Question

1) What are the structural and functional units of the kidney?
2) Arrange the organs of the human excretory system in the correct order, based on the passage of urine.
Ureter, Urethra, Kidney, Urinary bladder.

Answer 1

Hint: Kidney is the part of the excretory system which leads to formation of urine. The urine formation is done by specialized structures present in the kidney. These are responsible for removing wastes from the body and absorption of useful substances such as glucose and amino acids.

Complete answer:
Kidney is the organ which is present in the excretory system. A kidney consists of millions of nephrons. These nephrons are the functional units of the kidney. It consists of following parts:
> Bowman capsule: It encloses glomerulus. Combining glomerulus and Bowman's capsule is known as Malphigian body. It is responsible for glomerular filtration. All constituents of the blood's plasma are filtered in this part except proteins.
> Proximal Convoluted tubule: It maintains the pH via secretion H+ ions, ammonia and potassium ions. Absorbs glucose and amino acids.
> Henle’s loop: It is responsible for concentrating the urine.
> Distal convoluted tubule: It leads to reabsorb sodium and water and secretes hydrogen potassium and ammonia ions.
1)Nephron is the answer.
Urine is produced in the nephrons in the kidney. Then this urine is transported to the urinary bladder via ureters. These ureters are two in number which arises from the kidney. Then under voluntary control, urine is passed to the urethra by the process of micturition. Then urethra excretes the urine outside the body.

2) Order is: Kidney 🡪 Ureter 🡪 Urinary bladder 🡪 Urethra.

Note: Kidney is one of the excretory organs in the human body. This organ is responsible for removing the wastes from the body in the form of urine. Excess of salts such as ammonium ions, potassium are excreted from the kidney. This function is achieved by the nephrons in the kidney which are found to be millions in number.