Anatomy and Physiology The endocrine system 02 19 13


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Anatomy and Physiology The endocrine system 02 19 13

  1. 1. The Endocrine System Mr. Hunter Kennedy High
  2. 2. 03/14/2013 Anatomy and Physiology• Objective(s)• SWBAT• Explain the function of the endocrine system• Understand the function of posterior pituitary gland hormones and the hypothalamus• Bell Ringer : Where are PGs produced?
  3. 3. Endocrine System• The endocrine systemperforms the same generalfunction as the nervoussystem.• The nervous systemprovides a more rapidresponse than theendocrine system.•Nerve signals are sent viaelectrical impulses whilethe endocrine system (ES)communicates viacirculating hormones.
  4. 4. Endocrine System• Of the two types ofglands – exocrine andendocrine, the endocrinegland is part of theendocrine system.•These ductless glandssecrete hormone into theblood or into fluidsurrounding cells.•Exocrine glands secretesubstances through ductsto specialized regions ofthe body. – Sweat glands,mucous and salivaryglands.
  5. 5. • Endocrine glands secrete hormones intoEndocrine System intercellular spaces. • Hormones can diffuse into the blood and be carried throughout the body.• • Hormones may bind to cells that have hormone specific receptors on their surfaces. • These cells are known as target cells. The binding of the hormone with the receptor initiates a chemical reaction. • Hormones play an important role in homeostasis and metabolism. • Diseases may cause a gland to secrete too much or too little hormone. – Hypersecretion or Hyposecretion
  6. 6. • Two main classes of hormones areHormone Classes steroid and nonsteroid type hormones.• • Nonsteriod hormones are whole proteins, shorter chains of amino acids, or versions of a single amino acid. • Nonsteroid hormones act via a second messenger system. • Within this system hormones are released from endocrine glands and interact with receptors on target cells. This interaction causes chemical changes to occur within the cell’s interior.
  7. 7. • Within the second messengerHormone Classes system ATP within side the cell is turned into cAMP. Ex cAMP causes the thyroid cells to respond to• thyroid stimulating hormone by secreting the thyroid hormone thyroxine. • Nonsteriod hormones are first messengers that act on target cells. • The interaction of the target cell with receptors causes chemical changes to occur within the cell. This creates a second messenger within the cell that causes other reactions to take place.
  8. 8. Review 02/25/20131. Why does the nervous system produce a faster response than the endocrine system?2. Of the two types of glands, exocrine and endocrine, which one is part of the endocrine system?3. What is the difference between the two glands?4. What protein structures on the surface of cells do hormones bind to?5. What are the names of the cells in which hormones act upon?6. What are nonsteroid hormones and how do they act on target cells?
  9. 9. Steroid Hormones • The actions of lipid soluble steroid hormones do not occur by second messenger systems. • Because they are soluble in lipids they can pass directly through the plasma membrane of their target cells. • Once inside the cell’s nucleus, the steroid hormone can bind to receptors – lock and key model. • This hormone receptor complex acts on DNA which causes the formation of a new protein in the cytoplasm that produces specific effects in the target cell.
  10. 10. Steroid Hormones • An example of this type of hormone class would be estrogen. • Since the steps are quite involved for steroid hormones, their hormone response times are much slower than nonsteroid hormones. • Steriod hormones may also induce membrane receptors to produce a variety of secondary effects.
  11. 11. Hormonal Regulation • Negative feedback systems can regulate hormone levels within the blood. • As you recall, positive feedback systems amplify the condition instead of reversing them to normal levels. • Oxytocin secretion during birth increases muscle contractions for a successful delivery.
  12. 12. Prostaglandins (PGs) • PGs are tissue hormones that are found in a large variety of tissues. • They perform many important functions but are not like typical hormones. • PGs are produced within tissues and diffuse a short distance to act on cells within that tissue. • PGs typically influence the activities of neighboring cells. Hormones can influence the activities of widely separated targets. • PGs can be divided into separate classes – A, E and F.
  13. 13. Prostaglandins (PGs) • PGs can have influences on many body functions such as: • Respiration • Blood pressure • GI secretions • Inflammation • Reproductive Systems • Most PGs regulate cells by the production of cAMP. • Play roles in the treatment of various conditions including high blood pressure, ulcers, and asthma. • Aspirin cause their effects by altering the functions of PGs in the body.
  14. 14. Review 03/06/20131. What is the difference in the mechanism of action between nonsteroid hormones and steroid hormones?2. Once inside the cell, what do steroid hormones interact with?3. What is produced as a result of this interaction?4. What is the name of a steroid hormone produced in substantial quantities by females.5. Why are the response times for steroid hormones much slower than nonsteroid hormones?6. Describe what occurs in a negative feedback system for high levels of glucose.7. What are PGs and where are their target cells located?8. How do PGs produce effects on target cells?
