1. Endocrine System CHAPTER 31

2. WHAT WILL YOU LEARN? The endocrine system produces hormones, chemicals that act on cells to produce a response. The word “hormone” comes from the Greek word hormaein, “to set in motion.” This is, in fact, exactly what hormones do—set things in motion. Sometimes, the effects of the hormone occur over a long period of time. For example, hormones allow us to grow to our adult height, and they cause the physical changes that turn boys and girls into men and women. Other times, the effects of hormones are more immediate. Hormones with short-term effects help the body to maintain homeostasis. For example, insulin is a hormone that regulates blood sugar levels. The hormones produced by the endocrine system control many of the body’s functions. In this chapter, you will learn about the glands of the endocrine system, some of the hormones they produce, and how these hormones act to “set things in motion.” You will also learn about some of the disorders that occur when the body produces too much or too little of a certain hormone.

3. When you are finished with this chapter, you will be able to: 1.State the main function of the endocrine system. 2.List the glands that make up the endocrine system. 3.Describe the feedback mechanism that controls the endocrine system. 4.List the hormones produced by the different glands of the endocrine system. 5.Explain how the aging process affects the endocrine system. 6.Discuss various disorders that affect the endocrine system. 7.Discuss the special care needs of people who have endocrine system disorders.

4. Endocrine System: Endocrine / Exocrine Glands Endocrine glands produce hormones and release them directly into the bloodstream Exocrine glands produce substances that are released into a hollow organ or onto a surface Examples of exocrine glands include: The salivary glands in the mouth, which produce saliva The sweat glands in the skin, which produce sweat Exocrine glands are not part of the endocrine system

5. Endocrine glands include: Pituitary gland Pineal gland Thyroid gland Parathyroid glands Thymus gland Adrenal glands Pancreas Sex glands (gonads)

6. Location of Endocrine Glands Endocrine glands are found in specific places throughout the body The pituitary gland ◦Is about the size of a cherry ◦Lies underneath the brain ◦Is connected by a stalk, called the infundibulum, to the hypothalamus The pineal gland ◦Is located underneath the brain The thyroid gland ◦Is located in the neck ◦Is butterfly-shaped, with two oval lobes located on either side of the larynx; connected by a narrow band of tissue called the isthmus

7. Function of the Endocrine Glands The endocrine system controls many of the body’s processes, such as: ◦Growth and development ◦Reproduction ◦Metabolism

8. How the Endocrine System works Endocrine glands produce hormones, chemicals that act on cells to produce a response The hormones are released into the bloodstream The hormone travels in the blood until it reaches its target cell Once there, it attaches to a special receptor in the cell wall Attaching a hormone to a receptor causes a specific reaction in the cell

9. Negative Feedback System of Endocrine System The secretion of many hormones is initiated by feedback system Some change in the internal environment causes the gland to begin producing its hormone The gland continues to produce the hormone until the amount of hormone (or some other related substance) reaches a certain level in the body At that point, the gland stops producing the hormone The feedback system works very much like a central heating unit in a house

10. Pituitary Gland

11. Pituitary Gland: Posterior Lobe Antidiuretic hormone (ADH) secreted by the posterior lobe; acts on the kidneys ADH limits the amount of water lost from the body in the form of urine ADH causes the kidneys to save body fluid by decreasing the amount of urine produced The lack of ADH causes the kidneys to produce more urine, eliminating excess fluid from the body Oxytocin is a hormone that: ◦Causes labor to begin ◦Lets down milk in the breasts of a nursing mother

12. Pituitary Gland: Anterior Lobe Growth hormone is what causes our bodies to get bigger and taller as we move from infancy into adulthood Growth hormone is usually released in greater amounts during short periods of time, resulting in a child’s “growth spurts” The anterior lobe continues to release growth hormone long after the growing phase of development is finished because cells continue to need to be replaced throughout a person’s lifetime Thyroid-stimulating hormone (TSH) stimulates the thyroid gland ◦Produces thyroid hormones ◦Affects the rate of metabolism in the body’s tissues Adrenocorticotropic hormone (ACTH) stimulates the adrenal glands ◦Produces hormones ◦Helps the body to cope with stress

