Hormones that Affect Blood Sugar

1. Hormones that Affect Blood Sugar Insulin, glucagon, epinephrine, norepinephrine and cortisol

2. Pancreatic enzymes • The pancreas contains two types of cells: • one type produces digestive enzymes • the other type produces hormones • The hormone-producing cells are located in structures called theislets of Langerhans

3. Pancreas • More than 2000 tiny islets, each containing thousands of cells, are scattered throughout the pancreas. http://www.leedsth.nhs.uk/sites/diabetes/teenage/IsletsofLangerhans.php

4. Pancreas • The islets contain beta and alpha cells that are responsible for the production of two hormones: • insulin • Glucagon http://pathology2.jhu.edu/pancreas/anatphys/pancpart.htm

5. Effect of Insulin • Insulin is produced in the beta cells of the islets of Langerhans and is released when blood sugar levels increase.

6. Effect of Insulin • Insulin causes cells of the muscles, the liver, and other organs to become permeable to the glucose • The glucose leaves the blood and enters the cells

7. Effect of Insulin • In the liver, the glucose is converted into glycogen, the primary storage form for glucose. • Insulin enables the blood sugar level to return to normal and to maintain homeostasis

8. Glucagon • Glucagon is produced by the alpha cells of the islets of Langerhans, • Glucagon is released when blood sugar levels are low, such as after periods of fasting.

9. Glucagon • Glucagon promotes the conversion of glycogen to glucose, which is released into the blood. • As glycogen is converted to glucose in the liver, the blood sugar level returns to normal. http://www.biology.arizona.edu/biochemistry/problem_sets/carbomet/05t.html

10. Adrenal Glands • The adrenal glands are located above each kidney. • Each adrenal gland is made up of two glands encased in one shell. http://genericlook.com/anatomy/Adrenal-Gland/

11. Adrenal Glands • The inner gland, the adrenal medulla, is surrounded by an outer casing, called the adrenal cortex. • The adrenal medulla is regulated by the nervous system • The adrenal cortexis regulated by hormones http://iahealth.net/adrenal-gland/

12. Adrenal medulla • The adrenal medulla produces two hormones: • epinephrine (also known as adrenaline) • norepinephrine (noradrenaline) • The nervous system and the adrenal medulla are linked by the fact that both produce epinephrine.

13. Reaction to Stress • The hormone-producing cells within the adrenal medulla are stimulated by sympathetic nerves in times of stress. • Epinephrine and norepinephrine are released from the adrenal medulla into the blood.

15. Effects of Epinephrine and Norepinephrine • Blood sugar level rise • Glycogen is converted into glucose • The increased blood sugar level ensures that a greater energy reserve will be available for the tissues of the body.

16. Effects of Epinephrine and Norepinephrine • Epinephrine and norepinephrine cause an increase in: • heart rate increase • breathing rate • cell metabolism

17. Effects of Epinephrine and Norepinephrine • Blood vessels dilate, allowing more oxygen and nutrients to reach the tissues. • The iris of the eye dilates, allowing more light to reach the retina

18. The Adrenal Cortex • The Adrenal cortex produces three different types of hormones: • the glucocorticoids • the mineralocorticoids • small amounts of sex hormones

19. Glucocorticoids • The glucocorticoids are associated with blood glucose levels. • Cortisol increases the level of amino acids in the blood in an attempt to help the body recover from stress. • The amino acids are converted into glucose by the liver, thereby raising the level of blood sugar. • Any of the amino acids not converted into glucose are available for protein synthesis. • The proteins can be used to repair damaged cells.

20. Effects of Cortisol • Fats in adipose tissue are broken down into fatty acids. • A second source of energy is provided, helping conserve glucose in times of fasting. • Under the influence of cortisol, blood glucose uptake is inhibited in many tissues, especially in the muscles

21. Long-term stress responses • Thebrain identifies stressful situations. • The hypothalamus sends a releasing hormone to the anterior lobe of the pituitary • The pituitary secretes corticotropin, alsocalled adrenocorticotropic hormone (ACTH). • The blood carries the ACTH to the target cells in the adrenal cortex.

23. Long-term stress response • The cells of the adrenal cortex secrete mineralocorticoids and glucocorticoids which are carried to target cells in the liver and muscles. • As cortisol levels rise, cells within the hypothalamus and pituitary decrease the production of regulatory hormones, and, eventually, the levels of cortisol begin to fall. • This process is called a long-term stress response.

24. Short-term stress response • The brain identifies stressful situation • The hypothalamus sends a nerve signal to the adrenal medula • The adrenal medulla secretes epinephrine and norepinephrine.

25. Mineralocorticoids • Aldosterone is a mineralocorticoids prdoced by the adrenal cortex • Secretion of aldosterone increases sodium retention and water reabsorption by the kidneys, thereby helping to maintain body fluid levels.

27. Homework • Page 383 # 1 -- 7