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CNS (Central Nervous System)


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ZOO211 Anatomy & Physiology Finals Coverage under Sr. Salazar

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CNS (Central Nervous System)

  2. 2. FUNCTION <ul><li>Functions of the Nervous System </li></ul><ul><li>Control and communication system </li></ul><ul><li>Monitors Changes inside and outside the </li></ul><ul><li>body (sensory input) </li></ul><ul><li>Processes and interprets sensory input and </li></ul><ul><li>makes decisions (integration) </li></ul><ul><li>Affects a response (motor output) by affecting </li></ul><ul><li>glands, muscles etc. </li></ul><ul><li>Works closely in conjunction with the endocrine system </li></ul>
  3. 3. NEURONS <ul><li>Nerve Transmission </li></ul><ul><li>Neurons - Basic anatomic and functional unit of the nervous system </li></ul><ul><li>Respond to sensory and chemical stimuli, </li></ul><ul><li>conduct impulses and release specific chemical regulators </li></ul><ul><li>A nerve impulse is a wave of electrical charge sweeping from neuron to neuron </li></ul><ul><li>The gap lying between one neuron and the next is the synapse </li></ul><ul><li>Neurotransmitters move across the synapse </li></ul><ul><li>where they excite, inhibit or modify </li></ul>
  4. 4. MENINGES <ul><li>3 layers that lay directly on the surface of the brain tissue (parenchyma) and spinal cord. Offer a cushioning effect. </li></ul><ul><li>• Dura Mater - outer most layer that is thick and fibrous, that lines </li></ul><ul><li>the interior of the skull. </li></ul><ul><li>• Arachnoid - middle layer, is extremely thin and loosely encloses </li></ul><ul><li>the brain </li></ul><ul><li>• Pia Mater - inner most, mesh like and very vascular. It follows the convolutions of the brain </li></ul><ul><li>Meninges </li></ul><ul><li>• Spaces of the meninges - extradural, subdural and subarachnoid </li></ul>
  5. 5. VENTRICULAR SYSTEM <ul><li>Produces (~ 500mL/day) and circulates (~ 150mL) CSF. </li></ul><ul><li>• CSF is usually a clear colourless fluid that acts as a shock absorber </li></ul><ul><li>• The ventricular system is connected to the subarachnoid space (SAS) </li></ul><ul><li>• 3 main compartments - 2 lateral ventricles, 1 third ventricle and </li></ul><ul><li>1 fourth ventricle </li></ul><ul><li>• CSF is produced by the choroid plexus in each ventricle </li></ul><ul><li>• CSF is reabsorbed into the venous blood flow via the arachnoid villi </li></ul><ul><li>• Arachnoid villi are small granulations that project from the SAS into the venous outlets of the brain. </li></ul>
  6. 6. What are the major parts of the nervous system? <ul><li>The major divisions of the nervous system include: </li></ul><ul><li>Central Nervous System (CNS) </li></ul><ul><li>Peripheral Nervous System (PNS) </li></ul><ul><li>Autonomic Nervous System (ANS) </li></ul><ul><li>a. sympathetic nervous system </li></ul><ul><li>b. parasympathetic nervous system </li></ul>
  7. 7. What are the major parts of the nervous system? <ul><li>1. Central Nervous System </li></ul><ul><li>consists of the brain and the spinal cord </li></ul><ul><li>functions as a switchboard that controls and coordinates the activities of the whole nervous system </li></ul>
  8. 8. What are the major parts of the nervous system? <ul><li>2. Peripheral Nervous System </li></ul><ul><li>carries all the messages sent between the central nervous system and the rest of the body </li></ul>
