Endocrine Fall 2022 student.pptx

Concept: Hormonal Regulation Copyright © 2017, Elsevier Inc. All rights reserved. DEFINITION AND DESCRIPTION  Hormonal regulation is physiological mechanisms that regulate the secretion and action of hormones associated with the endocrine system.  The scope of hormonal regulation can also be thoug...

Concept: Hormonal Regulation Copyright © 2017, Elsevier Inc. All rights reserved. DEFINITION AND DESCRIPTION  Hormonal regulation is physiological mechanisms that regulate the secretion and action of hormones associated with the endocrine system.  The scope of hormonal regulation can also be thought about from the perspective of the hormones and gland represented. Copyright © 2017, Elsevier Inc. All rights reserved. 2 THE ENDOCRINE SYSTEM  Functions:  Differentiation of reproductive system and CNS in fetus  Stimulation of growth and development  Coordination of the male and female reproductive systems  Maintenance of internal environment  Adaptation to emergency demands of body Copyright © 2017, Elsevier Inc. All rights reserved. 3 HORMONES  General characteristics:  Specific rates and rhythms of secretion  Diurnal (HPA), pulsatile (Gonadotropin-releasing hormone), and cyclic (pancreas) and patterns that depend on circulating substances  Operate within feedback systems  Affect only target cells with appropriate receptors  Are excreted by kidneys or deactivated by liver or cellular mechanisms Copyright © 2017, Elsevier Inc. All rights reserved. 4 REGULATION OF HORMONE RELEASE  Hormones are released:  In response to an alteration in the cellular environment  To maintain a regulated level of certain substances or other hormones  Hormones are regulated by chemical, hormonal, or neural factors  Negative feedback Copyright © 2017, Elsevier Inc. All rights reserved. 5 HORMONE TRANSPORT AND ACTION  Hormones are released into the circulatory system by endocrine glands  Target cell  Up-regulation (increase)  Down-regulation (decrease)  Hormone effects:  Direct effects  Permissive effects Copyright © 2017, Elsevier Inc. All rights reserved. 6 STRUCTURE AND FUNCTION OF THE ENDOCRINE GLANDS  Hypothalamic-pituitary axis  Interaction between the hypothalamus, pituitary gland, and adrenal glands.  Controls reactions to stress and regulates many body processes including digestion, immunity, mood and emotions, sexuality, and energy storage and expenditure. Copyright © 2017, Elsevier Inc. All rights reserved. 7 HYPOTHALAMUS  Function – produce regulatory hormones Copyright © 2017, Elsevier Inc. All rights reserved. 8 ANTERIOR PITUITARY  Adrenocorticotropic hormone (ACTH)  Melanocyte-stimulating hormone (MSH)  Somatotropic hormones  Growth hormone  Prolactin  Glycoprotein hormones  Follicle-stimulating hormone  Luteinizing hormone  Thyroid-stimulating hormone Copyright © 2017, Elsevier Inc. All rights reserved. 9 ANTERIOR PITUITARY (CONT.)  Luteinizing hormone  Follicle-stimulating hormone  Beta-lipotropin  Beta-endorphins Copyright © 2017, Elsevier Inc. All rights reserved. 10 POSTERIOR PITUITARY HORMONES  Synthesized with their binding proteins in the supraoptic and paraventricular nuclei of the hypothalamus  Secreted by the posterior pituitary  Antidiuretic hormone (ADH)  Controls plasma osmolality  Oxytocin  Uterine contractions and milk ejection in lactating women Copyright © 2017, Elsevier Inc. All rights reserved. 11 PINEAL GLAND  Located near center of brain  Secretes melatonin  Regulates circadian rhythms and reproductive systems  Role in onset of puberty Copyright © 2017, Elsevier Inc. All rights reserved. 12 THYROID AND PARATHYROID GLANDS  Thyroid gland  Two lobes lie on either side of the trachea  Isthmus  Follicles (follicle cells surrounding colloid)  Parafollicular cells (C cells)  Secrete calcitonin  Regulation of thyroid hormone secretion  Thyrotropin-releasing hormone and thyroid-stimulating hormone Copyright © 2017, Elsevier Inc. All rights reserved. 