Transcript Document
Nervous system
Nervous system
• Nervous system consists of the brain, spinal
cord, and nerves.
• Nervous tissue consists of neurons; whereas
the brain and spinal cord contain all parts of
neurons, nerves contain only axons.
Nervous tissue
dendrite
nucleus
astrocyte
Microglia
cell body
Oligodendrocyte
axon
Neurons
• Motor Neurons
– Accept nerve impulses from the Central nervous
system (CNS)
– Transmit them to muscles or glands
• Sensory Neurons
– Accept impulses from sensory receptors
– Transmit them to the CNS
• Interneurons
– Convey nerve impulses between various parts of
the CNS
CNS & PNS
• Central nervous system = Brain + Spinal cord
• Peripheral nervous system = Cranial nerves + Spinal
nerves (gather info from sensors and conduct
decisions to effectors)
Nerves
• Structures containing many long fibers with myelin
sheath (axons / dendrites)
• Nerves do not contain cell bodies
Brain
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Cerebrum
Diencephalon
Cerebellum
Midbrain
Pons
Medulla
Brain stem
Cerebrum
• Cerebral Cortex
A thin but highly convoluted outer layer of gray matter
• 4 lobes:
frontal lobe; temporal lobe; parietal lobe; occipital lobe
White matter
The rest of cerebrum except cerebral cortex
• Responsible for higher mental capabilities
Diencephalon
A region encircling the 3rd ventricle
Consists of hypothalamus + thalamus + pineal gland
Hypothalamus forms floor of the 3rd ventricle
Thalamus located in the sides and roof of the 3rd ventricle
Pineal gland secretes melatonin
Helps integrate mental functions, primitive emotion
and sleep
Cerebellum
• Separated from the brain stem by the 4th ventricle
– Receives sensory input from the eyes, ears, joints,
and muscles
– Sends motor impulses out the brain stem to the
skeletal muscles
• Helps maintain balance and produce smooth
movements
Brain stem
• Contains the midbrain, the pons, and the medulla
oblongata
– Midbrain
• Acts as a relay station for tracts passing between
the cerebrum, and the spinal cord or cerebellum
– Pons
• Helps regulate breathing and head movements
– Medulla oblongata
• Contains reflex centers for vomiting, coughing,
sneezing, hiccuping, and swallowing
Spinal cord
• The center for many reflex actions (involuntary and
predictable response to a given stimulus)
• Contains white and butterfly-shaped gray matter
Spinal reflexes
• A reflex is an involuntary and predictable
response to a given stimulus.
• The brain is not involved in formulating the
response.
dorsal
ventral
Experiment
• Dissecting sheep brain, observing structure of
brain
• Observing prepared slides and learning the
structure of spinal
• Spinal Reflexes page 432