Structure of Nephron with Labelled Diagram and Functions

Structure of Nephron (Detailed Explanation)

The structure of nephron diagram can be divided into two main parts:

1. Renal Corpuscle (Filtration Unit)

• Located in the kidney cortex

• Composed of:

• Glomerulus: A network of capillaries where filtration begins

• Bowman’s Capsule: A cup-shaped structure that collects filtrate

The glomerulus filters blood, allowing water, glucose, ions, and small molecules to pass, while blocking large proteins and blood cells.

As described in detailed nephron studies , about 10–20% of plasma is filtered here, forming the initial filtrate.

2. Renal Tubule (Modification Unit)

This is a long tubular structure that converts filtrate into urine.

Parts of Nephron and Their Functions

1. Proximal Convoluted Tubule (PCT)

• Located in the cortex

• Highly coiled and lined with microvilli

• Major site of reabsorption

Reabsorbs:

• Glucose

• Amino acids

• Sodium ions

• Water

Contains many mitochondria for active transport

2. Loop of Henle

A U-shaped structure extending into the medulla

Descending Limb:

• Permeable to water

• Water moves out → filtrate becomes concentrated

Ascending Limb:

• Impermeable to water

• Ions move out → filtrate becomes dilute

Helps in concentration of urine and water balance

3. Distal Convoluted Tubule (DCT)

• Located in cortex

• Involved in selective secretion and absorption

Regulates:

• pH balance

• Electrolytes

• Blood pressure

Controlled by hormones like aldosterone and ADH

4. Collecting Duct

• Collects filtrate from multiple nephrons

• Final site of urine formation

Functions:

• Reabsorbs water (under ADH control)

• Concentrates urine

Presence of aquaporins allows water movement

Blood Supply of Nephron (Important for Exams)

Each nephron has a unique blood supply system:

1. Afferent Arteriole

• Brings blood into glomerulus

2. Glomerulus

• Site of filtration

• Contains fenestrated capillaries

Allows small molecules to pass but blocks proteins and RBCs

2. Efferent Arteriole

• Carries blood away from glomerulus

• Forms:

3. Peritubular Capillaries & Vasa Recta

• Surround tubules

• Help in reabsorption and secretion

This forms a portal system, unique in kidneys

Functions of Nephron (Core Concept)

The nephron performs three major processes:

1. Filtration

• Occurs in glomerulus

• Blood → filtrate

2. Reabsorption

• Useful substances reabsorbed into blood

3. Secretion

• Waste substances added to filtrate

These processes maintain:

• Water balance

• Ion concentration

• Blood pressure

Additional Functions of Nephron

Nephrons also help in:

• Regulation of blood pressure (Renin release)

• Production of red blood cells (via EPO)

• Activation of Vitamin D (calcitriol)

These are critical for overall body regulation

Kidney Diagram with Parts (Concept Clarity)

Key parts visible in a kidney diagram with parts:

• Cortex

• Medulla

• Renal pyramids

• Collecting ducts

• Ureter

Why is this Topic Important?

• Frequently asked in NEET and board exams

• Helps understand kidney disorders and urine formation

• Forms the base for topics like:

• Osmoregulation

• Excretion

• Hormonal control