Endocrine System Anatomy and Physiology PDF

ENDOCRINE The endocrine system plays a vital role in orchestrating transportation of chemicals across cell membranes, growth and development, metabolism, fluid and electrolyte balance, acid-balance, adaptation and reproduction. This interconnected network of glands is closely linked with the nervou...

ENDOCRINE The endocrine system plays a vital role in orchestrating transportation of chemicals across cell membranes, growth and development, metabolism, fluid and electrolyte balance, acid-balance, adaptation and reproduction. This interconnected network of glands is closely linked with the nervous and immune systems, regulating the functions of multiple body organs. The hypothalamus is responsible for this interrelationship. The pituitary gland, as the master gland, plays an important role in the regulation of endocrine hormones, its primary function is to secrete hormones into the bloodstream, which in turn affects endocrine glands such as the thyroid. ANATOMIC AND PHYSIOLOGIC OVERVIEW The endocrine system involves the release of chemical transmitter substances known as hormones. Hormones are generally produced by the endocrine glands but may also be produced by specialized tissues such as those found in the GI system. GI mucosa produces hormones that are important in the digestive process Gastrin Secretin Cholecystokinin Kidneys produce Erythropoietin – a hormone that stimulates the bone marrow to produce red blood cells; and the white blood cells produce cytokines that actively participate in the inflammatory and immune responses. The endocrine system has a unique relationship with the immune and the nervous system. Chemicals such as neurotransmitter like epinephrine, released by the nervous system can also function as hormones when needed. Hypothalamus – CONTROL CENTER OF THE ENDOCRINE SYSTEM Pituitary Gland – IS THE MASTER GLAND, BEC, IT TAKES THE STIMULATION FROM THE HYPOTHALAMUS PITUITARY – RELEASE GROWTH HORMONE (CAUSES THE CELLS TO GROW) THYROID – T3 AND T4 (REGULATES METABOLISM) AND CALCITONIN – LOWERS THE CALCIUM, GOES BACK TO THE BONE PITUITARY GLAND The pea-sized pituitary gland, located on the inferior aspect of the brain, is called the “master gland” because it regulates many key processes. It has two lobes: 1. Posterior lobe, which stores and releases oxytocin and antidiuretic hormone produced by the hypothalamus. These hormones are synthesized in the hypothalamus and travel from the hypothalamus to the posterior pituitary gland for storage. Vasopressin controls the excretion of water by the kidney; its secretion is stimulated by an increase in the osmolality of the blood or by a decrease in blood pressure. Oxytocin – secretion is stimulated during pregnancy and at childbirth. It also facilitates milk ejection during lactation and increases the force of uterine contractions during labor and delivery. Posterior Pituitary The most common disorder related to posterior pituitary lobe dysfunction is diabetes insipidus (DI), a condition in which abnormally large volumes of dilute urine is excreted as a result of deficient production of vasopressin. 2. Anterior lobe, which produces at least six hormones 6 HORMONES : GH - TSH - ACTH - FSH - LH - PRL – Anterior Pituitary Oversecretion (hypersecretion) of the anterior pituitary gland most commonly involves ACTH or GH and results in Cushing’s Syndrome or Acromegaly, a disorder caused by an excess of GH in adults. THYROID GLAND It is the largest endocrine gland; a butterfly shaped organ located in the lower neck anterior to the trachea. The apex of each lobe of the thyroid gland is along the lateral side of the thyroid cartilage. The two lobes of the thyroid function as one unit to produce two hormones: Triiodothyronine (T3) and thyroxine (T4), collectively referred to as thyroid hormone, are the body’s major metabolic hormones. Calcitonin maintains the blood calcium level by inhibiting the release of calcium from bone. Iodine is essential to the thyroid gland for synthesis of its hormones. The major use of iodine in the body is by the thyroid, and the major derangement in iodine deficiency is alteration of thyroid function. TRH (thyrotropin-releasing hormone) – is produced by the hypothalamus, It acts as a signal to the pituitary gland, which then releases TSH (thyroid stimulating hormone). TSH (thyroid stimulating hormone) – is produced by the pituitary gland and stimulates it to release thyroid hormones, primarily T3 and T4. NEGATIVE FEEDBACK LOOP