Chapter 15


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Chapter 15

  1. 1. Chapter 15 <ul><li>Endocrine System </li></ul>
  2. 2. Points to Ponder <ul><li>What is the endocrine system? </li></ul><ul><li>Compare and contrast exocrine and endocrine glands. </li></ul><ul><li>What are steroid and peptide hormones? </li></ul><ul><li>Name the major glands and their functions in the endocrine system. </li></ul><ul><li>What is diabetes (Type 1 and 2) and how might you prevent Type 1? </li></ul><ul><li>How do the endocrine nervous systems work with the rest of the systems in the body to maintain homeostasis? </li></ul>
  3. 3. Endocrine system <ul><li>Mostly comprised of glands </li></ul><ul><li>Secretes hormones that move through the bloodstream to target cells </li></ul><ul><li>Results in a slow but a prolonged response </li></ul>15.1 Endocrine glands
  4. 4. Endocrine system 15.1 Endocrine glands
  5. 5. What is a target cell? 15.1 Endocrine glands
  6. 6. Exocrine vs. endocrine glands <ul><li>Exocrine glands secrete their products into ducts that carry these products to other organs or outside the body </li></ul><ul><li>Endocrine glands secrete their products directly into the bloodstream </li></ul>15.1 Endocrine glands
  7. 7. What are hormones? <ul><li>Hormones are chemical signals that promotes communication between cells, body parts and even individuals </li></ul><ul><li>Hormones: </li></ul><ul><ul><li>Prostaglandins : local hormones affect neighboring cells and thus are not carried in the bloodstream </li></ul></ul><ul><ul><li>Pheromones : chemical signals that influence the behavior of other individuals </li></ul></ul><ul><ul><li>Peptide hormones : bind to a receptor in the plasma membrane causing the formation of cAMP which activates a cascade of enzymes </li></ul></ul><ul><ul><li>Steroid hormones : lipids that enter a cell and affect gene activity and thus protein synthesis </li></ul></ul>15.1 Endocrine glands
  8. 8. Action of peptide hormones 15.1 Endocrine glands
  9. 9. Action of steroid hormones 15.1 Endocrine glands
  10. 10. Major glands of the endocrine system <ul><li>Hypothalamus </li></ul><ul><li>Posterior pituitary gland </li></ul><ul><li>Anterior pituitary gland </li></ul><ul><li>Thyroid gland </li></ul><ul><li>Parathyroid glands </li></ul><ul><li>Adrenal glands </li></ul><ul><li>Pancreas </li></ul><ul><li>Testes </li></ul><ul><li>Ovaries </li></ul><ul><li>Thymus gland </li></ul><ul><li>Pineal gland </li></ul>15.2 Hypothalamus and pituitary gland
  11. 11. 1. Hypothalamus <ul><li>Regulates internal environment through the autonomic nervous system </li></ul><ul><ul><li>Helps control heartbeat </li></ul></ul><ul><ul><li>Helps control body temperature </li></ul></ul><ul><ul><li>Helps control water balance </li></ul></ul><ul><ul><li>Controls glandular secretions </li></ul></ul>15.2 Hypothalamus and pituitary gland
  12. 12. 2. Posterior pituitary gland <ul><li>Stores antidiuretic hormone (ADH) and oxytocin that are produced by the hypothalamus </li></ul><ul><ul><li>ADH : regulates water balance by reabsorbing water into the bloodstream </li></ul></ul><ul><ul><li>Oxytocin : causes uterine contractions during childbirth and allow milk to be released during nursing </li></ul></ul>15.2 Hypothalamus and pituitary gland
