Memmler’s The Human Body in Health and Disease 11 th edition

1. Memmler’s The Human Body in Health and Disease11th edition “It does not matter how slowly you go as long as you do not stop.” Confucius Chapter 22 The Urinary System

2. Excretion Body systems work interdependently to maintain homeostasis by excretion • Urinary – urinate waste products • Digestive – defecate waste products • Respiratory – exhale waste products • Integumentary – perspiration of waste products

3. Organs of the Urinary System • Two kidneys • Two ureters • Single urinary bladder • Single urethra

4. Male urinary system, showing blood vessels.   What vessel supplies blood to the kidney? What vessel drains the kidney?

5. Kidney Activities • Excretion • Urea (nitrogen based waste) • Water balance maintenance • Body fluid acid–base regulation • Blood pressure regulation • Angiotensin • Aldosterone • Red blood cell production regulation via erythropoietin

6. Acid Base balance • Memmler page 455 • Buffer System – accept or release ions to maintain H+ balance in body fluids • Bicarbonate, phosphate, and protein buffers • Respiration – alteration in breathing rate to retain CO2 or exhale CO2 (binds with water to make carbonic acid); short term regulation • Kidney function – absorbing or eliminating H+ ions; long term regulation

7. Kidney Structure • Membranous renal capsule of fibrous connective tissue • Adipose capsule of fat • Fascia anchors kidney to peritoneum and abdominal wall • Located in the retroperitoneal space • Right kidney lower than left to accommodate liver • When have renal pain, it is noted as “flank pain”.

8. Blood Supply to the Kidney • Renal artery supplies blood to the kidney structures • Nephrons are functional units for filtration of blood to make glomerular filtrate • Afferent arteriole enters the glomerular knot of capillaries and exits the knot as the efferent arteriole which then becomes the peritubular capillaries • Renal vein drains blood from venous structures after the nephron complex

9. Kidney Organization • Hilum (also known as Hilus) on the medial convex aspect • Renal cortex (outer portion) contains the nephrons and convoluted tubules • Renal medulla (inner portion) • Renal pyramids contain Loop of Henle and collecting tubules • Renal pelvis • Calyces • Ureter

10. Question:The renal pelvis forms the upper end of what urinary structure? a. nephronb. ureterc. urethra

11. Answer:b. ureter

12. Longitudinal section through the kidney. Its internal structure is shown (left), along with an enlarged diagram of nephrons (right). Each kidney contains more than 1 million nephrons. 

13. The Nephron Functional kidney unit • Glomerular (Bowman) capsule • Afferent arteriole • Glomerulus • Efferent arteriole • Peritubular capillaries • Proximal convoluted tubule (PCT) • Nephron loop (Loop of Henle) • Descending limb • Ascending limb • Distal convoluted tube (DCT) • Collecting duct

14. A nephron and its blood supply. The nephron regulates the proportions of water, waste, and other materials according to the body’s constantly changing needs. Materials that enter the nephron can be returned to the blood through the surrounding capillaries.   Which of the two convoluted tubules is closer to the glomerular capsule? Which convoluted tubule is farther away?

15. Question:What vessel carries blood away from the glomerulus?a. afferent arterioleb. renal veinc. efferent arteriole

16. Answer:c. efferent arteriole

17. Formation of Urine - Step 1 • Blood flows through an afferent arteriole into the glomerular capillary knot within Bowman’s capsule • The higher hydrostatic pressure in the afferent arteriole causes filtration of products across the filtration membrane into the capsule • water, glucose, electrolytes, waste • The more concentrated plasma flows out the efferent arteriole and through the peritubular capillaries ready to reabsorb ingredients the body may need.

18. Formation of Urine Step 2 • The fluids and products filtered across the membrane become glomerular filtrate (early form of urine). • As the filtrate passes down the nephron into the proximal convoluted tubule, receptor sites will attach and reabsorb ingredients the body may wish to recycle. • Transport Maximum – the receptors are overloaded and stop recycling material IE glucose • This reabsorption may be via diffusion, osmosis, or active transport • These fluid changes may be affected by release of • Aldosterone • Antidiuretic Hormone

19. Formation of Urine Step 3 • Tubular secretion occurs in the distal convoluted tubules where H+ ions may be excreted from the capillaries to the urine in order to maintain pH balance of the body; certain medications are excreted in this manner. • Countercurrent mechanism • Concentration of urine • Antidiuretic hormone (ADH) makes the walls of the DCT more permeable so that more water may be reaborsed which concentrates the urine.