HYPOTHALAMUS – releases TRH, that stimulates the anterior pituitary gland to release TSH, then thyroid releases T3 and T4 TRH – THYROTROPIN RELEASING HORMONE IF FOR EXAMPLE THERE IS A TUMOR IN THE ANTERIOR PITUITARY GLAND, THEREFORE I WILL NOT BE ABLE TO RELEASE T3 AND T4 (HYPOTHYROIDISM) Euthyroid - refers to the thyroid hormone production that is normal. FUNCTION OF THE THYROID HORMONE The main function of the thyroid hormone is to control cellular metabolic activity. T4, a relatively weak hormone, maintains body metabolism in a steady state. T3 is about 5x as potent as T4 and has a more rapid metabolic action. The thyroid hormones influence cell replication, are important in brain development and are necessary for normal growth. FUNCTION OF PARATHYROID GLAND Parathyroid glands produce parathyroid hormone, which plays a key role in the regulation of calcium levels in the blood. Precise calcium levels are important in the human body, since small changes can cause muscle and nerve problems. The parathyroid hormone stimulates the following functions:  Release of calcium by bones into the bloodstream  Absorption of calcium from food by the intestines  Conservation of calcium by the kidneys  Stimulates cells in the kidney to transforms weaker forms of vitamin D into the form that is strongest at absorbing calcium from the intestines ADRENAL GLANDS The adrenal glands are endocrine glands that produce a variety of hormones including adrenaline and the steroids aldosterone and cortisol. Each gland contains two distinct structures — the adrenal cortex and the adrenal medulla — that function as separate endocrine glands The adrenal cortex itself is divided into three main zones: the zona glomerulosa, the zona fasciculata and the zona reticularis. The adrenal medulla, the inner portion, produces catecholamines. Because catecholamines play an important role in the autonomic nervous system, the adrenal medulla is considered a neuroendocrine structure. ADRENAL CORTEX – STEROIDS, CORTISOL AND ALDOSTERONE ADRENAL MEDULLA – catecholamines ex. Epi and norepi- involved in our body’s Fight and fight response. PINEAL GLAND PINEAL GLAND The tiny pineal gland lies at the back of the third ventricle of the brain. It produces the hormone melatonin, which may play a role in the neuroendocrine reproductive axis as well as other widespread actions. MELATONIN RESPONSIBLE FOR SLEEP, IT IS NOT USUALLY PRODUCED IN THE MORNING GONADS The gonads include the ovaries (in females) and the testes (in males). The ovaries promote development and maintenance of the female sex characteristics, regulate the menstrual cycle, maintain the uterus for pregnancy and, along with other hormones, prepare the mammary glands for lactation. The testes produce spermatozoa and the male sex hormone testosterone. Testosterone stimulates and maintains male sex characteristics DISORDERS OF THE THYROID GLAND : HYPERTHYROIDISM HYPOTHYROIDISM is a metabolic imbalance that results - Inadequate production of T3 AND t4 from excessive thyroid hormone. The - Primary Cause is Hashimoto’s Disease most common form of hyperthyroidism is - HASHIMOTO – IS AN AUTOIMMUNE Graves’ disease (thyrotoxicosis), which DISORDER THAT CAUSES THE increases T4 production, enlarges the ANTIBODIES TO ATTACK AND DESTROY thyroid gland (goiter), and causes THE THYROID TISSUE. SO IF THE multisystem changes. THYROID GLAND IS DAMAGED IT Thyroid storm — an acute exacerbation CANNOT PRODUCE T3 AND T4 LIKE IT of hyperthyroidism — is a medical SHOULD emergency that may lead to heart failure. SIGNS AND SYMPTOMS : SIGNS AND SYMPTOMS : Hypotension 1. Weight loss Bradycardia 2. Heat intolerance Lethargy 3. Increased Heart rate and BP Cold Intolerance 4. Having Diarrhea Constipation 5. Smooth skin and soft hair Weight gain 6. At risk for cardiac dysrhythmias 7. Behavior changes LAB RESULTS : -Lab results will depend upon the underlying What Causes Hyperthyroidism? cause. -Grave’s Disease Primary – Low T3 and T4, elevated TSH -Toxic Nodular Goiter Secondary and Tertiary – Low T3, T4 and TSH -Thyroiditis -Too much Iodine TREATMENT : Levothyroxine 50mcg-100mcg or Liothyronine TREATMENT 12.5mcg – 25mcg OD Anti-thyroid drugs  Propylthiouracil 50mg NURSING INTERVENTIONS :  Methimazole 5mg Frequent rest periods  Radioactive Iodine Low calorie and high fiber Provide blankets Hyperthyroidism Teaching Tips  If the patient has exophthalmos MYXEDEMA COMA – or another ophthalmopathy, severe, life-threatening hypothyroidism leading suggest sunglasses or eye to decreased mental status and symptoms related patches to protect his eyes from to slowing of functions in multiple organs light.  