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86 Cards in this Set
- Front
- Back
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What does the Urinary System consist of?
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Two kidneys, two ureters, one urinary bladder, and one urethra.
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Nephrology
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Branch of medicine that deals with structure, function, and diseases of the male and female urinary systems.
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Urology
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The branch of surgery related to male and female urinary systems.
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Kidneys contribute to homeostasis of body fluids by
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1) Regulation of blood ionic composition
2) Regulation of pH 3) Regulation of blood volume 4) Regulation of blood pressure 5) Regulation of blood glucose level 6) Maintenance of blood osmolarity 7) Producing hormones 8) Excreting wastes (urea, ammonia, bilirubin, creatinine, etc.) and foreign substances. |
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What kind of organs are the paired kidneys?
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Retroperitoneal organs.
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Hilum
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A vertical fissure near the center of the concave medial border of the kidney, through which the ureter leaves and blood vessels, lymphatic vessels, and nerves enter and exit.
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What do the kidneys internally consist of?
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Cortex, medulla, pyramids, papillae, calyces, and renal pelvis.
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What makes up the functional portion or parenchyma, of the kidney?
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The renal cortex and the renal pyramids.
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Blood supply of the kidneys
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Blood enters the kidney through the renal artery--> segmental artery-->--> arcuate artery--> --> afferent arteriole--> glomerulus--> efferent arteriole--> peritubular capillary-->--> renal vein.
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Nephrons
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The functional units of the kidney
GLomerulus: in the renal cortex. THe PCT, loop of Henle, DCT and collecting duct connect to each other in that order. Often the loop of Henle will go deep into the medulla. |
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Functions of the nephrons
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1) Filtration blood-->nephron
2) Reabsorption nephron-->blood 3) Secretion blood-->nephron |
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Renal tubule
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Consists of a proximal convoluted tubule (PCT)--> loop of Henle--> distal convoluted tubule (DCT).
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What do distal convoluted tubules of several nephrons drain into?
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A single collecting duct.
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What do many collecting ducts drain into?
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A small number of papillary ducts.
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The loop of Henle
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Nephron loop.
Consists of a descending limb--> a thin ascending limb--> a thick ascending limb. |
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Number of nephrons:
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Constant from birth.
Won't increase in number, but may increase in size. |
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What happens if one kidney is removed?
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The other nephrons in the other kidney will hypertrophy.
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What are the three basic processes that the nephrons and the collecting ducts perform while producing urine?
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1) Glomerular filtration.
2) Tubular reabsorption. 3) Tubular secretion. |
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What do these three processes allow the nephrons to do?
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Maintain homeostasis of blood.
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Glomerular filtrate
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The fluid that enters the capsular space
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The principle of filtration
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To force fluids and solutes though a membrane by pressure.
It is the same in glomerular capillaries as in capillaries elsewhere in the body. |
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What are the 3 features of the renal corpuscle that enhance its filtering capacity?
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1) Large surface area across which filtration can occur.
2) The thin and porous nature of the filtration membrane. 3) The high level of glomerular capillary blood pressure. |
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What determines Net Filtration Pressure
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Blood hydrostatic pressure (GBHP) and opposing blood colloid osmotic (BCOP) and capsular hydrostatic pressures (CHP).
NFP = GBHP - CHP -BCOP |
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Why is there edema in some kidney diseases?
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Damaged glomerular capillaries become so permeable that plasma proteins enter the filtrate, causing edema.
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Glomerular Filtration Rate
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The amount of filtrate formed by both kidneys per minute.
In a normal adult, it is about 125 ml.minute. This amounts to 180 liters per day. |
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How is GFR regulated?
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The mechanisms that regulate GFR adjust blood flow into and out of the glomerulus and alter the glomerular capillary surface area available for filtration.
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Renal autoregulation
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Rise in BP causes GFR to increase, causing the walls of the afferent (entering) arterioles to stretch, triggering a reflex constriction and decrease if GFR back to previous level.
