Activity 1. The Food Journey

OBCEMEA, Coleen Margaret P.

OBCEMEA, Coleen Margaret P.

by Coleen Margaret Obcemea -
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  1. How does the food change in consistency and form?

  • Food changes in consistency and form through digestion, wherein food breaks into smaller molecules throughout the alimentary canal. Beginning with mechanical digestion, mastication occurs with the help of the teeth, tongue, and salivary glands. Salivary amylase initiates starch digestion (chemical digestion), breaking starch into maltose. After being chewed and mixed with saliva, food is shaped into bolus, a small, flexible, easily swallowed mass, and forced into the pharynx. Muscle contractions and mucus from the esophagus then transport food into the stomach. Rounds of propulsion and retropulsion, together with gastric juices and other stomach secretions, form food into chyme, a soupy liquid. At appropriate intervals, small quantities of chyme enter the pyloric sphincter. Peristalsis further propels food into the small intestine, where segmentation, constriction, and nutrient absorption occur. The remaining debris at the end of the ileum enters the large intestine. Eventually, after remaining in the large intestine for 3-10 hours, chyme has become solid or semisolid due to water absorption and is now referred to as feces. Feces is expelled from the body through mass peristaltic movements that push it from the sigmoid colon into the rectum. 

 

  1. How could the body absorb the nutrients from the foods we eat? 

  • The small intestine absorbs 90% of nutrients and water, making it responsible for most digestion and nutrient absorption. The epithelial layer of the small intestinal mucosa consists of absorptive cells and microvilli that absorb nutrients from chyme and transport them into the bloodstream and lymphatic vessels. Absorption of nutrients occurs through the processes of diffusion, facilitated diffusion, osmosis, and active transport. The large intestine absorbs the undigested material or remaining nutrients, such as Vitamin K, ions, and water. 

Reference

Tortora, G. J., & Derrickson, B. (2017). Principles of Anatomy and Physiology (15th ed.). John Wiley & Sons, Inc.