Q. 21 - Biology

Question

Describe the structure of the kidney.

Step-by-Step Solution

Answer

The kidneys are the bean-shaped excretory organs of humans responsible for removing waste products and maintaining electrolyte balance in the body. 

Introduction

The kidneys are organs responsible for removing wastes from the body, maintaining electrolyte balance, and regulating blood volume. Humans have a pair of kidneys.

Explanation

The above image shows a cross-section of one of the kidneys to describe the structure of the kidney. The different parts of the kidney are described as follows:

1. Renal capsule: It is the transparent fibrous membrane that encloses the kidney to protect it from damage and maintain its bean-like shape. The renal fascia is a membrane made up of connective tissue that separates the perinephric fat from the paranephric fat.
2. Renal cortex: It contains important structures of the nephron such as Bowman's capsule, glomerulus, and proximal and distal convoluted tubules.
3. Renal medulla: It is the inner portion of the kidney that is split into renal pyramids. The medulla contains parts of the nephron such as the loop of Henle, vasa recta, and collecting duct. 
4. Minor and major calyces: The renal pyramids drain the urine into individual minor calyces which combine to form the major calyx that finally drains the urine into the renal pelvis.
5. Renal pelvis: It is a funnel-shaped cavity that collects urine produced by the nephrons and directs it into the ureter.
6. Ureter: It transfers the urine from the kidney to the urinary bladder.
7. Nephron: It is the basic structural unit of the kidney and each kidney contains millions of nephrons.
8. Renal artery: It carries oxygen-rich blood to the kidneys. It subdivides into several tiny blood vessels called afferent arterioles that deliver blood to each nephron.
9. Renal vein: It receives deoxygenated blood from the kidney and drains into the inferior vena cava.