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The Nervous System
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  1. The Nervous System

  2. Functions of the Nervous System • Respond to internal and external stimuli • Transmit nerve impulses to and away from CNS • Interpret nerve impulses at the cerebral cortex • Assimilate experiences in memory and learning • Initiate glandular secretions and muscle contraction • Program instinctual behavior

  3. Divided into… • Central Nervous System (CNS) • Peripheral Nervous System (PNS)

  4. Central Nervous System (CNS) • Composed of: • Brain • Spinal Cord

  5. Peripheral Nervous System (PNS) • Composed of: • Cranial Nerves (from the brain) • Spinal Nerves (from the spinal cord) • Ganglia (clusters of cell bodies of neurons) • Plexuses (networks of nerves)

  6. Autonomic Nervous System (ANS) • Functional division of nervous system • Structures in the brain are the control centers of the ANS • Nerves are the pathways for conduction of these nerve impulses • Functions to automatically speed up or slow down body activities

  7. Neurons • Nerve cells found in both CNS and PNS

  8. Parts of a neuron • Cell Body • Similar to other types of cells • Contains a nucleus • Dendrites • Extensions that project from the cell body • Short and branching • Receive signals from other neurons • Transmit impulses to the cell body • Axon • Covered in a myelin sheath (like insulation on a wire) • Myelin is produced by Schwann cells • Transmit impulses away from the cell body

  9. Types of Neurons • Sensory Neurons: transmit impulses to the CNS • Somatic sensory: carry impulses from receptors in the skin, bones, muscles, and joints • Visceral sensory: carry impulses from the visceral organs • Motor Neurons: transmit impulses away from the CNS • Association neurons (interneurons): conduct impulses from sensory to motor neurons

  10. CNS: The Brain • Five Regions Brain Region Structures Telencephalon Cerebrum Diencephalon Thalamus, Hypothalamus, Pituitary Gland Mesencephalon Superior & Inferior colliculus, Cerebral peduncles Metencephalon Cerebellum and Pons Myelencephalon Medulla oblongata

  11. Cerebrum (Telencephalon) • Two hemispheres • Connected by the corpus collosum • Five lobes • Frontal, Parietal, Temporal, Occipital, Insular • Responsible for higher functions • Perception of sensory impulses, instigation of voluntary movement, memory, thought, and reasoning • Cortex (outer surface) has elevated fields (gyri/gyrus) and grooves (sulci/sulcus)

  12. 5 Lobes • Frontal Lobe: voluntary control of skeletal muscles; personality; intellectual process; verbal communication • Parietal Lobe: cutaneous and muscular sensations; understanding and utterance of speech • Temporal Lobe: interpretation of auditory sensations; auditory and visual memory • Occipital Lobe: integration of movements in focusing the eye; correlation of visual images with previous experiences; conscious seeing • Insular: memory; integration of other cerebral activities

  13. Diencephalon • Thalamus: a relay center for all sensory impulses to the cerebral cortex, except for smell • Hypothalamus: cardiovascular regulation, body temperature regulation, water and electrolyte balance, gastrointestinal activity and hunger, sleeping and wakefulness, sexual response, emotions, and control of endocrine functions through stimulation of the anterior pituitary • Pituitary Gland: has endocrine functions

  14. Mesencephalon (Midbrain) • Short section of the brain stem • Contains: • Superior colliculi(visual reflexes) • Inferior colliculi (auditory reflexes) • Cerebral peduncles (coordinates reflexes)

  15. Metencephalon • Pons • Relays impulses from one region of the brain to another • Many cranial nerves originate here • Involved with regulating respiratory rate • Cerebellum • Consists of two hemispheres • Involuntary coordination of skeletal-muscle contractions within muscles, tendons, joints, and sensory organs

  16. Mylencephalon • Medulla oblongata • Connects to spinal cord • Makes up much of the brain stem • Controls autonomic functions (heart rate, contraction of blood vessels, rate and depth of breathing)

  17. CNS: The Spinal Cord • Extends through the vertebral canal of the vertebral column • Conducts nerve impulses to and from the brain

  18. PNS: Cranial Nerves • Innervate structures of the head, neck, and trunk • Identified by Roman numerals in order of appearance from front to back • 12 cranial nerves

  19. PNS: Spinal Nerves • 31 pairs • 8 cervical • 12 thoracic • 5 lumbar • 5 sacral • 1 cocccygeal • After exiting the vertebral column, they split, combine, and split again forming a plexus (there are 4) • Cervical plexus • Brachial plexus • Lumbar plexus • Sacral plexus

  20. http://health.nih.gov/category/BrainandNervousSystem