  15. 15. • The pituitary gland is no smallerPituitary Gland than a pea in size but carries out very important functions. • It consists of two glands – each of a different type. • Anterior pituitary gland – adenohypophysis • Posterior pituitary gland – neurohypophysis • The anterior pituitary gland has the structure of an endocrine gland. • The posterior pituitary gland has the structure of nervous tissue.
  16. 16. • Hormones released from thePituitary Gland adenohypohysis serve different functions from those released from the neurohypophysis. • The pituitary gland is located in the sella turcica of the sphenoid bone. • The pituitary stalk attaches the pituitary gland to the hypothalamus.
  17. 17. • The anterior pituitary gland secretesAnterior Pituitary GlandHormones several major hormones. • Tropic hormones stimulates another endocrine gland to grow and secrete its hormones. • The anterior pituitary gland was sometimes called the master gland because it exerts control over various structures including the thyroid gland and the adrenal cortex. • Thyroid Stimulating Hormone – TSH stimulates the thyroid gland to secrete thyroid hormone.
  18. 18. • Thyroid Stimulating Hormone – TSHAnterior Pituitary GlandHormones stimulates the thyroid gland to secrete thyroid hormone. • Adrenocorticotropic Hormone – ACTH – acts on the adrenal cortex. Stimulates the adrenal cortex to increase in size and to secrete larger amounts of cortisol. • Follicle Stimulating Hormone – FSH stimulates the growth and estrogen secretion of primary ovarian follicles in the ovary. - In the male FSH aids in sperm production.
  19. 19. • Luteinizing Hormone – LH acts withAnterior Pituitary GlandHormones FSH to perform various functions. • Causes estrogen production increase and ovulation. • Stimulates the formation of the corpus luteum and its production of progesterone. • Stimulates the interstitial cells of the testes to secrete testosterone. • Growth Hormone – GH Speeds up the movement of amino acids out of the blood and into cells to promote anabolism of amino acids into tissue proteins.
  20. 20. • GH also promotes fat catabolism andAnterior Pituitary GlandHormones slows down glucose catabolism. Less glucose leaves the blood to enter cells. GH therefore increases blood glucose concentrations. • Hypersecretion of insulin produces hypoglycemia. • Hypersecretion of GH produces hyperglycemia. • Prolactin –PRL or lactogenic hormone. Stimulates the development of the breasts for producing milk during pregnancy.
  21. 21. ES Review 03/07/20131. What are the names of the anterior and posterior pituitary glands?2. What structure does the anterior pituitary gland have?3. What structure does the posterior pituitary gland have?4. Where is the pituitary gland located and what is it attached to?5. What is the function of a tropic hormone?6. What are the functions of TSH, ACTH and FSH?7. How does hypersecretion of GH produce hyperglycemia?8. What is the function of PRL?
  22. 22. • The neurohypophysis releases twoPosterior Pituitary hormones. • Antidiuretic Hormone (ADH) • Oxytocin (OT) • ADH accelerates the reabsorption of water from urine in the kidneys back into the blood. • More water moves out of the kidney tubules into the blood, less water remains in the kidneys and therefore less urine is excreted from the body. • ADH acts to decrease urine volume. • Hyposecretion of ADH results in diabetes insipidus – large volumes of urine are produced - Dehydration
  23. 23. • OT is secreted by the posteriorPosterior Pituitary pituitary of a female before and after she has a baby. • OT stimulates uterine contractions to initiate and maintain labor. • It stimulates glandular cells of the breast to release milk into ducts from which the baby can obtain nutrients. • Production of ADH and OT occurs in the hypothalamus. • Two groups of neurons make the posterior gland hormones and pass them along axons to the neurohypophysis. Release is controlled by nervous stimulation.
  24. 24. • The hypothalamus producesPosterior Pituitary Releasing hormones (RHs) and Inhibiting Hormones (IHs). • They travel to the adenohypophysis via a specialized capillary system. • They can cause the release of anterior pituitary hormones or inhibit their production and release into the general circulation. • The hypothalamus plays a dominant role in regulating many body functions including: • Body temperature • Appetite • Thirst
  25. 25. • The thyroid gland is located in the neck just inferior to the larynx.Thyroid Gland • The thyroid gland secretes two thyroid hormones, thyroxine – T4 and triiodothyronine – T3. It also secretes calcitonin (CT) • T4 is the most abundant thyroid hormone. • T3 is the more potent and is considered to be the principal thyroid hormone. • In order for T4 to be produced, the diet must contain sufficient amounts of iodine. • The thyroid gland can store thyroid hormone in its follicle cells until the hormone is needed and secreted into the blood.
  26. 26. • Thyroid hormones help to increaseThyroid Gland cell metabolism. • All body functions depend on thyroid secretion. • Calcitonin decreases the amount of calcium in the blood by acting on bone to inhibit its breakdown. • Less calcium will move out of bone into the blood. Concentration of blood Ca+ levels will decrease. • Calcitonin helps to maintain homeostasis of blood Ca+ levels – prevents hypercalcemia.