  13. 13. 3. Anterior pituitary gland <ul><li>Controlled by hypothalamic-releasing and hypothalalmic-inhibiting hormones </li></ul><ul><li>Hormones produced by the anterior pituitary: </li></ul><ul><ul><li>Thyroid-stimulating hormone (TSH): stimulates the thyroid to produce thyroid hormones </li></ul></ul><ul><ul><li>Adrenocorticotropic hormone (ACTH): stimulates the adrenal cortex to produce cortisol </li></ul></ul><ul><ul><li>Gonadotropic hormones : stimulate gonads to produce sex cells and hormones </li></ul></ul><ul><ul><li>Prolactin (PRL): stimulates mammary glands to develop and produce milk only after childbirth </li></ul></ul><ul><ul><li>Melanocyte-stimulating hormone (MSH): causes skin cells to produce melanin </li></ul></ul><ul><ul><li>Growth hormone (GH): promotes skeletal and muscular growth </li></ul></ul>15.2 Hypothalamus and pituitary gland
  14. 14. The hypothalamus and pituitary 15.2 Hypothalamus and pituitary gland
  15. 15. What happens when the body produces too much or too little GH? <ul><li>Pituitary dwarfism – too little GH is produced during childhood that results in small stature </li></ul><ul><li>Giantism – too much GH is produced during childhood that results in poor health </li></ul><ul><li>Acromegaly – overproduction of GH as an adult that results in larger than normal feet, hands, and face </li></ul>15.2 Hypothalamus and pituitary gland
  16. 16. What happens when GH is produced in improper results during childhood? 15.2 Hypothalamus and pituitary gland
  17. 17. What happens when GH is produced in high amounts during adulthood? 15.2 Hypothalamus and pituitary gland
  18. 18. 4. Thyroid gland <ul><li>A large gland located below the larynx </li></ul><ul><li>Iodine is needed in the diet to allow the thyroid gland to produce its hormones </li></ul><ul><li>It produces: </li></ul><ul><ul><li>Thyroid hormone (TH): regulates metabolism </li></ul></ul><ul><ul><li>Calcitonin : helps lower blood Ca 2+ levels by stimulating the deposition of calcium in the bones </li></ul></ul>15.3 Thyroid and parathyroid glands
  19. 19. Thyroid abnormalities <ul><li>Simple goiter – thyroid enlarges due to lack of iodine in the diet </li></ul><ul><li>Hypothyroidism – low blood levels of thyroid hormones </li></ul><ul><ul><li>Congenital hypothyroidism : thyroid does not develop properly and is characterized in a short, stocky person that may be mentally retarded </li></ul></ul><ul><ul><li>Myxedema : hypothyroidism in adults characterized by lethargy, weight gain, loss of hair, cold intolerant and thick, puffy skin </li></ul></ul><ul><li>Hyperthyroidism – excess thyroid hormones in the blood </li></ul><ul><ul><li>Exophthalimic goiter : such as seen in Graves' disease and is characterized by enlargement of the thyroid gland, protrusion of the eyes, hyperactive and suffers from insomnia </li></ul></ul><ul><ul><li>Thyroid tumor : can also cause hyperthyroidism </li></ul></ul>15.3 Thyroid and parathyroid glands
  20. 20. Thyroid abnormalities 15.3 Thyroid and parathyroid glands
  21. 21. 5. Parathyroid glands <ul><li>Small glands embedded in the surface of the thyroid gland </li></ul><ul><li>Produces parathyroid hormone (PTH): </li></ul><ul><ul><li>causes blood Ca 2+ level to increase by promoting osteoclast activity </li></ul></ul><ul><ul><li>Promotes reabsorption of Ca 2+ by the kidneys </li></ul></ul>15.3 Thyroid and parathyroid glands
  22. 22. Regulation of blood calcium 15.3 Thyroid and parathyroid glands
  23. 23. 6. Adrenal glands <ul><li>Glands that sit on top of the kidneys </li></ul><ul><li>2 parts of each gland </li></ul><ul><ul><li>Adrenal medulla : controlled by the nervous system </li></ul></ul><ul><ul><li>Adrenal cortex : portions are controlled by ACTH from the anterior pituitary </li></ul></ul>15.4 Adrenal glands
