CHAPTER 13 Endocrine System Endocrine System Overview Endocrine

CHAPTER 13 Endocrine System

Endocrine System Overview • Endocrine system – Consists of ductless glands • Secrete hormones directly into bloodstream – Affect the function of specific body organs • Regulates many intricate body functions 2

Pituitary Gland • Referred to as “master gland” – Secretes hormones that control functions of other glands – Known as hypophysis – Has two distinct lobes with specific functions 3

Pituitary Gland • Anterior Pituitary Gland = Adenohypophysis – Secretes Growth Hormone (GH) • Also called Somatotropic Hormone (STH) • Regulates growth of bone, muscle, and other body tissues – Secretes Adrenocorticotropic Hormone (ACTH) • Stimulates normal growth and development of adrenal cortex and secretion of corticosteroids 4

Pituitary Gland • Anterior Pituitary Gland – Secretes Thyroid-Stimulating Hormone (TSH) • Promotes and maintains normal growth and development of the thyroid gland • Stimulates secretions of the thyroid hormones – Secretes Lactogenic Hormone (LTH) • Also called Prolactin • Promotes development of breasts during pregnancy • Stimulates secretion of milk from breasts after delivery of baby 5

Pituitary Gland • Anterior Pituitary Gland – Secretes Follicle-Stimulating Hormone (FSH) • Stimulates secretion of estrogen and production of eggs in the female ovaries • Stimulates production of sperm in the male testes – Secretes Luteinizing Hormone (LH) • Stimulates female ovulation and the secretion of testosterone in the male – Melanocyte-Stimulating Hormone (MSH) • Controls intensity of pigmentation in pigmented cells of the skin 6

Pituitary Gland • Posterior Pituitary Gland = Neurohypophysis – Secretes Antidiuretic Hormone (ADH) • Decreases excretion of large amounts of urine • Increases reabsorption of water by the renal tubules – Secretes Oxytocin (OT) • Stimulates contraction of the uterus during childbirth • Stimulates release of milk from the breasts of lactating women in response to the suckling reflex of the infant 7

Pineal Gland • Tiny, pinecone-shaped gland – Located behind dorsal aspect of midbrain region – Plays a part in supporting body’s biological clock • Regulation of patterns of eating, sleeping, and reproduction – Secretes melatonin • Induces sleep 8

Thyroid Gland • Located in front of the neck just below the larynx, on either side of the trachea – Consists of a right and left lobe 9

Thyroid Gland • Secretes Triiodothyronine (T 3) – Helps regulate growth and development of body – Helps control metabolism and temperature – Secretes Thyroxine (T 4) • Helps maintain normal body metabolism – Secretes Calcitonin • Helps regulate the level of calcium in the blood 10

Parathyroid Glands • Four tiny rounded bodies located on dorsal aspect of thyroid gland – Secrete Parathyroid Hormone (PTH) • Also known as parathormone • Regulates level of calcium in blood 11

Thymus • Single gland located in mediastinum near the middle of the chest, just beneath sternum – Large in fetus and infants, shrinks with age – Secretes thymosin and thymopoietin • Stimulates production of T cells that are involved in the immune response 12

Adrenal Glands • Two small glands, one positioned atop each kidney • Also known as suprarenal glands – Consists of an adrenal cortex and an adrenal medulla • Each has independent functions 13

Adrenal Glands • Adrenal cortex secretes corticosteroids – Mineralocorticoids • Regulate how mineral salts (electrolytes) are processed in the body – Glucocorticoids • Influence metabolism of carbohydrates, fats, and proteins in the body • Necessary for maintaining normal blood pressure • Have an anti-inflammatory effect on the body • Increase glucose available during “fight-or-flight” responses by the body 14

Adrenal Glands • Adrenal cortex secretes – Gonadocorticoids • Sex hormones secreted in small amounts • Contribute to secondary sex characteristics in males and females 15

Adrenal Glands • Adrenal medulla secretes catecholamines – Epinephrine = adrenaline • Sympathiomimetic agent • Increases heart rate and force of heart muscle contraction • Dilates bronchioles in the lungs • Decreases peristalsis in the intestines • Raises blood glucose levels by causing the liver to convert glycogen into glucose 16

Adrenal Glands • Adrenal medulla secretes – Norepinephrine = noradrenaline • Known as a sympathomimetic agent • Produces a vasoconstrictor effect on the blood vessels, thereby raising blood pressure 17

Pancreas • Elongated gland located in upper left quadrant of the abdomen – Behind the stomach • Extends horizontally across the body – Beginning at first part of small intestines and ending at edge of spleen 18

Pancreas • Islets of Langerhans secrete: – Glucagon • Increases blood glucose levels by stimulating liver to convert glycogen into glucose when blood sugar is extremely low – Insulin • Makes it possible for glucose to pass from blood through cell membranes to be used for energy • Promotes conversion of excess glucose into glycogen for storage in the liver for later use 19

