Anatomy of Kidneys and Bladder - Urinary System Organs

1. Benjamin ChukwurahDoctory of Pharmacy CandidateClass of 2019 Anatomy of the Kidneys and Bladder

2. URINARY SYSTEM ORGANS • Kidneys (2) • Ureters (2) • Urinary bladder • Urethra

3. KIDNEY ANATOMY • Retroperitoneal • Partially protected by the 11th and 12th ribs • Right kidney slightly lower due to liver

6. KIDNEY ANATOMY • Protected by three connective tissue layers • Renal fascia • Attaches to abdominal wall • Adipose capsule • Fat cushioning kidney • Renal capsule • Fibrous sac • Protects from trauma and infection

8. KIDNEY ANATOMY Gross anatomy • Renal sinus • Renal parenchyma • Hilum

10. KIDNEY ANATOMY Renal sinus • Surrounded by renal parenchyma • Contains blood & lymph vessels, nerves, urine-collecting structures

11. KIDNEY ANATOMY Renal parenchyma • Glandular tissue • Forms urine • Two zones • Outer cortex • Inner medulla

12. KIDNEY ANATOMY Renal Flow • Renal columns divide medulla into 6 – 10 renalpyramids • The point of the pyramid is the renal papilla • Papilla is attached to the minor calyx

13. KIDNEY ANATOMY Renal Flow • 2 – 3 minor calices  Major calyx • 2 – 3 major calices  Renal pelvis • Renal pelvis  Ureter • Ureter  Bladder • Bladder  Urethra

15. Kidney Anatomy Renal Vasculature • Blood is supplied by the renal artery • Kidney receives about 21% of cardiac output

17. Nephron • The functional unit of a kidney • Filtration • Tubular reabsorption • Tubular secretion • ~1 million nephrons per kidney

18. Nephron • The nephron is partly in the renal cortex and partly in the renal medulla • Contains the following structures • Afferent/efferent arterioles • Glomerulus • Glomerular (Bowman’s) capsule • Renal tubule

21. Nephron Renal arterioles • Afferent arterioles bring in unfiltered blood into the kidney (renal corpuscle) • Efferent arterioles take filtered blood back into the body

22. Nephron Renal corpuscle • Glomerulus enclosed in two-layered glomerular capsule • “Bowman’s capsule” • Fluid filters from glomerular capillaries • “Glomerular filtrate” • Fluid collects in capsular space • Fluid flows into renal tubule

23. Nephron Glomerular filtration • Filtration membrane • Fenestrated endothelium of capillaries • Basement membrane of glomerulus • Slit membrane between “feet” of podocytes

25. Nephron Renal tubule • Leads from glomerular capsule • Ends at tip of medullary pyramid • ~3 cm long • Four major regions • Proximal convoluted tubule • Nephron loop (loop of Henle) • Distal convoluted tubule • Collecting duct

27. Renal Tubule Vasculature of tubule • Reclaim filtrate from renal tubule • Proximal and distal convoluted tubules • Peritubular capillaries • Loop of Henle • Vasa recta

28. Vasa Recta

29. Renal Tubule Proximal convoluted tubule (PCT) • Arises from glomerular capsule • Longest, most coiled region • Prominent microvilli • Function in absorption

30. Renal Tubule Nephron loop (Loop of Henle) • “U” – shaped, distal to PCT • Descending and ascending limbs • Thick segments • Active transport of salts • High metabolism, many mitochondria • Thin segments • Permeable to water • Low metabolism

31. Renal Tubule Distal convoluted tubule (DCT) • Coiled, distal to nephron loop • Shorter than PCT • Less coiled than PCT • Very few microvilli • Contacts afferent and efferent arterioles (regulation imparted)

32. Renal Tubules Collecting duct • DCTs of several nephrons empty into a collecting duct • Several collecting ducts merge into papillary duct • Drain into minor calyx

33. Juxtaglomerular Apparatus (JGA) • A group of cells found in the nephron which control renal function • Have three components • Macula densa • Granular cells • Mesangial cells

35. JGA Cells • Macula densa • Chemoreceptor cells, detect sodium chloride • Found on the DCT • Granular cells • Mechanoreceptor cells, detect pressure change • Found on afferent arterioles • Mesangial cells • Relay messages between macula densa and granular cells

36. The Ureters • The ureters are muscular tubes leading from the renal pelvis to the lower bladder.

37. The Urinary Bladder • A muscular sac on the floor of the pelvic cavity. • Contains the urine formed by the kidney. • Highly distensible and expands superiorly.

38. Bladder Anatomy • CAPACITY: • about 300 ml with a maximum capacity of 500 ml • Distended bladder is circular in shape • Bulges upward into abdominal cavity

39. Distended Empty

40. Bladder Anatomy The openings of the two ureters and the urethra mark a triangular area called the trigone on the bladder floor.

41. Bladder Muscles • Internal urethral sphincter • Round muscle that is under involuntary control • External urethral sphincter • Round muscle that is under voluntary control • Detrusor Muscle • The muscle that surrounds the bladder and aids in micturition.

43. The Urethra • Conveys urine from the urinary bladder to the outside of the body. • Male • ~18 cm long • Females • 3-4 cm long, puts women at greater risk of urinary tract infections

44. Urothelium • Transitional epithelium that can contract and expand to accommodate for organ size shift.