L35- Endocrine System PDF

L35- ENDOCRINE SYSTEM Dr.Pugazhandhi Bakthavatchalam Assistant Professor of Anatomy and Physiology, AUACAS, American University of Antigua LEARNING OUTCOMES At the end of this lecture, students should be able to  Describe gross anatomical features of the Hypothalamus, Pituitary, pineal glands...

L35- ENDOCRINE SYSTEM Dr.Pugazhandhi Bakthavatchalam Assistant Professor of Anatomy and Physiology, AUACAS, American University of Antigua LEARNING OUTCOMES At the end of this lecture, students should be able to  Describe gross anatomical features of the Hypothalamus, Pituitary, pineal glands and pancreas  Identify the section of Hypothalamus, Pituitary, pineal glands and pancreas  Discuss the clinical anatomy of endocrine glands  Describe gross anatomical features of the Thyroid, Parathyroid, and adrenal glands  Identify the sections of Thyroid, Parathyroid, thymus and adrenal glands  Discuss the clinical anatomy of above mentioned endocrine glands Introduction Differences between exocrine and endocrine gland Exocrine Gland Endocrine Gland Presence of duct No duct, directly into blood Mucous or serous secretion Hormone (to target organ) Eg: Sweat gland, salivary Eg: Pituitary gland, gland, gastric gland suprarenal gland, thyroid gland Introduction 1. Hypothalamus 2. Pituitary gland 3. Pineal gland 4. Thyroid gland 5. Parathyroid gland 6. Suprarenal gland 7. Pancreas 8. Ovary 9. Testis Introduction 1. Pituitary gland 2.Pineal gland 3. Thyroid gland 4. Parathyroid gland 5. Thymus 6. Suprarenal gland 7. Pancreas 8. Ovary 9. Testis 2. Pituitary gland 0.5 g in men slightly more in women. Located in hypophyseal fossa or sella turcica of sphenoid bone Lies below the hypothalamus Connected by infundibulum Covered by diaphragma sellae Relations of pituitary gland Laterally Superiorly - Cavernous sinus and - Optic chiasma its contents (separated by dura mater) Internal carotid artery Inferiorly - Sphenoid bone Pituitary gland - Sphenoid air sinus 2. Pituitary gland Divided into Anterior lobe (adenohypophysis) 7 hormones are made and secreted here Posterior lobe (neurohypophysis) Hormones secreted here are made in the hypothalamus ADH & Oxytocin 2. Pituitary gland Median eminence 2. Pituitary gland Anterior pituitary Pars distalis Largest section Pars tuberalis Collar of tissue which surrounds the infundibulum Pars intermedia A narrow band separated from pars distalis by hypophyseal cleft 2. Pituitary gland Posterior pituitary Pars nervosa The bulk of the posterior pituitary Median eminence The upper section of neurohypophysis above the pars tuberalis Infundibular stalk The ‘stem’ that connects the pars nervosa to the hypothalamus 2. Pituitary gland BLOOD SUPPLY Superior and inferior hypophyseal arteries, branches of internal carotid artery. The veins drain into the cavernous sinuses.  Pituitary gland HYPOTHALAMO- HYPOPHYSEAL PORTAL SYSTEM OF VEINS Anterior lobe receives venous blood from the hypothalamus Introduction 1. Pituitary gland 2. Pineal gland 3. Thyroid gland 4. Parathyroid gland 5. Thymus 6. Suprarenal gland 7. Pancreas  Pineal gland Small, spherical glands Lies in midline of the brain Below the posterior end of corpus callosum Represents an evagination of posterior part of roof of 3rd ventricles Connected to the brain by stalk containing nerve fibres Synthesizes melatonin- induced by darkness Pancreas Lies across the upper abdomen Extends from the inside of the C- loop of duodenum to the hilum of the spleen Lies posterior to the stomach and the peritoneum The head of the pancreas lies in the C-shaped duodenal curve while the tail of the pancreas lies toward the spleen Body of the pancreas lies between the head and the tail. Pancreas Serves 2 functions which are carried out by two different groups of cells within the organ These two groups of cells are designated as the exocrine and the endocrine portions of the pancreas  HORMONES OF THE PANCREATIC ISLETS GLUCAGON INSULIN SOMASTATIN (ALPHA CELLS) (BETA CELLS) (DELTA CELLS) Raises blood Lower blood Inhibit both insulin & sugar level sugar level glucagon release Thyroid gland  Largest endocrine gland  Anterior & lateral sides of trachea  2 