  9. 9. What are the major parts of the nervous system? <ul><li>3. Autonomic nervous system </li></ul><ul><li>controls involuntary activity such as the action of the heart and glands, breathing, digestive processes, and reflex actions </li></ul>
  10. 10. What are the major parts of the nervous system? <ul><li>3. Autonomic nervous system </li></ul><ul><li>a. sympathetic system </li></ul><ul><li>responds to the body’s needs during increased activity and in emergencies. </li></ul><ul><li>controls heartbeat, blood circulation, respiration and other unconscious activities. </li></ul>
  11. 11. What are the major parts of the nervous system? <ul><li>3. Autonomic nervous system </li></ul><ul><li>b.parasympathetic system </li></ul><ul><li>opposes the actions of the sympathetic system. </li></ul><ul><li>slows down heartbeat, diverts blood circulation, etc. </li></ul>
  12. 12. PARTS OF THE CENTRAL NERVOUS SYSTEM AND THEIR FUNCTIONS <ul><li>Brain </li></ul><ul><li>organ of thought and feeling </li></ul><ul><li>responsible for issuing nerve impulses, processing data, and the master control center over the body </li></ul><ul><li>divided into cerebrum, cerebellum and the brainstem </li></ul>
  13. 13. PARTS OF THE CENTRAL NERVOUS SYSTEM AND THEIR FUNCTIONS <ul><li>Brain </li></ul><ul><li>Cerebrum </li></ul><ul><li>forms the bulk of the brain </li></ul><ul><li>responsible for the higher thought processes such as memory, judgment and reason </li></ul>
  14. 14. PARTS OF THE CENTRAL NERVOUS SYSTEM AND THEIR FUNCTIONS <ul><li>Brain </li></ul><ul><li>a.1Parts of the Cerebrum </li></ul><ul><li>Frontal lobe </li></ul><ul><li>planning, consciousness, speech, memory, and reasoning </li></ul>
  15. 15. PARTS OF THE CENTRAL NERVOUS SYSTEM AND THEIR FUNCTIONS <ul><li>Brain </li></ul><ul><li>a.1Parts of the Cerebrum </li></ul><ul><li>Parietal lobe </li></ul><ul><li>houses the control centers for processing impulses related to the sense of touch; temperature, texture, size, shape and weight </li></ul>
  16. 16. PARTS OF THE CENTRAL NERVOUS SYSTEM AND THEIR FUNCTIONS <ul><li>Brain </li></ul><ul><li>a.1Parts of the Cerebrum </li></ul><ul><li>Occipital lobe </li></ul><ul><li>contains the centers responsible for sight. </li></ul>
  17. 17. PARTS OF THE CENTRAL NERVOUS SYSTEM AND THEIR FUNCTIONS <ul><li>Brain </li></ul><ul><li>a.1Parts of the Cerebrum </li></ul><ul><li>Temporal lobe </li></ul><ul><li>houses centers for the processing and correlation of the auditory (hearing) and olfactory (smell) senses. </li></ul>
  18. 18. PARTS OF THE CENTRAL NERVOUS SYSTEM AND THEIR FUNCTIONS <ul><li>Brain </li></ul><ul><li>b. Cerebellum </li></ul><ul><li>responsible for body balance, posture and the coordination of movement </li></ul><ul><li>receives, coordinates and modifies orders from the cerebrum </li></ul>
  19. 19. PARTS OF THE CENTRAL NERVOUS SYSTEM AND THEIR FUNCTIONS <ul><li>Brain </li></ul><ul><li>c. Brain stem </li></ul><ul><li>connects the cerebrum with the spinal cord </li></ul><ul><li>consists of the midbrain, pons, and medulla oblongata </li></ul>
  20. 20. PARTS OF THE CENTRAL NERVOUS SYSTEM AND THEIR FUNCTIONS <ul><li>Brain </li></ul><ul><li>Brain stem </li></ul><ul><li>pons – located between the midbrain and the medulla oblangata; connects the cerebellum and the cerebrum </li></ul>
  21. 21. PARTS OF THE CENTRAL NERVOUS SYSTEM AND THEIR FUNCTIONS <ul><li>Brain </li></ul><ul><li>Brain stem </li></ul><ul><li>medulla oblangata – lowest part of the brain stem; controls involuntary processes such as the heartbeat, breathing, digestion and body temperature regulation. </li></ul>