13 THYROID AND PARATHYROID GLANDS (CONT.)  Thyroid hormone  Secreted in response to TSH  90% T and 10% T 4 3  Most T then converted to T 4 3  Bound to thyroxine-binding globulin, thyroxine-binding prealbumin, albumin, or lipoproteins  Affects growth and maturation of tissues, cell metabolism, heat production, and oxygen consumption Copyright © 2017, Elsevier Inc. All rights reserved. 14 THYROID AND PARATHYROID GLANDS (CONT.)  Parathyroid glands  Small glands located behind the upper and lower poles of the thyroid gland  Produce parathyroid hormone (PTH)  Increases serum calcium and decreases serum phosphate  Antagonist of calcitonin (thus increases bone resorption and serum calcium)  Vitamin D (cofactor) needed for PTH function Copyright © 2017, Elsevier Inc. All rights reserved. 15 ENDOCRINE PANCREAS  The pancreas is both an endocrine and an exocrine gland  Houses the islets of Langerhans  Secretion of glucagon and insulin  Cells:  Alpha—glucagon  Beta—insulin and amylin  Delta—somatostatin and gastrin  F cells—pancreatic polypeptide Copyright © 2017, Elsevier Inc. All rights reserved. 16 ENDOCRINE PANCREAS (CONT.)  Insulin  Synthesized from proinsulin  Secretion is promoted by increased blood levels of glucose, amino acids, GI hormones  Facilitates the rate of glucose uptake into the cells of the body  Anabolic hormone  Synthesis of proteins, lipids, and nucleic acids  Amylin  Peptide hormone co-secreted with insulin  Delays nutrient uptake  Suppresses glucagon secretion Copyright © 2017, Elsevier Inc. All rights reserved. 17 ENDOCRINE PANCREAS (CONT.)  Glucagon  Secretion is promoted by decreased blood glucose levels  Stimulates glycogenolysis, gluconeogenesis, and lipolysis  Pancreatic somatostatin  Possible involvement in regulating alpha- and beta-cell secretions  Gastrin, ghrelin, and pancreatic polypeptides Copyright © 2017, Elsevier Inc. All rights reserved. 18 ADRENAL GLANDS  Adrenal cortex  Mineralocorticoids (aldosterone)  Glucocorticoids (cortisol)  Adrenal medulla  Adrenal medullary hormones (catecholamines epinephrine and norepinephrine)  Stress response Copyright © 2021, Elsevier Inc. All Rights Reserved. ADRENAL GLANDS (CONT.)  Adrenal cortex  Stimulated by adrenocorticotropic hormone (ACTH)  Glucocorticoid hormones  Direct effects on carbohydrate metabolism  Anti-inflammatory and growth-suppressing effects  Most potent naturally occurring glucocorticoid is cortisol Copyright © 2017, Elsevier Inc. All rights reserved. 20 ADRENAL GLANDS (CONT.)  Adrenal cortex (Cont.)  Mineralocorticoid hormones  Affect ion transport by epithelial cells  Increase the activity of the sodium pump of the epithelial cells  Cause sodium retention and potassium and hydrogen loss  Most potent naturally occurring mineralocorticoid is aldosterone  Regulated by the renin-angiotensin system Copyright © 2017, Elsevier Inc. All rights reserved. 21 ADRENAL GLANDS (CONT.)  Adrenal cortex (Cont.)  Adrenal estrogens and androgens  Estrogen secretion by the adrenal cortex is minimal  The adrenal cortex secretes weak androgens  Androgens are converted by peripheral tissues to stronger androgens such as testosterone Copyright © 2017, Elsevier Inc. All rights reserved. 22 ADRENAL GLANDS (CONT.)  Adrenal medulla  Chromaffin cells (pheochromocytes)  Chromaffin cells secrete the catecholamines epinephrine (majority) and norepinephrine  Release of catecholamines has been characterized as a fight or flight response  Catecholamines promote hyperglycemia Copyright © 2017, Elsevier Inc. All rights reserved. 