Download Nervous system Nervous system

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