20. Checkpoint 22-8:The first step in urine formation is glomerular filtration. What is glomerular filtration?

21. Summary of urine formation in a nephron.

22. Checkpoint 22-9:What are the four processes involved in the formation of urine?

23. Control of Blood Pressure • Juxtaglomerular apparatus: Specialized cells that regulate kidney function • Triggered by low blood pressure and/or low sodium content in the filtrate • Secretes renin – an enzyme that converts inactive Angiotensinogen; ACE converts Angiotensin 1 into active Angiotensin 2; the effects of Angiotensin 2 are: • Vasoconstriction (raises blood pressure), • Thirst, promotion of the release of ADH and aldosterone (raises blood volume).

24. Structure of the juxtaglomerular (JG) apparatus. Note how the distal convoluted tubule contacts the afferent arteriole (right). Cells in these two structures make up the JG apparatus.   The JG apparatus is made up of cells from which two structures?

25. Checkpoint 22-10: What substance is produced by the JG apparatus and under what conditions is it produced?

26. The Ureters • Long, slender, muscular tubes • Epithelial cell lining • Involuntary muscle layer • Fibrous connective tissue coat • Entirely extraperitoneal • Extend from kidney to urinary bladder • Move urine by gravity and peristalsis

27. The Urinary Bladder Temporary reservoir for urine • Multiple layers • Mucous membrane • Transitional epithelium • Rugae • Connective tissue • Three-layered coat of involuntary muscle tissue • Incomplete coat of peritoneum • Trigone

28. The Urethra Tube that extends from the bladder to the outside • Male • Part of both reproductive and urinary systems • Female • Entirely separate from reproductive system

29. Urination Process of expelling urine from bladder (micturition) • Involuntary control • Internal urethral sphincter • Voluntary control • External urethral sphincter

30. The Urine • 95% water, 5% dissolved solids and gases • pH averages 6.0 • Specific gravity measures amount of dissolved substances in the urine • Normal range 1.002 to 1.040

31. Normal Constituents Dissolved solids normally found in urine • Nitrogenous waste products • Urea (Blood Urea Nitrogen – B.U.N. – elevation means urea is not being removed by the kidney signaling renal disease) • Uric acid • Creatinine • Electrolytes • Sodium chloride • Sulfates • Phosphates • Pigment

32. Abnormal Constituents Urinalysis is evaluation of urine • Glucose - Glycosuria • Albumin - Albuminuria • Blood - Hematuria • Ketones • Diabetes mellitus and starvation • White blood cells • Pyuria • Casts • Nephron disease

33. Question:Which of these is NOT a normal constituent of urine?a. creatinineb. albuminc. sodium chloride

34. Answer:b. albumin

35. Question:The amount of dissolved substances in urine is indicated by what measurement?a. dialysisb. turbidityc. specific gravity

36. Answer:c. specific gravity

37. Kidney Disorders Kidney disorders may be acute or chronic • Acute glomerulonephritis • Most common kidney disease • Pyelonephritis • Hydronephrosis • Polycystic kidney • Tumors • Kidney stones (calculi) • Renal failure • Leads to uremia, high levels of nitrogenous waste in the blood

38. Renal Dialysis and Kidney Transplantation • Dialysis • Hemodialysis • Peritoneal dialysis • Kidney transplantation • Final option for treatment of kidney failure

39. Disorders of the Ureters • Subdivision at renal pelvis • Constricted or abnormally narrow parts (strictures) • Renal ptosis – a dropped kidney (out of position) • Ureterocele – a sac of fluid at the end of the ureter in the bladder causing an obstruction • Ureteral stones (kidney calculi)

40. Checkpoint 22-14:What is the scientific name for stones, as may occur in the urinary tract?

41. Bladder Disorders • Rupture • Cystitis • Interstitial cystitis • Tumors • 90% arise from epithelial lining • If bladder removed (cystectomy), ureters diverted to part of ileum in an ileal conduit • Urinary incontinence • Stress incontinence • Urge incontinence • Overflow incontinence • Enuresis

42. Disorders of the Urethra • Congenital anomalies • Narrowing of opening or urethra itself • Presence of valve-like structure at junction of urethra and bladder • Hypospadias • Urethritis • Straddle injuries

43. The Effects of Aging • Loss of ability to concentrate urine • Decrease in number and size of nephrons • Increase in blood urea nitrogen (BUN) • Urinary infections • Prostate enlargement • Decreased bladder capacity • Incontinence