The Mechanical and Chemical Digestion of Chicken sandwich
The digestion process is one of the essential processes for the survival of living organisms. The sophisticated food particles need to be broken down into smaller units and absorbable nutrients (Goodman, 2010). Therefore, the process of digestion is divided into, i.e., the mechanical and the chemical that functions concurrently through the gastrointestinal tract (GI). The chicken sandwich is majorly composed of lipids, proteins, and carbohydrates; therefore, to break them down, it requires the GI organs to function collectively. In this process, crucial roles are played by organs such as the pancreas, gallbladder, and liver.
The mechanical process of digestion begins from the mouth where the food substance is ingested and physically broken down through the action of the teeth in the process known as mastication. Mastication increases surface area for enzymatic activities. The salivary glands secrete the salivary amylase, which breaks down starch into simpler sugars. The base of tongues also secretes lingual lipase, which acts on the lipids in the mouth though, it has a small impact. The tongue manipulates the food and mixes it with mucus to necessitate easy swallowing leading to the formation of the bolus.
The movement of bolus down the GI tract is done through the rhythmic contraction of wavelike muscles in the process referred to as peristalsis. The food enters the stomach, where it is temporarily stored for a few hours. Minimal activities are happening here; however, gastric amylase continues to digest carbohydrates into disaccharides, hydrochloric acid (HCL) activates pepsinogen into pepsin enzyme which acts on the proteins resulting into formation of peptides. In contrast, the gastric lipase breaks down specific lipids into fatty acids (Goodman,2010). The HCL also provides an acidic environment in the stomach that kills pathogens that might be present in the ingested foods.
The stomach contains the cardiac and pyloric sphincter, which regulates the movement of food. The chime is released into the small intestine through the opening of the pyloric sphincter. This is where almost all the digestion processes are completed, and most of the absorption occurs.
The roles played by different accessory organs.
The liver plays a crucial role in the digestive system. It secretes the bile juice and detoxification of harmful substances. The bile contains salts, acids, cholesterols, water, phospholipids, and electrolytes; its primary function is to act as an emulsifier. After emulsification, there is reabsorption and recycling of the bile salts in the liver in the process called enterohepatic circulation. Moreover, there is detoxification of toxic substances in the liver. Finally, it acts as a dynamic warehouse for the storage of vitamins, minerals, sugars, and hormones.
Bile is produced by the liver stored and concentrated in the gallbladder, located on the liver’s right underside. Besides this organ, another vital accessory organ is the pancreas, which performs exocrine and endocrine functions. The exocrine glands secrete trypsin and chymotrypsin enzymes, which digests proteins (Da Poian, 2010). The endocrine functions of the pancreatic juice are the production of two hormones; glucagon and insulin. These hormones help regulate blood sugar levels in the body. Therefore, these organs perform a very crucial role in the digestion process.
To perform all the mentioned activities above, the body requires a constant and sufficient supply of energy. The metabolic synthesis of ATP from ADH takes place in the mitochondria (oxidative phosphorylation) and the substrate-level phosphorylation (glycolysis) taking place in the cytoplasm (Klein, Cohn & Alpers, 2006). The foundation of the aerobic and anaerobic cellular respiration is glycolysis, which results in the conversion of glucose and pyruvate.
Generally, mechanical digestion leads to the physical breakdown of complex food substances into smaller units. In contrast, the chemical process involves the enzymatic actions secreted by different glands to aid in food digestion. The accessory organs such as the liver, gallbladder, and pancreas perform vital roles as mentioned above. All these processes require a supply of energy in order to take place.
References
Goodman, BE (2010). Insight into Digestion and Absorption of Major Nutrients in Humans. Advance in Physiology Education. doi:10.1152/advan.00094.2009
Da Poian, A.T., El-Bacha, T. & Luz, M. RMP (2010).Nutrient Utilization in Humans: Metabolism Pathways. Nature Education 3(9): 11
Klein, S., Cohn, S.M., Alpers, D.H. (2006). Alimentary tract in nutrition: Modern Nutrition in Health and Disease. 10th Ed. Philadelphia.