The Urinary System PDF

THE URINARY SYSTEM  SYSTEM INTEGRATION FOOD, WATER INTAKE OXYGEN INTAKE ELIMINATION OF DIGESTIVE SYSTEM RESPIRATORY SYSTEM CARBON DIOXIDE NUTRIENTS, OXYGEN WATER,...

THE URINARY SYSTEM  SYSTEM INTEGRATION FOOD, WATER INTAKE OXYGEN INTAKE ELIMINATION OF DIGESTIVE SYSTEM RESPIRATORY SYSTEM CARBON DIOXIDE NUTRIENTS, OXYGEN WATER, CARBON SALTS DIOXIDE CIRCULATORY SYSTEM URINARY SYSTEM WATER SOLUTES ELIMINATION RAPID TRANSPORT ELIMINATION OF OF FOOD TO AND FROM ALL EXCESS WATER RESIDUES LIVING CELLS SALTS, WASTES URINARY SYSTEM TWO KIDNEYS TWO URETERS URINARY BLADDER URETHRA Filtration blood and separates toxic substances Regulation of the blood pressure & pH Elimination of the water from the blood & production of urine Secretion an enzyme called RENIN & ERYTHROPOIETIN Manufacture vitamin D KIDNEYS  Bean shaped, reddish brown. Located retroperitoneally between T12- L3 vertebral level. Size approx 10 x 6.5 x 3 cm. Weighs around 135-150 grams. Highly vascular organ. Receives 25 % of cardiac output.  FUNCTIONS OF KIDNEY ✓Regulation of the balance between water and electrolytes (inorganic ions) and the acid-base balance; ✓Excretion of metabolic wastes along with excess water and electrolytes in urine; ✓Excretion of many bioactive substances, including many drugs; ✓Secretion of renin, a protease important for regulation of blood pressure by cleaving circulating angiotensinogen to angiotensin I; ✓Secretion of erythropoietin,; ✓Conversion of the steroid prohormone vitamin D, initially produced in the skin, to the active form; ✓Gluconeogenesis during starvation, making glucose from amino acids to supplement this process in the liver.  CAPSULE Connective tissue capsule. OUTER LAYER – fibroblasts and collagen fibres Inner layer – MYOFIBROBLASTS MYOFIBROBLASTS resist volume and pressure variation that accompany variation in kidney function.  Each kidney has a thick outer CORTEX, surrounding a MEDULLA that is divided into 8 to 12 RENAL PYRAMIDS; each pyramid and its associated cortical tissue comprises a RENAL LOBE. THE APICAL PAPILLA of each renal pyramid inserts into a MINOR CALYX, a subdivision of two or three major calyces extending from the RENAL PELVIS.  The ureter carries urine from the renal pelvis and exits the RENAL HILUM, where the renal artery and vein are also located. Striations extending from the medulla into the cortex are called MEDULLARY RAYS; THESE PLUS THE ATTACHED CORTICAL TISSUE ARE CONSIDERED LOBULES. RENAL LOBE & LOBULE Cortical Labyrinth with interdigitating Medullary Rays KIDNEY (ORGANIZATION) P P RENAL LOBE P - a single pyramid with its associated P overlying cortex P RENAL LOBULE - defined within cortex and involves a P single medullary ray (central axis of P lobule) with adjacent cortical labyrinth - defined as a functional unit that consists of a collecting duct and all the nephrons that it drains  PAPILLA -- narrow, innermost tip of the pyramid CALYX -- each calyx is a division of the renal pelvis; opening into each calyx is the papilla of a pyramid. is an extension of the upper end of the ureter ✓ 90-95 % of blood passing through kidney is in cortex ✓ 5-10 % is in medulla  CORTEX MEDULLA MINOR CALYX CORTEX CALYX & MEDULLA RENAL PELVIS CAPSULE RENAL CORPUSCLE (GLOMERULUS) PROXIMAL TUBULE AND DISTAL TUBULE CORTEX MEDULLARY RAYS COLLECTING DUCTS MEDULLA CORTEX CAPSULA MEDULLARY RAY MEDULLARY RAY RENAL CORPUSCLES (GLOMERULES) MEDULLARY RAYS GLOMERULUS GLOMERULUS MEDULLARY RAY  BLOOD CIRCULATION THE RENAL ARTERIES transport oxygenated blood from the heart and aorta to kidneys for filtration THE RENAL VEINS Transport the filtered, deoxygenated blood from kidneys to the posterior vena cava and finally the heart  CORTEX RECEIVES OVER 10X MORE BLOOD SUPPLY THAN MEDULLA  BLOOD CIRCULATION RENAL CORTEX Interlobular artery Afferent arteriole Glomerular capillary Efferent arteriole Interlobular