The kidneys do the major work of the urinary system. The other parts of the urinary system are mainly passageways and storage areas.
Functions of kidneys are as follows:
1. BLOOD IONIC COMPOSITION
The urinary system regulates the levels of certain ions like sodium ion, calcium ions and phosphate ions due to which the concentration of certain ions are increased or decreased due to which rate of elimination of urine is disturbed.
2. BLOOD pH
The urinary system excrete variable amount of hydrogen ions into urine and conserve bicarbonate ion which buffers hydrogen ion and regulates the blood pH thus regulating the kidney function.
3. BLOOD VOLUME
The kidneys adjust blood volume by conserving or eliminating water in urine. An increase in the level of blood volume increases blood pressure; a decrease in blood volume decrease blood pressure.
4. BLOOD PRESSURE
Blood pressure is regulated by the enzyme rennin, which activates the rennin-angiotensin-aldosterone pathways. Increase blood pressure is due to increase in production of rennin.
5. BLOOD OSMOLARITY
By regulating loss of water and loss of solutes in urine it maintains blood osmolality up to 300 million moles per liter.
6. PRODUCTION OF HORMONES
The urinary system produces two hormones calcitriol, the active form of vitamin D helping in regulating calcium homeostasis and erythropoietin stimulates the production of red blood cells.
7. REGULATION OF BLOOD GLUCOSE LEVEL
It helps in maintaining blood glucose level by synthesis of new glucose molecule by process of gluconeogenesis.
8. EXCREATION OF WASTES AND FOREIGN SUBSTANCES
By elimination of urine the harmful chemicals are excreted out of the body.