large lobes connected by isthmus  Thyroid gland Lies at anterior part of the neck (C5-T1) Two lobes connected by isthmus Lateral lobes extend from oblique line of thyroid cartilage to 5th to 6th tracheal ring Isthmus- 2nd, 3th and 4th tracheal ring Pyramidal lobe:  Often ascends from the isthmus or the adjacent part of either lobe up to the hyoid bone  May be attached by a fibrous/fibromuscular band  “levator” of the thyroid gland  4. Thyroid gland Apex False capsule Derived from pretracheal fascia Superior & Inferior Parathyroid Thyroid Venous Gland Plexus Gland True capsule Isthmus Thickening of connective tissue Base Lateral view of Rt lobe 4. Thyroid gland MEDIAL RELATIONS Larynx, trachea Pharynx, oesophagus Cricothyroid Muscle and its nerve supply External laryngeal nerve Recurrent laryngeal nerve  4. Thyroid gland- Blood supply ARTERIAL SUPPLY Superior thyroid artery Branch of external carotid artery Passes to the upper pole Inferior thyroid artery Branch of thyrocervical trunk Passes behind the carotid sheath to the back of the gland 4. Thyroid gland- Blood supply VENOUS DRAINAGE Superior thyroid veins Drains the upper pole to the internal jugular vein Middle thyroid veins Drains from the lateral side of the gland to the internal jugular Inferior thyroid veins Often several Drain the lower pole to the brachiocephalic veins  5. Parathyroid glands Lies posterior to thyroid Embedded in true capsule of thyroid Within pretracheal fascia Between these, nerve and blood vessels SUPERIOR PARATHYROID GLANDS - more constant - superior to the inferior thyroid artery - dorsal to recurrent laryngeal nerve 5. Parathyroid glands INFERIOR PARATHYROID GLANDS It may lie: within capsule, inferior to the inferior thyroid artery outside capsule, superior to the inferior thyroid artery within the substance of thyroid gland  5. Parathyroid glands ARTERIAL SUPPLY Branches of the inferior thyroid artery supply the parathyroids. Maybe supplied by the superior thyroid arteries, thyroid ima artery, laryngeal arteries, tracheal arteries or oesophageal arteries 5. Parathyroid glands VENOUS DRAINAGE Drain into the plexus of veins on the anterior surface of the thyroid comprising the superior, middle and inferior thyroid veins 5. Parathyroid glands INNERVATION Supplied by thyroid branches of the cervical sympathetic ganglia with a mainly sensory function Detect stretch sensation within the glands that gives rise to the sensation of pain in some disorders 5. Parathyroid glands Thyroid gland Superior parathyroid gland Deep cervical nodes Inferior parathyroid gland Paratracheal nodes 5. Parathyroid glands INADVERTENT REMOVAL OF PARATHYROID GLANDS Variable positions of the parathyroid glands puts them in danger during surgical procedures in neck Results in tetany (muscle twitches & cramps) Decreased serum calcium levels 6.Suprarenal gland Also known as adrenal gland Two, yellowish and retroperitoneal organs They lie on the upper poles of the kidneys Consists of an outer cortex and an inner medulla 6. Suprarenal gland Surrounded by perinephric fat Enclosed by renal fascia Separated from the kidneys by a thin septum  6.Suprarenal gland ARTERIAL SUPPLY Superior suprarenal arteries from the inferior phrenic artery Middle suprarenal (one or more) from the aorta Inferior suprarenal (one or more) from the renal artery 6. Suprarenal gland VENOUS DRAINAGE - Via the suprarenal veins The left suprarenal vein drains into the renal vein. The right suprarenal vein drains into the inferior vena cava. 6. Suprarenal gland LYMPHATIC DRAINAGE Lateral (paraaortic) lumbar nodes 6. Suprarenal gland INNERVATION Nerve supply comes from The coeliac plexus The greater thoracic splanchnic nerves References Susan. 2008. Gray’s Anatomy- The Anatomical Basis of clinical Practise. 40th edition. New York: Elsvier. Snell, R.S. 2008. Clinical Anatomy by Regions. 8th edition. Philadelphia: Lippincott Williams & Wilkins. Ellis, H. 2006. Clinical Anatomy- A revision and Applied Anatomy for Clinical Students. 11th edition. Victoria: Blackwell Publishing. Moore, K.L., Dalle,A.F. & Agur, A.M. 2010. Clinically Oriented Anatomy. 6th edition.Philadelphia: Lippincott Williams & Wilkins.