1.) How does the food change in consistency and form?
Food changes consistency and form as it moves through the organs of the digestive system. When food is chewed and absorbed, the tongue and teeth begin the digestion process. Grain is lubricated with saliva, which starts chemical digestion, in which enzymes and other substances break down food into its simplest components. This begins in the mouth, where chewing mechanically breaks down food into smaller pieces, and saliva, which includes enzymes that aid in starch digestion, triggering a chemical process to prepare the meal for digestion.
More breakdown occurs when it reaches the stomach, where gastric acids turn proteins into chyme. Bile and pancreatic enzymes act on lipids, carbs, and proteins in the small intestine, converting them into absorbable molecules. The ileum absorbs nutrients and is covered with millions of finger-like projections called villi. The small intestinal walls absorb nutrients, while the large intestine absorbs water and electrolytes, and the leftover chyme hardens before becoming feces for defecation. The overall consistency and form of the food shift from a solid, complex structure to a liquid (chyme), and finally to a semi-solid known as feces, which is defecated out of the body.
2.) How could the body absorb the nutrients from the foods we eat?
Among the organs of the digestive system, the small intestine is primarily responsible for the process of nutrient absorption. It aids absorption by allowing enzymes to break down complicated compounds into simpler forms. To promote digestion, the small intestine's muscles combine food with digestive fluids from the pancreas, liver, and gut and push the mixture forward. Carbohydrates, proteins, and lipids are absorbed into the bloodstream through the lining of the small intestine and then supplied to the rest of the body by the blood. Absorbed nutrients are used for energy, growth, and homeostasis as they travel through the circulatory system.
References:
Tortora, G. J., & Derrickson, B. H. (2017). Tortora’s Principles of Anatomy & Physiology. Wiley.
Your digestive system. (2022, August 17). WebMD. https://www.webmd.com/heartburn-gerd/your-digestive-system
Your digestive system & How it works. (2023, February 28). National Institute of Diabetes and Digestive and Kidney Diseases. https://www.niddk.nih.gov/health-information/digestive-diseases/digestive-system-how-it-works