Urinary system
Functions of the Kidneys:
1. Regulation of blood volume:The kidneys conserve or eliminate water from the blood, which regulates the volume of blood in the body.
2. Regulation of blood pressure:The kidneys regulate blood pressure in 3 ways, by:-
o Adjusting the volume of blood in the body (by regulating the quantity of water in the blood - see above),
o Adjusting the flow of blood both into, and out of, the kidneys, and
o Via the action of the enzyme renin. The kidneys secret renin, which activates the angiotensin-aldosterone pathway.
3. Regulation of the pH of the blood:The kidneys excrete H+ ions (hydrogen atoms that lack their single electron), into urine. At the same time, the kidneys also conserve bicarbonate ions (HCO3-), which are an important buffer of H+.
4. Regulation of the ionic composition of blood:The kidneys also regulate the quantties in the blood of the ions (charged particles) of several important substances. Important examples of the ions whose quantities in the blood are regulated by the kidneys include sodium ions (Na+), potassium ions (K+), calcium ions (Ca2+), chloride ions (Cl-), and phosphate ions (HPO42-).
5. Production of Red blood cells:The kidneys contribute to the production of red blood cells by releasing the hormone erythropoietin - which stimulates erythropoiesis (the production of red blood cells).
6. Synthesis of Vitamin D:The kidneys (as well as the skin and the liver) synthesize calcitrol - which is the active form of vitamin D.
7. Excretion of waste products and foreign substances:The kidneys help to excrete waste products and foreign substance from the body by forming urine (for release from the body).
Examples of waste products from metabolic reactions within the body include ammonia (from the breakdown of amino acids), bilirubin (from the breakdown of haemoglobin), and creatinine (from the breakdown of creatine phosphate in muscle fibres). Examples of foreign substances that may also be exceted in urine include pharmaceutical drugs and environmental toxins.
Examples of waste products from metabolic reactions within the body include ammonia (from the breakdown of amino acids), bilirubin (from the breakdown of haemoglobin), and creatinine (from the breakdown of creatine phosphate in muscle fibres). Examples of foreign substances that may also be exceted in urine include pharmaceutical drugs and environmental toxins.
Structure of nephron
DISORDERS OF URINARY SYSTEM
CYSTITIS
Cystitis causes irritation of the lining and the wall of the urinary bladder. It occurs due to bacterial infection or due to mechanical abrasion. Cystitis is characterized by bloody or cloudy urine and pain in the lower abdomen. The urine also emits an unpleasant odor. According to Medline Plus, a website of the National Institutes of Health, this condition affects more women than men. This is primarily due to the fact that the urethra of women is much shorter than that of men. Escherichia coli, also known as E. coli, bacterium primarily is responsible for this condition.
Nephritis
Inflammation of the kidney is medically termed "nephritis." Prolonged use of acetaminophen, nonsteroidal anti-inflammatory drugs (NSAIDs) and aspirin can sometimes result in nephritis. It can also be a side effect of other medications such as antibiotics. Symptoms of nephritis include protein in the urine, urine suppression and convulsion. In cases of chronic nephritis, there is a danger of the kidney being damaged permanently. According to the U.S. Centers for Disease Control and Prevention (CDC), nephritis accounted for approximately 45,000 deaths in the U.S. in 2008.
Enuresis
Enuresis is a condition in which a person has little control over urination. Loss of control over bladder muscles is the primary cause. Neurologic disease, weakening of the bladder due to childbirth, injury or bladder obstruction can cause enuresis. Other causes of enuresis include stress, hormonal and genetic factors, and urinary tract infections. Malfunctions in the spinal cord and small bladder can also lead to this condition. A urologist can treat and sometimes cure this disorder with medication or surgery.
Kidney Stones
Calcium oxalate salts and uric acid results in formation of deposits or stones in the kidneys. These stones have a nucleus which can harbor bacteria, foreign bodies or blood clumps. Intake of excess calcium leads to formation of kidney stones. These stones develop inside or near the kidney, the ureter or the bladder. Passing these stones through the ureter results in severe pain. In few cases, kidney stones need to be removed surgically.
Urethritis
Bacterial infection can lead to urethritis. This disease is more predominant in males than females. Urethritis is characterized by symptoms such as burning sensation while passing urine or semen during ejaculation. A discharge from the tip of the penis is also observed in some cases. Urethritis can be treated with antibiotics. It is a sexually transmitted disease, thus abstaining from unprotected sex will lower the risk of contracting
Blood in the urine is a symptom and not a disease. This could mean that there is the presence of a serious disease of the ureter, bladder, kidney, prostate gland, urethra, or any part of the genito-urinary system. Sometimes blood exists in the urine as a first indication of cancer of the kidney or bladder. Even kidney stones may cause bleeding. Certain respiratory infections, such as tuberculosis, also may contribute to blood in the urine
Pyelonephritis is generally called "pelvis nephritis" and refers to inflammation of the renal pelvis and connective tissues of the kidney. As with cystitis, pyelonephritis is usually caused by bacterial infection but can also result from viral infection, mycosis, calculi, tumors, pregnancy, and other conditions. Acute pyelonephritis develops rapidly and is characterized by chills, fever, pain in the sides (flank), nausea, and an urge to urinate frequently. This often is the result of the spread of infection from the lower urinary tract or through the blood from other organs. Chronic pyelonephritis is thought to be caused by an autoimmune disease but is often preceded by a bacterial infection or urinary blockage.
respiratory infections, such as tuberculosis, also may contribute to blood in the urine
Azoturia /az·o·tu·ria/ excess of urea or other nitrogenous compounds in the urine. Polyuria: The excessive passage of urine (at least 2.5 liters per day for an adult) resulting in profuse urination and urinary frequency (the need to urinate frequently).
Polyuria is a classic sign of diabetes mellitus that is under poor control or is not yet under treatment. Polyuria occurs in some other conditions such as:
· Nephrogenic diabetes insipidus -- a genetic disease
· Polycystic kidney disease -- another genetic disease
· Pyelonephritis -- infection of kidneys
· Amyloidosis -- deposits of a substance called amyloid in the kidney
· Sjogren syndrome, and
· Myeloma.
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· Uremia or uraemia is a term used to loosely describe the illness accompanying kidney failure (also called renal failure), in particular the nitrogenous waste products associated with the failure of this organ.[1]
· In kidney failure, urea and other waste products, which are normally excreted into the urine, are retained in the blood. Early symptoms include anorexia and lethargy, and late symptoms can include decreased mental acuity and coma. Other symptoms include fatigue, nausea, vomiting, cold, bone pain, itch, shortness of breath, and seizures. It is usually diagnosed in kidney dialysis patients when the glomerular filtration rate, a measure of kidney function, is below 50% of normal.[2]
· Azotemia is another word that refers to high levels of urea, but is used primarily when the abnormality can be measured chemically but is not yet so severe as to produce symptoms. Uremia can also result in fibrinous pericarditis. There are many dysfunctions caused by uremia affecting many systems of the body, such as blood (lower levels of erythropoietin), sex (lower levels of testosterone/estrogen) and bones (osteoporosis and metastatic calcifications
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