13. Pituitary Gland: Anterior Lobe Prolactin stimulates the milk glands of the breasts to produce milk when a baby is born Gonadotropins regulate the functioning of the sex glands (gonads) in both males and females ◦Two types of gonadotropins: ◦Follicle-stimulating hormone (FSH) ◦Luteinizing hormone (LH)

14. Thyroid Gland The thyroid gland produces the following two hormones: ◦Thyroxine ◦Calcitonin

15. Thyroxine The hormone thyroxine sets the rate of metabolism for the cells of the body If the thyroid gland releases more thyroxine, the metabolic rate of the cells increases If the thyroid gland releases less thyroxine, the metabolic rate of the cells decreases The thyroid gland needs iodine to produce thyroxine Iodine is found in: ◦Fish and shellfish ◦Added to salt and other commercial products Goiter can occur when a person is deficient of iodine

16. Calcitonin Calcitonin regulates the level of calcium in the bloodstream Calcitonin transports the extra calcium to the bones Tetany (cramping of the skeletal muscles and an irregular heart beat) may result if the calcium level drops too low Too much calcium in the bloodstream causes muscles to become weak and slow to respond

17. Parathyroid Glands The parathyroid glands produce parathyroid hormone (PTH) PTH increases the amount of calcium in the blood: ◦Causes calcium to be released from the bones into the bloodstream ◦Helps the kidneys to keep calcium, instead of excrete it in the urine ◦Allows us to draw on stored calcium later in life The actions of calcitonin and PTH balance each other and help to keep the levels of calcium in the bloodstream constant

18. Parathyroid Glands If parathyroid glands are surgically removed or become damaged by disease: ◦PTH is not produced in adequate amounts ◦The calcium levels may drop, causing tetany Tumors of the parathyroid gland can cause an overproduction of PTH that results in: ◦Excess calcium being removed from the bones ◦Fragile bones ◦Formation of kidney stones

19. Thymus Gland The thymus gland secretes thymosin Thymosin helps infection-fighting T cells to mature An increase in the secretion of thymosin stimulates the body to produce more T cells during an infection or illness

20. Adrenal Glands Each adrenal gland has two separate parts: ◦The medulla, or inner portion ◦The cortex, or outer portion Each part secretes distinct hormones

21. Adrenal Glands: Medullary Hormones The medulla of the adrenal glands secretes two hormones: ◦Epinephrine ◦Norepinephrine Responsible for the “fight-or-flight” response of the body in emergency situations Help the heart and lungs deliver more oxygen and nutrients to the muscles, preparing the body to “stand up and fight or turn tail and run” ◦Dry mouth ◦Pounding heart

22. Adrenal Glands: Cortical Hormones Glucocorticoids: ◦Help to metabolize fats and proteins ◦Help to maintain a reserve of glucose that can be used in times of stress ◦Suppress the body’s inflammatory response Glucocorticoids are given in the form of drugs for severe inflammatory disorders such as: ◦Asthma ◦Rheumatoid arthritis ◦Severe allergic reactions Hydrocortisone is a common medication that is a glucocorticoid

23. Adrenal Glands: Cortical Hormones Mineralocorticoids help to regulate the level of certain minerals in the body, particularly sodium and potassium Aldosterone is the primary hormone in this group Aldosterone helps the kidneys to reabsorb sodium and secrete potassium Androgens are secreted in small amounts by the adrenal cortex Androgens are converted by the body into the sex hormones ◦Testosterone (in men) ◦Estradiol (in women)

24. Pancreas The pancreas is both an exocrine gland and an endocrine gland It functions as an exocrine gland by producing and secreting enzymes into the small intestine that help to digest food It functions as an endocrine gland by producing two hormones, insulin and glucagon

25. Pancreas: action of Insulin Special cells within the pancreas, called the islets of Langerhans, produce and secrete the hormone insulin Insulin affects all of the body’s cells Insulin allows glucose (sugar) to be transported from the bloodstream into the individual cells, where it is used for energy Insulin lowers the blood glucose level

