Urinary or Excretory System : Components, Functions and Disorders

Urinary Diseases and Disorders:

Urinary diseases include mainly the diseases of the kidneys, ureter, urinary bladder and urethra.

Components of the urinary system:

The urinary system contains a pair of large excretory glands which are bean shaped kidneys, at the back of the abdomen in the lumbar region, two ureters, urinary bladder and urethra.

Kidneys are mainly concerned with the regulation of amount of water in the body. In humans, more than half of the body weight is water, most of it is present inside the cells, in blood and about 12 liters in tissue fluid.

Functions of the kidneys:

• The function of the kidneys is to remove the toxins and impurities from the blood by filtration.
• Kidneys control and regulate the blood pressure.
• It produces a hormone named erythropoietin, which controls the rate of formation of red blood cells in the bone marrow.
• The urine is excreted by the kidneys through the ureters which open into the urinary bladder and to outside through urethra.
• Some salts such as sodium, calcium, potassium, magnesium, chlorine and amino acids are reabsorbed into the blood.
• Some are thrown out through the urine in the form of phosphates, urea and uric acid.
• Kidneys maintain the water and electrolytic balance of the body.
• It also maintains the acid-base equilibrium of the blood.
• It retains the vital substances of our body like glucose, amino acids, bicarbonates, phosphates and proteins.
• Glucose is normally reabsorbed by the system completely by the prominent tubules.
• The kidneys excrete the waste products of metabolism and other toxic substances.
• The end products of metabolism are proteins, urea, uric acid, creatine, phosphates and sulphates.

When the kidneys fail to excrete these toxic substances like uric acid, they accumulate in the blood and results in uraemia.

A man with good health and in average conditions, passes about 1.5 liters of urine daily. It should not be less than 600 ml to carry out the waste products. Fear, depression and shivering increases the urine out put but it comes to normal. Except in diabetes insipidus patients, the urine out put will be normal in others.

Disorders of the Urinary System:

One normal kidney is enough to maintain good health and two kidneys can tolerate a good deal of damage. The symptoms of kidney damage are mild and vague and they can be known in the last stage only. If the kidneys fail to work, acidosis is developed and poisoning by waste products occur, if he is not treated.

The disorders of the urinary system may result due to:

• Hypertension
• Pyelitis (infection)
• Oedema (dropsy)
• Congenital defects
• Injuries
• Tuberculosis
• Bright’s diseases (nephritis)
• Stone formation
• Tumours