10.15 Lesson 15: Metabolism of Food: Absorptive State

Metabolic reactions depends on how recently someone has eaten. During the absorptive state (which alternates with the post-absorptive state), ingested nutrients enter the blood and lymph from the GI tract, and glucose is readily available for ATP production.
An average meal requires about 4 hours for complete absorption, and given three meals a day, the body spends about 12 hours of each day in the absorptive state (the other 12 hours, during late morning, late afternoon, and most of the evening, are spent in the post-absorptive state).
Hormones (such as insulin) are the major regulators of reactions during each state.
Several things typically happen during the absorptive state: – most body cells produce ATP by oxidizing glucose – glucose transported to the liver is converted to glycogen or triglycerides – most dietary lipids are stored in adipose tissue. – amino acids in liver cells are converted to carbohydrates, fats, and proteins.