Presentation on theme: "TEACH Lesson Plan Manual for Herlihy’s The Human Body in Health and Illness 5th edition Chapter 14 Endocrine System."— Presentation transcript:
1 TEACH Lesson Plan Manual for Herlihy’s The Human Body in Health and Illness
5th edition Chapter 14 Endocrine System
2 Lesson 14.1 Structure and Function of the Endocrine System
List the functions of the endocrine system. Discuss the role and function of hormones in the body, including: Define hormone. Explain the process by which hormones bind to the receptor sites of specific tissues (targets). Explain the three mechanisms that control the secretion of hormones. Discuss the pituitary gland, including: Describe the relationship of the hypothalamus to the pituitary gland. Describe the location, regulation, and hormones of the pituitary gland.
3 Endocrine Glands Ductless glands Secrete hormones
Widely distributed throughout the body The endocrine system and its hormones help regulate metabolic processes involving carbohydrates, proteins, and fats. Can you think of other roles the endocrine system plays? (Hormones also play an important role in growth and reproduction. They also help regulate water and electrolyte balance and help the body meet the demands of infection, trauma, and stress.) The nervous system communicates through electrical signals called nerve impulses. Nerve impulses communicate information rapidly and generally achieve short-term effects. The endocrine system, in contrast, communicates through chemical signals called hormones. Refer students to Figure 14-1 on p. 260.
4 Hormones Chemical messengers that influence or control activities of other tissues and organs Classification Proteins (and protein-related substances) Steroids Hormones play an important role in growth and reproduction, along with regulation of water and electrolyte balance. With the exception of secretions from the adrenal cortex and the sex glands, all hormones are protein or protein related. The adrenal cortex and the sex glands secrete steroids. Hormones can have one or more target tissues. The target tissue is the one that a certain hormone specifically binds to.
5 Hormones and Their Receptors
Gland aims hormone at target organs Hormone activates receptors On cell membrane Within cell nucleus Why does the slide show the gland shooting an arrow at several organs? (The gland secretes a hormone that is directed toward a target organ. Most hormones affect several organs.) What are the two types of hormone receptor sites? (They are membrane receptors and intracellular receptors.) How is the specificity of the receptors like a lock and key? (Each receptor has a specific shape into which only certain hormones can fit.) A particular hormone is circulating in the blood. Why are some organs unaffected by it? (The unaffected organs lack the receptors for that particular hormone.)
6 Control of Hormonal Secretion
Feedback control Negative Positive Biorhythms Circadian and monthly Central nervous system Psychoneuroendocrinology Negative and positive feedback control are discussed on the following slides. What are some examples of biorhythms? (Students might mention the female menstrual cycle and the effects of jet lag.) Some drugs, such as steroids, are administered on a schedule in step with the body’s natural biorhythm. CNS controls the secretion of hormones in two ways: activation of the hypothalamus and stimulation of the sympathetic nervous system. The hypothalamus controls the pituitary gland, which is discussed on a later slide.
7 Control by Negative Feedback Loop
Example: As level of cortisol rises in the blood to needed level, cortisol shuts off further secretion of ACTH As level of cortisol drops, inhibition is relieved Many hormones are controlled by negative feedback; for example, cortisol. What happens to ACTH secretion when inhibition is relieved? (ACTH secretion increases, thereby stimulating the adrenal gland to secrete more cortisol. This is an example of negative feedback control.) Chapter 1 explained negative control with an analogy of a thermostat controlling temperature; when a room gets hot enough, the thermostat shuts off the furnace.
8 Control by Positive Feedback Loop
A bodily change stimulates further change in the same direction The following are some examples: During labor, pressure of baby’s head on cervix stimulates release of oxytocin Oxytocin stimulates uterine contraction, further increasing pressure on cervix More oxytocin is released until delivery To induce labor in some mothers, oxytocin is administered intravenously. This initiates a positive feedback loop that ultimately leads to delivery. Another example of control by positive feedback is activation of the blood clotting mechanism. Once the mechanism is started, clotting factors are sequentially activated until the bleeding stops. How are the nervous system and endocrine system related? (The CNS helps control the secretion of hormones in two ways: activation of the hypothalamus and stimulation of the sympathetic nervous system. In fact, the functions of the nervous system and the endocrine system are so closely related that the word psychoneuroendocrinology is used.)
