URINARY SYSTEM.pptxkucicigiccigigigggigkgkg

Power point notes on the anatomy and physiology of the urinary system

1. URINARY SYSTEM By hermann tchaks

2. INTRO The urinary system is made up of 2kidneys,2 ureters ,1 bladder,1 urethra. Nephrology is the branch of medicine that studies the kidney . Urology is the branch of medicine that studies the urinary tract of both males and females and the male reproductive system.

3. Anatomy of the kidney They are paired reddish bean shaped retroperitoneal organs. The right kidney is slightly lower than the left one bc of the pressing of the liver on it.

4. Each kidney has a size of 12*6*3cm. On the concave side of the kidney is its hilum ; where the renal artery and vein , lymphatics and nerves enter and leave the Kidney. The kidney has main parts : An outer cortex An inner medulla

5. The medulla is made up of 8-18 renal pyramids . The renal pyramids drain into the minor calyces. The minor calyces then fuse from each other to give major calyces. The major calyces then join the renal pelvis wc is continuous with the ureter.

6. Urine excretion route Renal pyramids renal papilla minor calyces major calyces renal pelvis ureter bladder

7. VASCULARISATION OF THE KIDNEY The kidney receives abt 25% of CO

8. Nephron This is fxnal unit of the kidney & there are abt 1.2 million nephrons per kidney It consists of 5 parts; i . Renal corpuscule , ii. Proximal convulated tubule iii. Medullary loop (loop of Henle ) iv. Distal convulated tubule v. Collecting duct

9. Bowman’s capsule -It has a visceral and parietal layer. -The visceral layer containing modified epithelial cells called podocytes wc have extensions called pedicels that wrap arnd the glomerular capillaries formx filtration slits

10. -The parietal layer is formed by simple squamous epith . -The space btwn the visceral and parietal layer is the capsular space.

11. Proximal convulated tubule Made up of simple cuboidal cells with microvilli for absorption. Loop of henle Consists of a descending limb, a thin segment and a thick ascending limb.

12. DCT and CD The thick ascending limb ,DCT and CD have simple cuboidal epith with a few microvilli. Part of the DCT come in contact with e afferent arteriole.

13. At this point of contact btwn both, cells are columnar and form the macula densa . That part of the afferent arteriole has modified smooth cells called juxtaglomerular cells. These 2 form the juxtaglomerular apparatus.

14. Renal Physiology There are 3 basic processes involved: ultrafiltration Selective reabsorption Tubular secretion

15. Ultrafiltration Filtration is ensured by fenestrated capillaries and podocytes . Albumin and other plasma proteins do not pass through the filtration slits.

16. Filtration pressure Filtration pressure = glomerular capillary hydrostatic pressure – oncotic pressure – capsular pressure. Glomerular filtration rate is abt 120ml/min

17. Glomerular blood hydrostatic pressure It’s the BP in glomerular capillaries. It promotes filtration by forcing water and solutes in blood plasma through the filtration membrane. It is abt 55mmHg

18. Capsular hydrostatic pressure It’s the hydrostatic pressure exerted against the filtration membrane by fluid already in the capsular space and renal tubule. It opposes filtration and is abt 15mmHg

19. Colloid osmotic(Oncotic) Pressure It’s the pressure brought abt by the presence of proteins such as albumin, globulins, and fibrinogen in blood plasma. Also opposes filtration. Abt 30mmHg

20. Tubular reabsorption 99% of the filtrate is reabsorbed back into the blood. PCT 65% of the filtrate is reabsorbed here. Glucose and aa are reabsorbed here by active transport. 50% of excreted urea is reabsorbed here by simple diffusion.

21. At the Loop of henle The descending is permeable to H2O . The thick has Na+/K+/Cl- transporters.25% of filtered Na+ and K+ and 35% of Cl- is reabsorbed here. The DCT & CD They contain Na+/ Cl - symporters wc transport both ions by AT.

22. Tubular secretion

23. Tubular secretion As fluid flows along the renal tubule and through the collecting duct, the tubule and duct cells secrete other materials, such as wastes, drugs, and excess ions, into the fluid. NB Tubular secretion removes a substance from the blood unlike hormone secretion wherecells release substances into interstitial fluid and blood.

24. Hormonal control of secretion and reabsorption RAAS System ANP PTH

25. FUNCTIONS OF THE KIDNEY Gluconeogenesis Hormone synthesis (EPO, Calcitriol) Regulation of BP regulation of blood volume Excretion of waste Maintenance of osmolarity

26. Ureter They are 2 in number and are each 25cm long. They conduct urine from the renal pelvis to the bladder.

27. Bladder Hollow distensible muscular organ situated in the pelvic cavity posterior to the pubic symphysis . Its wall is made up of the detrusor muscle. Its carryx capacity is 700-800ml and d desire to urinate is felt as from 200-400ml.

28. Urethra It conducts urine from the bladder to the exterior. In males, it’s approx 16cm and in females it is 4cm long. NB Urination is stimulated by the paraØ system.