Academic Presentation - The Urinary System PDF

THE URINARY SYSTEM Dr Anna Maceri School of Nursing and Midwifery  Important Copyright Notice for Western Sydney University Students The material in this presentation has been made available to you by and on behalf of Western Sydney University for your personal use and...

THE URINARY SYSTEM Dr Anna Maceri School of Nursing and Midwifery  Important Copyright Notice for Western Sydney University Students The material in this presentation has been made available to you by and on behalf of Western Sydney University for your personal use and study only. The material contained in this recorded lecture is subject to copyright protection. You may not make any further copies and share the recorded lectures in whole or in part by any hardcopy, digital and or online technologies.  The Urinary System Adrenal gland Renal vein Renal artery Kidney Aorta Ureter Rectum (cut) Uterus (part of female Urinary reproductive system) bladder Urethra  Functions Removal of wastes (eg. Urea, creatinine) Regulates water within the body Regulates the concentration of certain ions Regulates blood pH Production of hormone erythropoeitin for regulation of red blood cell production Conversion of Vit D to active form http://www.youtube.com/watch?v=zEpUQkQ-uKM The Kidney Renal Cortex Renal Medulla Renal Pelvis Major calyx Ureter Minor calyx Pyramid  The Nephron Bowmans capsule Efferent arteriole (exit) Renal glomerulus corpuscle Afferent arteriole (enter) Collecting duct 1. Renal corpuscle Glomerulus Glomerular capsule (Bowman’s capsule) Proximal Distal 2. Renal tubule convoluted convoluted PCT tubule tubule Loop of Henle DCT http://www.youtube.com/watch ?v=AfjUru7nTsk Loop of Henle  Urine Formation 1. Glomerular filtration – Solutes and fluid are forced out of the capillaries and into the capsule 2. Tubular reabsorption 1. Glomerular – Water and some solutes are filtration 2. Tubular returned back into the capillaries. reabsorption 3. Tubular secretion – Wastes, drugs and excess ions 3. Tubular are secreted into the renal tubule secretion from the capillaries.  Renal Corpuscle Glomerular filtration Efferent arteriole Solutes and fluid are forced Glomerular out of the capillaries and into capsule the capsule What substances are filtered into the filtrate? Water Glucose Afferent Amino acids arteriole Ions Nitrogenous wastes Proximal convoluted What substances are not tubule filtered into the filtrate? Glomerulus Blood cells Proteins (eg albumin)  Tubular reabsorption Proximal Convoluted Tubule – Water – Amino acids 100% – Glucose 100% – Ions (eg Na+) Loop of Henle – Descending- water only – Ascending- ions only; no water Distal Convoluted Tubule & Collecting Duct – Water and ions refined by hormones (eg PTH, ADH & aldosterone)  Urine Formation Please watch the following video about urine formation in the nephron: http://www.youtube.com/watch?v=vNvZaGcLzEo  Urine Clear to yellow in colour Urochrome (pigment from hemoglobin breakdown) Slight odour; Slightly acidic Specific gravity of 1.001 to 1.035 95% water 5% dissolved solutes – Main solute is urea (breakdown of amino acids) – Uric acid (breakdown of nucleic acids) – Creatinine (breakdown of creatinine phosphate found in muscle) – Na+ , K+ ,other ions  Hormonal Influence Aldosterone http://www.youtube.com/watch?v=PDE2qdS2ZvY ↓Blood pressure ↓ Renin (released by kidneys) + Angiotensinogen (produced by liver) ↓ Angiotensin I ↓ Converted into Angiotensin II (by ACE in lungs) ↓ ↑ Aldosterone secretion by adrenal cortex ↓ ↑ Na and H 0 reabsorption by DCT & CD of nephrons + secretion of K + 2 + ↓ ↑ Blood volume & BP  Hormonal Influence Antidiuretic hormone (ADH) Post pituitary gland Low BP (eg. dehydration) detected by receptors in hypothalamus Stimulates posterior pituitary to release ADH Influences collecting duct to increase H20 reabsorption Results in increased blood volume & BP Results in reduced urine production  Hormonal Influence Atrial Natiuretic Peptide (ANP) High Blood Volume and Blood Pressure Released by right atrium due to increased stretch caused by increased blood volume Inhibits Na2+ reabsorption more Na2+ remains in urine along with water Increases urine output Results in reducing BV and BP  Hormonal Influence Parathyroid hormone (PTH) Secreted by parathyroid gland Low blood Ca2+ levels stimulates secretion Acting on distal convoluted tubule Increases Ca2+ reabsorption back into the blood  Functions Erythropoeitin Low levels of oxygen in blood (hypoxia) are detected by kidney cells Stimulates release of erythropoeitin by kidney Stimulates red bone marrow to increase production of RBCs. Aims to increase oxygen being transporting by the RBCs by increasing the number of RBCs  Functions Vit D activation Sunlight stimulates Vit D precursor production in skin Kidneys convert inactive Vit D into active form that can be used by body Regulates Blood pH If acidic - H+ is secreted into filtrate and HCO3- reabsorbed into blood  Bladder & Urethra Bladder- Wall consists of layers of smooth muscle Wall stretches as bladder fills Contracts to expel urine into urethra Urethra- Longer in males Passes through prostate gland and penis Internal urethral sphincter (involuntary) located at base of bladder External urethral sphincter (voluntary) located in pelvic floor  Micturition 1. Bladder wall (detrusor muscle) contracts 2. Internal urethral sphincter relaxes & opens 3. External urethral sphincter relaxes & opens a) Stretch receptors detect stretch in bladder wall b) Afferent impulses to sacral region of spinal cord c) Detrusor contracts & internal urethral sphincter relaxes & opens d) Decreased impulses from somatic efferent neurons causes external urethral sphincter to relax and open e) Urine able to be expelled External urethral sphincter can remain contracted and closed by impulses from the brain to delay urinating to later  Across the life span..... Newborn voids 5-40 times/day Incontinence in infants is normal as nervous system is unable to control the external urethral sphincter By 24months toddlers begin toilet training as they begin to develop control of the external urethral sphincter  Across the life span..... 3% of elderly adults have normal kidney function Kidneys shrink Nephrons decrease in size and number Bladder shrinks in size and capacity (600 down to 250ml) Loss of bladder tone – increased frequency Incontinence  Across the life span..... Pregnancy-related changes Kidneys enlarge with increased blood flow – Increased glomerular filtration rate – Increased urine production Ureters become dilated and elongate – increased urine retention –risk of UTI Decreased bladder tone; capacity increases Increased urination THE END