23 AGING AND THE ENDOCRINE SYSTEM  Organ atrophy and weight loss with vascular changes  Decreased secretion and clearance of hormones  Variable change in receptor binding and intracellular responses Copyright © 2017, Elsevier Inc. All rights reserved. 24 Alterations of Hormonal Regulation Copyright © 2017, Elsevier Inc. All rights reserved. MECHANISMS OF HORMONAL ALTERATIONS  Failure of feedback systems  Dysfunction of an endocrine gland  Secretory cells are unable to produce, obtain, or convert hormone precursors  The endocrine gland synthesizes or releases excessive amounts of hormone  The endocrine gland fails to produce adequate amounts of hormone  Increased hormone degradation or inactivation  Ectopic hormone release Copyright © 2017, Elsevier Inc. All rights reserved. 26 DISEASES OF THE POSTERIOR PITUITARY  Syndrome of inappropriate antidiuretic hormone secretion (SIADH)  Hypersecretion of ADH or ectopic production  For diagnosis, normal adrenal and thyroid function must exist  Clinical manifestations are related to enhanced renal water retention  Hyponatremia  Serum hypoosmolality  Thirst, dyspnea, altered LOC Copyright © 2017, Elsevier Inc. All rights reserved. 27 DISEASES OF THE POSTERIOR PITUITARY (CONT.)  Diabetes insipidus  Insufficiency of ADH  Clinical manifestations  Polyuria and polydipsia  Partial or total inability to concentrate the urine  Neurogenic  Insufficient amounts of ADH  Nephrogenic  Inadequate response to ADH in nephrons (kidney)  Psychogenic  Manifestations are related to enhanced water excretion, hypernatremia, and serum hyperosmolality  Polyuria, polydipsia, dehydration  Water deprivation test Copyright © 2017, Elsevier Inc. All rights reserved. 28 DI SIADH COMPARE AND CONTRAST Urine output Urine osmolality (concentation) Serum sodium Serum osmolality Symptoms Copyright © 2017, Elsevier Inc. All rights reserved. 29 DISEASES OF THE ANTERIOR PITUITARY  Hypopituitarism causes  Pituitary infarction  Sheehan syndrome  Hemorrhage  Shock  Others:  Head trauma  Infections  Tumors Copyright © 2017, Elsevier Inc. All rights reserved. 30 DISEASES OF THE ANTERIOR PITUITARY (CONT.)  Hypopituitarism (Cont.)  Panhypopituitarism  ACTH deficiency  TSH deficiency  FSH and LH deficiency  GH deficiency  GH deficiency in children = dwarfism Copyright © 2017, Elsevier Inc. All rights reserved. 31 DISEASES OF THE ANTERIOR PITUITARY (CONT.)  Hyperpituitarism  Commonly caused by a benign, slow-growing pituitary adenoma  Manifestations:  Headache and fatigue  Visual changes  Hyposecretion of neighboring anterior pituitary hormones Copyright © 2017, Elsevier Inc. All rights reserved. 32 DISEASES OF THE ANTERIOR PITUITARY (CONT.)  Hypersecretion of growth hormone (GH)  Acromegaly  Hypersecretion of GH during adulthood  Giantism  Hypersecretion of GH in children and adolescents  Influences growth and has significant effects on glucose, lipid, and protein metabolism  Connective tissue proliferation  Adenoma causing hyperpituitarism  Visual effects Copyright © 2017, Elsevier Inc. All rights reserved. 33 DISEASES OF THE ANTERIOR PITUITARY (CONT.)  Hypersecretion of prolactin  Caused by prolactinomas (prolactin producing tumors)  In females, increased levels of prolactin cause amenorrhea, galactorrhea, hirsutism, and osteopenia  In males, increased levels of prolactin cause hypogonadism, erectile dysfunction Copyright © 2017, Elsevier Inc. All rights reserved. 34 THYROID DISORDERS  Primary  Increased or decreased thyroid hormone levels  Decreased TH and increased TSH Copyright © 2017, Elsevier Inc. All rights reserved. 35 ALTERATIONS OF THYROID FUNCTION EXEMPLAR:  Hyperthyroidism HYPERTHYROIDISM Thyrotoxicosis (any cause of increased TH levels)   Hyperthyroidism – excessive TH from thyroid  Elevated TH and decreased TSH  Primary (thyroid gland dysfunction) – 2 types  Graves disease (antibodies cause growth in thyroid)  Pretibial myxedema (waxy, discolored induration of skin)  Hyperthyroidism resulting from nodular thyroid disease  Goiter  Thyroiditis (infection)  Secondary (TSH secreting pituitary adenomas  Same clinical manifestations: increased metabolic rate Copyright © 2017, Elsevier Inc. All rights reserved. 