Endocrine System PDF

ENDOCRINE SYSTEM School of Laboratory Medicine and Medical Sciences ANATOMY UKZN INSPIRING GREATNESS  OBJECTIVES To differentiate between endocrine and exocrine glands To list all glands that make up the endocrine system and p...

ENDOCRINE SYSTEM School of Laboratory Medicine and Medical Sciences ANATOMY UKZN INSPIRING GREATNESS  OBJECTIVES To differentiate between endocrine and exocrine glands To list all glands that make up the endocrine system and provide a brief description regarding their location, function and hormones produced by the glands where necessary To briefly describe endocrine disorders, their cause and anomalies associated wit them  ENDOCRINE SYSTEM System of ductless glands Regulates body functions via hormones secreted into the bloodstream.  ENDOCRINE SYSTEM Major Endocrine Glands: Hypothalamus Pituitary Gland Thyroid Gland Parathyroid Gland Thymus Adrenal Gland  ENDOCRINE SYSTEM Other organs containing endocrine tissue: Pancreas Kidneys Heart Digestive Tract Placenta Testes Ovaries Pineal Gland  HYPOTHALAMUS ‘Master Gland’ Function : Control centre Attached to roof of third ventricle, near thalamus Continuously receive information on status of body systems via nerve impulses Monitors composition & temperature of blood Messages interpreted, evaluated : outgoing messages dispatched via nerves / hormones  2. PITUITARY GLAND Pea sized mass of glandular tissue Lies in sella turcica Slender stalk: Infundibulum connects pituitary gland to hypothalamus 2 parts : Neurohypophysis Adenohypophysis Indirectly controls : Growth Metabolism Sexual reproduction Lactation  2. PITUITARY GLAND: PARTS Neurohypophysis Adenohypophysis Small posterior lobe Large anterior lobe Stores hormones Releases hormones Oxytocin Growth hormone (GH) Anti Diuretic hormone Thyroid Stimulating hormone (ADH)/vasopressin (TSH) Adenocorticotropic hormone (ACTH) Lutenizing hormone (LH) Follicle stimulating hormone (FSH) Melanocyte stimulating hormone (MSH) Prolactin (PRL)  2. PITUITARY GLAND: HORMONES HORMONES EFFECTS Posterior Oxytocin (OC) Stimulates contraction of uterus & contractile Pituitary cells of breast (milk-ejection reflex) ADH Prevents excess urine production GH General body growth ACTH Stimulate adrenal cortex to release hormone TSH Controls thyroid gland Anterior LH Stimulates sexual & reproductive function Pituitary FSH Stimulate production of sperm in testis & egg in ovaries MSH Related to skin pigmentation PRL Initiates milk production in breast  3. THYROID GLAND Located in middle anterior part of neck: below larynx, in front of trachea “Butterfly” shape 2 lobes connected by isthmus ↑ in size : puberty & pregnancy Rich blood supply: able to deliver high levels of hormones in short period of time Produces Thyroxin (T4) & Tri-iodothyronine (T3) Calcitonin : involved in calcium & phosphate homeostasis  4. PARATHYROID GLAND Small rounded mass Attached to posterior surface of thyroid gland Produces Parathyroid hormone (PTH) Controls homeostasis of calcium & phosphate in blood by activating Vitamin D  5. THYMUS Plays a role in the immune system Produces thymosin, thymic humaral factor & thymic factor Responsible for maturation of T-lymphocytes HORMONES OF THYROID, PARATHYROID & THYMUS ORGAN HORMONE EFFECT energy utilization Thyroid gland T3 & T4 (Follicular cells)  oxygen consumption growth & development Thyroid gland Calcitonin  Calcium ion concentration (C cells) in body fluids Parathyroid PTH  Calcium ion concentration in body fluids Thymus Thymosin Maturation & functional competence of immune system  6. ADRENAL GLAND Located superior to the kidney Divided into: (i) outer cortex (ii) inner medulla  6. ADRENAL GLAND ADRENAL CORTEX ADRENAL MEDULLA Secretes steroid hormones Secretes hormones controlled by ANS Glucocorticoids Epinephrine (Adrenaline) (metabolism) eg. cortisol Mineralocorticoids