Kidneys:
They play a crucial role in excretion by removing urea and other nitrogenous wastes from the bloodstream. They also eliminate excess water, ions, hormones, and drugs from the body. Through the process of filtration, reabsorption, and secretion, the kidneys help maintain the body’s internal balance and regulate its composition.
The kidneys are solid, oval structures with a red-brown colouration, encased in a transparent membrane, and located at the back of the abdominal cavity.
Oxygenated blood is supplied to the kidneys through the renal artery, which branches off from the aorta.
Deoxygenated blood is carried away from the kidneys by the renal vein to the vena cava.
Each kidney is connected to the bladder in the lower abdomen by a tube called the ureter.
Microscopic Structure of Kidneys:
The kidney tissue is composed of numerous capillaries and tiny tubes known as renal tubules. When the kidney is sliced lengthwise, it reveals two distinct regions: the dark outer cortex and the lighter inner medulla. At the point where the ureter connects to the kidney, there is a cavity called the pelvis.
The renal artery branches into multiple arterioles and capillaries, primarily within the cortex. Each arteriole leads to a glomerulus, which is a network of capillaries enclosed by a cup-shaped structure called Bowman’s capsule. This capsule connects to a coiled renal tubule. The tubule then merges with a collecting duct, which travels through the medulla before emptying into the pelvis. The kidney cortex contains thousands of glomeruli, with a significant total surface area of their capillaries.