36 THYROID STORM  Occurs under physiologic stress  Hyperthermia, tachycardia, heart failure, agitation, etc Copyright © 2017, Elsevier Inc. All rights reserved. 37 ALTERATIONS OF THYROID FUNCTION EXEMPLAR: HYPOTHYROIDISM  Hypothyroidism: deficient production of TH by thyroid = decreased cellular regulation  Primary hypothyroidism  Autoimmune thyroiditis (Hashimoto disease)  Subacute thyroiditis  Painless thyroiditis  Postpartum thyroiditis  Myxedema coma  Congenital hypothyroidism Copyright © 2017, Elsevier Inc. All rights reserved. 38 HYPOTHYROIDISM  Primary (decreased production of TH)  Decreased TH, increased TSH  Most common is Hashimoto disease (autoimmune) – gradual destruction of thyroid  Secondary  Inadequate TSH = low TH  Myxedema: altered composition of dermis and other tissues  Myxedema coma: severe hypothyroidism Copyright © 2017, Elsevier Inc. All rights reserved. 39 ALTERATIONS OF PARATHYROID FUNCTION  Hyperparathyroidism (high PTH)  Primary hyperparathyroidism  Excess secretion of PTH from one or more parathyroid glands  Secondary hyperparathyroidism  Increase in PTH secondary to chronic hypocalcemia  Manifestations (for all):  Hypercalcemia (blood)  Hypophosphatemia  Hypercalciuria: kidney stones  Pathologic fractures (osteoporosis) Copyright © 2017, Elsevier Inc. All rights reserved. 40 ALTERATIONS OF PARATHYROID FUNCTION (CONT.)  Hypoparathyroidism  Abnormally low PTH levels  Usually caused by parathyroid damage in thyroid surgery  Manifestations:  Hypocalcemia  Muscle spasms, tetany  Chvostek and Trousseau signs  Hyperphosphatemia Copyright © 2017, Elsevier Inc. All rights reserved. 41 DYSFUNCTION OF THE ENDOCRINE PANCREAS: DIABETES MELLITUS  A group of metabolic diseases characterized by hyperglycemia resulting from  Defects in insulin secretion  Defect in insulin action  Both  The American Diabetes Association (ADA) classifies four categories of diabetes mellitus:  Type 1  Type 2  Other specific types  Gestational diabetes Copyright © 2017, Elsevier Inc. All rights reserved. 42 METABOLIC SYNDROME  Simultaneous presence of metabolic factors that increase risk for type 2 DM     Abdominal obesity Hyperglycemia Hypertension Hyperlipidemia Copyright © 2021, Elsevier Inc. All Rights Reserved. DIAGNOSIS OF DIABETES  In individuals with symptoms  Glycosylated hemoglobin (HbA1c)  Greater than or equal to 6.5%  Fasting plasma glucose  Greater than or equal to 126 mg/dl (fasting for at least 8 hours)  Oral glucose tolerance testing  Greater than or equal to 220 mg/dl  Random glucose levels  In individual with classic hyperglycemic symptoms, greater than or equal to 200 mg/dl  Glycosylated Hemoglobin  Permanent attachment of glucose to hemoglobin molecules – reflects the average plasma glucose exposure over the life of a RBC (approx. 120 days) Copyright © 2017, Elsevier Inc. All rights reserved. 44 PREDIABETES  Elevated blood glucose levels but do not reach standard for diagnosis of diabetes Copyright © 2017, Elsevier Inc. All rights reserved. 45 Diabetes Type 1 Diabetes Type 2 Primary Beta-cell defect/failure Insulin resistance with inadequate insulin secretion Less common Pediatric Increasing Most common Adults Increasing Environmental and genetic factors Environmental and genetic Associated with longterm obesity Copyright © 2017, Elsevier Inc. All rights reserved. 