Transcript Unit 10 Chapter 36 The Nervous System

Unit 10
Chapter 36
The Nervous System
The Nervous System
Neurons
Nerves cells, the basic unit of structure &
function of the nervous system
The Nervous System
Neuron structure:
Dendrites
Branchlike extensions that receive impulses &
carry them toward the cell body
Cell body
Location of the nucleus & much of the
cytoplasm
Axons
Extensions carrying the impulse away from the
cell body
The Nervous System
 Categories of neurons:
 Sensory neurons carry impulses from the body
to the spinal cord & brain
 Motor neurons carry impulses from the spinal
cord & brain to the body
 Interneurons are found within the spinal cord &
brain, pass response impulses between sensory
& motor
The Nervous System
 Transmitting an Impulse:
 Each impulse consists of an electrical charge
that travels the length of a neuron’s cell
membrane to a gap, called a synapse
 The impulse is caused by the depolarization of
chemicals surrounding the cell membrane
 Chemicals called nuerotransmitters, are
released into the synapse, which stimulates a
charge in the next neuron
Transmitting an impulse along the axon
Click on image to play video.
Transferring signals across the synapse
to an adjoining neuron
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The Nervous System
Division of the Nervous System:
Central Nervous
System (CNS)
Consists of the
brain and spinal cord
Peripheral Nervous
System (PNS)
Consists of the nerves
that carry messages
to & from the CNS
The Central Nervous System
Anatomy of the Brain:
Cerebrum
Largest lobe, controlling voluntary movement,
intelligence, memory, & the senses
Cerebellum
Located at the back,
controlling balance, posture, and coordination
Medulla oblongata
Located within the brain stem,
controlling involuntary (vital) activities
Cerebrum
Cerebellum
Medulla
The Peripheral Nervous System
 Somatic Nervous System
(SNS)
Made up of cranial & spinal
nerves, relaying voluntary
information between the
CNS and the skin & muscles
 Autonomic Nervous
System (ANS)
Made up of the sympathetic
& parasympathetic systems,
relaying involuntary
responses, not under
conscious control
The Peripheral Nervous System
Reflexes
An automatic, unconscious response for
protecting the body
This response travels to the spinal cord
where it responds directly back to a muscle
The Senses
Sensing Chemicals:
Odor chemicals stimulate nerve endings in
the nasal passages, which transmit
through the olfactory nerve to the
cerebrum
Chemical dissolved in saliva
stimulate nerve endings in
the taste buds of your
tongue, detecting only
sweet, sour, bitter & salty
The Senses
Sensing light:
The eye’s retina contains nerve enedings
called rods & cones, which transmit
impulses through the optic nerve to the
cerebellum
Rods and Cones
The eye
The Senses
Sensing vibrations (sound)
Sounds waves vibrates
the eardrum, the three
small bones—hammer,
anvil, & stirrup—then the
nerve endings in the
cochlea, which transmit
impulses through the
auditory nerve to the
cerebrum
The ear
Click on image to play video.
The Senses
Sense of Balance:
Within the inner ear are three
semicircular canals, which contain fluid &
nerve endings that transmit impulses to
the cerebellum
The Senses
Sense of Touch:
Nerve endings in the dermis of your skin
respond to temperature, pressure and
pain, transmitting impulses through
sensory neurons to the CNS