S2 Ch14 (DS)

• What are the 3 main nutrient groups?

  Carbohydrates, proteins, fats
• What is the movement of food through the alimentary canal called?

  Peristalsis
• What are the 3 enzymes?

  Carbohydrase, protease, lipase
• What is the structure of carbohydrates?

  Carbon, hydrogen, oxygen
• The simplest type of carbohydrate is known as: Monosaccharides
• An example of monosaccharide is: Glucose
• Many monosaccharide units can be chemically combined in long chains to form: polysaccharides
• What are the 3 types of carbohydrates ?

  Monosaccharides, disaccharides, polysaccharides
• 3 examples of monosaccharide are: glucose, fructose and galactose
• 3 examples of disaccharide are: sucrose, maltose and lactose
• 3 examples of polysaccharide are: starch, cellulose and glycogen
• What is the structure of proteins?

  Carbon, hydrogen, oxygen, nitrogen
• Proteins are formed from small molecules called: amino acids.
• Amino acids are chemically combined in long chains to form: polypeptides
• Polypeptides are folded into a specific 3D shape to form a functional: protein
• What is the structure of fats?

  Carbon, hydrogen, oxygen
• Fats are made of: 1 glycerol and 3 fatty acids chemically combined together
• Nutrient molecules must be: small, soluble, diffusable
• Complex molecules such as: starch, proteins and fats are too large to cross into the bloodstream
• Simple molecules such as: monosaccharides, amino acids, glycerol, fatty acids are able to cross into the bloodstream
• Define digestion: to break down complex nutrient molecules into small, soluble and diffusible molecules for absorption
• What is physical digestion?

  Breaking down large pieces of food into smaller pieces, no new substances are formed
• What is chemical digestion: breaks down complex molecules into simpler molecules, new substances are formed
• 2 ways physical digestion is made possible: teeth chewing the food into smaller pieces, process of peristalsis (stomach churns food, mixing it with digestive juices)
• Chemical digestion is made possible by: enzymes which speed up extremely slow digestion
• Enzymes are: specific to the reactants they work on
• Carbohydrates are digested by: carbohydrase enzymes
• Proteins are digested by: protease enzymes
• Fats are digested by: lipase enzymes
• Digestion (physical and/or chemical) occurs in: mouth, oesophagus (saliva still mixed with food), stomach, duodenum (closest to stomach)
• Absorption occurs in: ileum and colon
• Physical digestion in mouth: chewing breaks up large pieces of food into smaller pieces which increases surface area to volume ratio for faster digestion by enzymes
• Chemical digestion in mouth: carbohydrase enzyme found in saliva digests starch (polysaccharide) into maltose (disaccharide)
• The oesophagus is a muscular tube connecting the mouth to the stomach, food is moved by: peristalsis
• Physical digestion in stomach: peristalsis continues in stomach, churning and mixing food with gastric juice
• Chemical digestion in stomach: gastric juice contains a protease enzyme which digests protein molecules into polypeptides
• The small intestine consists of 3 segments: duodenum (nearest to stomach), jejunum, ileum (nearest to the large intestine)
• Food in duodenum will be chemically digested by enzymes in: intestinal juice (by glands in duodenum) and pancreatic juice (by pancreas, secreted into the duodenum)
• PHYSICAL digestion in small intestine: liver produces bile released into the duodenum, which acts on fats, emulsifying large globules of fats into smaller droplets
• After emulsification, smaller droplets of fats can be chemically digested more efficiently by enzymes