Question

Which of the following is responsible for the normal brown colour of human stools?
A. Bilirubin
B. Hemoglobin
C. Insulin
D. None of the above

Answer 1

Hint: The characteristic brown colour present in human stools is due to the presence of various pigments produced in the body. Since the elimination of these pigments is through faeces, it takes up the characteristic colour of the pigments. Thus, the analysis of the colour of stools can be helpful in assessing the disorders associated with certain organs secreting these pigments.

Complete step by step answer: The human liver produces two pigments such as bilirubin and biliverdin which are produced as an end product by the degradation of haemoglobin. These pigments are yellowish-brown in colour, and being waste products of the breakdown pathway, they are also excreted out. The excretion of these pigments is through faeces or stools. Thus, imparting the characteristic brown colour to the stools is by bilirubin.
i. Hemoglobin is an iron-containing pigment, which imparts the characteristic red colour to the blood. The main function of these molecules is to transport gases, both oxygen and carbon dioxide. A low haemoglobin level can indicate anaemia.
ii. Insulin is a hormone secreted by the beta cells of the pancreas. This hormone helps in keeping the blood glucose levels within the normal range. It helps in facilitating reuptake of glucose and keeping the sugar levels normal. Any damage in the levels of insulin secreted results in a high blood sugar level leading to hyperglycemia.
Hence, the correct answer is option A.

Note: Any diseases or disorders of the liver causes an increase in the level of bile pigments. This can result in a condition known as jaundice, by which eventually these pigments get deposited in the eyes and beneath the skin giving it a yellowish appearance.