Chapter24 urinarymarieb
- 1. Ch 24: Urinary System Objectives Identify and describe the components of the urinary system and their function Describe the (histological) organization of the nephron Identify the blood vessels that supply blood to the nephrons Describe the blood flow through and around the nephron Developed by Trace a drop of filtrate as it becomes urine John Gallagher, MS, DVM
- 2. Functions of Urinary System (Kidneys): ● Regulate fluid balance (fluid volume) of the body ● Excrete organic waste products and conserve nutrients, etc Stabilize pH Regulate electrolyte concentrations in the blood Endocrine functions
- 3. Kidney Location •Lateral to vertebral column high on body wall, under floating ribs, in retroperitoneal position (posterior to the parietal peritoneum) •The right kidney is slightly inferior to the left kidney in order to accommodate the liver •Surrounded by the renal capsule with a fat pad •12 x 6 x 3 cm •Bean shaped •Hilus – indentation
- 4. Internal Anatomy Cortex: outer layer, light reddish brown, granular appearance (due to many corpuscles) Medulla: darker striped appearance (due to tubules) Subdivided into distinct renal pyramids, terminating with a papilla. Separated by renal columns from the cortex. Pelvis: Expanded proximal ureter Compare to Fig 23.3
- 6. Renal Circulation 20-25% of cardiac output!!
- 7. R L
- 8. Nephron = functional unit (p712) (>106/kidney) Nephron = 1. Renal Corpuscle 1. Glomerulus 2. Bowman’s (Renal) Capsule 2. PCT (proximal convoluted tubule) 3. LOH (loop of Henle) 4. DCT (distal convoluted tubule) 5. Collecting duct
- 10. The Renal Corpuscle Filtration: Passage across three barriers 1. Capillary endothelium Fenestrated What gets through? 2. Basement membrane 3. Glomerular epithelium (= visceral layer of Bowman’s capsule) slit pores between pedicles of podocytes Note: Capsular Epithelium is simple squamous epithelium
- 11. Juxtaglomerular (JG) Apparatus Juxtaglomerular Apparatus = Macula densa + Juxtaglomerular cells (smooth muscle fibers from afferent arteriole) Macula densa monitors NaCl and flow through the DCT JG cells produce renin and EPO
- 12. Blood Pressure
- 13. This diagram has an important inaccuracy!
- 14. This diagram has the same inaccuracy! Fig 24.7
- 15. This diagram is correct! The DCT passes by the afferent and efferent arterioles to form the JG apparatus
- 16. Two Types of Nephrons Fig 24.9 Cortical nephrons (85%) shorter, mostly in cortex of kidney, produce "standard" urine Juxtamedullary nephrons (15%), "juxta = next to" the medulla - responsive to ADH, can produce concentrated urine due to longer Loops of Henle
- 17. Urine collection: Collecting ducts within each renal papilla release urine into minor calyx → major calyx → renal pelvis → ureter
- 18. Ureters From kidney to bladder Enter the posterior bladder at an angle » Trigone Retroperitoneal Transitional Epithelium Nephroliths This is another inaccuracy!!
- 19. Nephrolithiasis (kidney stones) Occurs when urine becomes too concentrated and substances crystallize. Symptoms arise when stones begin to move down ureter causing intense pain. Kidney stones may form in the pelvis, calyces, or in the ureter. (Rarely in the bladder.)
- 20. Urinary Bladder Retroperitoneal, behind pubis Internal folds - rugae - permit expansion (max. holding capacity ~ 1L) Trigone - area at base delineated by openings of ureters and urethra - without muscle Internal urethral sphincter - involuntary sphincter
- 21. Urinary Bladder
- 22. Urinary Bladder Histology 1. transitional epithelium from renal pelvis to neck of urethra. 2. detrusor muscle – smooth muscle full bladder empty bladder
- 23. Urethra, Female External urethral sphincter – voluntary at pelvic floor 3-5 cm – from base of bladder to vestibule UTIs (esp. E.coli)
- 24. Urethra, Male Male – 18-20 cm 1. prostatic urethra – from base of bladder through prostate gland 2. membranous urethra – between prostate gland & base of penis 3. penile (spongy) urethra – traverses penis to orifice
- 25. Male vs. Female Fig 24.15
- 26. A drop of filtrate 1. Blood in the afferent 7. Collecting Duct arteriole goes to 8. Minor calyx 2. Glomerular capillaries 9. Major calyx 3. Podocytes 10. Renal Pelvis 4. Bowman’s Space 11. Ureter 5. PCT 12. Urinary Bladder 6. LOH 13. Urethra 7. DCT 1. Prostatic, membranous and penile in male
- 27. Kidneys may sustain 90% loss of nephrons and still not show apparent symptoms!!! 1/750 of population only have 1 kidney! Manneken Pis Fountain Brussels, 1619