46 EXEMPLAR: TYPE 1 DIABETES MELLITUS  Types:  Idiopathic type 1 (less common)  Autoimmune type 1 (genetic + environmental)  Pancreatic atrophy and specific loss of beta cells; hyperglycemia when 80%-90% cells lost  Macrophages, T-cytotoxic cells, antibodies  Alterations in insulin (lack of), amylin (decreased), glucagon (increased) Copyright © 2017, Elsevier Inc. All rights reserved. 47 TYPE 1 DIABETES MELLITUS (CONT.)  Manifestations:  Hyperglycemia  Polydipsia  Polyuria  Polyphagia  Weight loss  Fatigue  Other  Recurrent infections  Prolonged wound healing  Visual changes  Paresthesias Copyright © 2017, Elsevier Inc. All rights reserved. 48 EXEMPLAR: TYPE 2 DIABETES MELLITUS  Ranges from insulin resistance with relative insulin deficiency to insulin secretory defect with insulin resistance  Caused by genetic-environmental interaction  Risk factors are age, obesity, hypertension, physical activity, poor diet, and family history  Metabolic syndrome Copyright © 2017, Elsevier Inc. All rights reserved. 49 TYPE 2 DIABETES MELLITUS (CONT.)  Initial insulin resistance (suboptimal response of insulin- sensitive tissues (especially liver, muscle and adipose tissue)  Later loss of beta cells  Manifestations (nonspecific): fatigue, pruritus, recurrent infections, visual changes, or symptoms of neuropathy; often overweight, dyslipidemic, hyperinsulinemic, and hypertensive  Same diagnostic criteria Copyright © 2017, Elsevier Inc. All rights reserved. 50 ACUTE COMPLICATIONS OF DIABETES MELLITUS  Hypoglycemia  Diabetic ketoacidosis (DKA)  Hyperosmolar hyperglycemic nonketotic syndrome (HHNKS) Copyright © 2017, Elsevier Inc. All rights reserved. 51 Hypoglycemi a Diabetic Ketoacidosis (DKA) Hyperglycem ic hyperglycemi c Nonketotic Syndrome Risk factors Taking insulin or oral hypoglycemics Fluctuating glucose Type 1 diabetics Undiagnosed diabetes Stress (infection, illness) Type II diabetes Older adults Stress (infection, illness) Onset Rapid Slow Slowest Clinical Manifestations Pallor, sweating, tachycardia, tremors, anxiety, restlessness Polyuria, polydipsia, lethargy, Kussmaul respirations, fruity breath Polyuria, polydipsia, hypovolemia, hypotension, tachycardia Glucose > 250 mg/dl. Low bicarbonate, Glucose > 600mg/dl, lack of ketosis Laboratory Low blood analysis sugar (less Copyright © 2017, Elsevier Inc. All rights reserved. than 60 mg/dl) 52 CHRONIC COMPLICATIONS OF DIABETES MELLITUS  Microvascular disease  Diabetic retinopathy  Diabetic nephropathy  Diabetic neuropathies  Macrovascular disease  Cardiovascular disease  Stroke  Peripheral vascular disease  Infection Copyright © 2017, Elsevier Inc. All rights reserved. 53 ALTERATIONS OF ADRENAL FUNCTION  Disorders of the adrenal cortex:  Cushing disease  Excessive anterior pituitary secretion of ACTH  Cushing syndrome  Manifestations resulting from chronic excess cortisol Copyright © 2017, Elsevier Inc. All rights reserved. 54 ALTERATIONS OF ADRENAL FUNCTION  Disorders of the adrenal cortex  Congenital adrenal hyperplasia  Hyperaldosteronism  Primary hyperaldosteronism (Conn disease)  Secondary hyperaldosteronism Copyright © 2017, Elsevier Inc. All rights reserved. 55 ALTERATIONS OF ADRENAL FUNCTION (CONT.)  Disorders of the adrenal cortex (Cont.)  Hypersecretion of adrenal androgens and estrogens  Feminization  Virilization Copyright © 2017, Elsevier Inc. All rights reserved. 56 ALTERATIONS OF ADRENAL FUNCTION (CONT.)  Disorders of the adrenal cortex (Cont.)  Adrenocortical hypofunction (not enough cortisol)  Addison disease (primary adrenal insufficiency)  Addisonian crisis  Secondary hypocortisolism Copyright © 2017, Elsevier Inc. All rights reserved. 57 ALTERATIONS OF ADRENAL FUNCTION (CONT.)  Disorders of the adrenal medulla  Adrenal medulla hyperfunction  Caused by tumors derived from the chromaffin cells of the adrenal medulla  Pheochromocytomas  Secrete catecholamines on a continuous or episodic basis Copyright © 2017, Elsevier Inc. All rights reserved. 58