Question

Filtration of blood is done by
A) Ureters
B) Urinary bladder
C) Liver
D) Nephrons

Answer 1

Blood is a body fluid in humans and other animals that delivers necessary substances such as nutrients and oxygen to the cells and transports metabolic waste products away from those same cells Blood filtration is important to remove all the harmful toxins and excessive fluids from the blood therefore keeping it clean.

Complete answer:
Filtration of blood takes place in the kidney. About one quarter of the blood is filtered by the kidney. The functional units of the kidney are called Nephrons which form an integral part of the urinary system.
The blood is supplied to the kidney by the renal artery and this blood is filtered after which urine is produced. Each renal artery divides into segmental arteries supplying blood to the segments of the kidney. These arteries enter renal columns as interlobar arteries which further divide into arcuate arteries. Division of these arteries produce interlobular arteries which enter the renal cortex and form afferent arterioles.
One afferent arteriole is received by each Nephron which divides into a capillary network called glomerulus. Each kidney has about 1 million nephrons and they are connected together by connective tissue. Nephrons are composed of tubules and associated blood vessels. The tubular part of the nephron is hollow and filled with fluid.
There are two parts in a nephron:
i) Renal corpuscle (malpighian body) - filters blood plasma, and
ii) Renal tubule- The filtered fluid passes through it.

Let us analyse all the options to find the correct answer
Option A: Ureter is a duct through which urine exits from the kidney. Hence, this is an incorrect option.
Option B: The ureters drain the urine in the Urinary bladder which stores the urine. Hence, this is an incorrect option.
Option C: The main functions of liver are in digestion, storage and production of bile. Hence, this is an incorrect option.
Option D: Nephron is the functional unit of the kidney which is responsible for blood filtration. They are microscopic, tube like and help in removal of waste from the fluid. Hence, this is the correct option.

Thus, the correct answer is option (D) Nephrons.

Note:
i) Blood filtration is important to remove toxins and harmful substances.
ii) It helps in maintaining blood osmolarity.
iii) It helps in removing the end products of metabolism which are not required in the body.
iv) Kidney helps to regulate arterial blood pressure.