Norepinephrine (homeostasis of ions) eg. (Noradrenaline) Aldosterone Gonadocorticoids (oestrogens & androgens)  ADRENAL HORMONES REGION HARMONES EFFECT Cortex Mineralocorticoid: Renal reabsorption of sodium ions 1. Zona glomerulos Aldosterone & water. renal potassium ion loss 2. Zona fasciculata Glucocorticoid: Releases amino acids from skeletal cortisol muscle & lipids from adipose. Promotes liver glycogen & glucose formation Anti inflammatory effect 3. Zona Reticularis Androgens Medulla Epinephrine cardiac activity (Adrenaline), blood pressure Norepinephrine glycogen breakdown (Noradrenaline) blood glucose  7. PANCREAS Flattened organ Lies retroperitoneally & transversly across posterior abdominal wall Posterior to stomach, between doudenum on right & spleen on left Classified as exocrine & endocrine Hormones: Islets of Langerhans secrete: Glucagon,  cells :  blood glucose Insulin,  cells:  blood glucose Growth hormone inhibiting hormone (GHIH),  cells : inhibits glucagon & insulin  HORMONES OF PANCREAS CELLS HARMONE EFFECT Alpha () cells Glucagon Glucose synthesis & glycogen breakdown in liver  Blood glucose concentration Beta () cells Insulin Stimulation of lipids & glycogen storage & formation  Blood glucose concentration Delta () cells Somatostatin Inhibits secretion of insulin & glucagon  12 & 13. TESTES & OVARIES TESTES: Located within scrotum Produce testosterone Stimulates development of male sexual characteristics OVARIES: Located in pelvic cavity Produce oestrogen & progesterone Responsible for development & maintenance of female characteristics & menstrual cycle HORMONES OF REPRODUCTIVE SYSTEM CELLS HORMONES EFFECT Testes 1. Testosterone 1. Maturation of sperm Interstitial cells 2. Inhibin Male secondary sex characteristics 2. Inhibits secretion of FSH Ovaries 1. Oestrogen 1. Follicle maturation Follicle cells 2. Inhibin Female secondary sex characteristic 2. Inhibits secretion of FSH Corpus Luteum Progesterone Prepare uterus for implantation Prepare breast for secretory function  OTHER ENDOCRINE TISSUES KIDNEYS: Renal Erythropoietic factor: erythropoietin is responsible for the increased production of RBC’s in bone marrow. HEART: Atrial Natriuretic factor (ANF) is a powerful vasodilator hormone secreted by heart muscles. GIT: Stomach gastrin, enteric gastrin, secretin, cholecystokinin, enterocrinin, gastric inhibiting hormone PLACENTA: Human chorionic gonadotropin, oestrogen, progesterone, relaxin  ENDOCRINE DISORDERS 2 Categories: Abnormal hormone production Abnormal cellular sensitivity ACROMEGALY: Over production of growth hormone after the epiphyseal plates have fused Bone shape changes Cartilaginous areas of skeleton enlarge Broad facial features Enlarged lower jaw  ENDOCRINE DISORDERS CRETINISM A condition of severely stunted physical and mental growth Results from thyroid hormone insufficiency in infancy  ENDOCRINE DISORDERS GOITER Enlarged thyroid gland Results from thyroid hormone hyposecretion Due to iodine insufficiency  ENDOCRINE DISORDERS CUSHING’S SYNDROME Results from hypersecretion of glucocorticoids Lipid reserves are mobilized Adipose tissue accumulates in cheeks & base of neck  PROSTAGLANDINS Regulators of cell metabolism Pathology: Important in normal physiology of: Induce Inflammation Smooth muscle Promote fever Blood flow Intensify pain Platelet function Nerve transmission Immune response Secretion Reproduction Respiration Fat Metabolism Inflammation FEEDBACK CONTROL OF HORMONE RELEASE Regulation Eg. Production of releasing substance / inhibiting substance → Release of hormone from pituitary gland → stimulates hormone release by target gland → hormone exert normal effect & influence further release of a releasing or inhibiting substance → inhibit release of hormone from pituitary gland  Miss NP Ngubane Email: [email protected] Consultation: Fridays from 9h00 to 11h00