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Q3L02 The Nervous System


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Q3L02 The Nervous System

  2. 2. The Nervous System <ul><li>Complex network of neurons that regulates bodily processes </li></ul><ul><li>Has two major portions that functions as an integrated whole: 1) The Central Nervous System 2) The Peripheral Nervous System </li></ul>
  3. 3. Central Nervous System <ul><li>CNS – consists of the brain and the spinal cord </li></ul>
  4. 4. Spinal Cord <ul><li>2 Major Functions: </li></ul><ul><li>Carries sensory information from receptors throughout the body to the brain AND conducts information from the brain to muscles and glands. </li></ul><ul><li>Plays a key role in various reflexes – e.g. the hammer tap, hot stove! (behaviour produced without help from the brain) </li></ul>
  5. 5. Damage to CNS <ul><li>Originally thought be permanent </li></ul><ul><li>Scientists have since been able to implant nerve fibers from outside the spinal cord onto the damaged area to allow the damaged spinal nerves to grow through the implants. </li></ul><ul><li>Also know now that the brain can change itself by adapting neurons to serve new functions when old neurons die or are damaged. </li></ul>
  6. 6. PERIPHERAL SYSTEM <ul><li>Made up of all the nerves and neurons not contained in the brain and spinal cord. </li></ul><ul><li>Allows the brain and spinal cord to communicate with the sensory systems of the eyes, ears, skin, and mouth and allows the brain and spinal cord to control the muscles and glands of the body. </li></ul><ul><li>PNS divided into two major systems: somatic and autonomic </li></ul>
  7. 7. The Somatic Nervous System <ul><li>Senses  CNS and from CNS  muscles </li></ul><ul><li>Only voluntary muscles are controlled by the SNS (e.g. walking, raising hands, smelling flower, seeing art) </li></ul><ul><li>Nerves coming from the senses to the spinal cord and the brain are called sensory pathways (made up of sensory neurons) </li></ul><ul><li>Nerves carrying messages to skeletal muscles are called motor pathways (made up of motor neurons) </li></ul>
  8. 8. AUTONOMIC NERVOUS SYSTEM <ul><li>Autonomic suggests automatic! </li></ul><ul><li>Controls organs, glands, and involuntary muscles – parts of the body that keep us alive (heart, lungs, blood vessels and glands) </li></ul><ul><li>Transmits info to and from the CNS = automatic links from CNS with vital internal organs. </li></ul><ul><li>Operates continuously, involuntarily and without awareness. </li></ul><ul><li>Divided into two systems: sympathetic division and parasympathetic division . </li></ul>
  9. 9. Sympathetic <ul><li>Fight-or-flight system – responsible for reacting to stressful events and bodily arousal in emergency situations! </li></ul><ul><li>To increase energy, sugar is released into the bloodstream. To hasten distribution of blood to muscles, heart beats faster. Facilitates survival in the face of danger. </li></ul><ul><li>Located on the middle of the spinal column – running from near the top of the ribcage to the waist area. </li></ul>
  10. 10. Parasympathetic <ul><li>After the danger passes, the parasympathetic division of the ANS takes over. </li></ul><ul><li>Restores us to a calmer state. </li></ul><ul><li>Reverses changes mage by the sympathetic system. </li></ul><ul><li>Responds more slowly than sympathetic – can take 20 – 30 min to calm down. </li></ul>
  11. 11. Major Functions of the ANS Body Organ Sympathetic Division Parasympathetic Division Pupil of the eye Heart Stomach Intestines Adrenal gland Blood vessels in the skin Bladder Dilates Rapid, accelerates Inhibits activity Inactive Secretes adrenalin and noradrenaline Constricts Relaxes Constricts Slows Stimulates activity Active No intervention Dilate Contracts
  12. 12. Schematic diagram of the NS Nervous System (NS) Central NS Peripheral NS Brain Spinal Cord Somatic NS (Voluntary) Autonomic NS (Involuntary) Sympathetic NS (Arousing) Parasympathetic NS (Calming)