  22. 22. PARTS OF THE CENTRAL NERVOUS SYSTEM AND THEIR FUNCTIONS <ul><li>Brain </li></ul><ul><li>Brain stem </li></ul><ul><li>Mid brain – the middle part of the three main divisions of the brain; helps control the movement of the eyes and the size of the pupils </li></ul>
  23. 23. PARTS OF THE CENTRAL NERVOUS SYSTEM AND THEIR FUNCTIONS <ul><li>Spinal cord </li></ul><ul><li>allows signals to be sent from the brain to the parts of the body </li></ul><ul><li>receives messages from the parts of the body to the brain </li></ul><ul><li>acts as a coordinating center responsible for some simple reflexes </li></ul>
  26. 26. BLOOD SUPPLY
  28. 28. <ul><li>INTERNAL CAROTID ARTERY </li></ul><ul><li>• Not all ICA occlusions become symptomatic. It depends on the </li></ul><ul><li>amount of collateral blood supply primarily from the C of W </li></ul><ul><li>• The degree of deficits vary, from asymptomatic to a catastrophic </li></ul><ul><li>infarction (similar to MCA </li></ul>
  29. 29. <ul><li>MIDDLE CEREBRAL ARTERY </li></ul><ul><li>• MCA is the largest branch that comes off the ICA </li></ul><ul><li>• It has deep branches that supply part of the internal capsule and </li></ul><ul><li>basal ganglia (putamen, caudate nucleus and globus pallidus) </li></ul><ul><li>• It passes out to the lateral surface of the cerebral hemisphere where </li></ul><ul><li>it supplies blood to the cortical areas of the temporal, frontal and </li></ul><ul><li>parietal lobes </li></ul>
  30. 30. The Endocrine System <ul><li>Controls many body functions </li></ul><ul><ul><li>exerts control by releasing special chemical substances into the blood called hormones </li></ul></ul><ul><ul><li>Hormones affect other endocrine glands or body systems </li></ul></ul><ul><li>Derives its name from the fact that various glands release hormones directly into the blood, which in turn transports the hormones to target tissues via ducts. </li></ul>
  31. 31. The Endocrine System <ul><li>Exocrine glands - transport their hormones to target tissues via ducts. </li></ul><ul><li>Endocrine Emergencies: </li></ul><ul><ul><li>from common: </li></ul></ul><ul><ul><ul><li>Diabetes </li></ul></ul></ul><ul><ul><ul><li>to the unusual: </li></ul></ul></ul><ul><ul><ul><ul><li>Thyrotoxicosis </li></ul></ul></ul></ul>
  32. 32. The Endocrine System <ul><li>Consists of several glands located in various parts of the body. </li></ul><ul><li>Pituitary gland : a small gland located on a stalk hanging from the base of the brain - AKA </li></ul><ul><li>“ The Master Gland” </li></ul><ul><ul><li>Primary function is to control other glands. </li></ul></ul><ul><ul><li>Produces many hormones. </li></ul></ul><ul><ul><li>Secretion is controlled by the hypothalamus in the base of the brain. </li></ul></ul>
  33. 33. The Endocrine System <ul><li>The Pituitary Gland is divided into 2 areas, which differ </li></ul><ul><ul><li>structurally and functionally </li></ul></ul><ul><ul><li>each area has separate types of hormone production. </li></ul></ul><ul><li>The two segments are: </li></ul><ul><ul><li>Posterior Pituitary: </li></ul></ul><ul><ul><ul><li>produces oxytocin and antidiuretic hormone ( ADH ) </li></ul></ul></ul><ul><ul><li>Anterior Pituitary: </li></ul></ul><ul><ul><ul><li>produces thyroid-stimulating hormone ( TSH ) </li></ul></ul></ul><ul><ul><ul><li>growth hormone ( GH ) </li></ul></ul></ul><ul><ul><ul><li>adrenocorticotropin ( ACTH ) </li></ul></ul></ul><ul><ul><ul><li>follicle-stimulating hormone ( FSH ) </li></ul></ul></ul>
