motor neurons in brain and
spinal cord
Nerve Impulse
• Begins when a neuron is stimulated by
env. or another neuron
• Resting Potential: a neuron without an
impulse
– Inside of neuron is more negative than
outside
• Action Potential: change in charge
– Inside of neuron becomes more positive
Inside is negative
Domino effect passes
action potential down axon
Resting Potential
Inside becomes positive
Inside returns to negative
Myelin
• Myelin sheath:
fatty layer
which insulates
axon
• Speeds up
impulse
Synapse
• Synapse: The space between the
axon terminal of one neuron and
the dendrites of the next neuron.
• Axon terminal
releases
neurotransmitters.
35.2 “Organization of
the N.S”
• Objective:
–Distinguish between the
Central Nervous System & the
Peripheral Nervous System.
The Central Nervous
System
• Brain
• Spinal Cord
The Brain
• Four lobes, two halves
• Major regions:
– Cerebrum – conscious activity/thought
– Cerebellum – coordinates movement
– Brain stem – connect brain and spinal cord,
controls many involuntary fxns
– Thalamus – receives sensory messages
– Hypothalamus – controls primitive needs and
emotions
The Brain
The Spinal Cord
• 31 pairs of nerves
branch off
• Controls reflex arc
Peripheral Nervous
System
• All nerves outside of
brain and spinal cord
• Sensory – receives
internal and external
stumuli
• Motor – controls muscles
and glands
Peripheral Nervous
System
• Motor Division
– Somatic NS – controls all voluntary activity
– Autonomic NS – involuntary activity
• Sympathetic – controls body during
times of stress
– Ex - speeds up heart rate
• Parasympathetic – controls body
normally, returns body to normal state
after stress
– Ex – slows heart rate
N.S. Concept Map
Nervous System
Central NS
Brain
Peripheral NS
Spinal Cord
Motor
Somatic
Sensory
Autonomic
Sympathetic
Parasympathetic
Chapter 35.3
“The Senses”
• Objective:
–List and discuss the 5
senses.
The Five Senses
• Sight, Sound, Taste, Touch,
Smell
• There are 5 general categories
of sense receptors.
– Pain receptors
– Thermoreceptors - temperature
– Mechanoreceptors – touch, sound
– Chemoreceptors - chemicals
– Photoreceptors - light
Vision
• Photoreceptors
in retina
–Rods – detect
light
–Cones – detect
color
Hearing
• Acoustic Receptors: a special type
of mechanoreceptor.
– Respond to sound (disturbance of air)
– Found in inner ear.
• Semicircular canals: fluid filled
tubes that help you maintain your
balance
The Ear
Semicircular canals
Smell & Taste
• Chemoreceptors
–Respond to taste
& smell (chemical
stimuli)
• Found in tongue,
roof of mouth,
nasal cavity.