26. Pancreas: Action of Glucagon Glucagon is responsible for raising the blood glucose level When the glucose levels in the bloodstream drop, when a person has not eaten for some time, the pancreas secretes glucagon Glucagon stimulates the liver to release the glucose that has been stored as glycogen into the bloodstream, to supply the cells of the body with fuel for energy

27. Sex Glands The sex glands (or gonads) secrete hormones that: ◦Cause the onset of puberty ◦Regulate reproduction

28. The Effects of Aging on Endocrine System The normal processes of aging: ◦decrease the amount of hormones produced ◦slow the secretion by the endocrine glands Decrease in thyroid hormone levels slows the body’s metabolism In women, menopause occurs as a result of decreased hormone production by the ovaries In men, secretion of hormones by the testes decreases, affecting sexual drive and function

29. Disorders of the Endocrine System Disorders of the endocrine system can be caused: ◦When the body produces too much or too little of a certain hormone ◦By disorders of the hypothalamus, the pituitary gland, or the specific endocrine gland responsible for the hormone ◦As a result of poor nutrition Corrective measures may be needed to restore the body’s homeostasis and prevent the imbalances from causing health problems

30. Pituitary Dwarfism A deficiency in the amount of growth hormone secreted during the growing years results in a condition known as pituitary dwarfism A person with pituitary dwarfism is much smaller than average, but still well proportioned If the condition is diagnosed while the person is still a child, growth hormone may be given to help stimulate growth

31. Pituitary Gigantism An excess in the amount of growth hormone secreted during the growing years results in a condition known as pituitary gigantism A person with pituitary gigantism is much larger than average, but still well proportioned

32. Acromegaly The secretion of too much growth hormone after a person has reached adulthood causing excessive growth of the bones of the hands, feet, and face Causes disproportioned appearance, especially in the face and hands Person does not grow taller

33. Thyroid Disorders Secretion of thyroid hormones is controlled by the pituitary gland Thyroid disorders can be caused by: ◦Pituitary gland abnormalities ◦Thyroid gland abnormalities ◦Nutrient deficiencies, such as a lack of iodine A simple blood test can be used to detect imbalances in thyroid hormones Once detected, these imbalances can usually be treated

34. Hyperthyroidism Hyperthyroidism or Graves’ disease is caused by the excessive secretion of thyroxine In a person with hyperthyroidism, the metabolic rate of the body’s cells is increased Signs and symptoms of hyperthyroidism: ◦Increased hunger accompanied by weight loss ◦Irregular heartbeat ◦Inability to sleep ◦Irritability ◦Confusion ◦Increased perspiration, and intolerance to heat Hyperthyroidism may be treated by: ◦Surgically removing part of the thyroid gland ◦Destroying part of the gland with radiation

35. Hypothyroidim Hypothyroidism results when thyroxine secretion is too low In children, hypothyroidism, if left untreated, can result in a condition known as cretinism ◦Cretinism is characterized by a lack of physical growth and mental development Most cases of hypothyroidism develop later in life, as a result of a disorder of the: ◦Hypothalamus ◦Pituitary gland, or ◦Thyroid gland Hypothyroidism is more common among women and the elderly Hypothyroidism is treated by administering thyroxine in the form of a pill

36. Hypothyroidism: Signs / Symptoms Most cases of hypothyroidism develop later in life, as a result of a disorder of the: ◦Hypothalamus ◦Pituitary gland, or ◦Thyroid gland Hypothyroidism is more common among women and the elderly Hypothyroidism is treated by administering thyroxine in the form of a pill

37. Adrenal Gland Disorders Two of the most common adrenal gland disorders are: ◦Addison’s disease ◦Cushing’s syndrome Result from imbalances of the adrenal cortical hormones

38. Addison’s Disease In Addison’s disease, the adrenal cortex is destroyed, resulting in low levels of the adrenal cortical hormones A person with Addison’s disease experiences: ◦Muscle weakness and atrophy ◦Dark discoloration of the skin ◦Disturbances in the body’s salt and water balance ◦Hypertension A person with Addison’s disease may need assistance with walking and range-of-motion exercises

