The Endocrine System

1. 30 The Endocrine System

2. Learning Outcomes 30.1 Define the term endocrine glands. 30.2 Describe the general functions of the endocrine system. 30.3 Define the term hormone. 30.4 Explain the difference in hormone control by positive and negative feedback loops.

3. Learning Outcomes (cont.) 30.5 Describe the locations of the hypothalamus, pituitary gland, pineal body, thyroid gland, parathyroid glands, adrenal glands, pancreas, thymus, and gonads. 30.6 List the hormones released by the pituitary gland and give the functions of each. 30.7 List the hormones released by the thyroid gland and parathyroid glands and give the functions of each.

4. Learning Outcomes (cont.) 30.8 List the hormones released by the adrenal glands and give the functions of each. 30.9 List the names of the endocrine cells of the pancreas, the hormones released by them, and the function of each hormone. 30.10 List the hormones released by the pineal body, thymus, and gonads, and give the functions of each.

5. Learning Outcomes (cont.) 30.11 Name the hormones produced by the kidneys and heart, listing which organ produces the hormone, and the hormone’s function. 30.12 Describe stressors and their effect on the body. 30.13 Describe the causes, signs and symptoms, and treatment of various endocrine disorders.

6. secrete into bloodstream to hormones target tissues Introduction • The endocrine system includes the organs of the body that secrete hormones directly into body fluids such as blood • Regulates chemical reaction in cells and therefore control functions of the organs, tissues, and other cells Glands

7. Hormones • Endocrine glands • Ductless • Release hormones • Directly into target tissues • Into bloodstream to be carried to target tissues • Hormones – chemicals secreted by a cell that affect the functions of other cells

8. Hormones Hormones (cont.) • Many are derived from steroidsthat easily cross the cell membrane • Examples of steroidal hormones • Estrogen • Progesterone • Testosterone • Cortisol

9. Nonsteroidal hormones Made of amino acids or proteins and cannot cross the cell membrane easily Bind to receptors on the surface of the cells G-protein – activated by the hormone-receptor complex Activates enzymes inside cell Prostaglandins Local, or tissue, hormones Derived from lipid molecules Do not travel in the bloodstream Target tissues are located close by Produced by organs such as Kidneys Heart Stomach Uterus Brain Hormones (cont.)

10. Feedback Loops • Control hormone levels • Negative feedback loop • Hormone release stops in response to decrease in stimulus • Stimulus (eating) raises blood glucose levels • Pancreas releases insulin in response to elevated blood glucose • Blood glucose decreases as it is used by the body or stored in the liver • Insulin release stops as blood glucose levels normalize

11. Feedback Loops (cont.) • Positive feedback loop • As long as stimulus is present, action of hormone continues • Infant nursing at mother’s breast  stimulates hypothalamus  stimulates posterior pituitary • Oxytocin released  stimulates milk production and ejection from mammary glands • Milk release continues as long as infant continues to nurse

12. ANSWER: E Apply Your Knowledge Match the following: ___ Chemicals that effect cell function A. Nonsteroidal hormone ___ Easily cross cell membranes B. Steroidal hormone ___ Made of amino acids C. G-protein ___ Target nearby cells D. Prostaglandins ___ Activated by hormone-receptor E. Hormones complex ___ Cannot cross cell membranes easily ___ Estrogen and cortisol B A D C A B VERY GOOD!

13. Glands Hypothalamus • Hormones • Oxytocin • Antidiuretic hormone (ADH) • Hormones transported to the posterior pituitary for storage • Directs posterior pituitary to release hormones

14. Glands Pituitary Gland • Controlled by the hypothalamus • Located at the base of the brain • Protected by a bony structure called the sella turcica • The optic chiasm is located just above the pituitary gland • Carries visual information to the brain for interpretation • Two lobes • Anterior lobe • Posterior lobe Pituitary Gland

15. Pituitary Gland (cont.) Stimulates milk production Growth hormone Prolactin Stimulates increase in size of muscles and bones Anterior Lobe Thyroid-stimulating (TSH) Luteinizing Stimulates the thyroid gland to release its hormones Females: stimulates ovulationand estrogen production Males: stimulates testosterone production Follicle-stimulating Adrenocorticotropic (ACTH) Females: stimulates estrogen production and maturation of the ova Males: stimulates sperm production Stimulates the adrenal cortex to release its hormones

