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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
cell body
axon
astrocyte
Oligodendrocyte
Microglia
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
• Cerebrum
• Diencephalon
• Cerebellum
• Midbrain
• Pons
• Medulla
Brain stem
Cerebrum
• Cerebral CortexA 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