1. Human urinary system .

3. Structure of urinary system
It consist of these parts:
A) kidneys –these are bean shaped structure ,present just below the diaphragm .Each kidney is of 10 cm in length,5 cm in breadth and 3 cm in thickness and weight 150 gm.
B) Ureter- urine passes from kidneys into urinary bladder .
C) Urinary bladder- it is a pear shaped sac situated in lower abdominal cavity.
D) Urethra- it starts from lower part of urinary bladder and leads to exterior.

4. Urine formation
Urine formation takes place in kidneys .it involves these steps:
A) Filtration :impurities from blood are filtered
In kidneys and filtrate is formed ,which contains sodium ,calcium ,glucose ,amino acids ,along with urea ,ammonia and large amount of water
B) Reabsorption : some useful substances like Glucose ,some vitamins some water is reabsorbed and dilute urine is formed .
C) Secretion : it plays a minor role in urine formation . Substances like pigments and medicines are excreted by putting them into urine .

5. Kidneys
Kidneys are bean shaped organs that are located just below the rib cage .
Kidneys remove urea –waste product formed by the breakdown of proteins –from the blood through small filtering units called as nephrons .
Nephron is the functional unit of kidneys ,it consist of of blood vessels ----urea together with water and other waste products form the urine ,as it passes through nephrons .

6. Diseases related to kidneys
 kidney stones :are clumps of calcium oxalate that can be found anywhere in the urinary tract. Kidney stones form when chemicals in the urine become concentrated enough to form a solid mass, according to the Cleveland Clinic. They can cause pain in the back and sides, as well as blood in the urine. Many kidney stones can be treated with minimally invasive therapy.

7. Kidney failure
Kidney failure, also called renal failure and chronic kidney disease, can be a temporary (often acute) condition or can become a chronic condition resulting in the inability of the kidneys to filter waste from the blood. Other conditions, such as diabetes and hypertension, can cause chronic kidney disease However, renal disease may lead to chronic kidney failure, which may require dialysis treatments or even a kidney transplant.