Question

Describe the major metabolic events that occur during the absorptive state following the breakfast which includes protein, fats and carbohydrates

Answer 1

The process which causes chemical and energy transformation of the food substances, is called metabolism. After digestion and absorption, the food is utilized by oxidative process in order to burn the carbohydrate, protein and fat to release the energy slowly and this process is called catabolism. Anabolism is the process where part of the released energy is utilized by the tissues for the physiological actions whereas rest of the energy is stored as rich energy phosphate bonds and in the form of carbohydrates, proteins and fats in the tissues. During adsorptive state, after the meal, anabolism occurs more than catabolism. Once the food is ingested through mouth, salivary amylase is secreted in order to digest carbohydrates. Carbohydrates break down in mouth, stomach and the intestine. Protein digestion occurs in stomach and small intestine whereas fat digestion starts from mouth due to the presence of lingual lipase followed by stomach and intestine. Carbohydrates are absorbed from small intestine as monosaccharides, proteins are absorbed from small intestine as amino acids and fats are absorbed as fatty acids from upper part of small intestine. From the small intestine after absorption carbohydrates, proteins and fats are transported across the intestine and enters the bloodstream and then they are taken up by lymph and tissues. The maximum time taken for absorptive state is 4 hours. Food uptake increases the blood glucose concentration stimulating beta cells of pancreas that release insulin in blood followed by glucose absorption of liver hepatocytes, adipose tissue and muscle cells. In the liver, glucose is converted to glycogen via intermediary glucose 6 phosphate in order to store glycogen in the liver. Amino acids are converted to ketone bodies and later it may be converted to acetyl CoA as per need. Amino acids can be utilized to form actin as well as myosin to rebuild muscle fibers. Excess lipids are stored in adipose tissues in order to increase fat reserve.

Carbohydrate metabolism :

Protein metabolism :

Lipid metabolism :