Life Science Chapter 21 The Nervous System


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Life Science Chapter 21 The Nervous System

  1. 1. The Nervous System
  2. 2. <ul><li>Neuron – working unit of the nervous system </li></ul>
  3. 3. <ul><li>Axon – carries messages away from the cell body </li></ul>
  4. 4. <ul><li>dendrites – receive the messages and send them to the cell body </li></ul>
  5. 5. <ul><li>Terminal Bud – send messages to other neurons </li></ul>
  6. 6. 3 types of neurons <ul><li>Sensory neurons – send info to the spinal cord or brain </li></ul><ul><li>Interneurons – send info out of brain and spinal cords to the motor neurons </li></ul><ul><li>Motor neurons – send info from brain and spinal cord to muscles or glands </li></ul>
  7. 7. Sensory neuron (hand) Motor neuron (arm) Interneuron
  8. 8. Synapse <ul><li>Small space in between neurons </li></ul><ul><li>Neurotransmitters are released in the synapse and starts an impulse in the next neuron </li></ul>
  9. 9. Synapse
  10. 10. Divisions of the Nervous System <ul><li>CNS – central nervous system – brain and spinal cord </li></ul><ul><li>PNS – peripheral nervous system – all the nerves outside the CNS </li></ul>
  11. 11. Central Nervous System <ul><li>Brain 100 billion neurons </li></ul><ul><li>3 major parts </li></ul>
  12. 12. 1. Cerebrum <ul><li>Divided into hemispheres </li></ul><ul><li>Memory is stored </li></ul>
  13. 14. Cerebrum
  14. 17. 2. Cerebellum <ul><li>Under the cerebrum </li></ul><ul><li>Coordinated voluntary muscle movements </li></ul>
  15. 18. 3. Brainstem <ul><li>Connects the brain to the spinal cord </li></ul><ul><li>Made up of the </li></ul><ul><ul><li>Mid brain </li></ul></ul><ul><ul><li>Pons </li></ul></ul><ul><ul><li>Medulla </li></ul></ul><ul><li>Controls homeostasis of heart, breathing, blood pressure, involuntary muscle movements </li></ul>
  16. 19. Peripheral Nervous System <ul><li>2 divisions of the peripheral nervous system </li></ul>
  17. 20. Peripheral Nervous System Somatic Nervous System Skeletal Muscle Autonomic Nervous System Heartrate, breathing, digestion, salivary glands
  18. 21. Reflex <ul><li>Involuntary response to a stimulus </li></ul><ul><li>Involves a pathway called a ( reflex arc ) over which impulses travel </li></ul>
  19. 22. Reflex arc <ul><li>Impulse is sent to the spinal cord </li></ul><ul><li>Impulse passes to an interneuron in the spinal cord which immediately relays the impulse to motor neurons </li></ul><ul><li>Motor neurons transmit the impulse to muscles in your arm </li></ul><ul><li>Your arm pulls back (Without thinking!) </li></ul>
  20. 23. Steps of a reflex arc <ul><li>Receptor </li></ul><ul><li>Sensory neuron </li></ul><ul><li>Interneuron (spinal cord) </li></ul><ul><li>Motor neuron </li></ul><ul><li>Effector – “response” </li></ul>
  21. 26. Your Endocrine System
  22. 27. Endocrine system <ul><li>System of glands that release their products into the blood stream and broadcast messages throughout the body </li></ul>
  23. 28. Hormones <ul><li>Affect specific tissues called target cells </li></ul><ul><li>Target cells – control activities in parts of the body other than right around the gland </li></ul>
  24. 29. Glands of the Endocrine System
  25. 30. Hypothalamus <ul><li>Part of the brain </li></ul><ul><li>Produces hormones that influence the pituitary gland </li></ul>
  26. 32. Pituitary Gland <ul><li>“ Master Gland” </li></ul><ul><li>Secretes numerous hormones </li></ul><ul><li>Growth-stimulating Hormone </li></ul><ul><li>Hormones to control specific glands </li></ul><ul><li>Thyroid Stimulating Hormone (TSH) </li></ul><ul><ul><li>Tells thyroid to produce thyroxine </li></ul></ul><ul><li>The Follicle Stimulating Hormone </li></ul><ul><ul><li>Stimulates activity in the ovary and testes </li></ul></ul>
  27. 34. Thyroid Gland <ul><li>Located in the neck </li></ul><ul><li>Makes thyroxine </li></ul><ul><li>Regulates metabolism </li></ul>
  28. 36. Parathyroid Glands <ul><li>Embedded in the thyroid gland </li></ul><ul><li>Secrete parathormone </li></ul><ul><li>Controls the metabolism of calcium </li></ul><ul><li>Necessary for nerve function, blood clotting, and proper growth of teeth and bones </li></ul>
  29. 38. Adrenal Glands <ul><li>Two glands located on top of the kidneys </li></ul><ul><li>Each gland has 2 distinct regions </li></ul>
  30. 41. Adrenal Cortex <ul><li>Secretes two types of steroid hormones </li></ul><ul><li>promotes the conversion of body fat and protein into glucose </li></ul><ul><li>promotes the reabsorbtion into the blood stream of sodium and chloride ions by the kidney tubules </li></ul><ul><ul><li>This affects the water balance and maintains BP </li></ul></ul>
  31. 42. Adrenal Medulla <ul><li>Secretes adrenalin in times of emergency </li></ul><ul><li>Increases the blood sugar level </li></ul><ul><li>Speeds heart and breathing rates </li></ul>
  32. 44. Islets of Langerhans <ul><li>Located in the pancreas </li></ul><ul><li>Secrete insulin and glucagon </li></ul>
  33. 46. Insulin <ul><li>Helps take glucose into cells </li></ul><ul><li>Lowers blood sugar levels by taking it out of the blood and storing it in the liver and muscle cells </li></ul>
  34. 47. Glucagon <ul><li>Stimulates the release of sugar from the liver </li></ul><ul><li>Raises blood sugar level </li></ul>
  35. 48. Gonads <ul><li>Sex glands </li></ul><ul><li>Testes </li></ul><ul><li>Secrete testosterone – develop male secondary sex characteristics </li></ul><ul><li>Ovaries </li></ul><ul><li>Secrete estrogen - develop female secondary sex characteristics </li></ul>
  36. 51. Endocrine Control <ul><li>Negative feedback system </li></ul><ul><li>Controls the amount of hormone an endocrine gland produces </li></ul><ul><li>Works like a thermostat in your house </li></ul>
  37. 52. Negative feedback system <ul><li>Start: 1. Hormone level low </li></ul><ul><li>2. Hormone production increases </li></ul><ul><li>3. Hormone level high </li></ul><ul><li>4. Hormone production slowed down </li></ul><ul><li>End: 5. Hormone level low </li></ul>
  38. 53. Endocrine Feedback System of TSH Hypothalamus Pituitary Gland Thyroid Stimulating Hormone Thyroid Gland Thyroxin stimulates Inhibits
  39. 54. Endocrine System Disorders
  40. 55. Goiter <ul><li>Enlargement of the thyroid gland </li></ul><ul><li>Results in not being able to make thyroxine </li></ul><ul><li>Often associated with iodine deficiency in the diet </li></ul>
  41. 58. Diabetes <ul><li>Insulin deficiency </li></ul><ul><li>Results in an elevated blood sugar level </li></ul><ul><li>Also an inability of the body to store the sugar glycogen in the liver </li></ul>