Digestion

Vocab Words: Ingestion: the food that you eat Digestion: a series of chemical reactions, whereby you convert the ingested food to smaller and smaller molecule forms Absorption: small molecular forms are absorbed through cells of your digestive system and pass into nearby blood or lymphatic vessels Transport: your circulatory system delivers the small molecular nutrients to your body cells

6.1.1 Explain why digestion of large food molecules is essential.

Large food molecules need to be broken down into smaller ones, to be absorbed. Molecule Type Molecular Form Digested Molecular Form After Digestion Protein Amino Acids Lipids Tryglycerides Glycerol and Fatty Acids Carbohydrates Polysaccharides, Disaccharides, Monosaccharides Monosaccharides Nucleic Acids DNA/RNA Nucleotides

2. When digesting food molecules, they are broken down into their smallest components, in other words we hydrolyse them. They are then reassembled into larger molecules we can use.

6.1.2 Explain the need for enzymes in digestion.

Enzymes break down large food molecules into smaller food molecules. Enzymes speed up the process of digestion by lowering the activation energy needed for the reaction. Enzymes allow digestion to occur quickly while remaining at a normal body temperature.

6.1.3 State the source, substrate, products, and optimum pH conditions for one amylase, one protease, and one lipase.

Amylase Protease Lipase Enzyme Salivary Amylase Pepsin Pancreatic Lipase Source Salivary Glands Chief cells in stomach lining Pancreas Substrate Starch Proteins Triglycerides such as fats and acids Products Maltose and Glucose Amino Acids Fatty acids and Glycerol Optimum pH 7 (Neutral) 1.5-2 (Acidic)

6.1.4 Draw and label a diagram of the digestive system.

6.1.5 Outline the functions of the stomach, small intestine, and large intestine.

Food is brought from your mouth to the stomach through a muscular tube called the esophagus. Which after you swallow moves the food to your stomach through smooth muscle contractions. Called Perstalsis.

Stomach: Stomach secretes HCL which kills bacteria, to prevent food poisoning. HCL provides optimum pH for Pepsin. Stomach secretes Pepsin for protein digestion. A Mucus lining protects the stomach walls for the Hydrochloric Acid. Pepsin, HCL, and the Mucus lining are collectively known as Gastric Juices.

Gastric Pit:

Small Intestine: The main function of the small intestine is absorption. Has villi lining the walls, to increase the surface area for absorption. Receives enzymes from the pancreas, liver, and gall bladder. These enzymes are: Accessory Organs Enzyme Gall Bladder Bile Liver Pancreas Trypsin(protease), lipase, amylase, bicarbonate

Large Intestine: Moves material that has not been digested on. Absorbs water, which helps in moving the food along. Produces wastes to be rid of through the anus. Home to mutualistic bacteria. Our body provides nutrients, water, and a warm environment. The bacteria synthesize vitamin K.

6.1.6 Distinguish between absorption and assimilation.

Absorption vs. Assimilation Absorption: small molecular forms are absorbed through cells of your digestive system and pass into nearby blood or lymphatic vessels. Assimilation: occurs when food molecules becomes the part of the bodies tissues. *Absorption is followed by assimilation

6.1.7 Explain how the structure of the villus is related to its roles in absorption and transport of products of digestion.

Structure of Villus: Many villi increase the surface area for absorption. Epithelium is only one cell layer thick, so food can be quickly absorbed. Microvilli on the villi further increase the surface area for more absorption. Protein channels and pumps are present in the microvilli for rapid absorption. The plasma membranes of the microvilli contain brush border enzymes, which complete digestion of proteins/carbs. Mitochondria in the epithelium provide the ATP needed for active transport. Blood capillaries are very close to the epithelium layer so diffusion in small. Lacteal takes away fat for absorption.

Capillaries Epitheal Cell Layer Artery Vein