Activity 1
Answer the following questions:
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How does the food change in consistency and form?
Food changes in consistency and form as the digestive system breaks it down to absorb nutrients into the body. This is done through various mechanical and chemical processes and exposure to substances in the gastrointestinal tract which promote the change in the food’s overall appearance and composition. As food enters the mouth or oral cavity, it undergoes chewing (mechanical digestion) and hydrolysis (salivary enzyme-assisted digestion) to produce bolus–a ball-like mixture of food and saliva. Afterward, it is swallowed and passed through the esophagus until it reaches the stomach where it is subjected to further digestion such as churning, hydrolysis (gastric enzymes), and chemical digestion to make chyme–a thick and semifluid mixture of food and digestive secretions. It is then followed by the small intestine which involves hydrolysis (pancreatic enzymes and bile) and absorption of nutrients. It then proceeds into the large intestine or colon wherein it aids in the further absorption of water, ions, and vitamins. Afterwards, it ends up in the rectum which stores the waste products until it is ready to be released.
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How could the body absorb the nutrients from the foods we eat?
Absorption of nutrients in the body is mainly observed in the small and large intestines wherein its villi and microvilli absorb the nutrients of the digested food through diffusion. After the food is physically and chemically broken down into smaller molecules in the first half of the digestive process, it is then absorbed into the bloodstream and transported to the various cells and tissues in the body. Some examples of macronutrients or biomolecules absorbed in the body include carbohydrates, proteins, and lipids which all have unique processes in their digestion and absorption. Carbohydrates are digested by amylase which breaks them down into maltose and is absorbed into the bloodstream as glucose. Proteins are digested by gastric juices and pepsin which breaks them down into peptides and is absorbed into the bloodstream as amino acids. Lastly, lipids are digested by bile and pancreatic lipase which breaks down triglycerides and is absorbed into the bloodstream as fatty acids, monoglycerides, and glycerol.
Reference
Biga, L. M., Dawson, S., Harwell, A., Hopkins, R., Kaufmann, J., LeMaster, M., Matern, P., Morrison-Graham, K., Oja, K., Quick, D., Runyeon, J., OSU OERU, & OpenStax. (2019). Anatomy & Physiology (1st ed.) [Ebook]. OpenStax/Oregon State University. https://open.oregonstate.education/aandp/
khanacademymedicine. (2014, May 15). Meet the gastrointestinal tract! | Gastrointestinal system physiology | NCLEX-RN | Khan Academy [Video]. YouTube. https://www.youtube.com/watch?v=Oh_Pt_UrtEE
Tortora, G. J., & Derrickson, B. H. (2017). Tortora’s Principles of Anatomy & Physiology. Wiley.