- The role of the stomach is to act as the storage for food and allow its slow release into the small intestine at intervals. Also, it allows food churning which helps break the food into smaller particles for easier for digestion. It is also a site of absorption of some foods. The liver serves to regulate the amount of blood components that circulate in peripheral blood. This includes the regulation of blood concentration of glucose and lipids after digestion. It also secretes bile which is important in the digestion of fats in diet. Salivary glands produce saliva which helps in food lubrication for easier swallowing. They also produce the enzyme amylase which helps in the digestion of carbohydrates in the mouth before the food is swallowed. The small intestine is the region where most of the digestion process takes place and forms the main region of nutrient absorption after the digestion is complete. It also secretes some hormones that are important in digestion of fats and carbohydrates.
The gallbladder acts as the site of storage of the bile that is secreted by the liver. This bile is important for the digestion of fats in the meals. If the stomach is damaged or dysfunctional, it can result in vitamin B12 deficiency because the stomach produces the intrinsic factor important for its absorption leading to anemia. Also, the digestion of proteins will be affected which may result in malnutrition because of lack of essential hormones like renin. Dysfunction of the liver can result the person passing feces with a lot of fats since the bile needed for their digestion will be missing. Also, the patient will be hyperglycemic after meals but hypoglycemic long after meals because the glucose regulation done by the liver normally will be defective. Damage of salivary glands will lead to a dry mouth hence difficulty in swallowing. Damage of the small intestine will greatly reduce the surface area for digestion hence may lead to malnutrition and weight loss. The effects of gallbladder dysfunction are the same as for liver dysfunction.
- It is very long, has numerous microvilli and the walls of the lumen are folded to increase the surface area. This increased surface area ensures as many nutrients are absorbed after the digestion of food as possible.
- Mucus cells secrete the mucus necessary for food lubrication, the parietal cells secrete hydrochloric acid, and chief cells produce pepsinogen. The longitudinal muscles of the stomach assist in longitudinal movement of food while the round muscles are responsible for the squeezing motion of the stomach motion during churning. The sub-mucosa contains the secretory glands for the enzymes and hydrochloric acid.
- Failure of the pancreas to produce pancreatic juice means there will be incomplete digestion of proteins thus can result in protein malnutrition. If the gall bladder is removed on the other hand, there will be defective digestion of fats in the body which will lead to low absorption and hence steatorrhea.
- The importance of ATP- it is used as a substrate in signal transduction pathways be kinases. It is also incorporated into nucleic acids in the process of transcription. It is also a neurotransmitter believed to signal the sense of taste. Carbohydrate metabolism occurs in the cytoplasm and the mitochondria in the cell. Acetyl Co-enzyme A is needed during this metabolism. The byproducts are carbon four oxide and water.
References
Pickering, W. R. (1999). Complete Biology. Oxford: Oxford University Press.
Roberts , M. B. (1986). Biology: A Functional Approach. Chicago: Nelson Thornes.