vein Peritubular capillary Arcuate artery Arcuate vein Vasa recta Interlobar artery Interlobar vein RENAL MEDULLA Segmental artery RENAL PELVIS Renal artery Renal vein START HERE END HERE 28 Blood Supply to the Nephron RETE MIRABILE ARTERIO-ARTERIAL rete mirabile artery-artery  THE NEPHRON  A nephron eliminates wastes from the body, regulates blood volume and blood pressure, controls levels of electrolytes and metabolites, and regulates blood pH. Its functions are vital to life and are regulated by the endocrine system by hormones such as antidiuretic hormone, aldosterone, and parathyroid hormone.  Histology of the Nephron & Collecting Duct Single layer of epithelial cells forms walls of entire tube Distinctive features due to function of each region – microvilli – cuboidal versus simple – hormone receptors 26-34  RENAL CORPUSCLE  RENAL CORPUSCLE GLOMERULI -surrounded by Bowman's capsules. BOWMAN'S CAPSULE - the capsule that surrounds the glomerulus. GLOMERULUS - a network of blood capillaries hided into Bowman's capsule.  GLOMERULUS GLOMERULUS BOWMAN'S CAPSULE  PROXIMAL TUBULE RENAL CORPUSCLE (GLOMERULUS) PARIETAL LAYER OF BOWMAN CAPSULE PODOCYTE'S NUCLEI CAPSULAR SPACE DISTAL TUBULE  BOWMAN'S CAPSULE Cells of the OUTER or PARIETAL layer of Bowman's capsule form a simple squamous epithelium. Cells of the INNER layer, podocytes in the visceral layer, are extremely complex in shape. Small foot-like processes, pedicles, of their cytoplasm form a fenestrated epithelium around the fenestrated capillaries of the glomerulus.  The openings between the pedicles are called FILTRATION SLITS. They are spanned by a thin membrane, the filtration slit membrane. Between the podocytes and the endothelial cells of the capillaries a relatively THICK BASAL LAMINA, which can be subdivided into an outer lamina externa, a middle lamina densa and an inner lamina interna.  The basal lamina and the slit membranes FORM THE GLOMERULAR FILTRATION BARRIER, which prevents some large molecules from entering the capsular space between the outer and inner epithelial layers of Bowman's capsule. Mesangial cells in the glomerulus form the connective tissue that gives structural support to podocytes and vessels. STRUCTURE OF RENAL CORPUSCLE GLOMERULUS THE PODOCYTES THE PODOCYTE THE PODOCYTE PEDICELS PEDICELS  BLOOD-URINE BARRIER - Filtration Membrane  FILTRATION SYSTEM OR A BARRIER: B A 1- FENESTRATED SECTION THROUGH CAPILLARY OF ENDOTHELIUM OF THE GLOMERULUS. GLOMERULUS B 2- GLOMERULAR BASEMENT MEMBRANE (GBM) 3- FILTRATION SLITS OF THE PODOCYTE 50 JUXTAGLOMERULAR APPARATUS JUXTAGLOMERULAR APPARATUS MACULA DENSA – portion of terminal distal straight tubule adjacent to renal corpuscle JUXTAGLOMERULAR CELLS – specialized smooth muscle cells of afferent arteriole which contain rennin in secretory granules EXTRAGLOMERULAR MESANGIAL CELLS OR LACIS CELL  JUXTAGLOMERULAR APPARATUS REGULATION OF BLOOD PRESSURE JUXTAGLOMERULAR CELLS –secreting RENIN in response to falling blood pressure MACULA DENSA –influences the increase or decrease of resorption of sodium ions, MESANGIAL CELL –LACIS CELL- secrete RENIN  MESANGIAL CELL SPECIALISED CELLS IN GLOMERULUS. ALSO ATTACHED TO CAPILLARIES SUPPORT CONTRACTION PHAGOCYTOSIS SECRETION  Histology of Renal Tubule & Collecting Duct  PROXIMAL CONVOLUTED TUBULE(P) – simple cuboidal with brush border of microvilli that increase surface area DESCENDING LIMB OF LOOP OF HENLE – simple squamous ASCENDING LIMB OF LOOP OF HENLE – simple cuboidal to low columnar (D) DISTAL CONVOLUTED & COLLECTING DUCTS – simple cuboidal composed of principal & intercalated cells which have microvilli  P D P D P P D  Proximal convoluted tubule： B A FUNCTION: A Transport majority (~65% to 67%) of B recovered water, ions, and glucose from the filtrate and added back to the blood. 