9 Hypothalamus and Pituitary Gland
Hypothalamus controls pituitary function Connected to anterior pituitary through capillaries and to posterior pituitary through tissue extension Refer students to Figure 14-4 B and C on p. 264. The hypothalmus controls the anterior pituitary by releasing hormones. There are specific releasing hormones for each hormone of the anterior pituitary. For example, CRH—corticotropin-releasing hormone—stimulates the release of ACTH by the anterior pituitary. What is the name of the capillaries that connect the anterior pituitary to the hypothalamus? (These capillaries are called the hypothalamic-hypophyseal portal system.) Why is there no similar portal system in the posterior pituitary? (The posterior pituitary is nervous tissue because it is a direct extension of the hypothalamus.) A stalk of tissue attaches the pituitary gland to the undersurface of the hypothalamus.
10 Pituitary Gland: Two Parts
Anterior pituitary Adenohypophysis Controlled by releasing hormones of hypothalamus Posterior pituitary Neurohypophysis Extension of hypothalamus Refer students to Figure 14-4, A, on p. 264. Why is the anterior pituitary called the adenohypophysis and the posterior pituitary called the neurohypophysis? (The anterior pituitary is composed of glandular tissue [adeno = glandular]. The posterior pituitary is a direct extension of the hypothalamus, which is nervous tissue.) Releasing hormones from the hypothalamus reach the adenohypophysis through the portal capillaries. The posterior pituitary does not need releasing hormones.
11 Hormones of Anterior Pituitary
Tropic hormones TSH ACTH Growth hormone Gonadotropins FSH and LH Prolactin The anterior pituitary secretes at least six hormones that are aimed at their respective target organ, causing the organ to secrete hormones. There are other hormones, described later, that are not controlled by the pituitary gland; for example, insulin. Why do some people call the anterior pituitary the master gland but others call the hypothalamus the master gland? (The anterior pituitary secretes six hormones that control many glands. The hypothalamus controls the anterior pituitary.) Predict some possible consequences of surgically removing the anterior pituitary. (There will be diminished or absent function in each of the target organs. Hormone replacement therapy is necessary. For instance, supplementation by cortisol compensates for the lack of ACTH.)
12 Hormones of Posterior Pituitary
Antidiuretic hormone (ADH) Oxytocin What are the target organs for oxytocin and ADH? (The target organs for oxytocin are the uterus and the breasts. The target organ for ADH is the kidney. The functions of each are described in detail in later chapters.) ADH is released in response to a concentrated blood (increased osmolarity) and decreased blood volume; both occur in dehydration. The target organs of oxytocin in the female are the uterus and the mammary glands.
13 A Tiny Third Lobe: A Fetal Structure
In addition to anterior and posterior glands, there is a gland that has a melanocyte-secreting hormone (MSH) Adult cells produce a polypeptide called pro-opiomelanocortin (POMC) What eventually happens to the tiny third lobe? (The cells are incorporated into the tissue of the anterior pituitary gland; hence, the adult pituitary has no tiny third lobe.) The polypeptide is degraded in the pituitary gland to ACTH and endorphins.
14 Lesson 14.2 Other Major Endocrine Glands and Their Hormones
Identify the other major endocrine glands and their hormones, and explain the effects of hyposecretion and hypersecretion.
15 Thyroid Gland: Hormones
Follicular cells secrete T3 and T4 into colloid for storage FSH releases T3, T4 into the blood Parafollicular cells secrete calcitonin Why may an enlarged thyroid gland be palpable or be visible? (It is located in the neck, anterior to the trachea, right under the skin.)
16 What Thyroid Hormones Do
T3 and T4 Regulate metabolism Permit proper functioning of all other hormones Promote normal maturation of the nervous system Promote normal growth and development Calcitonin Helps regulate calcium levels in the blood T4 is also called thyroxin. Ask students to predict some consequences of hyposecretion of thyroid hormones. (Answers will include slowed-down heart rate, constipation, lack of energy, and weight gain.) What would you expect from hypersecretion of thyroid hormones? (Answers will include a speeded-up heart rate, diarrhea, excess energy, weight loss, and exophthalmia.) All thyroid hormone drugs will be T3, T4, or a mixture of the two.
