Endocrine & Metabolic Disorders PDF

Chapter 9 Other Systems ENDOCRINE SYSTEM Hormonal Regulation The endocrine system comprises many glands in the body; these glands secrete hormones Hormones are used to relay informatio...

Chapter 9 Other Systems ENDOCRINE SYSTEM Hormonal Regulation The endocrine system comprises many glands in the body; these glands secrete hormones Hormones are used to relay information to cells and organs to regulate body functions When the endocrine system works correctly, body systems work smoothly The hypothalamus and pituitary gland along with nervous system make up the central network that controls the other glands Hypothalamus Regulates the autonomic nervous system (ANS) and helps maintain body homeostasis ➤ Manages temperature, sweat, sexual behavior, thirst, fear, blood pressure (BP), sleep ➤ Controls the release of pituitary hormones through ‡ Corticotropin-releasing hormone (CRH) ‡ Thyrotropin-releasing hormone (TRH) ‡ Growth-hormone-releasing hormone (GHRH) ‡ Somatostatin Mnemonic: The hypothalamus tells a “TALE“ = Temperature, Appetite, Libido, Emotion Pituitary gland: the “master” gland Lies close to the hypothalamus No direct effect on the nervous system → regulates other glands Anterior pituitary gland releases ➤ Growth hormone (GH), adrenocorticotropic hormone (ACTH), follicle-stimulating hormone (FSH), prolactin, luteinizing hormone (LH), thyroid-stimulating hor- mone (TSH) Posterior pituitary gland releases ➤ Antidiuretic hormone (ADH), oxytocin Pituitary gland is responsible for the secretion of TSH, which stimulates the thyroid gland to release the thyroid hormones (thyroxine [T4] and triiodothyronine [T3]) Thyroid gland Follicular cells secrete thyroxine (T4) and triiodothyronine (T3) → help regulate metab- olism and protein synthesis C cells secrete calcitonin → affects calcium and phosphorus homeostasis Produces hormones that act to control the rate at which cells burn the fuel from food Parathyroid glands Release parathyroid hormone (PTH) PTH regulates the homeostasis of calcium and phosphate in the blood and the calci- fication of bone Adrenal gland Adrenal cortex controls the release of ➤ Corticosteroids ‡ Example: aldosterone → regulates potassium and sodium levels, maintains fluid and electrolyte balances 257 Book_5566_Ch09.indd 257 18-04-2024 22:20:39  258 NPTE Final Frontier – Mastering the NPTE ➤ Glucocorticoids ‡ Example: cortisol → regulates carbohydrate metabolism, aids immune func- tion, reduces inflammation, promotes gluconeogenesis ➤ Androgens and androstenedione: regulate sexual functions Adrenal medulla controls the release of ➤ Epinephrine and norepinephrine → support fight-or-flight response, increase blood glucose levels, stimulate ACTH production Islets of Langerhans (pancreas) Secrete insulin, glucagon, amylin → control blood sugar ➤ Insulin: lowers blood glucose levels, increased use of carbohydrates ➤ Glucagon: stimulates glucose production by the liver to increase glucose levels (especially in the fasting state) ➤ Amylin: delays gastric emptying, suppresses release of glucagon Kidneys Conversion to active form of vitamin D Ovaries Secrete estrogen and progesterone ➤ Estrogen: regulates female reproductive organs, controls female sexual characteristics ‡ Menstrual cycle and pregnancy ➤ Progesterone: stimulates breast tissue for lactation and prepares endometrium for implantation of the fertilized ovum Testes Androgens (testosterone): control male sexual characteristics Figure 85. Endocrine System. Book_5566_Ch09.indd 258 18-04-2024 22:20:40  Other Systems 259 Pineal gland Secretes hormone melatonin ➤ Melatonin: regulates sleep–wake cycles Thymus Produces thymosin ➤ Thymosin: aids production and development of T-cells for the immune system Metabolic syndrome (syndrome X) Collection of risk factors that increase the risk of heart disease, stroke, and diabetes mel- litus (DM) Risk factors Diagnosis requires 3 or more of the following factors: ➤ Abdominal obesity: waist circumference ≥ 40 in (> 102 cm) for males or ≥ 35 in (> 89 cm) for females ➤ High triglyceride: ≥ 150 mg/dL ➤ Cholesterol: high-density lipoprotein (HDL) < 40 mg/dL in males or < 50 mg/ dL in females ➤ High BP: systolic blood pressure (SBP) ≥ 130 mmHg, diastolic blood pressure (DBP) ≥ 85 mmHg ➤ Blood sugar: fasting plasma glucose ≥ 100 mg/dL Etiology Collection of risk factors responsible Unhealthy lifestyle: sedentary lifestyle with little to no physical activity, abdomi- nal obesity, and insulin resistance are dominant underlying risk factors for metabolic syndrome Certain diseases and hormonal imbalances Treatment: management of risk factors Lifestyle