6.1.1 Explain why digestion of large food molecules is essential.
Food molecules are essentially energy for the functioning of the cells in our bodies. At first, these food molecules are too big to be absorbed, this is why we have our digestion system. Through the process, food molecules inside us are broken down into smaller pieces in order for our cell membranes to be able to diffuse the molecules into the cells. As it can be seen in the picture above, insoluble food molecules are going through the process of digestion and at the end it is divided into various smaller molecules.
6.1.2 Explain the need for enzymes in digestion.
Chemical digestion occurs throughout the digestion process, and substances such as enzymes help speed up chemical reactions. Enzymes are proteins that are there to make the process easier, without enzymes, the process would be way longer requiring more energy which could be stored with enzymes. They provide active sites, in order to the process to occur efficiently. We have tons of different enzymes for specific parts, like pepsin in our stomach, maltase, sucrase, lactase in our small intestine, and much more. pH and temperature needs to be controlled, because if the pH is above or lower the activity , or the temperature increases, the active site will change meaning that the substances, enzymes won’t work to it’s potential. However, since enzymes are factors that speed up the reactions of the food molecules, it does not influences in the actual execution of the process, in other words, if enzymes did not act in digestion, the process would still perform its task, it would only take a significantly greater time for substances to break down.
6.1.3 State the source, substrate, products, and optimum pH conditions for one amylase, one protease and one lipase.
The table shows us the three most common digestive enzymes, which are salivary amylase (amylase), pepsin (protease), and pancreatic lipase (lipase). Salivary amylase occurs on salivary glands, which work upon the molecule named starch. The result will be a maltose, with an optimum pH of a 7. Pepsin occurs on stomach walls, which work upon the molecule named protein. The result will be small polypeptides, with an optimum pH of a 1.5. Pancreatic lipase occurs on the pancreas, which work upon the molecule named triglycerides (fats or oil). The result will be a fatty acids and glycerol, with an optimum pH of a 7.
6.1.4 Draw and label a diagram of the digestive system.
The digestive system starts with the food going from the mouth which contains mechanical and chemical digestion. After swallowing, the food will travel from the mouth into the esophagus a pathway that leads to the stomach. Food is kept for a bit in the stomach where it will mix itself with gastric juices. The pancreas will produce insulins and enzymes, and contains proteases which digest proteins, and amylases which digest starch molecules. The liver will clean your blood by removing toxins, but it also contains the gallbladder which create bile which will breaks down lipids. Later on the food stored in the stomach, will go down to the small intestine. In the small intestine, it will continue digestion by absorbing the nutrients released by the food. Later on, digestion continues with the large intestine which will absorb the water and also contain bacteria. The rectum which is the final part of the large intestine will store the waste until it’s released by the anus.
6.1.5 Outline the function of the stomach, small intestine and large intestine.
Stomach: Several sequence of smooth muscle contractions caled the peristalsis forces the food through the esophagus down directly to the stomach. The food is kept for some time inside the stomach. During that time, food is mixed with gastric juice , which contains components such as pepsin, hydrochloric acid, and mucus. The muscular wall of the stomach agitates the food and gastric juices in order to mix themselves. Later on the food goes down into the small intestine through the open valve at the lower end of the stomach.
Small Intestine: Molecules are being produced in order to continue the digestive system. The small intestine has an inner wall called the villi which contains capillary bed and a lacteal. The villi will increase the surface area for the absorption of molecules like glucose, amino acids, and fatty acids. When the glucose ans amino acids are absorbed, they will go into a capillary bed of an villus, while fatty acids will go into the lacteal. Molecules are then taken into body cells which bonds with a nutrient molecule.
Large Intestine: The large intestine is the thick, lower end of the digestive system. It contains the appendix, colons, and the rectum as seen in the picture. The colons will mix water,vitamin with mucus and bacteria in the large intestine, its the longest path in the large intestine. The rectum is the final part of the intestine, they store waste until it’s release by the anus. It’s main fuction is to absorb water, and contains bacteria which will eat the cellulos causing waste materials, basically maintaning a good healthy environment inside the large intestine.
6.1.6 Distinguish between absorption and assimilation.
Absorption: Occurs in the small intestine, and it’s when the food enters the body and as a result the food molecules will pass through a layer of cells, and into the body tissues.
Assimilation: Happens when food moleucles becomes part of bodies tissues. As observed in the image, assimilation occurs in the circulatory system while absorption occur on the digestive.
6.1.7 Explain how the structure of the villus is related to its role in absorption and transport of the products of digestion.
There are a great number of villus, which help increase the surface area for absorption, and the microvilli in the villus will help even further in the process. Also, the villus has a surface membrane which food passes through in order to be absorbed quickly. Mitochondria will help create ATP in order to the active transport to work, and the lacteal will eliminate the fats after absorption.
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