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- a nitrogenous compound produced by metabolic processes in the body
- broken down from protein along with urea and ammonia
Primary function of kidneys
- excretion of waste products
- assist in regulating the body's water, electrolytes and acid-base balance
- lie behind the parietal peritoneum (retroperitoneal) just below the diaphragm on each side of the vertebral column
- dark red bean shaped
- 4-5inches (10-12cm) long, 2-3 inches (5-7.5 cm) wide and about 1 inch (2.5cm) thick
- right kidney is lower than left due to liver location
- functional unit of the kidney, resembling a microscopic funnel with a long stem and two convoluted sections
- responsible for filtering the blood and processing the urine.
- 3 major functions: controlling body fluid levels by selectively removing or retaining water, assisting with the regulation of the pH of the blood, and removing toxic waste from the blood
Hormonal influence on nephron function
when the body has suffered increased fluid loss through hemorrhage, diaphoresis, vomiting, diarrhea or other means, the blood pressure drops. This decreases amount of filtrate produced by the kidneys. The posterior pituitary gland releases antidiuretic hormone (ADH).
- antidiuretic hormone
- causes the cells of the distal convoluted tubules to increase their rate of water reabsorption returning water to the bloodstream which raises the blood pressure to a more normal level and causes urine to be concentrated.
Major functions of kidneys
- urine formation-glomerual filtration, tubular reabsorption and secretion: 1000-2000 mL of urine formed each day
- fluid and electrolyte control-maintain correct balance of fluid and electrolytes within a normal range by excretion, secretion, and reabsorption
- acid-base balance-maintain pH of blood (7.35-7.45) at normal range by directly excreting hydrogen ions and forming bicarbonate for buffering
- Excretion of waste products-direct removal of metabolic waste products contained in the glomerular filtrate
- blood pressure regulation-regulation of blood pressure by controlling the circulation volume and renin secretion
- RBC production-secretion of erythropoietin, which stimulates bone marrow to produce RBC's
- regulation of calcium-phosphate metabolism-regulation of vitamin D activation
Gross anatomical structure
- renal capsule-outer covering made up of a strong layer of connective tissue
- renal cortex-below renal capsule contains 1.25 million renal tubules which are part of the microscopic filtration system.
- medulla-dark color, contains triangular pyramids
- papillae-narrow part points of pyramids that empty urine into the calyces
- calyces-cuplike extensions of the renal pelvis that guide urine into the renal pelvis
- renal pelvis-an expansion of the upper end of the ureter
- ureter-delivers urine to the bladder
- Nephron-functional unit of the kidney, resembling a microscopic funnel with a long stem and two convoluted sections
- responsible for processing the urine
- 3 functions: 1-controlling body fluid levels by selectively removing or retaining water, 2) assisting with the regulation of the pH of the blood and 3) removing toxic waste from the blood
- body's entire blood is filtered 60 times a day
- Nephron consists of two main structures: the renal corpuscle and the renal tubule
- Renal corpuscle: composed of a tightly bound network of capillaries called the glomeruli that are held inside a cuplike structure, Bowman's capsule.
- Renal arteries: composed of R and L, branch off the abdominal aorta and enter the kidney at the hilus. The renal arteries continue branching until blood is delivered to the glomerules by the afferent arteriole.
- blood leaves the glomerulus through the efferent arteriole to the pertibular capillary
- blood finally reaches the renal veins and flows into the inferior vena cava
Three phases of urine formation and location
- 1) Filtration of water and blood products occurs in the glomerulus of Bowman's capsule.
- 2) Reabsorption of water, glucose and necessary ions back into the blood occurs primarily in the proximal convoluted tubules, Henle's loop, and the distal convoluted tubules. This process reclaims important substances needed by the body
- 3) Secretion of certain ions, nitrogenous waste products, and drugs occurs primarily in the distal convoluted tubule. This process is the reverse of reabsorption; the substances move from the blood to the filtrate
Urine composition and characteristics
- 1000-2000 mL a day produced
- mental, physical health, oral intake and blood pressure influence urine production
- 95% water, remainder is nitrogenous wastes and salts
- transparent yellow, caused by urochrome, a pigment resulting from the body's destruction of hemoglobine
- slightly acidic with pH of 4.6-8 and specific gravity of 1.003-1.030
- urinalysis can show if the body's homeostasis has been compromised with the spillage of certain substances
- Albumin-if present indicated possible renal disease, increased blood pressure, or toxicity of the kidney cells from heavy metals
- Glucose-(glycosuria) if present indicates a high blood glucose level. Blood glucose rises above the renal threshold, the point at which the renal tubules can no longer absorb and glucose spills into the urine
- Erythrocytes-(hematuria) in the urine may indicate infection, tumors, or renal disease. Occasionally an individual may have a renal calculus and irritation produces hematuria
- Ketone bodies-(ketoaciduria or ketonuria) occurs when to many fatty acids are oxidized. Seen with diabetes mellitus, starvation, or any other metabolic condition in which fats are rapidly catabolized.