17 Abnormal Thyroid Secretion
Hypothyroidism: Deficiency of T3/T4 Results in a slowed-down metabolic rate or myxedema Hyperthyroidism: Excess of T3/T4 Causes accelerated metabolic rate or Graves’ disease What happens if a pregnant woman takes an antithyroid drug, such as propylthiouracil? (The baby will have a deficiency of thyroid hormones and may develop cretinism. This condition is marked by extreme delays in physical and intellectual growth.) Explain why extreme exophthalmia may cause corneal ulceration. (The eyelids cannot cover the bulging eyes, so the cornea dries out, ulcerates, and scars. Early treatment is essential.)
18 Control of T3 and T4 Secretion
Releasing hormone (TRH) TSH T3 and T4 Negative feedback loop by T3 and T4 TRH, or thyrotropin releasing hormone, begins the sequence of events leading to the release of T3/T4. How is secretion of T3 and T4 controlled through negative feedback? (TSH stimulates the thyroid gland to secrete T3 and T4. T3 and T4 shut down further secretion of TSH by the anterior pituitary.) Explain the negative feedback effect of T3 and T4 on the hypothalamus. (Elevations of T3 and T4 suppress hypothalamic-releasing hormone. This suppresses further secretion of TSH by the anterior pituitary.)
19 The Need for Iodine T3 = triiodothyronine
T4 = tetraiodothyronine (thyroxine) Iodine essential for synthesis of T3 and T4 Iodine deficiency causes goiter or enlargement of thyroid gland Iodine deficiency interferes with negative feedback loop How does the negative feedback loop help explain why iodine deficiency can lead to a goiter? (If you have a lack of iodine, you may not make sufficient thyroid hormones. The negative feedback control fails, resulting in a persistent secretion of TSH. The thyroid gland is continually stimulated by TSH and enlarges [a goiter].) Why is iodized salt commonly used? (The use of iodized salt ensures an adequate intake of iodine and prevents the formation of goiter. The “goiter belts” in this country attest to the importance of adequate dietary iodine.)
20 Four Parathyroid Glands
Lie along posterior wall of thyroid gland Are most important regulator of blood calcium Secrete parathyroid hormone (PTH), which elevates blood calcium level Parathyroid hormone stimulates the kidneys to reabsorb calcium from the urine. At the same time, PTH causes the kidneys to excrete phosphate. Working with vitamin D, PTH increases the absorption of dietary calcium by the digestive tract (intestine). PTH from the parathyroid and calcitonin from the thyroid regulate blood calcium levels within very narrow limits. The parathyroid hormone (PTH) is the most important hormone in this regulatory process.
21 PTH Raises Blood Calcium
Three mechanisms Bone Resorption Kidney Reabsorbs Ca2+ from urine Intestine Absorbs dietary Ca2+ Refer students to Figure 14-6 on p. 270. PTH has three target organs, bones, kidney, and intestine. Ask students to trace the negative feedback loop controlling secretion of PTH. (The stimulus for PTH release is declining levels of calcium in the blood. When PTH is secreted, it stimulates the target organs, thereby raising plasma calcium levels and shutting off further stimulation of PTH. This loop is independent of the hypothalamus and pituitary glands.) Resorption refers to the process whereby osteoclastic activity moves calcium from the bone to the blood. Resorption should not be confused with reabsorption. In the blood, calcium and phosphate exist in inverse levels; as one rises, the other falls. Drinking large amounts of carbonated soft drinks raises phosphate levels and lowers calcium levels in the blood. Under the influence of PTH, the bones will send calcium to the blood. The long-term effect of this can be softened bones, also called osteomalacia.
22 Blood Calcium: Imbalances
Thyroid gland secretes calcitonin in response to elevated blood calcium level Calcitonin lowers blood calcium level By bone by stimulating osteoblastic activity By kidney by excreting excess calcium Why does osteoblastic activity lower levels of blood calcium? (Osteoblastic activity moves calcium from the blood and deposits it in the bone.)