  34. 34. The Endocrine System <ul><li>And even more… </li></ul><ul><ul><li>luteinizing hormone ( LH ) </li></ul></ul><ul><ul><li>prolactin </li></ul></ul><ul><li>Let’s go over these one at a time... </li></ul><ul><li>Posterior Pituitary </li></ul><ul><ul><li>Oxytocin (the natural form of pitocin) </li></ul></ul><ul><ul><ul><li>stimulates gravid uterus </li></ul></ul></ul><ul><ul><ul><li>causes “let down” of milk from the breast. </li></ul></ul></ul><ul><ul><li>ADH (vasopressin) causes the kidney to retain water. </li></ul></ul>
  35. 35. The Endocrine System <ul><li>Anterior Pituitary </li></ul><ul><ul><li>Primarily regulates other endocrine glands </li></ul></ul><ul><ul><li>rarely a factor in endocrinological emergencies </li></ul></ul><ul><ul><li>TSH stimulates the thyroid gland to release its hormones, thus  metabolic rate </li></ul></ul><ul><li>Anterior Pituitary… </li></ul><ul><ul><li>Growth hormone ( GH ) </li></ul></ul><ul><ul><ul><li> glucose usage </li></ul></ul></ul><ul><ul><ul><li> consumption of fats as an energy source </li></ul></ul></ul><ul><ul><li>ACTH stimulates the adrenal cortex to release its hormones </li></ul></ul><ul><ul><li>FSH & LH stimulates maturation & release of eggs from ovary. </li></ul></ul>
  36. 36. The Endocrine System <ul><li>The Thyroid Gland </li></ul><ul><ul><li>lies in the anterior neck just below the larynyx. </li></ul></ul><ul><ul><li>Two lobes, located on either side of the trachea, connected by a narrow band of tissue called the isthmus . </li></ul></ul><ul><ul><li>Sacs inside the gland contain colloid </li></ul></ul><ul><li>Within the colloid are the thyroid hormones: </li></ul><ul><ul><li>thyroxine ( T4 ) </li></ul></ul><ul><ul><li>triiodothyronine ( T3 ) </li></ul></ul><ul><ul><ul><li>When stimulated (by TSH or by cold), these are released into the circulatory system and  the metabolic rate. </li></ul></ul></ul><ul><ul><li>“ C” cells within the thyroid produce the hormone calcitonin . </li></ul></ul>
  37. 37. The Endocrine System <ul><li>Calcitonin , when released, lowers the amount of calcium in the blood. </li></ul><ul><li>Inadequate levels of thyroid hormones = hypothyroidism, or Myxedema. </li></ul><ul><li>Myxedema symptoms: </li></ul><ul><ul><li>Facial bloating </li></ul></ul><ul><ul><li>weakness </li></ul></ul><ul><ul><li>cold intolerance </li></ul></ul><ul><ul><li>lethargy </li></ul></ul><ul><ul><li>altered mental status </li></ul></ul><ul><ul><li>oily skin and hair </li></ul></ul><ul><ul><li>TX: replacement of thyroid hormone. </li></ul></ul>
  38. 38. The Endocrine System <ul><li>Increased thyroid hormone release causes hyperthyroidism, commonly called Graves’ disease. </li></ul><ul><ul><li>Signs and symptoms: </li></ul></ul><ul><ul><ul><li>insomnia, fatigue </li></ul></ul></ul><ul><ul><ul><li>tachycardia </li></ul></ul></ul><ul><ul><ul><li>hypertension </li></ul></ul></ul><ul><ul><ul><li>heat intolerance </li></ul></ul></ul><ul><ul><ul><li>weight loss </li></ul></ul></ul><ul><ul><li>Long term hyperthyroidism: </li></ul></ul><ul><ul><ul><li>Exopthalmos </li></ul></ul></ul><ul><ul><ul><ul><li>bulging of the eyeballs (picture Barbara Bush) </li></ul></ul></ul></ul><ul><ul><ul><li>In severe cases - a medical emergency called thyrotoxicosis can result. </li></ul></ul></ul>
  39. 39. The Endocrine System <ul><li>Parathyroid Glands </li></ul><ul><ul><li>small, pea-shaped glands, located in the neck near the thyroid </li></ul></ul><ul><ul><li>usually 4 - number can vary </li></ul></ul><ul><ul><li>regulate the level of calcium in the body </li></ul></ul><ul><ul><li>produce parathyroid hormone -  level of calcium in blood </li></ul></ul><ul><ul><li>Hypocalcemia can result if parathyroids are removed or destroyed. </li></ul></ul>
