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Nervous system

Explore the structure and functions of the nervous system, including neurons, CNS, PNS, brain lobes, and reflex actions. Learn about the brain, spinal cord, and reflex mechanisms through practical experiments and observations.

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Nervous system

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  1. Nervous system

  2. 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.

  3. Nervous tissue dendrite nucleus astrocyte cell body Microglia Oligodendrocyte axon

  4. 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

  5. CNS & PNS • Central nervous system = Brain + Spinal cord • Peripheral nervous system = Cranial nerves + Spinal nerves (gather info from sensors and conduct decisions to effectors)

  6. Nerves • Structures containing many long fibers with myelin sheath (axons / dendrites) • Nerves do not contain cell bodies

  7. Brain • Cerebrum • Diencephalon • Cerebellum • Midbrain • Pons • Medulla Brain stem

  8. 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

  9. 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

  10. 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

  11. 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

  12. Spinal cord • The center for many reflex actions (involuntary and predictable response to a given stimulus) • Contains white and butterfly-shaped gray matter

  13. Spinal reflexes • A reflex is an involuntary and predictable response to a given stimulus. • The brain is not involved in formulating the response.

  14. dorsal ventral

  15. Experiment • Dissecting sheep brain, observing structure of brain • Observing prepared slides and learning the structure of spinal • Spinal Reflexes page 432

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