Question

Which of the following is the correct path taken by urine in our body?
(a) Kidney $\rightarrow$ Ureters $\rightarrow$ Bladder $\rightarrow$ Urethra
(b) Kidney $\rightarrow$ Urethra $\rightarrow$ Bladder $\rightarrow$ Ureters
(c) Kidney $\rightarrow$ Bladder $\rightarrow$ Urethra $\rightarrow$ Ureters
(d) Kidney $\rightarrow$ Bladder $\rightarrow$ Ureters $\rightarrow$ Urethra

Answer 1

Hint: Filtration of blood through a system of fine tubules forms urine. It is a toxic metabolic nitrogenous waste that needs to be transported, stored temporarily, and finally pushed out of the body.

Complete step by step answer:
The excretory system performs the function of the removal of metabolic nitrogenous wastes from the body. It includes a pair of kidneys where urine is formed. This urine is carried by a pair of ureters from each kidney to the urinary bladder. The single urethra finally discharges urine from the body.

Additional Information:
Kidneys: The paired kidneys are bean-shaped and reddish-brown. The right kidney is slightly lower than the left kidney because the liver seizes considerable space on the side above the right kidney. Both the kidneys bear a notch known as hilum from which blood vessels, lymph vessels, nerves, and ureters enter or leave. It also secretes erythropoietin - a hormone to induce red blood cells’ production.
Ureter: They are paired, narrow, tubular structures that open into the urinary bladder. Ureters are composed of stratified transitional epithelium.
Urinary bladder: It is a pear-shaped muscular sac found in the pelvic cavity. It temporarily stores urine. Urine exerts pressure on the inner walls of the urinary bladder when its volume exceeds 200-400 mL. This activates the stretch receptors on the wall of the urinary bladder and urges a person to urinate.
Urethra: It is a canal-like structure that extends from the floor of the bladder to the exterior. The male urethra is much longer than the female urethra as it carries both urine and semen while the female urethra discharges only urine.
So, the correct answer is ‘Kidney $\rightarrow$ Ureters $\rightarrow$ Bladder $\rightarrow$ Urethra.’

Note: The opening of the urethra is controlled by specialized muscles known as sphincters. They are of two types: external sphincter and internal sphincter. The internal sphincter is involuntary which is present at the junction site of the urethra and urinary bladder. The external sphincter is present inferior to the internal sphincter. It is voluntary. Micturition or urination occurs via a combination of voluntary and involuntary muscle contractions.