The opposite happens when GFR fails. Special cells in the proximal convoluted tubule sense the GFR and there is negative auto feedback to control GFR. |
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Adrenergic sympathetic (ANS) fibers
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Cause constriction of afferent arterioles during sympathetic stimulation and reduce GFR.
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Hormonal regulation
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Angiotensin 2: Potent constrictor of afferent arterioles decrease GFR (Objective 5).
Arial natriuretic peptide (ANP): Secreted by atrial stretching (high blood volume). ANP increases GFR (thereby reducing blood volume). |
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Reabsorption
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Returns 99% of the filtered water and many of the filtered solutes to the bloodstream using both active and passive transport processes.
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Tubular secretion
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The transfer of materials from the blood and tubule cells into tubular fluid, helps control blood pH and helps eliminate waste substances from the body.
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Solute reabsorption drives
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Water reabsorption
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What are the three processes of reabsorption and secretion?
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1) Diffusion
2) Active transport: The enrgy derived from ATP is used to "pump" a substance across a membrane. Symporters and antiporters actively add or remove. 3) Osmosis: mechanism for water reabsorption by the renal tubule & collecting duct. |
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Reabsorption in the PCT
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The majority of solute and water reabsorption from filtered fluid occurs in the proximal convoluted tubules and most absorptive processes involve Na+.
PCT Na+ transporters promote reabsorption of 100% of most organic solutes, such as glucose and amino acids. 80-90% of bicarbonate ions. 65% of water, Na+, and K+. 50% of Cl-. And a variable amount of Ca2+, MG2+, and HPO4^-2. |
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Source of urea & ammonia
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The deamination of amino acids in the liver, both are toxic.
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Where and how are urea and ammonia filtered in the blood?
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Both are filtered at the glomerulus and secreted by the proximal convoluted tubule cells into the tubular fluid.
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What promote secretion of H+?
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Na+/H+ antiporters.
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What does the Loop of Henle do to Na+, Cl- and K+?
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Reclaims the ions from the tubular lumen fluid.
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What happens to Na+ and K+ in the collecting duct?
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Na+ goes into the blood and K+ goes into the urine.
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What happens in the Distal Convoluted Tubule?
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Major site where parathyroid hormone (PTH) stimulates reabsorption of Ca2.
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Angiotensin 2
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Triggered by low BP.
It increases blood volume and blood pressure, decreasing the GFR, by increasing Na+ reabsorption in the PC. Major regulator of electrolyte reabsorption and secretion. |
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Aldosterone
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Same as angiotensin2, especially regulating Na+ and K+ balance.
Also increases reabsorption of water in the collecting duct. Secreted by adrenal cortex in response to increase in angiotensin 2. |
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Antidiuretic hormone
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Released by posterior pituitary.
It regulates water reabsorption by increasing the water permeability of cells. Does NOT directly change GFR. |
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Atrial natriuretic peptide
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Released by stretching of atria (heart).
It can inhibit both water and electrolyte reabsorption. Ex: Increase urine output and therefore decrease blood volume. |
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What does the rate at which water is lost from the body depend on?
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Mainly on ADH, which controls water permeability of principal cells in the collecting duct (and in the last portion of the distal convoluted tubule). Osmolarity in PCT is 300 (same as plasma).
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Where does osmolality increase?
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In the descending loop of Henle. (Medulla concentrated)
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Where is solute removed, but H2O not removed?
And what does that cause? |
In the ascending loop of Henle.
This causes filtrated to DCT to have decrease osmolarity (<80). |
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What happens if ADH is not present?
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Dilute urine excreted.
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What happens if ADH is present?
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H2O diffuses out of urine and it concentrates. THis conserves water.
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What does Urea recycling cause?
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A build up of urea in the renal medulla maintaining a high osmolarity.
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Diuretics
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Drugs increase urine flow rate. THey whorl by a variety of mechanisms.
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Urinalysis
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An analysis of the volume and physical, chemical, and microscopic properties of urine. It reveals much about the state of the body.
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Renal plasma clearance
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Expresses how effectively the kidneys remove/ clear a substance from blood plasma. It is most important for determining renal function and drug dosages.