23 Parathyroid Glands: Abnormal Secretion
Hyposecretion: Hypocalcemic tetany, causing carpal spasm Hypersecretion: Hypercalcemia “Bones, stones, moans, and groans” Hyposecretion of PTH is both more serious and more common than hypersecretion. Calcium normally stabilizes nerve and muscle membranes; therefore, a deficiency can cause sustained or tetanic contractions of muscles with carpal spasm. Tetany, more seriously, affects the larynx and breathing apparatus. Patients with this condition will become unable to breathe. Explain why “bones, stone, moans, and groans” are caused by hypercalcemia. (All these effects are caused by calcium leaving the bones and being deposited in other organs, such as the kidney.)
24 Adrenal Glands Located above kidneys Adrenal medulla Adrenal cortex
Inner region Secretes catecholamines Adrenal cortex Outer region Secretes steroids The adrenal glands secrete two entirely different hormones with different effects. Refer students to Figure 14-8 on p The most important structures to note here are the outer cortex and inner medulla.
25 Adrenal Medulla Extension of sympathetic nervous system
Fight-or-flight response Increases heart rate and blood pressure Mobilizes body for emergencies Catecholamines Epinephrine Norepinephrine Epinephrine and norepinephrine prolong the fight-or-flight response of the central nervous system. The adrenal medulla also causes bronchodilation and changes blood flow patterns. A tumor of the adrenal medulla is called pheochromocytoma. What are some likely clinical effects of this tumor? (The presenting and life-threatening sign is severe hypertension; other sympathetic effects will be present. A measurement of urinary catecholamine levels is used in diagnosing pheochromocytoma.)
26 Adrenal Cortex: Steroids
Sugar: Glucocorticoids Cortisol, most important Salt: Mineralocorticoids Aldosterone Sex: Sex hormones Testosterone, most important “Sugar, salt, and sex” is an easy way to remember the three classes of steroids from the adrenal cortex. In a general way, the classifications reflect the steroids.
27 Glucocorticoids Affect carbohydrates
Convert amino acids into glucose (gluconeogenesis) and help maintain blood glucose levels between meals Affect protein and fat metabolism, burning both substances as fuel to increase energy production The chief glucocorticoid is cortisol. Cortisol is a hormone that is secreted in greater amounts during times of stress. Cortisol also has an anti-inflammatory effect. The secretion of cortisol involves the hypothalamus, anterior pituitary gland, and adrenal gland. Refer students to Figure 14-8, B, on p. 272. Have students describe negative feedback of cortisol secretion. (As cortisol levels rise, the cortisol suppresses the anterior pituitary, thereby decreasing the secretion of ACTH and the adrenal secretion of cortisol.)
28 Mineralocorticoids and Sex Hormones
The chief mineralocorticoid is aldosterone Aldosterone plays an important role in the regulation of blood volume, blood pressure, and the concentration of electrolytes The primary target organ of aldosterone is the kidney Aldosterone stimulates the kidney’s reabsorption of salt and water and excretion of potassium Sex hormones Female: Estrogens Male: Androgens Why does aldosterone affect blood volume? (Too little aldosterone decreases reabsorption of salt and water by the kidneys, thereby lowering blood volume. Excess aldosterone has the opposing effect.)
29 Abnormal Secretion of Steroids
Hyposecretion Addison’s disease Acute adrenal cortical insufficiency Hypersecretion Cushing’s syndrome Three virilizing effects are low voice, male hair distribution, and larger bones and muscles. What hormones are undersecreted in Addison’s disease? (Cortisol, aldosterone, and testosterone are undersecreted.) Why might a patient in acute adrenal cortical insufficiency develop adrenal shock? (A deficiency of aldosterone causes diuresis, low blood volume, low blood pressure, and shock.) Why does the patient with Cushing’s syndrome have a moon face and a buffalo hump? (Cortisol causes a redistribution of fat and retention of fluid.)