  40. 40. The Endocrine System <ul><li>Pancreas </li></ul><ul><ul><li>a key gland located in the folds of the duodenum </li></ul></ul><ul><ul><li>has both endocrine and exocrine functions </li></ul></ul><ul><ul><li>secretes several key digestive enzymes </li></ul></ul><ul><li>Islets of Langerhans </li></ul><ul><ul><li>specialized tissues in which the endocrine functions of the pancreas occurs </li></ul></ul><ul><ul><li>include 3 types of cells: </li></ul></ul><ul><ul><ul><li>alpha (  ) </li></ul></ul></ul><ul><ul><ul><li>beta (  ) </li></ul></ul></ul><ul><ul><ul><li>delta (  ) </li></ul></ul></ul><ul><ul><li>each secretes an important hormone. </li></ul></ul>
  41. 41. The Endocrine System <ul><li>Alpha (  ) cells release glucagon , essential for controlling blood glucose levels. </li></ul><ul><li>When blood glucose levels fall,  cells  the amount of glucagon in the blood . </li></ul><ul><li>The surge of glucagon stimulates the liver to release glucose stores (from glycogen and additional storage sites). </li></ul><ul><li>Also, glucagon stimulates the liver to manufacture glucose - </li></ul><ul><li>gluconeogenesis. </li></ul>
  42. 42. The Endocrine System <ul><li>Beta Cells (  ) release insulin (antagonistic to glucagon). </li></ul><ul><li>Insulin  the rate at which various body cells take up glucose. Thus, insulin lowers the blood glucose level. </li></ul><ul><li>Insulin is rapidly broken down by the liver and must be secreted constantly. </li></ul><ul><li>Delta Cells (  ) produce somatostatin, which inhibits both glucagon and insulin. </li></ul>
  43. 43. The Endocrine System <ul><li>Adrenal Glands </li></ul><ul><ul><li>2 small glands that sit atop both kidneys. </li></ul></ul><ul><ul><li>Each has 2 divisions, each with different functions. </li></ul></ul><ul><li>the Adrenal Medulla secretes the catecholamine hormones norepinephrine and epinephrine (closely related to the sympathetic component of the autonomic nervous system). </li></ul>
  44. 44. The Endocrine System <ul><li>The Adrenal Cortex secretes 3 classes of hormones, all steroid hormones: </li></ul><ul><ul><li>gluticocorticoids mineralocorticoids </li></ul></ul><ul><ul><li>androgenic hormones </li></ul></ul><ul><li>One at a time… </li></ul><ul><ul><li>gluticocorticoids: </li></ul></ul><ul><ul><li>accounts for 95% of adrenal cortex hormone production </li></ul></ul><ul><ul><li> the level of glucose in the blood </li></ul></ul><ul><ul><li>Released in response to stress, injury, or serious infection - like the hormones from the adrenal medulla. </li></ul></ul>
  45. 45. The Endocrine System <ul><li>Mineralocorticoids: </li></ul><ul><ul><li>work to regulate the concentration of potassium and sodium in the body. </li></ul></ul><ul><li>Prolonged  in adrenal cortex hormone results in Cushing’s Disease. </li></ul><ul><li>Signs & Symptoms of Cushing’s Disease: </li></ul><ul><ul><li>  in blood sugar levels </li></ul></ul><ul><ul><li>unusual body fat distribution </li></ul></ul><ul><ul><li>rapid mood swings </li></ul></ul>
  46. 46. The Endocrine System <ul><li>And - if there is an  in mineralocorticoids as well </li></ul><ul><ul><li>A serious electolyte imbalance will occur due to the  potassium excretion by the kidney, which results in hypokalemia. </li></ul></ul><ul><li>Sodium can also be retained by the kidney, resulting in hyponatremia. </li></ul><ul><ul><li>Causes: </li></ul></ul><ul><ul><ul><li>dysrhythmias </li></ul></ul></ul><ul><ul><ul><li>coma </li></ul></ul></ul><ul><ul><ul><li>death </li></ul></ul></ul><ul><ul><li>usually results from a tumor - TX? Removal of tumor. </li></ul></ul>
