The Endocrine System • Controls many body • Derives its name from functions the fact that various – exerts control by glands release releasing special hormones directly into chemical substances into the blood, which in turn the blood called hormones transports the – Hormones affect other hormones to target endocrine glands or body tissues via ducts. systems The Endocrine System • Exocrine glands - • Endocrine transport their Emergencies: hormones to target – from common: tissues via ducts. • Diabetes • to the unusual: – Thyrotoxicosis The Endocrine System • Pituitary gland: a small gland located on a stalk • Consists of several hanging from the base of the brain - AKA glands located in various parts of the • “The Master Gland” body. – Primary function is to control other glands. – Produces many hormones. – Secretion is controlled by the hypothalamus in the base of the brain. The Endocrine System • The two segments are: • The Pituitary Gland is – Posterior Pituitary: divided into 2 areas, • produces oxytocin which differ and antidiuretic hormone (ADH) – structurally and – Anterior Pituitary: functionally • produces thyroid- – each area has stimulating hormone separate types of (TSH) hormone production. • growth hormone (GH) • adrenocorticotropin (ACTH) • follicle-stimulating hormone (FSH) The Endocrine System • And even more… • Posterior Pituitary – luteinizing hormone – Oxytocin (the (LH) natural form of pitocin) – prolactin • stimulates gravid uterus • Let’s go over these • causes “let down” of milk from the one at a time... breast. – ADH (vasopressin) causes the kidney to retain water. The Endocrine System • Anterior Pituitary • Anterior Pituitary… – Primarily regulates – Growth hormone other endocrine (GH) glands • glucose usage – rarely a factor in • consumption of endocrinological fats as an energy emergencies source – TSH stimulates the – ACTH stimulates the thyroid gland to adrenal cortex to release its release its hormones hormones, thus metabolic rate – FSH & LH stimulates maturation & release of eggs from ovary. The Endocrine System • The Thyroid Gland • Within the colloid are the thyroid hormones: – lies in the anterior neck just below the – thyroxine (T4) larynyx. – triiodothyronine (T3) – Two lobes, located • When stimulated on either side of the (by TSH or by trachea, connected cold), these are by a narrow band of released into the tissue called the circulatory system isthmus. and the – Sacs inside the metabolic rate. gland contain colloid – “C” cells within the thyroid produce the hormone calcitonin. The Endocrine System • Calcitonin, when • Myxedema symptoms: released, lowers the – Facial bloating amount of calcium in – weakness the blood. – cold intolerance • Inadequate levels of – lethargy thyroid hormones = – altered mental hypothyroidism, or status Myxedema. – oily skin and hair – TX: replacement of thyroid hormone. The Endocrine System • Increased thyroid – Long term hormone release hyperthyroidism: causes • Exopthalmos hyperthyroidism, – bulging of the commonly called eyeballs (picture Graves’ disease. Barbara Bush) – Signs and • In severe cases - a symptoms: medical emergency • insomnia, fatigue called thyrotoxicosis • tachycardia can result. • hypertension • heat intolerance • weight loss The Endocrine System • Parathyroid Glands – produce parathyroid – small, pea-shaped hormone - level of glands, located in the calcium in blood neck near the thyroid – usually 4 - number can – Hypocalcemia can vary result if parathyroids – regulate the level of are removed or calcium in the body destroyed. The Endocrine System • Pancreas • Islets of Langerhans – a key gland located in – specialized tissues in the folds of the which the endocrine duodenum functions of the – has both endocrine and pancreas occurs exocrine functions – include 3 types of – secretes several key cells: digestive enzymes • alpha ( ) • beta () • delta () – each secretes an important hormone. The Endocrine System • Alpha () cells • The surge of glucagon release glucagon, stimulates the liver to essential for release glucose stores controlling blood (from glycogen and glucose levels. additional storage • When blood glucose sites). levels fall, cells • Also, glucagon the amount of stimulates the liver to glucagon in the blood . manufacture glucose - • gluconeogenesis. The Endocrine System • Beta Cells () release • Insulin is rapidly insulin (antagonistic to broken down by the glucagon). liver and must be • Insulin the rate at secreted constantly. which various body • Delta Cells () cells take up glucose. produce somatostatin, Thus, insulin lowers which inhibits both the blood glucose glucagon and insulin. level. The Endocrine System • Adrenal Glands • the Adrenal Medulla – 2 small glands that sit secretes the atop both kidneys. catecholamine hormones – Each has 2 divisions, norepinephrine and each with different epinephrine (closely functions. related to the sympathetic component of the autonomic nervous system). The Endocrine System • One at a time… • The Adrenal Cortex – gluticocorticoids: secretes 3 classes of – accounts for 95% of hormones, all steroid adrenal cortex hormones: hormone production – gluticocorticoids – the level of glucose mineralocorticoids in the blood – androgenic hormones – Released in response to stress, injury, or serious infection - like the hormones from the adrenal medulla. The Endocrine System • Mineralocorticoids: • Signs & Symptoms of – work to regulate the Cushing’s Disease: concentration of – in blood sugar levels potassium and sodium – unusual body fat in the body. distribution • Prolonged in – rapid mood swings adrenal cortex hormone results in Cushing’s Disease. The Endocrine System • And - if there is an • Sodium can also be in mineralocorticoids retained by the kidney, as well resulting in hyponatremia. – A serious electolyte imbalance will occur – Causes: due to the potassium • dysrhythmias excretion by the • coma kidney, which results • death in hypokalemia. – usually results from a tumor - TX? Removal of tumor. The Endocrine System • Gonads and Ovaries: • Ovaries: – the endocrine glands – located in the associated with human abdominal cavity reproduction. adjacent to the uterus. – Female ovaries – Under the control of produce eggs LH and FSH from the – Male gonads produce anterior pituitary they sperm manufacture • estrogen • both have endocrine • protesterone functions. The Endocrine System • Estrogen and • Testes: Progesterone have – located in the scrotum several functions, – produce sperm for including sexual reproduction development and – manufacture preparation of the testosterone - uterus for implantation • promotes male growth and masculinization of the egg. – Controlled by anterior pituitary hormones FSH and LH. The Endocrine System • Endocrine • Complications of Emergencies: Diabetes: • Diabetes Mellitus – contributes to heart – one of the most disease common diseases in – stroke North America. – kidney disease – insulin secretion by – blindness the Beta () cells of the islets of Langerhans in the pancreas. The Endocrine System • Pathophysiology of • The other 2 major Diabetes: food sources are • Glucose Metabolism – proteins – Glucose (dextrose) is a – fats simple sugar required • Most sugars in the by the body to produce human diet are energy. complex and must be – Sugars, or broken down into carbohydrates, are 1 of 3 major food sources simple sugars: used by the body. glucose, galactose and fructose - before use. The Endocrine System • Breakdown of sugars • To be converted into is carried out by energy, glucose must enzymes in the gastro first be transmitted intestinal system. through the cell – As simple sugars, these membrane. BUT - the are absorbed from the glucose molecule is GE system into the large and doesn’t body. readily diffuse through – More than 95% enter the cell membrane. the body as glucose. The Endocrine System • Glucose must pass • The rate at which into the cell by glucose can enter the binding to a special cell is dependent upon carrier protein on the insulin levels. cell’s surface. – Insulin serves as the – Facilitated diffusion - messenger - travels via doesn’t use energy. blood to target tissues. The carrier protein – Combines with specific binds with the glucose insulin receptors on the and carries it into the surface of the cell cell. membrane.
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