30 Pancreas Across upper abdomen Islets of Langerhans secrete hormones
Alpha cells secrete glucagon Beta cells secrete insulin It is noteworthy that one organ, the pancreas, secretes the hormones that increase and decrease blood glucose levels. Refer students to Figure 14-9 (p. 274) to show how the pancreas regulates blood glucose.
31 Pancreas Regulates Blood Glucose
Blood glucose level rises, pancreas secretes insulin Blood glucose level falls, pancreas secretes glucagon Pancreatic function does not depend upon the anterior pituitary. What is the stimulus for the release of insulin? (Rising blood glucose levels stimulate the release of insulin.) What is the stimulus for the release of glucagon? (Falling blood glucose levels stimulate the release of glucagon.) Remember “pig”: pancreas, insulin, glucagon.
32 Insulin in Normal Metabolism
Carbohydrate Increased transport of glucose into cell Use of glucose as fuel Storage of excess glucose as glycogen Protein Stimulation of protein synthesis Fat Stimulation of fatty acid synthesis Insulin fosters the cellular use of glucose for fuel. With the exception of glucose breakdown, insulin drives the metabolic pathways in the direction of synthesis.
33 Deficiency of Insulin Called diabetes mellitus
Has devastating effects if left untreated Before insulin therapy was discovered, diabetes mellitus was described as a “melting down of the flesh and the limbs into urine.”
34 Insulin Deficiency or Ineffectiveness
Hyperglycemia Glucosuria Polyuria/polydipsia Polyphagia Acidosis Fruity odor to the breath Rapid fatty acid catabolism causes formation of acetone The symptoms of diabetes arise from hyperglycemia and rapid and uncontrolled fatty acid breakdown. For example, in the hyperglycemia column, we see that hyperglycemia progresses to dehydration and shock. Excess glucose in the blood is called hyperglycemia. Glucose in the urine is called glucosuria. Excretion of a large volume of urine is called polyuria. Excessive thirst is called polydipsia. Polyuria causes an excessive loss of body water, thereby stimulating the thirst mechanism in an attempt to replace the water lost in the urine. Polyphagia refers to excessive eating. An excess of H+ in the blood causes acidosis. Because the cells cannot burn glucose as fuel, they burn fatty acids instead. Acetone smells fruity and makes the patient’s breath smell like rotten apples.
35 Glucagon Pancreatic hormone secreted by alpha cells of the islets of Langerhans Primary action is to increase blood glucose levels How does glucagon raise the blood glucose levels? (By stimulating the conversion of glycogen to glucose in the liver and by stimulating the conversion of proteins into glucose [gluconeogenesis].) Diabetic people with an infection always have difficulty in controlling their blood glucose levels; they require frequent blood glucose monitoring and additional insulin.
36 Other Glands Gonads Thymus Pineal Testes secrete testosterone
Ovaries secrete progesterone and estrogen Thymus Secretes thymosins Affects immune function Pineal Secretes melatonin Affects biological clock Adipose tissue secretes unhealthy cytokines The thymus gland is much larger in a child than in an adult. It shrinks as the child enters puberty. Melatonin is thought to play a role in the sleep–wake cycle.
37 Other Hormones Organ-specific hormones Prostaglandins
Secreted by organs such as heart, kidney, digestive organs Prostaglandins Secreted by most tissues Most act locally Play a role in regulation of smooth muscle contraction, inflammatory response, and pain Most organs in the body secrete their own hormones. These will be discussed as each organ is discussed. For example, the renin-angiotensin-aldosterone system functions with the kidney in regulating blood volume and blood pressure. How do aspirin and ibuprofen work? (Aspirin and ibuprofen block the synthesis of prostaglandins, which enhance the inflammatory response and increase the sensitivity of nerve endings to pain.)
38 Adipose Tissue Hormones
Excess tissue secretes cytokines Weight issues lead to: Problems with the heart and blood vessels Diabetes mellitus Cancer Joint disease Adipose tissue contains many narrow blood vessels; in fact, miles of additional blood vessels may be required to carry blood throughout the excess fat. The additional narrowed blood vessels increase blood pressure and strain the heart. Adipose tissue secretes several cytokines that adversely affect glucose metabolism and predispose the person to type 2 diabetes mellitus. Added weight puts stress on the joints of the body.
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