HUMAN EXCRETORY SYSTEM :



KIDNEYS :

The kidneys are bean-shaped organs that serve several essential regulatory roles in vertebrates. They are Located at the rear of the abdominal cavity in the retroperitoneal space, the kidneys receive blood from the paired renal arteries, and drain into the paired renal veins. Each kidney excretes urine into a ureter which empties into the bladder.They remove excess organic molecules from the blood, and it is by this action that their best-known function is performed: the removal of waste products of metabolism. Kidneys are essential to the urinary system and also serve homeostatic functions such as the regulation of electrolytes, maintenance of acid–base balance, and regulation of blood pressure (via maintaining the salt and water balance). They serve the body as a natural filter of the blood, and remove water-soluble wastes which are diverted to the bladder. In producing urine, the kidneys excrete wastes such as urea and ammonium. They are also responsible for the reabsorption of water, glucose, and amino acids. The kidneys also produce hormones including calcitriol and erythropoietin. An important enzyme renin is also produced in the kidneys which acts in negative feedback.

Renal physiology is the study of kidney function, while nephrology is the medical specialty concerned with kidney diseases. Diseases of the kidney are diverse, but individuals with kidney disease frequently display characteristic clinical features. Common clinical conditions involving the kidney include the nephritic and nephrotic syndromes, renal cysts, acute kidney injury, chronic kidney disease, urinary tract infection, nephrolithiasis, and urinary tract obstruction. Various cancers of the kidney exist. The most common adult renal cancer is renal cell carcinoma. Cancers, cysts, and some other renal conditions can be managed with removal of the kidney. This is known as nephrectomy. When renal function, measured by the glomerular filtration rate, is persistently poor, dialysis and kidney transplantation may be treatment options. Although they are not normally harmful, kidney stones can be extremely painful.

CONDITIONS OF KIDNEYS :

Pyelonephritis (infection of kidney pelvis)
Bacteria may infect the kidney, usually causing back pain and fever. A spread of bacteria from an untreated bladder infection is the most common cause of pyelonephritis.

Glomerulonephritis
An overactive immune system may attack the kidney, causing inflammation and some damage. Blood and protein in the urine are common problems that occur with glomerulonephritis. It can also result in kidney failure.

Kidney stones (nephrolithiasis): 
Minerals in urine form crystals (stones), which may grow large enough to block urine flow. It's considered one of the most painful conditions. Most kidney stones pass on their own but some are too large and need to be treated.

Nephrotic syndrome: 
Damage to the kidneys causes them to spill large amounts of protein into the urine. Leg swelling (edema) may be a symptom.

Polycystic kidney disease:
A genetic condition resulting in large cysts in both kidneys that impair their function.

Acute renal failure (kidney failure)
A sudden worsening in kidney function. Dehydration, a blockage in the urinary tract, or kidney damage can cause acute renal failure, which may be reversible.
Chronic renal failure: A permanent partial loss of kidney function. Diabetes and high blood pressure are the most common causes.

End stage renal disease (ESRD):
Complete loss of kidney function, usually due to progressive chronic kidney disease. People with ESRD require regular dialysis for survival.

Papillary necrosis
Severe damage to the kidneys can cause chunks of kidney tissue to break off internally and clog the kidneys. If untreated, the resulting damage can lead to total kidney failure.

Diabetic nephropathy: 
High blood sugar from diabetes progressively damages the kidneys, eventually causing chronic kidney disease. Protein in the urine (nephrotic syndrome) may also result.

Hypertensive nephropathy: 
Kidney damage caused by high blood pressure. Chronic renal failure may eventually result.
Kidney cancer: Renal cell carcinoma is the most common cancer affecting the kidney. Smoking is the most common cause of kidney cancer.

Interstitial nephritis: 
Inflammation of the connective tissue inside the kidney, often causing acute renal failure. Allergic reactions and drug side effects are the usual causes.

Minimal change disease:
A form of nephrotic syndrome in which kidney cells look almost normal under the microscope. The disease can cause significant leg swelling (edema). Steroids are used to treat minimal change disease.
Nephrogenic diabetes insipidus: 
The kidneys lose the ability to concentrate the urine, usually due to a drug reaction. Although it's rarely dangerous, diabetes insipidus causes constant thirst and frequent urination.

Renal cyst: 
A benign hollowed-out space in the kidney. Isolated kidney cysts occur in many normal people and almost never impair kidney function.

KIDNEY DISEASE: CAUSES :



Your kidneys may be small, but they perform many vital functions that help maintain your overall health, including filtering waste and excess fluids from your blood. Serious kidney disease may lead to complete kidney failure and the need for dialysis treatments or a kidney transplant to stay alive. While effective treatments are available for many kidney diseases, people are sometimes unaware that kidney disease can often be prevented. The following are the ten major causes of kidney disease.

In the United States the two leading causes of kidney failure, also called end stage kidney disease or ESRD, are diabetes (also called Type 2, or adult onset diabetes) and high blood pressure. When these two diseases are controlled by treatment, the associated kidney disease can often be prevented or slowed down.

Many effective drugs are available to treat high blood pressure. In addition, healthy lifestyle changes, such as losing weight and regular exercise, often help to control, and may even help to prevent, high blood pressure.

Careful control of blood sugar in diabetics helps to prevent such complications as kidney disease, coronary heart disease and stroke. When diabetics have associated high blood pressure, special drugs called angiotensin converting enzyme (ACE) inhibitors may help to protect their kidney function.

The third leading cause of end stage kidney disease in the U.S. is glomerulonephritis, a disease that damages the kidneys' filtering units, called the glomeruli. In many cases, the cause of this disease is not known, but some cases may be inherited and others may be triggered by an infection.

Some of the other diseases that may affect the kidneys include infections, kidney stones and inherited diseases such as polycystic kidney disease. The kidneys can also be damaged by overuse of some over-the-counter pain killers and by taking illegal drugs such as heroin. Some of these diseases can be cured. In other cases, treatments can help to slow the disease and prolong life.

End stage kidney disease occurs when about 90 percent of kidney function has been lost. People with kidney failure may experience nausea, vomiting, weakness, fatigue, confusion, difficulty concentrating and loss of appetite. It can be diagnosed by blood and urine tests.