16. Pituitary Gland (cont.) Oxytocin Posterior Lobe Females: causes contraction of the uterus and ejection of breast milk Males: stimulates contraction of the prostate and vas deferens during sexual arousal Antidiuretic hormone (ADH) Stimulates the kidneys to conserve water

17. Apply Your Knowledge ANSWER: D, E Match the following: ___ Stored in posterior pituitary A. Follicle-stimulating hormone ___ Milk production B. Prolactin ___ Produced by hypothalamus C. Luteinizing hormone ___ Stimulates sperm production D. ADH ___ Maturation of ova E. Oxytocin ___ Stimulates ovulation ___ Conservation of water ___ Production of testosterone ___ Contraction of uterus B D, E A A C Super! D C E

18. Thyroid hormones Calcitonin T3 T4 Glands Thyroid Gland • Located below the larynx • Divided into follicles that store some of the hormones Major hormones Stimulate protein synthesis and increase cellular energy production Lowers blood calcium levels by activating osteoblasts that build new bone tissue

19. Glands Parathyroid Glands • Four located on the posterior surface of the thyroid gland • Secrete parathyroid hormone (PTH) • Agonist to calcitonin by raising blood calcium levels through activation of osteoclasts (dissolve bone) • As bone dissolves, calcium levels in blood increase

20. True or False: __ Thyroid hormones stimulate protein synthesis. __ The thyroid gland does not store hormones. __ PTH activates osteoblasts. __ Calcitonin increases cellular energy production. __ The four parathyroid glands are located on the thyroid gland. __ Calcitonin lowers blood calcium levels. Apply Your Knowledge ANSWER: T Thyroid follicles store some hormones. F F PTH activates osteoclasts. Thyroid hormone increases cellular energy production. F T T Bravo!

21. Glands Adrenal Glands • Located on top of each kidney • Divided into the adrenal medulla and adrenal cortex • Adrenal medulla • Central portion • Hormones • Epinephrine • Norepinephrine • Same effects as sympathetic nervous system

22. Adrenal Glands (cont.) • Adrenal cortex • Outermost portion • Secretes many hormones, but main ones are • Aldosterone • Stimulates body to retain sodium and water • Important in maintaining BP • Cortisol • Released when stressed • Decreases protein synthesis, resulting in slowed tissue repair • Decreases inflammation

23. Apply Your Knowledge ANSWER: Match the following: ____ Adrenal medulla A. Cortisol ____ Sodium retention B. Epinephrine ____ Decreases inflammation C. Aldosterone ____ Sympathetic effects D. Norepinephrine ____ Maintains blood pressure ____ Released during stress ____ Adrenal cortex B, D C A B, D C A Excellent! A, C

24. Glands Pancreas • Located behind the stomach • Both exocrine gland and endocrine gland • Exocrine – secretes digestive enzymes into a duct leading to the small intestine • Endocrine – secretes hormones into bloodstream

25. Blood glucose concentrations Blood glucose concentrations Protein synthesis Protein synthesis Pancreas (cont.) • Islets of Langerhanssecrete hormones into bloodstream • Alpha cells secrete glucagon • Beta cells secrete insulin Insulin Glucagon

26. Yippee! Apply Your Knowledge What are the effects of insulin and glucagon? ANSWER: Insulin decreases blood glucose concentration and increases protein synthesis. Glucagon does just the opposite. It increases blood glucose and decreases protein synthesis.

27. Pineal body Small gland Located between cerebral hemispheres Melatonin Regulates circadian rhythms May play a role in onset of puberty Thymus gland Located between lungs Thymosin Promotes production of T lymphocytes Glands Other Hormone-Producing Organs

28. The gonads Ovaries Estrogen Progesterone Testes Testosterone Stomach Gastrin Small intestine Secretin Cholecystokinin Heart Atrial natriuretic peptide– regulates BP Kidneys Erythropoietin – stimulates blood cell production Glands Other Hormone-Producing Organs (cont.)