59 LOOP OF HENLE  ANTIDIURETIC HORMONE (ADH) MAKES COLLECTING DUCTS MORE PERMEABLE TO WATER AND INCREASES THE RATE AT WHICH WATER MOLECULES ARE PULLED OSMOTICALLYFROM THE FILTRATE. ASCENDING LIMB ASCENDING LIMB  DISTAL CONVOLUTED TUBULE located within cortex contacts renal corpuscle at macula densa to form juxtaglomerular apparatus (below) morphology similar to straight portion function: ion exchange DISTAL CONVOLUTED TUBULE: Function: regulates Na+ , K + concentration, in a response to aldosterone secretion. 65  P D P P P D D  COLLECTING TUBULES (COLLECTING DUCTS)  The collecting system starts in the cortex as a continuation of the distal convoluted tubules and descend through the medulla  As the ducts coalesce and increase in size, the cells of the tubes change from somewhat squamous to cuboidal to columnar and similarly become increasing stratified  They terminate at the tip of the renal pyramid as the papillary ducts COLLECTING DUCTS: COLLECTING DUCTS Simple cuboidal/columnar epi. Function: resorbs Na+，H2O , transfers K+， regulated by aldosterone and ADH 69  COLLECTING TUBULE AND DUCT -Drain urine from nephron to renal pelvis. - Lie on medullary ray within cortex. - Progressively increase in diameter towards medulla. - Simple epithelium - Squamous to cuboidal. - Cell boundaries are seen Two types of cells in collecting tubule and collecting duct 1 ) Light cells 2 ) Dark cells  LIGHT CELLS - Collecting duct or CD cells - Principal cells of system - Pale staining cells - Basal infoldings present - Single primary cilium - Few short microvilli - Small, spherical mitochondria - Possess abundance of ADH regulated water channels AQP-2 responsible for water permeability of colllecting duct  Dark Cells Known as Intercalated Cells or IC cells. Less in number. Cytoplasm is denser. Many mitochondria. No basal infoldings. Basally located interdigitations with neighbouring cells. Numerous vesicles present in apical cytolplasm. Secretes Hydrogen(H+) or Bicarbonate(HCO3-) ions.  RENAL PAPILLA RENAL CALYX and RENAL PELVIS  RENAL PELVIS RENAL CALYX URETER  3 LAYERS IN WALL 1. TUNICA MUCOSA transitional epithelium & lamina propria since organ must inflate & deflate mucus prevents the cells from being contacted by urine 2. TUNICA MUSCULARIS inner longitudinal & outer circular smooth muscle layer –distal 1/3 has additional longitudinal layer peristalsis contributes to urine flow 3. TUNICA ADVENTITIA layer of loose connective tissue anchors in place contains lymphatics and blood vessels to supply ureter  TRANSITIONAL EPITHELIUM (UROTHELIUM) TUNICA MUSCULARIS TUNICA MUCOSA LUMEN TUNICA ADVENTITIA Transitional Epithelium TUNICA ADVENTITIA outer circular TUNICA MUSCULARIS inner longitudinal  inner longitudinal TUNICA MUSCULARIS outer circular TUNICA ADVENTITIA URINARY BLADDER  The wall consist of 4 layers: 1.TUNICA MUCOSA; lined by up to 14 cell layers of transitional epith that rests on lamina propria of loose c. tissue 2.TUNICA SUBMUCOSA; highly vascular and rich in elastic fibers 3. TUNICA MUSCULARIS; inner and outer longitudinal; middle circular layer of smooth muscles (dextruser muscles) 4. TUNICA SEROSA/ ADVENTITIA The longi muscles form sphincters at ureterovesical junction to prevent backflow of urine and at neck of bladder to regulate urine emptying TUNICA SUBMUCOSA TUNICA MUSCULARIS TUNICA MUCOSA Transitional epithelia changes depending on how full the urinary bladder is OUTER LONGITUDINAL MIDDLE CIRCULAR INNER LONGITUDINAL TUNICA MUSCULARIS Urethra  WALL OF URETHRA CONSIST 4 LAYERS: 1. TUNICA MUCOSA; epith. transitional but changes to stratified squamous at external urethral orifice 2. T. SUBMUCOSA; has cavernous tissue spaces that are typical of erectile tissue 3. T. MUSCULARIS; has inner and outer longi and middle layer of smooth muscles as in bladder but towards external urethral orifice, it acquires an external layer of skeletal muscle called striated urethralis muscle 4. T. SEROSA/ ADVENTITIA