39. Cushing’s Syndrome Cushing’s syndrome results from: ◦Excessive secretion of glucocorticoids ◦Disorders of the pituitary gland that affect ACTH secretion ◦Disorders of the adrenal gland itself ◦Administering high doses of steroid medications, such as hydrocortisone, for a long period of time Signs / Symptoms Pockets of fat in the abdomen, on the back, and in the face Increased facial hair High blood glucose levels, since one of the effects of glucocorticoids is to decrease the use of glucose by the tissues

40. Diabetes Mellitus (DM) Diabetes mellitus results when the pancreas is unable to produce enough insulin Diabetes mellitus can occur in people of all ages and races People between the ages of 65 and 74 years and people of African descent are affected most often Diabetes mellitus is the most common of all endocrine gland disorders and is the seventh leading cause of death among the elderly There are two types of diabetes mellitus, type I and type II

41. Juvenile Diabetes (Type I) Caused by destruction of the insulin-producing cells of the pancreas Form of diabetes that most often affects children Most people who have type I diabetes are diagnosed while they are children or young adults

42. Insulin A person with type I diabetes mellitus must receive daily injections of insulin The insulin is injected into the subcutaneous layer of the skin, where it is absorbed by the bloodstream Several types of insulin are available The types of insulin differ in the speed at which they start working and how long they last in the body Some patients or residents receive only one injection of insulin each day, while others may receive two or three Insulin can also be delivered continuously by a pump device

43. Hypoglycemia / Hyperglycemia People who are receiving insulin injections need to have their blood glucose levels monitored closely ◦Nursing assistants may help with glucose monitoring if properly trained Too much insulin causes hypoglycemia, a dangerous drop in blood glucose ◦Hypoglycemia robs the brain of the glucose that is essential for it to function Too little insulin results in hyperglycemia, or too much glucose in the bloodstream ◦If a person’s blood glucose level increases too much, he can enter a state called diabetic coma ◦If not treated, diabetic coma can lead to death

44. Diabetic Diet People who are receiving insulin injections must eat an adequate amount of nutritious food at regular intervals ◦Meals ◦Snacks A person with type I diabetes must eat a diet with specific amounts of: ◦Carbohydrates ◦Sugars ◦Fats ◦Proteins to react with the amount of injected insulin

45. Diabetic Diet If a person does not eat at the recommended time after receiving her insulin, her blood glucose level can drop too low, resulting in a condition known as insulin shock If one of your patients or residents with diabetes refuses to eat, only partially finishes his meal or snack, or vomits after eating report this to the nurse immediately

46. Type II Diabetes Mellitus (DM) Type II diabetes mellitus: most common in overweight adults In people with type II diabetes mellitus: ◦The pancreas still produces some insulin but the cells of the body are unable to respond to the insulin ◦The body is unable to transport the glucose into the cells ◦This results in higher blood glucose levels Symptoms of type II diabetes mellitus may occur gradually and go undetected for a long time

47. Type II Diabetes Mellitus (DM) Type II diabetes is treated through: ◦Diet ◦Exercise ◦Use of oral medications to increase the effectiveness of insulin People with severe type II diabetes may need to be treated with insulin injections, especially during times of illness or stress When caring for a person with type II diabetes, be sure to watch closely the amounts and types of food the person eats

48. Hypoglycemia / Hyperglycemia: Symptoms Signs and symptoms of hyperglycemia and hypoglycemia are often very similar and should be reported to the nurse immediately. These signs include: ◦Excessive hunger ◦Excessive thirst ◦Weakness, dizziness, or both ◦Drowsiness and confusion ◦Shaking and increased perspiration

49. Complications of DM Many organ systems can be affected by uncontrolled diabetes mellitus of either type Low insulin levels increase the release of lipids (fats) into the bloodstream The lipids then build up in the linings of the arteries, damaging the blood vessels and possibly leading to: ◦Atherosclerosis ◦High blood pressure ◦Heart disease ◦Kidney disease ◦Blindness (diabetic retinopathy)

50. Preventing Complications Early detection of diabetes mellitus is essential for preventing complications Once diabetes mellitus is diagnosed, measures can be taken to keep the disease under control and minimize the risk of developing complications: ◦Weight loss (if applicable) ◦Regular exercise ◦Close attention to recommended diet ◦Proper use of prescribed medications