29. Back Back

30. Apply Your Knowledge ANSWER: Match the following: ___ Between lungs A. Pineal body ___ Melatonin B. Heart ___ Estrogen/testosterone C. Kidneys ___ Gastrin D. Thymus gland ___ Secretin E. Small intestine ___ Erythropoietin F. Stomach ___ Atrial natriuretic peptide G. Gonads ___ Thymosin ___ Cholecystokinin D A G F E C B D Good Job! E

31. The Stress Response • Stressor • Any stimulus that produces stress • Types • Physical factors • Psychological factors • Positive stimuli

32. The Stress Response (cont.) • Physiologic response to stress caused by hormone release • General stress syndrome • Increased heart rate, respiratory rate, and BP • Increase in glucose and fatty acids in blood, which leads to weight loss • Increase in cortisol if stress prolonged • Decreased body repair • Susceptibility to illness

33. Apply Your Knowledge ANSWER: Match the following: ___ Extreme heat A. Physical stress ___ Death of friend B. Psychological stress ___ Fractured leg C. Positive stimulus ___ Wedding ___ Exam ___ Hearing an explosion nearby ___ “A” on an exam ___ Flu ___ Car stolen A B A C B Very Good! B C A B

34. Common Diseases and Disorders

35. Common Diseases and Disorders(cont.)

36. Common Diseases and Disorders(cont.)

37. ANSWER: F Correct! Apply Your Knowledge True or False: ___ Acromegaly develops as a result of too much growth hormone in a child. ___ In diabetes insipidus, the kidneys fail to reabsorb water. ___ Too little growth hormone in childhood results in dwarfism. ___ Myxedema is the result of hyperthyroidism. ___ Addison’s disease is the result of too little corticosteroid. ___ Cushing’s disease is the result of too little ACTH. ___ Cretinism is an extreme form of hyperthyroidism present at birth. in an adult T T hypothyroidism F T F too much ACTH F hypothyroidism

38. 30.1 Endocrine glands are ductless glands, releasing hormones directly into the bloodstream and tissues. 30.2 The organs of the endocrine system produce hormones that regulate the chemical reactions within cells, controlling the functions of organs, tissues, and other cells. 30.3 Hormones are chemicals released by cells that affect the functioning of other cells. In Summary

39. In Summary (cont.) 30.4 In a negative feedback loop, a stimulus causes a body reaction, which is detected by another area of the body, which stops the reaction. The rise in blood sugar causing the pancreas to release insulin to lower blood sugar is an example. In a positive feedback loop, a stimulus begins a process which will continue as long as the stimulus continues; as happens with a nursing infant, where the suckling releases milk from the mother’s breast until the suckling stops.

40. In Summary (cont.) 30.5 The hypothalamus, pituitary, and pineal glands are located within the brain. The thyroid and parathyroid glands are located in the neck. The thymus is found in the mediastinum. The adrenal glands are located above each kidney, and the pancreas is located behind the stomach. In females, the gonads (ovaries) are in the abdominal cavity and in males, the gonads (testes) are found within the scrotal sac.

41. In Summary (cont.) 30.6 The pituitary gland releases the following hormones: GH, MSH, ACTH, TSH, FSH, LH, PRL, ADH and OT. Each hormone’s specific function may be found in Table 30-1. 30.7 The thyroid gland releases calcitonin, T3, and T4 which are important in growth and protein synthesis. The parathyroid releases PTH which balances the action of calcitonin.

42. 30.8 The adrenal medulla secretes epinephrine and norepinephrine, which work with the sympathetic nervous system. The adrenal cortex produces many hormones, but the two major ones are aldosterone for BP maintenance and cortisol, which decreases inflammation. 30.9 The endocrine cells of the pancreas are known as the Islets of Langerhans. The two types of cells are Alpha cells, which release glucagon, and Beta cells, which release insulin. In Summary (cont.)

43. In Summary (cont.) 30.10 The pineal body releases melatonin to regulate circadian rhythms, the thymus releases thymosin and thymopoietin to promote T cell production, ovaries release estrogen and progesterone (females), and the testes (males) release testosterone. 30.11 The kidneys produce erythropoietin, affecting the bone marrow, and the heart produces atrial natriuretic peptide, affecting BP.

44. In Summary (cont.) 30.12 Stressors are defined as stimuli that produce a stress response, a physiologic response to the stimulus that changes the body’s functioning in some way. 30.13 The diseases and disorders of the endocrine system are as varied as the organs and hormone dysfunctions that cause them. An overview of these conditions is in Table 30-2, and more detail on the most common of these conditions is found in the Pathophysiology section at the end of this chapter.

45. End of Chapter 30 Its not stress that kills us, it is our reaction to it. ~ Hans Selye