Ovaries • Female sex glands = female gonads – Pair of almond shaped glands • Located in upper pelvic cavity, on either side of lateral wall of uterus • Near fimbriated ends of the fallopian tubes – Responsible for producing mature ova and releasing them at monthly intervals during ovulation 20

Ovaries • Hormones secreted by the ovaries – Estrogen • Promotes maturation of ovum in the ovary • Stimulates vascularization of uterine lining each month to prepare for implantation of a fertilized egg • Contributes to secondary sex characteristic changes in female with onset of puberty – Progesterone • Primarily responsible for changes within the uterus in anticipation of a fertilized ovum • Responsible for development of maternal placenta after implantation of a fertilized ovum 21

Testes • Testes = male gonads = testicles – Two small ovoid glands located in scrotum – Primary organs of male reproductive system – Responsible for production of sperm and secretion of androgens (male steroid hormones) – Secrete testosterone • Responsible for secondary sex characteristic changes that occur in male with onset of puberty • Responsible for maturation of sperm 22

PATHOLOGICAL CONDITIONS Pituitary Gland

Acromegaly • Pronounced – (ak-roh-MEG-ah-lee) • Defined – Chronic metabolic condition characterized by the gradual, noticeable enlargement and elongation of the bones of the face, jaw, and extremities, due to hypersecretion of the human growth hormone after puberty 24

Diabetes Insipidus • Pronounced – (dye-ah-BEE-teez in-SIP-ih-dus) • Defined – Deficiency in secretion of antidiuretic hormone (ADH) by posterior pituitary gland • Characterized by large amounts of urine and sodium being excreted from the body 25

Dwarfism • Pronounced – (DWARF-ism) • Defined – Generalized growth retardation of body due to deficiency of human growth hormone – Also known as congenital hypopituitarism or hypopituitarism 26

Gigantism • Pronounced – (JYE-gan-tizm) • Defined – Proportional overgrowth of body’s tissue due to hypersecretion of human growth hormone before puberty 27

Hypopituitarism • Pronounced – (high-poh-pih-TOO-ih-tah-rizm) • Defined – Complex syndrome resulting from absence or deficiency of pituitary hormone(s) 28

PATHOLOGICAL CONDITIONS Thyroid Gland

Cancer, Thyroid Gland • Pronounced – (CAN-sir, THIGH-royd gland) • Defined – Malignant tumor of the thyroid gland – Leads to dysfunction of gland inadequate or excessive secretion of thyroid hormone 30

Goiter, Simple; Nontoxic • Pronounced – (GOY-ter simple; nontoxic) • Defined – Hyperplasia of thyroid gland • Results from a deficient amount of iodine in diet, required for synthesis of T 3 and T 4, thyroid hormones produced by the thyroid gland 31

Graves’ Disease (Hyperthyroidism) • Pronounced – (high-per-THIGH-royd-izm) • Defined – Hypertrophy of thyroid gland resulting in excessive secretion of thyroid hormone • Causes extremely high body metabolism, thus creating multisystem changes 32

Graves’ Disease Hyperthyroidism • Three distinguishing characteristics – Hyperthyroidism – Thyroid gland enlargement (goiter) – Exophthalmia • Unnatural protruding of the eyes 33

Hypothyroidism • Pronounced – (high-poh-THIGH-royd-izm) • Defined – Condition in which there is a shortage of thyroid hormone causing an extremely low body metabolism due to a reduced usage of oxygen 34

Hypothyroidism • Most severe form known as myxedema – Water retention all over body in connective tissues – Person has puffy appearance and thick tongue – Reduced metabolic rate 35

Thyroiditis (Hashimoto’s) • Pronounced – (thigh-royd-EYE-tis) – (HASH-ee-moh-TOZ) • Defined – Chronic inflammation of the thyroid gland, leading to enlargement of the thyroid gland 36

Thyrotoxicosis (Thyroid Storm) • Pronounced – (thigh-roh-toks-ih-KOH-sis) • Defined – Acute, sometimes fatal, incident of overactivity of the thyroid gland resulting in excessive secretion of thyroid hormone 37

PATHOLOGICAL CONDITIONS Parathyroid Gland

Hyperparathyroidism (Hypercalcemia) • Pronounced – (high-per-pair-ah-THIGH-royd-izm) – (high-per-kal-SEE-mee-ah) • Defined – Overactivity of any one of the parathyroid glands – Leads to high levels of calcium in blood and low levels of calcium in bones 39

Hypoparathyroidism • Pronounced – (high-poh-pair-ah-THIGH-royd-izm) • Defined – Decreased production of parathyroid hormone resulting in hypocalcemia – Characterized by nerve and muscle weakness with muscle spasms or tetany 40

PATHOLOGICAL CONDITIONS Adrenal Glands

Addison’s Disease • Pronounced – (AD-ih-sons dih-ZEEZ) • Defined – Life-threatening disease process due to failure of the adrenal cortex to secrete adequate mineralocorticoids and glucocorticoids • Resulting from an autoimmune process, a neoplasm, an infection, or a hemorrhage in the gland 42