Moisten the conjunctivae often SIGNS AND SYMPTOMS : with artificial tears. Warn the Hypoxia patient with severe lid retraction Decreased cardiac output to avoid sudden physical Decreased LOC movements that might cause the Bradycardia lid to slip behind the eyeball. Hypotension and Hypothermia   Elevate the head of the bed to NURSING PRIORITIES : reduce periorbital edema. Maintain a patent airway  Stress the importance of regular Monitor patient’s cardiac rhythm medical follow-up after discharge Administer large doses of thyroid meds as because hypothyroidism may ordered develop from 2 to 4 weeks Warm the patient postoperatively.  Drug therapy require careful monitoring and comprehensive patient teaching. NURSING INTERVENTIONS :  Keep them comfortable, keep the environment cool and quiet  Monitor Weight  Educate them on their medications  Surgical interventions (thyroidectomy)  Monitor them for “THYROID STORM” Thyroid storm (also called thyroid crisis and thyrotoxic crisis) happens when your thyroid gland releases a large amount of thyroid hormone in a short amount of time. It’s a rare complication of hyperthyroidism. Thyroid storm is a medical emergency and is life- threatening. S/S : Agitation, Fever, Delirium, LOC There are 4 small glands that make this hormone, which helps your body manage the calcium levels it needs. WHAT DOES YOUR PTH DO? It pulls calcium out of the bones and into the bloodstream It causes an increase reabsorption of calcium at the kidneys It causes increase absorption of calcium in the intestines HYPERPARATHYROIDISM MAY BE DUE TO 2 CAUSES : - Primary is when there's a problem within the parathyroid gland itself, usually a benign (non- cancerous) tumor of the gland. (Adenoma) - Secondary is when the glands are fine but a condition, like kidney failure, lowers calcium levels and causes the body to react by producing extra parathyroid hormone. SIGNS AND SYMPTOMS : Consistent hypercalcemia Fatigue - Muscle weakness - Bone pain and deformities Nausea and Vomiting Kidney stones Constipation Nursing Interventions : Safety Diet Increased Fluid Treatment : Furosemide – helps in excretion of excess calcium Calcitonin – helps to tone down calcium levels in the blood  Phosphates – to bring phosphorus levels up Surgery HYPOPARATHYROIDISM - Insufficient secretion of PTH which causes calcium levels to go down - PTG are not working correctly MOST COMMON CAUSE IS THYROIDETOMY SIGNS AND SYMPTOMS ARE THE SAME AS THOSE WITH HYPOCALCEMIA Muscle cramps Numbness Tingling Tetany or Seizures Dysrhythmias Chvostek’s Sign Trousseau’s Sign TREATMENT  Calcium gluconate  Administer Calcium and Vitamin D supplements  Phosphate Binders (calcium carbonate, sevelamer) NURSING CARE :  SEIZURE PREC – PAD THE SIDE RAILS  O2 ON BEDSIDE  While awaiting diagnosis of hypoparathyroidism in a patient with a history of tetany, maintain a patent I.V. line and keep 10% calcium gluconate solution available.  Monitor for Chvostek’s and Trousseau’s signs. CUSHING’S and ADDISON’S DISEASE MAJOR ROLES : ADRENAL CORTEX STEROID HORMONES – (aldosterone and cortisol) FUNCTION OF ALDOSTERONE :  Regulates our BP through RAAS  Retention of Sodium – too much aldosterone, too much water and sodium  Secretes Potassium FUNCTIONS OF CORTISOL :  Helps the body deal with stress such as injury and illness  Increases Blood Glucose – by metabolizing sugar in what you eat  Breaks down fats, protein and carbs  Electrolyte regulation  CUSHING’S DISEASE CUSHING’S SYNDROME - Specific cause of cushing’s syndrome, due - General condition of elevated cortisol to a pituitary tumor levels - A pituitary tumor producing excessive - This condition is characterized by high ACTH, which stimulates the adrenal levels of cortisol (a steroid hormone) in glands to produce cortisol. the body. SIGNS AND SYMPTOMS : Fragile skin Truncal Obesity Moon face Ecchymosis Striae (purplish on extremities and abdomen) Elevated Blood Pressure Hyperglycemia Hirsutism Buffalo Hump (dorsocervical fat pad) Depression NURSING INTERVENTION : - For tumor of the adrenal gland – prepare for Adrenalectomy - Educate the patient about cortisol replacement therapy after surgery - Monitor for sugar and electrolytes - Emotional Support The recommended initial screening test for Cushing’s syndrome is Overnight Dexamethasone suppression test ADDISON’S DISEASE In Addison's disease, the adrenal glands make too little cortisol