  47. 47. The Endocrine System <ul><li>Gonads and Ovaries : </li></ul><ul><ul><li>the endocrine glands associated with human reproduction. </li></ul></ul><ul><ul><li>Female ovaries produce eggs </li></ul></ul><ul><ul><li>Male gonads produce sperm </li></ul></ul><ul><li>both have endocrine functions. </li></ul><ul><li>Ovaries: </li></ul><ul><ul><li>located in the abdominal cavity adjacent to the uterus. </li></ul></ul><ul><ul><li>Under the control of LH and FSH from the anterior pituitary they manufacture </li></ul></ul><ul><ul><ul><li>estrogen </li></ul></ul></ul><ul><ul><ul><li>protesterone </li></ul></ul></ul>
  48. 48. The Endocrine System <ul><li>Estrogen and Progesterone have several functions, including sexual development and preparation of the uterus for implantation of the egg. </li></ul><ul><li>Testes: </li></ul><ul><ul><li>located in the scrotum </li></ul></ul><ul><ul><li>produce sperm for reproduction </li></ul></ul><ul><ul><li>manufacture testosterone - </li></ul></ul><ul><ul><ul><li>promotes male growth and masculinization </li></ul></ul></ul><ul><ul><li>Controlled by anterior pituitary hormones FSH and LH. </li></ul></ul>
  49. 49. The Endocrine System <ul><li>Endocrine Emergencies: </li></ul><ul><li>Diabetes Mellitus </li></ul><ul><ul><li>one of the most common diseases in North America. </li></ul></ul><ul><ul><li> insulin secretion by the Beta (  ) cells of the islets of Langerhans in the pancreas. </li></ul></ul><ul><li>Complications of Diabetes: </li></ul><ul><ul><li>contributes to heart disease </li></ul></ul><ul><ul><li>stroke </li></ul></ul><ul><ul><li>kidney disease </li></ul></ul><ul><ul><li>blindness </li></ul></ul>
  50. 50. The Endocrine System <ul><li>Pathophysiology of Diabetes: </li></ul><ul><li>Glucose Metabolism </li></ul><ul><ul><li>Glucose (dextrose) is a simple sugar required by the body to produce energy. </li></ul></ul><ul><ul><li>Sugars, or carbohydrates, are 1 of 3 major food sources used by the body. </li></ul></ul><ul><li>The other 2 major food sources are </li></ul><ul><ul><li>proteins </li></ul></ul><ul><ul><li>fats </li></ul></ul><ul><li>Most sugars in the human diet are complex and must be broken down into simple sugars: glucose, galactose and fructose - before use. </li></ul>
  51. 51. The Endocrine System <ul><li>Breakdown of sugars is carried out by enzymes in the gastro intestinal system. </li></ul><ul><ul><li>As simple sugars, these are absorbed from the GE system into the body. </li></ul></ul><ul><ul><li>More than 95% enter the body as glucose. </li></ul></ul><ul><li>To be converted into energy, glucose must first be transmitted through the cell membrane. BUT - the glucose molecule is large and doesn’t readily diffuse through the cell membrane. </li></ul>
  52. 52. The Endocrine System <ul><li>Glucose must pass into the cell by binding to a special carrier protein on the cell’s surface. </li></ul><ul><ul><li>Facilitated diffusion - doesn’t use energy . The carrier protein binds with the glucose and carries it into the cell. </li></ul></ul><ul><li>The rate at which glucose can enter the cell is dependent upon insulin levels. </li></ul><ul><ul><li>Insulin serves as the messenger - travels via blood to target tissues. </li></ul></ul><ul><ul><li>Combines with specific insulin receptors on the surface of the cell membrane. </li></ul></ul>