Urinary System PDF

URINARY SYSTEM Objectives: Identify parts and main functions of the renal system Anatomy and function of the Kidney Physiology of the Kidney: Filtration, Reabsorption and Secretion The ureters The urinary bladder The Urethra Parts and main functions of the renal system Function: remo...

URINARY SYSTEM Objectives: Identify parts and main functions of the renal system Anatomy and function of the Kidney Physiology of the Kidney: Filtration, Reabsorption and Secretion The ureters The urinary bladder The Urethra Parts and main functions of the renal system Function: removal of body waste from blood and excrete it in the form of yellow liquid or Urine. Anatomy of the Kidney: Renal cortex – outer region Renal medulla – inside the cortex Renal pelvis – inner collecting tube where the urine collects Medullary pyramids – triangular regions of tissue in the medulla contain the Nephrons Anatomy of the Kidney: Nephrons: The structural and functional units of the kidneys Each kidney has approximately 1 million nephrons Responsible for forming urine Main structures of the nephrons Glomerulus Renal tubule Glomerulus ❑Main function : blood Filtration ❑Glomerulus is A specialized capillary bed branched into an Afferent arteriole and an Efferent arteriole ❑Bowman’s capsule: collects liquid waste that is filtered out of the blood.  Water, sugar, salts and solutes smaller than proteins are forced through capillary walls Blood cells cannot pass out to the capillaries Filtrate is collected in the glomerular capsule and leaves via the renal tubule Renal Tubule Renal Tubule Two functions: Reabsorption and Secretion Most reabsorption occurs in the proximal convoluted tubule The peritubular capillaries reabsorb several materials Some water Glucose Salts and Ions (Na, HCO3 )  Secretion : takes additional molecules from the blood (waste) to be added to the filtrate, include: - Urea - Uric acid - Medications - H+ Ions ( to balance pH of the blood) Collecting Duct: - Urine enters the collecting duct - All collecting ducts transport urine to the Renal Pelvis.  Other functions for the kidney: Urine formation Excretion of waste products Regulation of electrolytes Regulation of acid-base balance (H+/ HCO3) Control of water balance Control Osmolarity or BP: The kidney secrets the hormone renin + The adrenal cortex also releases aldosterone Regulation of RBC production: The kidneys release erythropoietin that stimulates the bone marrow to produce RBCs Cont.: Other functions for the kidney: Synthesis the active form of vitamin D (Vitamin D is necessary for calcium balance and thus bone formation) Regulation of calcium and phosphorus balance Secretion of prostaglandins The Ureters: 1 ureter per kidney Long tubes of smooth muscles that connect each kidney to the bladder Enter bladder at an oblique angle to prevent flow blockage Propel urine toward bladder through peristalsis  The Urinary Bladder: Smooth muscular sac that temporarily stores urine until it is released. Anatomic capacity is (1.5-2)L Wall of the bladder contains four layers Adventitia—Outer layer/connective tissue Detrusor—smooth muscle Submucosal layer—loose connective tissue Mucosal lining—Inner layer/impermeable to water  The Urethra : Thin-walled tube that carries urine from the bladder to the outside of the body by peristalsis Release of urine is controlled by two sphincters: Internal urethral sphincter (involuntary) External urethral sphincter (voluntary)