Introduction: All the systems of our body work in coordination to carry out various metabolic process which involves the utilization of energy at the same time waste is produced.
e.g., water and CO2 are produced during respiration while fecal matter is produced through digestion.
⮚ The waste materials (mainly nitrogenous materials like ammonia, urea, uric acid etc.) are toxic to our body so it is essential to remove them from our body for which urinary system act as excretory system.
⮚ Removal of these substances need large amount of water available because water is utilized for conversion of nitrogenous waste materials in the form of urine while the necessary substances are reabsorbed back to maintain the fluidity. In this way the urinary system has a dual function that is
- Disposal of waste materials
- Maintaining osmoregulation.
Structure of urinary system:
⮚ It consists of
- pair of kidney
- pair of ureter
- pair of urinary bladder
⮚ Incase of females the urinary passage is called urinary aperture or urinary orifice but incase of male it is called urinogenital aperture.
⮚ There are a pair of kidneys are present which lying on the either side of vertebral column.
⮚ It is bean shaped and deep red in colour.
⮚ It is about 10 cm long, 5 cm wide and weighs about 127g incase of male it is slightly heavier that is 150 g.
⮚ The right kidney is slightly lower than the left kidney because it is pushed by the liver.
Internal structure of kidney:
⮚ The outer surface is having convex in appearance while the inner surface is concave in appearance.
⮚ Towards the concave surface there is a depression is present called hilum through which blood vessels, lymph vessels, nerves, ureters are enter and leave.
⮚ It is a protective covering of connective tissue called renal capsule which is made up of white fibrous tissue.
⮚ When we cut the kidney into longitudinal section then it forms a outer thick mass of tissue called cortex and a inner thin mass called medulla.
⮚ The cortex is a solid and uniform mass while medulla is turn into triangular or conical regions called medullary pyramid which collectively form major and minor calyx. Both these form a funnel like structure called renal pelvis.
⮚ The end of each pyramid called renal papillae that goes to the pelvis while cortex also extends towards the same region called renal column.
⮚ The substance of the renal medulla contain millions of excretory tubules called ‘Nephron’’ which is the structural and functional unit of kidney. Due to this the kidney performs the function of filtering out the nitrogenous waste materials out of the blood that passes through them.