- Leukocytes seen when infection is present.
- Two ureters
- Urine passes through from nephrons to lower part of urinary bladder
- 10-12 inches
- enter the bladder at ureterovesical junction
- mucous membrane folds as they enter bladder to prevent backflow of urine
- temporary storage pouch for urine
- composed of collapsible muscle
- located anterior to the small intestine and posterior to the symphysis pubis
- can be palpated in abdominal cavity as it fills
- can hold up to 750-1000mL of urine
- once bladder has 250mL of urine urge is felt due to stretch receptors becoming activated and a message sent to spinal cord
- two sphincter control the release of the urine-internal and external
- internal sphincter located at the bladder neck is composed of involuntary muscle and as the bladder becomes full and the stretch receptors cause contractions, pushing the urine past the internal sphincter composed of skeletal or voluntary muscle at the terminus of the urethra
- terminal portion of the urinary system
- small tube that carries urine by peristalsis from the bladder out of its external opening, the urinary meatus
Laboratory and diagnostic examinations
- Urinalysis: most common, may be done during assessments of other body systems, culture and sensitivity could be done
- Specific Gravity: measures hydration status and give information about the kidneys ability to concentrate urine. Decreased by high fluid intake, reduced renal concentrating ability, diabetes insipidus, and diuretic use. Increased in dehydration due to fever, diaphoresis, vomiting, diarrhea, and diabetes mellitus and inappropriate secreation of ADH. Values range 1.003-1.030
- Blood urea nitrogen: BUN, assesses the kidney's ability to rid the blood of nonprotein nitrogen (NPN) waste and urea, which result from protein breakdown. Range 10-20 mg/dL
- Blood creatinine: catabolic product of creatine used in skeletal muscle contraction. Creatinine as with BUN is excreted entirely by the kidneys and is therefore directly proportional to renal excretory function. Normal renal excretory function , the serum creatinine level should remain constant and normal. Elevation could be glomerulonephritis, pyelonephritis, acute tubular necrosis, and urinary obstruction. Test is uses to diagnose impaired kidney function. The creatinine level is affected little by dehydration, malnutrition or hepatic function. Range 0.5-1.1mg/dL male; 0.6-1.2 mg/dL female
- Creatinine clearance: creatinine is created during muscle contraction and then excreted by glomerular filtration. Related to muscle mass and pt avoids excessive physical activity prior to test. Ranges serum: 0.5-1.1 mg/dL female, 0.6-1.2 mg/dL male; urine 87-107 ml/min female, 107-139 mL/min male
- Prostate-Specific Antigen:PSAorganic specific glycoprotein produced by normal prostatic tissuerange-<4 ng/mLelevated levels result from prostate cancer, benign prostatic hypertrophy (BPH) and prostasis
- Osmolality: weight of the solute compared with its own weight. Results give information on the concentrating ability of the kidney
- Kidney-Ureter-Bladder radiography-assesses the general status of the abdomen and the size, structure and position of the urinary tract structures. May indicate tumors, calculi, glomerulonephritis, cysts and other conditions
- IV pyelogram or IV urography: evaluates structures of the urinary tract, filling of the renal pelvis with urine, and transport of urine via the ureters to the bladder. NPO 8 hrs prior to with light laxative. May indicate structural deviations, gydronephrosis, calculi within the urinary tract, polycystic renal disease, tumors and other conditions
- Retrograde pyelography- examination of lower urinary tract with a cystoscope under aseptic conditions.
- Voiding cystourethrography: with other tests detects abnormalities of the urinary bladder and the urethra. Indwelling catheter placed and dye injected to outline urinary bladder. Structural abnormalities, diverticula and reflux into ureter may be detected
- Endoscopic procedures: visual examination of hollow organs using a scope and light source. cystoscopy is a visual examination to inspect, treat or diagnose disorders of the urinary bladder and proximal structures. Patient is placed in lithotomy position.
- Renal angiography: evaluates blood supply to the kidneys, evaluates masses and detects possible complications after kidney transplant. A small radiopaque catheter into an artery and inject dye.
- Renal venogram: assesses kidney's venous drainage. Femoral vein catheter access.