and, often, too little of another hormone, aldosterone. SIGNS AND SYMPTOMS : Low sodium and sugar (salt cravings) Tired and weak Low blood pressure Increased pigmentation (hyperpigmentation on the skin) Diarrhea Nausea Depression NURSING INTERVENTIONS : Monitor for hypoglycemia and hyperkalemia Administering hormone replacement therapy -Remember low cortisol and aldosterone levels so we need to give it to them synthetically (prednisone, hydrocortisone) Educate the patient to report if they have stress such as illness – for dr to increase the dose Take medications regularly – do not abruptly stop For replacing aldosterone (Floricef) – consume enough salt while taking these meds Diet should be high in protein and carbs WATCH OUT FOR ADDISONIAN CRISIS ADDISONIAN CRISIS (ADRENAL GLAND CRISIS) SIGNS AND SYMPTOMS:  Syncope/Confusion/Weakness -  Hyperkalemia  Very Low Blood Pressure -  Severe vomiting/diarrhea (dehydration) TREATMENT :  IV Corticosteroid – SOLUCORTEF IV PUSH  START ON IV FLUID D5, 0.9 REMENEBER :  Cortisol is replaced through IV hydrocortisone  IV fluids to restore salt and hydration  Electrolytes (like potassium and sodium) should be corrected  Continuous monitoring to stabilize the patient DIABETES INSIPIDUS Diabetes insipidus happens when the kidneys are not able to concentrate the urine appropriately due to which a lot of dilute urine is excreted. Antidiuretic hormone (ADH) controls the amount of water that is excreted in the urine. ADH is also known as vasopressin. It is made in the part of the brain known as the hypothalamus. Then it is stored PATHOPHYSIOLOGY Normally, ADH is synthesized in the hypothalamus and then stored by the posterior pituitary gland. When it’s released into the general circulation, ADH increases the water permeability of the distal and collecting tubules of the kidneys, causing water reabsorption. If ADH is absent, the filtered water is excreted in the urine instead of being reabsorbed, and the patient excretes large quantities of dilute urine. SIGNS AND SYMPTOMS : The cardinal sign of diabetes insipidus is extreme polyuria usually 4 to 16 L/day of dilute urine but sometimes as much as 30 L/day. polydipsia, particularly for cold, iced drinks nocturia fatigue (in severe cases) dehydration, characterized by weight loss, poor skin turgor, dry mucous membranes, headache, dizziness, tachycardia, and hypotension NURSING INTERVENTION : Check vital signs Ask how much and how often they urinate Monitor I and O (urine spec. gravity) Daily weight Hypotonic fluids as ordered Usually dr’s prescribe : vasopressin and desmopressin Educate to change position slowly SYNDROME OF INAPPROPRIATE ANTIDIURETIC HORMONE (SIADH) - ADH BEING RELEASED INAPPROPRIATELY WHAT HAPPENS IN SIADH? ADH being released inappropriately KIDNEYS hold into more and more water FLUID volume keep going up FLUID overload can occur SIADH happens when your body makes excess amounts of antidiuretic hormone (ADH). SIADH causes your body to retain too much water and commonly leads to hyponatremia SYMPTOMS Muscle cramps or weakness. Headache. Problems with balance Mental changes, such as confusion, memory problems and/or strange behavior. Seizures or coma very rare(in severe cases) Treatment for SIADH depends on its cause 1. limit your fluid intake 2. For severe hyponatremia, IV solution Sodium = hydration, blood pressure control, nerve signals, muscle contractions, and nutrient transport! In summary  Diabetes Insipidus (DI): Not enough ADH, so the kidneys can't retain water. The person produces large amounts of dilute urine, leading to dehydration and high sodium.  Syndrome of Inappropriate Antidiuretic Hormone (SIADH): Too much ADH, leading to water retention, causing low sodium in the blood (hyponatremia), and concentrated urine. DIABETES MELLITUS Diabetes is a chronic disease that occurs either when the pancreas does not produce enough insulin or when the body cannot effectively use the insulin it produces. Insulin is a hormone that regulates blood glucose. Hyperglycemia is a common effect of uncontrolled diabetes and over time leads to serious damage to many of the body's systems, especially the nerves and blood vessels. Symptoms of diabetes include: feeling very thirsty needing to urinate more often than usual blurred vision feeling tired losing weight unintentionally Over time, diabetes can damage blood vessels in the heart, eyes, kidneys and nerves. Type 1 diabetes Type 1 diabetes (previously known as insulin-dependent, juvenile or childhood-onset) is characterized