What is the primary driving force for filtration in the nephron?

• A. Glomerular hydrostatic pressure
• B. Peritubular capillary pressure
• C. Renal tubular secretion
• D. Osmotic pressure in the Bowman's capsule

Answer: (A)

Verified step by step guidance

1. Understand the process of filtration in the nephron: Filtration occurs in the glomerulus, where blood plasma is filtered into the Bowman's capsule. This process is driven by pressure gradients.
2. Identify the primary driving force for filtration: The glomerular hydrostatic pressure is the force exerted by the blood within the glomerular capillaries, pushing water and solutes out of the blood and into the Bowman's capsule.
3. Compare the other options: Peritubular capillary pressure is involved in reabsorption, not filtration. Renal tubular secretion refers to the active transport of substances into the tubular fluid, which is unrelated to filtration. Osmotic pressure in the Bowman's capsule opposes filtration rather than driving it.
4. Relate the concept to physiology: Glomerular hydrostatic pressure is maintained by the blood pressure in the afferent arteriole, which is higher than the pressure in the efferent arteriole, creating the necessary gradient for filtration.
5. Conclude the reasoning: Based on the physiological mechanisms, the primary driving force for filtration in the nephron is glomerular hydrostatic pressure.