modification: healthy diet, weight loss, exercise, smoking cessation can reverse or reduce the risk for developing metabolic syndrome Medications: control cholesterol, BP, DM Diabetes mellitus (DM) Characteristics Chronic disorder of carbohydrate, fat, and protein metabolism due to insufficient or defective insulin action in the body Caused by abnormally high levels of sugar or glucose in blood May be acquired, autoimmune, environmental, genetic, or ethnicity-related (more prevalent in Native American, Hispanic or Latino, Native Hawaiian, and Pacific Islander individuals) Types Type 1 DM: insulin-dependent; juvenile-onset diabetes (5%–10% of cases) ➤ Little or no insulin produced ‡ Due to a decrease in the size of islet cells ‡ Requires insulin injections, pump, or inhalation ➤ Abrupt onset of symptoms ➤ Age of onset ‡ Peaks at about the age of puberty ‡ Usually occurs at < 30 years of age ➤ Etiology: possible viral and autoimmune factors resulting in destruction of islet cells ➤ Risk factors: autoimmune, environmental, and genetic factors ➤ Individuals prone to ketoacidosis and ketonuria (ketone bodies in urine) ‡ Ketones alter arterial pH to become more acidic (ie, decrease pH) ‡ Kussmaul breathing: sign of diabetic ketoacidosis (DKA) Book_5566_Ch09.indd 259 18-04-2024 22:20:40  266 NPTE Final Frontier – Mastering the NPTE Figure 86. Hyperthyroidism. Excessive secretion of PTH; disrupts calcium, phosphate, and bone metabolism Increases serum calcium and decreases serum phosphate ➤ Takes calcium from bones → demineralizes bones ➤ Increased serum calcium can cause kidney stones Clinical manifestations ➤ Fatigue, drowsiness, confusion, poor memory, slowed mentation, myalgias, depression, stocking-and-glove sensory loss, hyperactive deep tendon reflexes (DTRs), osteopenia, gout or pseudogout, proximal muscle weakness, arthralgia, myalgia, nausea, vomiting, constipation, peptic ulcers, pancreatitis, kidney stones ➤ Mnemonic: “Moans, groans, stones, and bones” ‡ “Moans” = mental problems (drowsiness, depression, confusion, poor memory) ‡ “Groans” = myalgia, arthralgia, gout ‡ “Stones” = kidney stones or renal calculi ‡ “Bones” = bone decalcification Treatment: surgical removal of the gland Adrenal disorders Addison disease (primary adrenal insufficiency) Hypofunction of adrenal gland Book_5566_Ch09.indd 266 18-04-2024 22:20:41  Other Systems 267 Figure 87. Hypothyroidism. Decreased production of cortisol and aldosterone Etiology: autoimmune process, infection, neoplasm, hemorrhage, and medica- tions such as antifungals, adrenolytic agents, etomidate, rifampin, phenytoin, and phenobarbital S/S ➤ Dark pigmentation of the skin (appears very tan) ➤ Postural hypotension ➤ Progressive fatigue ➤ Hyperkalemia ➤ GI disturbances, anorexia, and weight loss ➤ Nausea, vomiting ➤ Arthralgias, myalgias ➤ Tendon calcification ➤ Hypoglycemia Treatment ➤ Acute adrenal insufficiency ‡ Replacement therapy → fluids, electrolytes, glucose, cortisol ‡ Identification of underlying cause ➤ Chronic adrenal insufficiency ‡ Drug therapy → lifelong administration of corticosteroids and mineralocorticoids Secondary adrenal insufficiency Lack of pituitary ACTH because of insufficient stimulation of adrenal cortex Causes: removal of pituitary gland, rapid withdrawal of drugs, hypothalamic or ­pituitary tumors Book_5566_Ch09.indd 267 18-04-2024 22:20:42  268 NPTE Final Frontier – Mastering the NPTE Cushing syndrome Hyperfunction of the adrenal gland Increased secretion of cortisol by the adrenal cortex ➤ Cortisol is a stress hormone that increases the release of stored glucose into the blood, stops digestion during the fight-or-flight response, and suppresses the immune system (inflammatory) S/S ➤ “Moon face” appearance (round face) ➤ “Buffalo hump” at the neck (fatty deposit) ➤ Truncal obesity: protuberant abdomen with accumulation of fatty tissue and stretch marks ➤ Muscle wasting and weakness ➤ Decreased density of bones (especially spine) ➤ HTN ➤ Kyphosis and back pain ➤ Easy bruising ➤ Psychiatric and emotional disturbances ➤ Impaired reproductive function: decreased libido and changes in menstrual cycle ➤ DM ➤ Slow wound healing ➤ Females: masculinizing effect (eg, hair growth, breast atrophy, voice changes) ➤ Thinning of scalp hair ➤ Hypokalemia Treatment ➤ Decrease excess ACTH levels: irradiation or surgical excision of pituitary tumor, drug therapy ➤ High-protein diet recommended for individuals with muscle wasting ➤ Electrolyte and fluid balance ➤ Patients with surgical resection of adrenal gland will need lifelong administration of glucocorticoids Figure 88. Cushing Syndrome. Book_5566_Ch09.indd 268 18-04-2024 22:20:42