by deficient insulin production and requires daily administration of insulin. Type 2 diabetes affects how your body uses sugar (glucose) for energy. It stops the body from using insulin properly, which can lead to high levels of blood sugar if not treated. Gestational diabetes is hyperglycemia with blood glucose values above normal but below those diagnostic of diabetes. Gestational diabetes occurs during pregnancy. NURSING INTERVENTIONS : Emphasize that adherence to the treatment plan is essential. It’s crucial to bring the patient’s blood glucose level within an acceptable range (usually less than 120 mg/dl before a meal and 180 mg/dl between meals) and alleviate or prevent diabetic ketoacidosis (DKA) or hypoglycemia. For the patient with unstable diabetes who isn’t experiencing DKA, monitor blood glucose levels several times per day as prescribed until they stabilize. Administer insulin as prescribed DKA – Diabetic Ketoacidosis TYPE 1 DIABETES MELLITUS (INSULIN DEPENDENT) Patients with Type 1 diabetes must take exogenous insulin for life because their pancreas no longer produces insulin. American Diabetes Association (ADA). Standards of Medical Care in Diabetes—2024. Diabetes Care. Treatment Type Function Examples Provides continuous insulin throughout Insulin glargine (Lantus), Long-acting Basal Insulin the day and night to maintain steady blood insulin detemir (Levemir), insulin sugar levels. insulin degludec (Tresiba) Rapid-acting or Insulin lispro (Humalog), Bolus (Mealtime) Taken before meals to cover the rise in short-acting insulin aspart (Novolog), Insulin blood sugar after eating. insulin insulin glulisine (Apidra) A combination of long-acting and short- Combination Mixed insulin Humalog 75/25, Novolog acting insulin to cover both background Insulin (basal + bolus) 70/30 and mealtime insulin needs. Delivers insulin continuously throughout Continuous Medtronic MiniMed, Insulin Pump the day and offers bolus doses for meals. insulin delivery Tandem t:slim Can be paired with CGM. Continuous Glucose Provides continuous blood sugar levels, Dexcom G6, Medtronic Glucose Monitor monitoring helping to adjust insulin doses in real time. Guardian (CGM) device Helps lower blood sugar by causing Canagliflozin (Invokana), SGLT2 Inhibitors Oral medication kidneys to excrete excess glucose. May dapagliflozin (Farxiga) help with weight loss. Mimics amylin (a hormone produced with Injectable insulin) to help control blood sugar after Amylin Analog Pramlintide (Symlin) hormone meals, slow stomach emptying, and prevent glucose production by the liver. TYPE 2 DIABETES MELLITUS (NON INSULIN INDEPENDENT) Treatment Type Function Examples First-line treatment. It helps Oral the body use insulin more Metformin Metformin medication effectively and reduces glucose (Glucophage) production in the liver. Glimepiride (Amaryl), Oral Stimulate the pancreas to Sulfonylureas glipizide (Glucotrol), medication release more insulin. glyburide (Diabeta) Increase insulin release and Oral decrease glucagon production Sitagliptin (Januvia), DPP-4 Inhibitors medication after meals by inhibiting DPP-4 linagliptin (Tradjenta) enzyme. Inhibit sodium-glucose Canagliflozin cotransporter 2 (SGLT2) in (Invokana), Oral kidneys, preventing glucose SGLT2 Inhibitors empagliflozin medication reabsorption and promoting (Jardiance), glucose excretion through dapagliflozin (Farxiga) urine. Mimic the action of GLP-1 (a Exenatide (Byetta), natural hormone) to increase GLP-1 Receptor Injectable liraglutide (Victoza), insulin release, reduce Agonists medication semaglutide appetite, and slow stomach (Ozempic) emptying. Improve insulin sensitivity by Thiazolidinediones Oral Pioglitazone (Actos), making the body’s cells more (TZDs) medication rosiglitazone (Avandia) responsive to insulin. Insulin glargine Insulin therapy for patients (Lantus), insulin Injectable who need it for blood sugar Insulin detemir (Levemir), medication control. Can be used with insulin aspart other oral medications. (Novolog) Slow the breakdown of Alpha-glucosidase Oral carbohydrates in the intestine, Acarbose (Precose), Inhibitors medication helping to reduce post-meal miglitol (Glyset) blood sugar spikes. Lower blood sugar by binding Bile Acid Oral bile acids in the intestines, Colesevelam Sequestrants medication leading to changes in glucose (Welchol) metabolism. Dopamine Agonists Oral Improves insulin sensitivity by Bromocriptine Treatment Type Function Examples medication stimulating dopamine (Cycloset) receptors in the brain.