What is the structure of the renal corpuscle ?How does its structure contribute to the filtering of the blood?
The correct answer and explanation is :
Structure of the Renal Corpuscle
The renal corpuscle is the initial filtering unit of the nephron, located in the kidney’s cortex. It consists of two main components:
- Glomerulus – A network of capillaries where blood filtration occurs.
- Bowman’s Capsule – A double-layered structure that surrounds the glomerulus and collects the filtrate.
The glomerulus is supplied by the afferent arteriole and drained by the efferent arteriole, creating a high-pressure system that forces plasma and small molecules out of the blood into Bowman’s capsule. The capsule has two layers:
- Parietal layer (outer layer): Composed of simple squamous epithelium, providing structural support.
- Visceral layer (inner layer): Made of specialized cells called podocytes, which have foot-like projections (pedicels) that wrap around glomerular capillaries and form filtration slits.
How Its Structure Contributes to Blood Filtration
The renal corpuscle is designed for efficient filtration due to:
- High Glomerular Pressure – The difference in diameter between the afferent (wider) and efferent (narrower) arterioles increases pressure, promoting filtration.
- Filtration Membrane – Composed of:
- Fenestrated Endothelium: Capillary walls have pores allowing small molecules (water, ions, glucose, urea) to pass while preventing blood cells from escaping.
- Basement Membrane: A negatively charged layer that prevents large proteins from being filtered out.
- Filtration Slits of Podocytes: Further regulate what enters Bowman’s capsule, ensuring selective filtration.
- Selective Permeability – Only small solutes pass through while large molecules like proteins and cells remain in the blood, preventing loss of essential components.
Thus, the renal corpuscle ensures efficient, selective, and high-pressure filtration, forming glomerular filtrate, which later undergoes modification to form urine.