Conn’s Disease (Primary Aldosteronism) • Pronounced – (PRYE-mary al-doss-STAIR-ohn-izm) • Defined – Condition characterized by excretion of excessive amounts of aldosterone • Leads to an increased volume of blood and hypertension • Causes body to retain extra sodium and excrete extra potassium 43

Cushing’s Syndrome • Pronounced – (CUSH-ings SIN-drom) • Defined – Cluster of symptoms in the adrenal gland as a result of an excessive amount of cortisol or ACTH circulating in blood 44

Cushing’s Syndrome • Cushing’s Syndrome – Symptoms • • • Central obesity Round “moon” face Edema Hypertension Supraclavicular fat pads (buffalo hump) Muscular weakness and wasting Skin infection Poor wound healing Low potassium level Emotional changes 45

Pheochromocytoma • Pronounced – (fee-oh-kroh-moh-sigh-TOH-mah) • Defined – Vascular tumor of adrenal medulla – Produces extra epinephrine and norepinephrine – Leads to persistent or intermittent hypertension and heart palpitations 46

Virilism • Pronounced – (VEER-il-izm) • Defined – Development of male secondary sex characteristics in the female due to the excessive secretion of adrenocortical androgens from the adrenal cortex 47

Virilism • Virilism – Symptoms • • Excessive hair on the body and face (hirsutism) Absence of menstruation Deepening of the voice Acne Oily skin Muscular hypertrophy Atrophy of the breasts and uterus Ovarian changes 48

PATHOLOGICAL CONDITIONS Pancreas

Diabetes Mellitus • Pronounced – (dye-ah-BEE-teez MELL-ih-tus) • Defined – Disorder of pancreas in which beta cells of islets of Langerhans of the pancreas fail to produce an adequate amount of insulin • Results in body’s inability to appropriately metabolize carbohydrates, fats, and proteins 50

Diabetes Mellitus • Classifications – Type I Diabetes – Formerly known as Insulin-Dependent Diabetes Mellitus (IDDM) • • Usually occurs before age of 30 Sudden onset Controlled with insulin injections Individuals are prone to developing ketosis 51

Diabetes Mellitus • Classifications – Type II Diabetes – Formerly known as Non-Insulin-Dependent Diabetes Mellitus (NIDDM) • Usually appears in adults after age of 40 • Majority of these individuals are obese • Usually controlled through diet and exercise 52

Diabetic Retinopathy • Pronunciation – (dye-ah-BET-ik ret-in-OP-ah-thee) • Defined – Disorder of blood vessels of retina in which capillaries of the retina undergo localized areas of bulging (microaneurysms), hemorrhages, leakage, and scarring • Consequence of 8 -10 year duration of diabetes mellitus 53

Gestational Diabetes • Pronounced – (jess-TAY-shun-al dye-ah-BEE-teez) • Defined – Disorder in which women who are not diabetic before pregnancy develop diabetes during the pregnancy • Inability to metabolize carbohydrates • Results in hyperglycemia 54

Pancreatic Cancer • Pronounced – (pan-kree-AT-ik CAN-sir) • Defined – Life-threatening primary malignant neoplasm typically found in head of pancreas 55

Pancreatitis • Pronounced – (pan-kree-ah-TYE-tis) • Defined – Acute or chronic destructive inflammatory condition of the pancreas • Creates symptoms that vary from mild self-limiting pancreatic edema to massive necrotizing hemorrhagic pancreatitis 56

Diagnostic Techniques, Treatments, and Procedures Endocrine System

Diagnostic Techniques, Treatments, and Procedures • Thyroid function tests – Tests that measure blood levels of hormones T 3, T 4, and TSH • Thyroid-Stimulating Hormone (TSH) Blood Test – Measures concentration of TSH in blood • Used to differentiate primary hypothyroidism from secondary hypothyroidism 58

Diagnostic Techniques, Treatments, and Procedures • Fasting Blood Sugar (FBS) – Blood glucose sample taken usually early in the morning after the person has been without food or drink since midnight 59

Diagnostic Techniques, Treatments, and Procedures • Glucose Tolerance Test (GTT) – Test that evaluates person’s ability to tolerate a concentrated oral glucose load by measuring glucose levels: • Prior to glucose administration • 30 minutes after glucose administration • 1, 2, and 3 hours after glucose administration 60

Diagnostic Techniques, Treatments, and Procedures • Radioactive Iodine Uptake (RAIU) Test – Thyroid function test – Evaluates function of thyroid gland – Administers radioactive iodine – Places gamma ray detector over thyroid gland – Determines percentage of radioactive iodine absorbed by gland over specific time periods 61

Diagnostic Techniques, Treatments, and Procedures • Serum Glucose Tests – Tests that measure amount of glucose in blood at time sample was drawn • Thyroid Echogram (Ultrasound) – Examination to distinguish solid thyroid nodules from cystic nodules 62

Diagnostic Techniques, Treatments, and Procedures • Thyroid scan – Examination to determine position, size, shape, and physiological function of thyroid gland through use of radionuclear scanning 63