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Blood Sugar Regulation

Blood Sugar Regulation. Pancreas. Pancreas. Pancreas. Two cell types to produce: digestive enzymes – exocrine glands (acini) hormones – islets of Langerhans. 1 – 2% of pancreas are the islets of Langerhans. Islets of Langerhans. Two hormones are produced: insulin – beta ( β ) cells

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Blood Sugar Regulation

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  1. Blood Sugar Regulation

  2. Pancreas

  3. Pancreas

  4. Pancreas Two cell types to produce: • digestive enzymes – exocrine glands (acini) • hormones – islets of Langerhans 1 – 2% of pancreas are the islets of Langerhans

  5. Islets of Langerhans Two hormones are produced: • insulin – beta (β) cells • glucagon – alpha (α) cells blue = cell nuclei green = insulin red = glucagon

  6. Hormone Structure • insulin • peptide hormone • glucagon • peptide hormone • Insulin and glucagon are referred to as antagonistic hormones.

  7. Glycogen • A glucose polymer made up of many glucose subunits • “Storage form of glucose” • Stored within liver and muscle

  8. Body cells take up more glucose. Insulin Beta cells of pancreas are stimulated to release insulin into the blood. Liver takes up glucose and stores it as glycogen. STIMULUS: Rising blood glucose level (for instance, after eating a carbohydrate- rich meal) Blood glucose level declines to set point; stimulus for insulin release diminishes. Homeostasis: Blood glucose level (about 90 mg/100 mL) Blood glucose level rises to set point; stimulus for glucagon release diminishes. STIMULUS: Dropping blood glucose level (for instance, after skipping a meal) Alpha cells of pancreas are stimulated to release glucagon into the blood. Liver breaks down glycogen and releases glucose into blood. Glucagon Figure 45.12 Action of Insulin • c

  9. Example of Insulin’s Effect on Body Cells - Muscle Cell Glucose OUTSIDE CELL Insulin Insulin Receptors Signal Transduction Pathway Exocytosis INSIDE CELL GLUT 4 Transporters (proteins that transport glucose across plasma membrane) GLUT 4 Protein Vesicles

  10. When is insulin released? after eating hyperglycemia beta cells decreased blood sugar cellular signals for insulin release increased glucose uptake glycogen production in liver

  11. Body cells take up more glucose. Insulin Beta cells of pancreas are stimulated to release insulin into the blood. Liver takes up glucose and stores it as glycogen. STIMULUS: Rising blood glucose level (for instance, after eating a carbohydrate- rich meal) Blood glucose level declines to set point; stimulus for insulin release diminishes. Homeostasis: Blood glucose level (about 90 mg/100 mL) Blood glucose level rises to set point; stimulus for glucagon release diminishes. STIMULUS: Dropping blood glucose level (for instance, after skipping a meal) Alpha cells of pancreas are stimulated to release glucagon into the blood. Liver breaks down glycogen and releases glucose into blood. Glucagon Action of Glucagon

  12. What does glucagon do? breaks down glycogen hypoglycemia alpha cells increased blood sugar cellular signals for glucagon release glucose release from liver glucose production in liver

  13. Diabetes Mellitus – Type I • also known as juvenile diabetes or insulin-dependent diabetes Cause • immune system attacking insulin-producing beta cells • no insulin production Symptoms • increased thirst, hunger and urination Treatment • daily dosage of insulin

  14. Diabetes Mellitus – Type II • also known as adult-onset diabetes or non-insulin-dependent diabetes Cause • Poor diet, lack of exercise • Excess glucose in the blood for a long period of time causes the pancreas to become overworked and tired • Beta cells produce some, but not enough insulin (deficiency) • A reduction in the number of functional insulin receptors • reduced responsiveness of cells to insulin = insulin resistant Symptoms • increased thirst, hunger and urination • fatigue / lethargy

  15. Type II Diabetes Glucose Insulin Glucose Treatment • maintain healthy diet and frequent exercise • medication only upon progression of disease state • Regular exercise can reduce and stop symptoms Exocytosis Insulin GLUT 4 Protein Vesicles ExerciseGLUT 4 Protein Vesicles

  16. Canadian Connection Frederick Banting & Charles Best • Nobel Prize – 1923 • insulin isolation • tied off ducts to digestive tract • cell producing digestive enzymes shrivelled • only islets of Langerhans remained

  17. Video Testimonies • University of Alberta • developed islet cell transplant method Islet Transplant Animation Photo Journal News Feature

  18. Stress Regulation

  19. Adrenal Glands adrenal – “next to” the renal system Two main sections: • adrenal cortex  long-term stress • adrenal medulla  short-term stress

  20. Adrenal Cortex Long-term stress sends ACTH (adrenocorticotropic hormone) Anterior pituitary adrenal cortex Adrenal cortex produces two types of hormones: • glucocorticoids • mineralcorticoids ACTH

  21. 1. Glucocorticoids • class of steroid hormones for glucose regulation • specific example: cortisol What happens when you’re stressed out? • glucose not taken in by muscles • amino acids made into glucose • fat tissue broken down for energy

  22. 2. Mineralcorticoids • class of steroid hormones for mineral regulation • specific example: aldosterone What happens when you’re stressed out? • blood pressure rises due to increase sodium & H2O reabsorption in kidneys

  23. Adrenal Medulla Short-term stress detected by hypothalamus Produces two hormones: • epinephrine (adrenaline) • norepinephrine (noradrenaline) • both compounds are examples of catecholamines, which are also neurotransmitters

  24. Hormone Structures • epinephrine • hydrophilic • norepinephrine • hydrophilic

  25. Flight-or-Fight Response What’s your response? • increased heart rate • increased breathing • blood vessel dilation  more O2 delivery • iris dilation  collect maximum visual information • these responses are induced by catecholamine release

  26. Stress Nerve signals Hypothalamus Spinal cord (cross section) Releasing hormone Nerve cell Anterior pituitary Blood vessel Adrenal medulla secretes epinephrine and norepinephrine. Nerve cell Adrenal cortex secretes mineralocorticoids and glucocorticoids. ACTH Adrenal gland Kidney (a) Short-term stress response (b) Long-term stress response Effects of epinephrine and norepinephrine: Effects of mineralocorticoids: Effects of glucocorticoids: 1. Glycogen broken down to glucose; increasedblood glucose 1. Retention of sodiumions and water bykidneys 1. Proteins and fatsbroken down andconverted to glucose,leading to increasedblood glucose 2. Increased blood pressure 3. Increased breathing rate 2. Increased bloodvolume and bloodpressure 4. Increased metabolic rate 5. Change in blood flow patterns, leading to increased alertness and decreased digestive and kidney activity 2. Immune system may be suppressed

  27. Classwork/Homework • Section 8.2 – Pg. 383 #1-8,9

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