Composition of the Urinary System

1. Composition of the Urinary System

2. Functions of the kidney Removes nitrogenous wastes Urea Uric acid Creatinine Ammonia Maintains homeostasis Fluid balance Electrolyte balance Acid-base balance Excretory Organ Via blood filtration & formation of urine Regulation of Blood Pressure Juxtaglomerular apparatus RAA system Renin Angiotensin Aldosterone Urine formation Filtration Occurs in renal corpuscle Reabsorption Occurs in proximal convoluted tubule Also occurs in distal convoluted tubule It takes things back into blood Secretion Occurs in distal convoluted tubule Blood gives things up to the urine Concentration Occurs in collecting tubules See next slide

3. URINE FORMATION

4. The Filtration Membrane From the plasma to the capsular space, fluid passes through three barriers. foot processes fenestrated epithelium basement membrane

5. The Filtration Membrane Almost any molecule smaller than 3 nm can pass freely through the filtration membrane into the capsular space. These include: Water, electrolytes, glucose, amino acids, lipids, vitamins, and nitrogenous wastes Kidney infections and trauma commonly damage the filtration membrane and allow plasma proteins or blood cells to pass through.

6. Glomerular Filtration Rate (GFR) • is the amount of filtrate formed per minute by the two kidneys combined. • For the average adult male, GFR is about 125 ml/min. • This amounts to a rate of 180 L/day. • An average of 99% of the filtrate is reabsorbed, so that only 1-2 L of urine per day is excreted.

7. GFR must be precisely controlled. • If GFR is too high • - increase in urine output • - threat of dehydration and electrolyte depletion. • If GFR is too low • - insufficient excretion of wastes. • c. The only way to adjust GFR from moment to moment is to change glomerular blood pressure.

8. Urine Properties • Composition and Properties of Urine • Fresh urine is clear, containing no blood cells and little proteins. If cloudy, it could indicate the presence of bacteria, semen, blood, or menstrual fluid.

9. Urine Volume • An average adult produces 1-2 L of urine per day. • a. Excessive urine output is called polyuria. • b. Scanty urine output is oliguria. An output of less than 400 mL/day is insufficient to excrete toxic wastes.

10. Diuresis refers to excretion of large amount of urine. Natriuresis refers to enhanced urinary excretion of sodium

11. Hemodialysis artificially clearing wastes from the blood

12. Urine Storage and Elimination

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

14. The Urinary Bladder - is a muscular sac on the floor of the pelvic cavity. - is highly distensible and expands superiorly.

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

16. The Urethra - conveys urine from the urinary bladder to the outside of the body. Femalesmale 3-4 cm ~18 cm greater risk of urinary tract infections

17. Appearance Clear = normal Cloudy = ? Infection If sediment = kidney disease Dark = ?blood, ?bilirubin, ?concentrated Color Urochrome pigment = yellow comes from breakdown of hemoglobin Concentration More Concentrated = Deeper Yellow Change of Color From: Meds Vitamin = yellow Diseases Blood = red-brown Liver = Orange Foods Rhubarb = red-brown Odor Normal = ammonia-like smell from breakdown of urea Unpleasant = ? infection Quantity Average per 24 hours = 1500 cc 60 cc per hour GFR = 125 cc/min Thus, 7500 cc/ hour Urine Made Per Hour = 60 cc Urine GFR Per Hour = 7500 cc KEY: 1 % of filteredurineremains urine; 99 % becomes reabsorbed back into blood Oliguria = 100 - 400 cc per day Anuria = less than 100 cc per day Polyuria = diabetes, nerves, diuretics

18. Renal Calculi (Kidney Stones) • Made of crystals of calcium phosphate and uric acid • Gradually they get larger until they block ureters • First sym severe pain • Other sym nausea and vomiting, frequency, chills, fever, hematuria • Diagnosis by symptoms, ultrasound, or x-ray • Rx –increase fluids to flush out stone, medications, and if needed LITHOTRIPSY

19. Nephritis • Inflammation of the kidney (kidney infection) • Incontinence –involuntary urination

20. Cystitis • Inflammation of the mucous membrane lining of the urinary bladder • Most common cause – E.Coli • Sym- DYSUIA (painful urination) and frequency • Usually in females (shorter urethra) • Rx - antibiotics

21. Hematuria • Hematuria is the presence of red blood cells in the urine. Often, the urine appears normal to the naked eye, but In gross hematuria, the urine is red or the color of cola, which can be seen with the naked eye.

22. Urinary Tract Infection • What are urinary tract infections? • Urinary tract infections are a serious, but common, health problem that affects millions of people each year. With the reason remaining unclear, women are especially prone to urinary tract infections. • What causes urinary tract infections? • Normal urine is sterile and contains fluids, salts, and waste products. It is free of bacteria, viruses, and fungi. An infection occurs when microorganisms, usually bacteria from the digestive tract, cling to the opening of the urethra, the hollow tube that carries urine from the bladder to the outside of the body, and begin to multiply.