Question

Kidneys are vital organs for survival. Several factors like infections, injury or restricted blood flow to kidneys reduce the activity of kidneys. This leads to the accumulation of poisonous wastes in the body, which can even lead to death. In case of kidney failure, an artificial kidney can be used. An artificial kidney is a device to remove waste products from the blood through dialysis.

i. a. Name the artery that brings oxygenated blood to the kidney.

b. Name the cluster of the thin-walled blood capillaries present in the Bowman's capsule.

ii. In the human excretory system, name the organ which stores urine. Is this organ under hormonal control or nervous control?

iii. List two major steps involved in the formation of urine and state in brief their functions.

OR

iii. In which part of the nephron does selective reabsorption take place? List the factors which the amount of water reabsorbed depends on.

Answer 1

i. a. The artery that brings oxygenated blood to the kidney is the renal artery.

b. The cluster of thin-walled blood capillaries present in the Bowman's capsule is known as the glomerulus.

ii. The organ which stores urine in the human excretory system is the urinary bladder. This organ is under both hormonal and nervous control. Hormonally, it's influenced by antidiuretic hormone (ADH) that affects the volume of urine. Nervously, it's regulated by the autonomic nervous system that controls the bladder's need to expel urine.

iii. Two major steps involved in the formation of urine include:

• Filtration: Occurs in the glomeruli of the kidneys, where blood plasma is filtered into the Bowman's capsule, removing waste but retaining essential substances.
• Reabsorption and Secretion: Takes place in the renal tubules, where necessary nutrients and water are reabsorbed back into the bloodstream, and additional wastes are secreted into the tubular fluid to form urine.

OR

iii. Selective reabsorption in the nephron occurs primarily in the renal tubules, where substances like glucose, amino acids, salts, and a significant amount of water are reabsorbed from the initial filtrate. The amount of water reabsorbed depends on the body's excess water and the amount of dissolved waste to be excreted. Factors influencing the amount of water reabsorbed include the body's hydration levels and the concentration of waste substances in the blood, which need to be filtered out and excreted.