  24. 24. Adrenal medulla <ul><li>Inner portion of the adrenal glands </li></ul><ul><li>Hypothalamus initiates stimulation of hormone secretion in the adrenal medulla </li></ul><ul><li>Produces: hormones that allow a short-term response to stress (“fight or flight” response) </li></ul><ul><ul><li>Epinephrine (adrenaline) </li></ul></ul><ul><ul><li>Norepinephrine </li></ul></ul>15.4 Adrenal glands
  25. 25. Adrenal cortex <ul><li>Outer portion of the adrenal glands </li></ul><ul><li>Produces hormones that provide a long-term response to stress </li></ul><ul><li>2 major types of hormones: </li></ul><ul><ul><li>Mineralocorticoids : </li></ul></ul><ul><ul><ul><li>regulate salt and water balance </li></ul></ul></ul><ul><ul><ul><li>e.g. aldosterone (targets the kidney) </li></ul></ul></ul><ul><ul><li>Glucocorticoids : </li></ul></ul><ul><ul><ul><li>regulate carbohydrate, protein and fat metabolism </li></ul></ul></ul><ul><ul><ul><li>Suppress the body’s inflammatory response </li></ul></ul></ul><ul><ul><ul><li>e.g. cortisol and cortisone </li></ul></ul></ul>15.4 Adrenal glands
  26. 26. Summary of the adrenal glands 15.4 Adrenal glands
  27. 27. Adrenal glands can malfunction <ul><li>Addison’s disease – hyposecretion of glucocorticoids by the adrenal cortex characterized by bronzing of the skin </li></ul>15.4 Adrenal glands
  28. 28. Adrenal glands can malfunction <ul><li>Cushing syndrome – hypersecretion of glucocorticoids by the adrenal cortex characterized by weight gain in the trunk of the body but not arms and legs </li></ul>15.4 Adrenal glands
  29. 29. 7. Pancreas <ul><li>Fish-shaped organ behind the stomach </li></ul><ul><li>Composed of 2 tissues: </li></ul><ul><ul><li>Exocrine: produces and secretes digestive juices </li></ul></ul><ul><ul><li>Endocrine (islets of Langerhans): produces and secretes hormones </li></ul></ul><ul><ul><ul><li>Insulin – secreted when blood glucose is high and stimulates uptake of glucose by cells (muscle and liver) </li></ul></ul></ul><ul><ul><ul><li>Glucagon – secreted when blood glucose is low and stimulates the breakdown of glycogen in the liver </li></ul></ul></ul>15.5 Pancreas
  30. 30. Regulation of blood glucose 15.5 Pancreas
  31. 31. Health focus: What is diabetes? <ul><li>Inability to control blood glucose levels </li></ul><ul><li>There are two types: Type 1 and Type 2 </li></ul><ul><li>18 million people in the US have diabetes </li></ul><ul><li>General symptoms: </li></ul><ul><ul><li>Frequent urination </li></ul></ul><ul><ul><li>Unusual hunger and/or thirst </li></ul></ul><ul><ul><li>Unexplained change in weight </li></ul></ul><ul><ul><li>Blurred vision </li></ul></ul><ul><ul><li>Sores that heal slowly or not at all </li></ul></ul><ul><ul><li>Excessive fatigue </li></ul></ul><ul><li>Long-term effects are blindness, loss of limbs, nerve deterioration, kidney and cardiovascular disease </li></ul>15.5 Pancreas
  32. 32. Diabetes: Understanding the 2 types <ul><li>Type 1 : </li></ul><ul><ul><li>Usually early-onset </li></ul></ul><ul><ul><li>Autoimmune disorder that tends to run in families </li></ul></ul><ul><ul><li>Pancreatic cells are attacked and cannot produce insulin </li></ul></ul><ul><ul><li>Need insulin injections </li></ul></ul><ul><li>Type 2 : </li></ul><ul><ul><li>Usually adult-onset and most common type </li></ul></ul><ul><ul><li>Tends to occur in obese, sedentary people </li></ul></ul><ul><ul><li>Cells do not respond to insulin </li></ul></ul><ul><ul><li>Usually diet and exercise are important for controlling this and may even prevent this! </li></ul></ul>15.5 Pancreas