- Computed Tomography: CT, differentiates masses of the kidney
- Magnetic Resonance Imaging: MRI, diagnoses of pathologic conditions of the renal system
- Renal scan: radionuclide tracer substance will be taken up by renal tubular cells or excreted by the glomerular filtrate injected IV. Images then taken
- Ultrasonography: use of sound waves to produce images of deep body structures. Visualize size, shape, and position of the kidney and delineate any irregularities in structure
- Transrectal ultrasound, renal biopsy, urodynamic studies
- Diuretics to enhance urinary output
- Thiazide Diuretics: act at the distal convoluted tubule to impair sodium and chloride reabsorption, leading to excretion of electrolytes and water. The thiazide diuretic chlorothiazide (Diuril) affects electrolytes to cause hypokalemia, hyponatremia, and /or hypercalcemia. Hypochloremic alkalosis occurs from a deficiency of chloride. Main uses are systemic edema and control of mild to moderate hypertension, although it may take a month to achieve the full antihypertensive effect. Chlorothiazide is contraindicated in anuria.
- Loop Diuretics: act primarily in the ascending Henle's loop to inhibit tubular reabsorption of sodium and chloride. Most potent of diuretics and may lead to significant electrolyte depletion. Lasix causes hypokalemia, hypochloremia, hyponatremia, hypocalcemia and/or hypomagnesia. Can cause hypochloremic alkalosis. Used in nephrotic syndrome, heart failure and pulmonary edema.
- Potassium-Sparing Diuretics: act on the distal convoluted tubule to inhibit sodium reabsorption and potassium secretion. The aldosterone antagonist spironolactone (Aldactone) blocks aldosterone in the distal tubule to promote potassium uptake in exchange for sodium secretion. Although it can be used in combination with other diuretics, primarily in the treatment hypertension and edema, spironolactone is most frequently used for its potassium-sparring quality.
- Osmotic Diuretics: act at the proximal convoluted tubule to increase plasma osmotic pressure, causing redistribution of fluid toward the circulatory vessels. Osmotic diuretics are used to manage edema, promote systemic diuresis in cerebral edema, decrease intraocular pressure, and improve kidney function in acute renal failure. The osmotic diuretic mannitol (osmitrol) increases osmolarity of glomerular filtrate; decreases reabsorption of water electrolytes; and increases urinary output, sodium and chloride, which actually has minimal effect on acid-base balance. Avoid extravasation (escape of the medication form the blood vessel into the tissues), which may lead to tissue irritation or necrosis.
- Nursing considerations: record daily morning weights, keep accurate I&O, document BP, HR and respirations 4x daily until medication is regulated and the vital signs stabilize. Assess BUN, serum electrolytes and urine. Avoid overuse of salt. Salt substitutes are contraindicated due to potassium effects. Need to add daily potassium sources (baked potatoes, apricots, bananas naval oranges). Serum levels of other medications may increase as a result of diuretic therapy.
Medications for UTI's
- 4 groups:
- Quinolone: NegGram (Nalidixic acid) treat UTI caused by gram negative microbes.
- Nitrofurantoin: (Macrodantin) effective against both gram positive and negative microbes
- Methanamine: (mandelamine) suppresses fungi and gram negative and positive organisms. Used with chronic UTI patients
- Fluroquinolone: Norfloxacin (Noroxin) broad spectrum antibiotic effective against gram positive and negative organisms. Used to treat UTI's, gonorrhea, gonococcal urethritis. Administered with glass of water 1 hour before or 2 hours after meals with antacids.
- a patient with stress incontinence can learn to control leakage by performing Kegal or pubococcygeal exercises that tighten the muscles of the perineal floor.
- develop awareness of the appropriate muscle group by trying to stop flow of urine during voiding.
- tighten muscles and hold for 10 seconds then relax for 10 seconds. groups of 10-20 4 times a day.
- could take 4-6 weeks to learn to control leakage.
- inability to void even with an urge to void.
- caused by stress, interference with the spincter muscles during surgery to the perineaum, occlusion of the urethra by calculi, infection or tumor; medication side effects or perineal trauma secondary to vaginal delivery.
- CM: bladder is distended and may be palpated above the symphysis pubis.
- ASS: Subj: c/o frequency with or without symptoms of burning, urgency, nocturia, and occasionally acute discomfort.OBJ: bladder distention, frequent voids, small amts, incontinence
- MM: catheter, surgical release of obstructions, administer analgesics and antispasmodics.
- NI: provide private, relaxed environment, bladder training, warm showers or sitz baths warm beverages. Residual urine checked