  27. 27. Review 03/12/131. Name two hormones produced by the posterior pituitary gland.2. What are the functions of ADH and OT?3. Hyposecretion of ADH may result in what physiological condition?4. Where are ADH and OT produced?5. What controls the release of ADH and OT into the blood?6. What are some of the functions of the body that the hypothalamus controls?7. Where is the thyroid gland located?8. Name and describe the functions of the hormones produced by the thyroid gland.
  28. 28. • Small glands found on the back ofParathyroid Glands the thyroid gland. • There are usually four of these glands. • Secretion of Parathyroid Hormone (PTH) • PTH increases Ca+ concentration in the blood. • The opposite effect of Calcitonin. • PTH stimulates osteoclasts (bone resorbing cells) to increase their breakdown of bone matrix. This moves Ca+ out of bone into blood.
  29. 29. • Low levels of Ca+ in the blood canParathyroid Glands cause: • Overactive nerve cells • Muscle spasms resulting from constant nervous stimulation • High levels of Ca+ can cause : • The death of brain and heart cells
  30. 30. • The adrenal glands are located onAdrenal Glands the top of each kidney. • The are composed of two glands : • Adrenal Cortex • Adrenal Medulla • The two glands produce different hormones. • The adrenal cortex is divided into three zones or layers. • Hormones secreted by all three layers are called corticoids. • The outer zone secrete mineralocorticoids – MCs. • Main MC is aldosterone.
  31. 31. • The middle zone secretesAdrenal Glands glucocorticoids – GCs • Hydrocortisone or Cortisol is the chief glucocorticoid. • The innermost, deepest zone of the cortex secretes small amounts of sex hormones that resemble testosterone. • Mineral Corticoids - Aldosterone help to control the amount of NaCl in the blood. It increases the amount of Na+ in the blood and decreases the amount of K+ in the blood. More K+ will be lost in urine. • Aldosterone speeds up the kidneys reabsorption of water.
  32. 32. • Glucocorticoids help to maintain blood glucose concentrations by the process ofAdrenal Glands gluconeogenesis. • Amino acids or fatty acids are converted to glucose within the liver. • Glucocorticoids: • Promote the catabolism of tissue proteins into amino acids – transported to the liver and turned into glucose and enters blood. • Maintain normal blood pressure • Produce anti-inflammatory effect – example: hydrocortisone cream / ointment • Production of ant-immunity or anti-allergy effect. – Decrease in the production of antbodies. • Responding to stress • Production of androgens in male and females.
  33. 33. Review 03/14/20131. Where are the parathyroid glands located?2. What is the function of PTH?3. Where are the adrenal glands located?4. What are the names of the two glands that the adrenal gland is divided into?5. How many layers is the adrenal cortex divided into?6. What is the function of aldosterone?7. How do glucocorticoids help to maintain blood glucose concentrations?
  34. 34. Endocrine System 03/19/2013 Adrenal Medulla• Adrenal Medulla is the inner portion of the adrenal gland.• It secretes the hormones epinephrine and norepinephrine• These hormones are released directly into the blood and are involved in the body’s flight or fight response.
  35. 35. Adrenal Medulla• In response to stress the hypothalamus causes the anterior pituitary to release ACTH.• This causes the adrenal cortex to release glucocorticoids. In addition, the adrenal medulla will release norepinephrine and epinephrine.• Anti-inflammatory responses can cause blood vessel constriction and promote the spread of infections along with HBP.
  36. 36. Pancreatic islets – islets of Langerhans• Glands are small clumps of cells scattered among the exocrine pancreatic cells.• Alpha cells ( A cells ) secrete glucagon.• Beta cells ( B cells ) secrete insulin• Glucagon accelerates glycogenolysis in the liver• Glycogen  Glucose in liver• Increase blood glucose• Insulin decreases blood glucose levels.
  37. 37. Pancreatic Islets• Normal glucose levels = 70 to 100 mg per 100 ml of blood.• Hyposecretion of insulin = type 1 diabetes mellitus• Type 2 diabetes mellitus = some decrease in insulin and abnormalities in insulin target cell receptors. Blood glucose levels are increased.
  38. 38. Other Endocrine Glands • Pineal gland – production• Thymus gland hormone = of melatonin – regulates Thymosin for development onset of puberty and and function of immune menstrual cycle. system. • Timekeeping for the body –• Placenta – Temporary internal clock endocrine gland – hormone • Ghrelin –secreted by = chorionic gonadotropins- stomach – boosts appetite• Secreted in urine / and slows metabolism. pregnancy Test • ANH atrial natriuretic• estrogen and progesterone hormone – loss of Na+ ions and water from kidney • Antagonist to aldosterone