  33. 33. 8. Testes <ul><li>Gonads found in males </li></ul><ul><li>Produce androgens (e.g. testosterone) </li></ul><ul><ul><li>Stimulates growth of the penis and testes </li></ul></ul><ul><ul><li>Responsible for 2 male sex characteristics such as facial, underarm and pubic hair </li></ul></ul><ul><ul><li>Prompts the larynx and vocal cords to enlarge resulting in a lower voice </li></ul></ul><ul><ul><li>Promotes muscular strength </li></ul></ul>15.6 Other endocrine glands
  34. 34. 9. Ovaries <ul><li>Gonads found in females </li></ul><ul><li>Produce estrogen and progesterone </li></ul><ul><ul><li>Stimulates growth of the vagina and uterus </li></ul></ul><ul><ul><li>Responsible for secondary sex characteristics such as female body hair, fat distribution and breast development </li></ul></ul><ul><ul><li>Responsible for egg maturation </li></ul></ul><ul><ul><li>Regulates the uterine cycle </li></ul></ul>15.6 Other endocrine glands
  35. 35. Bioethical focus: You decide <ul><li>Hormone replacement therapy (HTR) is often used to counteract some of the problems associated with menopause or to prevent an increased risk of osteoporosis </li></ul><ul><li>2002 a study found that HTR: </li></ul><ul><ul><li>May have risks that outweigh the benefits </li></ul></ul><ul><ul><li>Does not significantly increase the quality of life </li></ul></ul><ul><ul><li>Significantly increased the risk of breast cancer </li></ul></ul><ul><ul><li>May increase the risk of cardiovascular disease </li></ul></ul><ul><ul><li>Can prevent fractures as a result of osteoporosis </li></ul></ul>15.6 Other endocrine glands
  36. 36. 10. Thymus gland <ul><li>Lies beneath the sternum </li></ul><ul><li>This gland is largest and most active during childhood </li></ul><ul><li>T lymphocytes mature here </li></ul><ul><li>Secretes hormones called thymosins that aid in differentiation of lymphocytes </li></ul>15.6 Other endocrine glands
  37. 37. 11. Pineal gland <ul><li>Located in the brain </li></ul><ul><li>Secretes melatonin that regulates the sleep/wake cycle (circadian rhythm) </li></ul><ul><li>May also regulate sexual development </li></ul>15.6 Other endocrine glands
  38. 38. Hormones from other tissues <ul><li>Erythropoietin : secreted by the kidney to increase red blood cell production </li></ul><ul><li>Leptin : produced by fat cells and acts on the hypothalamus to give a feeling of being satiated </li></ul><ul><li>Prostaglandins : </li></ul><ul><ul><li>A groups of potent chemicals that are not carried in the bloodstream but work locally on neighboring cells </li></ul></ul><ul><ul><li>Some cause smooth muscle contraction </li></ul></ul><ul><ul><li>Major impact on reproductive organs </li></ul></ul><ul><ul><li>Many other roles in the body </li></ul></ul><ul><ul><li>Aspirin and ibuprofen block the synthesis of these </li></ul></ul>15.6 Other endocrine glands
  39. 39. Homeostasis <ul><li>The nervous and endocrine systems are important in maintaining homeostasis by: </li></ul><ul><ul><li>The hypothalamus bridges regulatory functions of both systems </li></ul></ul><ul><ul><li>The nervous system is able to respond to changes in the external environment </li></ul></ul>15.7 Homeostasis
  40. 40. How the nervous and endocrine systems work with other body systems 15.7 Homeostasis