Here is a sample journal entry describing the digestion and absorption of a fatty acid molecule:
Day 1
I begin my journey as a fatty acid molecule in a bowl of chips. When the chips are eaten, I am mixed with saliva in the mouth. Saliva contains amylase which begins to break down starches from the chips, but I am not affected at this stage. The bolus of food is swallowed and travels down the esophagus through peristalsis.
Day 2
I pass through the lower esophageal sphincter into the stomach. Gastric secretions containing hydrochloric acid and enzymes like lipase begin to break me down. The mechanical churning of the stomach muscles also helps to emulsify my fatty parts. Gastrin is released from the stomach walls to promote secretion of gastric juices for my digestion.
Day 3
The chyme containing my partially digested remains exits the stomach through the pyloric sphincter into the small intestine. Bile secreted by the liver and pancreatic enzymes enter the duodenum from the pancreas to help with my absorption. Lipase from the pancreas finishes hydrolyzing my fatty acid chains into fatty acids and glycerol that can be absorbed.
Day 4
I now travel along the small intestine where I encounter microvilli on the intestinal walls with absorption sites. My fatty acid and glycerol molecules are actively transported across the intestinal cells with the help of proteins and emulsifiers. Coenzyme A binds to my fatty acids to prepare them for use or storage.
Day 5
What remains of me passes through the large intestine with water reabsorption. Eventually I exit the body as part of the stool. My fatty parts have now been absorbed and will either be utilized for energy or stored as triglycerides in adipose tissue.