What is physical digestion? - Physical digestion is the breaking up of food particles to increase the surface area to volume ratio of food particles., What is chemical digestion? - Chemical digestion is the enzymatic breakdown of large complex food molecules into smaller soluble molecules that can be absorbed into cells., What are the end-products of digestion? - Glucose, amino acids, fatty acids and glycerol., What is emulsification? - Emulsification is the breaking up of large fat globules into smaller fat droplets by bile in the small intestine. This increases the surface area to volume ratio of fat droplets, which increases the rate of fat digestion by lipase., What is ingestion? - Ingestion is the intake of food via the mouth., What is absorption? - Absorption is the process whereby digested food substances are taken into the body cells., What is assimilation? - Assimilation is the process by which some of the absorbed nutrients are converted into new cytoplasm or used to release energy via cellular respiration. , What is egestion? - Egestion is the removal of undigested food substances from the body., What is the function of the hepatic portal vein? - The hepatic portal vein transports blood rich in glucose and amino acids from the small intestine to the liver., State the chemical digestion process occurring in the mouth. - Starch is digested to maltose by salivary amylase., State the chemical digestion process occurring in the stomach. - Protein is digested to polypeptides by pepsin (protease)., State the chemical digestion processes occurring in the stomach. - Starch is digested to maltose by pancreatic amylase; maltose is digested to glucose by intestinal maltase; proteins are digested to polypeptides by proteases; polypeptides are digested to amino acids by peptidases; lipids are digested to fatty acids and glycerol by intestinal lipase and pancreatic lipase., What are the roles of the liver and gallbladder in emulsification? - The liver produces bile. The gallbladder stores and releases bile., What is the role of the liver and pancreas when blood glucose concentration increases. - The pancreas detects the increase in blood glucose concentration and secretes more insulin into the bloodstream. The liver responds to insulin by absorbing more glucose, breaking glucose down via aerobic respiration and converting excess glucose to glycogen., What is the role of the liver and pancreas when blood glucose concentration decreases. - The pancreas detects the decrease in blood glucose concentration and secretes more glucagon into the bloodstream. The liver responds to glucagon by breaking down glycogen to glucose and releasing glucose to the bloodstream., What is a hormone? - A hormone are chemical substances produced in very small quantities by an endocrine gland. It is transported in the bloodstream to the target organ(s) where is exerts its effect(s). The hormone is broken down after it has exerted its effect., State the pH of the mouth, stomach and small intestine. - Mouth: 7 (neutral); stomach: 2 (acidic); small intestine (8) alkaline, What are the functions of the liver? - Bile production, deamination, detoxification, breakdown of hormones, regulation of blood glucose concentration, How is the small intestine adapted for absorption? - 1. Folds and furrows + 2. Numerous finger-like projections called villi + 3. Epithelial cells have numerous microvilli to increase SA:V ratio; 4. One-cell thick epithelium to reduce diffusion distance; 5. Each villus supplied with blood capillaries and a lacteal to transport substances away, maintaining a steep concentration gradient; 6. Epithelial cells have many mitochondria to release energy via aerobic respiration for active transport, What are the end-products of digestion? - Glucose (and other single sugars), amino acids, fatty acids and glycerol, What are the fates of glucose after absorption? - Glucose can be (1) broken down via aerobic respiration to release energy, (2) converted to other biomolecules like amino acids. Excess glucose is stored as glycogen in liver cells and muscle cells., What are the fates of amino acids after absorption? - Amino acids are used for to synthesise new protoplasm or enzymes, hormones and other proteins. Excess amino acids are broken down in the liver into urea and glucose. Urea is excreted by the kidneys while glucose can either be used for respiration or stored as glycogen., What the fates of fats after absorption? - Fats can be used to build new protoplasm or deposited as fatty tissues for long-term energy storage.,

Nutrition in Humans - Flash card

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