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Composition of the Urinary System • Functions of the kidney 1. Removes nitrogenous wastes – – – – 2. 1. 2. – – 3. – Juxtaglomerular apparatus RAA system » Renin » Angiotensin » Aldosterone – 4. Occurs in proximal convoluted tubule Also occurs in distal convoluted tubule It takes things back into blood Secretion – Via blood filtration & formation of urine Occurs in renal corpuscle Reabsorption – Regulation of Blood Pressure – Filtration – Fluid balance Electrolyte balance Acid-base balance Excretory Organ – 4. Urine formation Maintains homeostasis – – – 3. Urea Uric acid Creatinine Ammonia • Occurs in distal convoluted tubule Blood gives things up to the urine Concentration – Occurs in collecting tubules See next slide URINE FORMATION The Filtration Membrane From the plasma to the capsular space, fluid passes through three barriers. foot processes fenestrated epithelium basement membrane 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. 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. GFR must be precisely controlled. a. If GFR is too high - increase in urine output - threat of dehydration and electrolyte depletion. b. 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. 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. 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. Diuresis refers to excretion of large amount of urine. Natriuresis refers to enhanced urinary excretion of sodium Hemodialysis artificially clearing wastes from the blood Urine Storage and Elimination The Ureters The ureters are muscular tubes leading from the renal pelvis to the lower bladder. The Urinary Bladder - is a muscular sac on the floor of the pelvic cavity. - is highly distensible and expands superiorly. The openings of the two ureters and the urethra mark a triangular area called the trigone on the bladder floor. The Urethra - conveys urine from the urinary bladder to the outside of the body. Females 3-4 cm greater risk of urinary tract infections male ~18 cm • 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 filtered urine remains urine; 99 % becomes reabsorbed back into blood – Oliguria = 100 - 400 cc per day – Anuria = less than 100 cc per day – Polyuria = diabetes, nerves, diuretics 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 Nephritis • Inflammation of the kidney (kidney infection) • Incontinence – involuntary urination 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 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. 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.