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Dialysis
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The separation of large solutes from smaller ones through use of a selectively permeable membrane.
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Hemodialysis
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Filtering blood through an artificial kidney machine that filters the blood of wastes and adds nutrients.
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What does urine go through to get to the urethra?
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Drains through papillary ducts--> minor calyces, which joint to become major calyces that unite to form the renal pelvis.
From the renal pelvis, urine drains--> ureters and then --> the urinary bladder. And finally, out of the body by way of the urethra. |
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Ureters
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Transport urine from the renal pelvis to the urinary bladder, primarily by peristalsis, but hydrostatic pressure and gravity also contribute.
Each of the two ureters connects the renal pelvis of one kidney to the urinary bladder. |
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Urinary bladder
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Hollow muscular organ situated in the pelvic cavity posterior to the pubic symphysis. The wall contains the detrusor muscle, which consists of three layers of smooth muscle tissue.
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Internal urethral sphincter
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Near the opening to the urethra, composed of circular fibers of the muscularis. Involuntary.
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External urethral sphincter
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Below the internal sphincter, composed of skeletal, voluntary, muscle.
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Micturition Reflex
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Urine is expelled from the urinary bladder (urination or voiding).
When the volume of urine in the bladder reaches a certain amount (usually 200-400ml), stretch receptors in the urinary bladder wall transmit impulses that initiate a spinal micturition reflex. |
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Urethra
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The urethra is a tube leading from the floor to the urinary to the exterior.
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The function of the urethra
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To discharge urine from the body.
The male urethra also serves as the duct for ejaculation of semen (reproductive fluid). |
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Incontinence
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A lack of voluntary control over micturition.
Failure to void urine completely or normally is termed retention. |
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How does blood contribute to waste management?
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Transports wastes.
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How does the liver contribute to waste management?
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The primary site for metabolic recycling.
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How do the lungs contribute to waste management?
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Excrete CO2, H2O and heat.
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How do the sweat glands contribute to waste management?
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Eliminate excess heat, water, and CO2-plus small quantities of salts and urea.
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How does the GI tract contribute to waste management?
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Eliminates solid, undigested foods, waste some CO2, H2O, salts and heat.
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What do the kidneys develop from?
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Mesoderm
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After age 40 what happens to the kidney function and why?
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THe effectiveness of kidney function begins to decrease because they shrink.
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By what percentage does the renal blood flow and filtration decrease?
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50%
20 yr old: 260 g 80 yr old: 200 g. |
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Nocturia
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Decrease need to urinate at night.
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Dysruia
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Painful urination
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Retention
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Inability to completely empty the bladder.
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Hematuria
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Blood in the urine. usually microscopic.
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Kidney stones
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Crystals of calcium type molecules in urine can precipitate and solidify. They may block the ureters and can sometimes be removed by shock wave lithotripsy.
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Urinary tract Infection
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Either an infection of part of the urinary system or the presence of large numbers of microbe in urine.
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Chronic renal failure
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A progressive and generally irreversible decline in glomerular filtration rate.
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Polycystic kidney disease
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One of the most common inherited disorder.
In infants it results in death at birth or shortly thereafter. In adults, it accounts for 6-2% of kidney transplantations. The kidney tubules become riddled with hundreds or thousands of cysts, and inappropriate apoptosis of cells in noncystic tubules leads to progressive impairment of renal function and eventually renal failure. |
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Azotemia
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Presents of urea or other nitrogen-containing substances in the blood.
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Enuresis
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Involuntary voiding of urine after the age at which voluntary control has typically been attained.
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Hydronephrosis
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Swelling of the kidney due to dilation of the renal pelvis and calyces as a result of an obstruction to the flow of urine.
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Nocturnal enuresis
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Discharge of urine during sleep, resulting in bed-wetting, occurs in about 15% of 5-year olds, and generally resolves spontaneously, afflicting only about 1% of adults. May have a genetic component, but also has several different causes.
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Polyuria
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Excessive urine formation.
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Uremia
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Toxic levels of urea in the blood resulting from severe malfunction of the kidneys.
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