Question

The total filtrate formed in 24 hours in human kidney is
A. 1.8 litres
B. 8.0 litres
C. 18 litres
D. 180 litres

Answer 1

Hint: The chief excretory organs of our body is the kidneys. There are two kidneys present in the body on either side of the spinal cord, below the ribs. The kidneys filter blood and excrete the substances that can be toxic to the body. Primary excretory products are urea, uric acid, carbon dioxide, and excess water. The kidney filters the entire amount of blood multiple times in a day.

Complete answer:
The kidneys are bean shaped excretory organs present on each side of the spine. They are composed of subunits called nephrons. The nephrons filter blood and excrete toxic substances like urea and uric acid.
The blood enters the nephron through the afferent arterioles that continue forward to form an arterial bed of capillaries called glomerulus. The glomerulus is surrounded by a capsule-like structure called the Bowman’s capsule. The Bowman’s capsule is connected to the renal tubules. The first part of the tubule is known as the Proximal Convoluted Tubule or PCT. It travels down to form the Loop of Henle which ascends upwards to form the Distal Convoluted Tubule or DCT. The DCT remains connected to the collecting tubule – a tube like structure that is common for many nephrons.
The glomerular filtration is the earliest step in urine formation. The blood enters the glomerulus through afferent arterioles and exits through the efferent arterioles. The afferent arterioles are larger in diameter than the efferent ones. This ensures that a hydrostatic pressure is always maintained within the glomerulus since the amount of blood entering exceeds the amount of blood leaving it. This creates an efficient filtration system. The process is also known as ultrafiltration since it can filter even minute particles present in the blood.
Glomerular Filtration rate is the amount of filtrate formed by the glomerulus per minute. The heart sends around 1 Litre blood to the kidneys every minute, which is processed by the glomerulus to form around 125 ml filtrate. Thus, it can be calculated to 180 litres of filtrate in 24 hours.

Hence, the correct answer is option (D).

Note: The kidneys filter blood to excrete toxic substances from the body. The excretory product is known as urine which is formed in the kidneys. The glomerulus of the nephrons initially filters blood to form a filtrate. The filtrate is then passed on to the tubules for further processing and converted to urine. The glomerulus is able to filter the entire volume of blood in the body multiple times in a day.