Unit 6.1 and H Digestion/Absorption – Flashcards

Enzyme: amylase- salivary gland, 7, amylose (starch), maltose (and glucose) Lipase- pancreas, 8, lipids, fatty acids and glycerol

rate of digestion at body temperature would be too slow/ enzymes increase the rate of digestion; enzymes break large molecules down into small/soluble molecules; for absorption/diffusion into blood

bile pigments

esophagus stomach small intestine large intestine pancreas liver gall bladder anus

at low temperatures, rate of reaction increase as temperature increases; more kinetic energy/faster movement of molecules means more collisions between enzyme/active site and substrate; optimum temperature is temperature at which rate of enzyme-catalyzed reaction is fastest; at high temps enzymes are denatured and stop working; denatured means change of structure in enzyme/protein resulting in loss of its biological properties/ no longer can carry out its functions; too much kinetic energy/vibrations breaks bonds that give enzyme specific shape; optimum pH is one at which rate of enzyme-catalyzed reaction is fastest; rate of reaction reduced as increase or decrease pH (from optimum); strong acids and alkalis can denature enzymes; affect (weak, ionic, hydrogen) bonds that hold enzyme in specific shape; at low substrate concentrations, as increase concentration get increase in rate of reaction; more chance of collision between substrate and enzyme/active site; at high substrate concentration, have no change in rate as increase concentration; all active sites occupied

D. Maltose

cellulose/lignin; cellulase not present/ no enzymes for digestion lignin

A. Absorption of water

A) 20/29x100=69% B) higher percentage of those with stomach cancer have H. pylori infection; higher median of those with stomach cancer have H. pylori infection; infection/high level antibodies does not mean that gastric cancer will always result/many infected did not develop gastric cancer; not all of those with stomach cancer had H. pylori infection C) pepsinogen would not be broken down to pepsin; pepsin would not work as well due to incorrect pH; it is not known if humans would respond int eh same way as gerbils

B) II and III

stomach

starch is a large molecule; large molecules/ starch cannot be absorbed by the intestine/ villi/ epithelial cells; glucose produced by digestion of starch can be absorbed; starch/glucose is a useful source of energy; starch is not stored in humans; glucose is stored as glycogen not starch; starch is not soluble/could not be transported by blood

H. pylori is a bacterium which causes gastritis; stomach ulcers are open sores in the stomach wall; prolonged presence of ulcers many lead to the formation of tumours; cancer of the stomach is a malignant tumor in the stomach wall; about 80% of gastric ulcers are caused by H. pylori; H. pylori survives in the stomach mucosa; producing urease; which neutralizes gastric acid; colonization by H. pylori opens up/ weakens the (protective) (mucosal/mucus) lining; for digestive attack by gastric acid/ HCL causing ulcers; linking H. pylori to stomach ulcers was a paradigm shift in medicine; cause was previously thought to be stress/ lifestyle/ diet; H. pylori now thought to be primary cause/ now treated as infectious disease

C) Small intestine

C) stomach - yes, small intestine - no, large intestine - no

absorption is taking up of a substance by the skin/ mucous membrane/digestive tract/ cell membranes/ layers of cells/ the bloodstream

villus intestinal wall has many folds to increase surface area; surface of villus close to blood vessels so materials can easily diffuse; surface of villus close to lymph vessels so lipids can be easily absorbed; greater surface area related to greater rate of diffusion; villus wall consists of single layer of cells

D) I, II, III, and IV

microvilli increase the surface of the plasma membrane exposed to the digested food; increased surface area allows for increased absorption of foods 9 by diffusion); lipids are absorbed by simple diffusion; hydrophilic food substances/ e.g. fructose are absorbed by facilitated diffusion; channel proteins help hydrophilic food substances to pass though the hydrophobic core of plasma membrane; mitochondria produce the ATP required for active transport; pump proteins in the plasma membrane actively transport glucose / amino acids / mineral ions; pinocytic vesicles are formed by endocytosis; each vesicle contain small droplets of fluid from the lumen of the ileum; membranes from these vesicles originate from plasma membrane; these vesicles contain channels for facilitated diffusion and pumps for active transport; digested foods can be absorbed from these vesicles into the cytoplasm;

1. (i) villus - absorption of (soluble) food/ for mixing of food with secretions/ increased surface area for digestion 2. lacteal/ lymphatic duct/ vessel - transport of fat/ lipid (ii) 3. circular 4. longitudinal

a cells of the pancreas produce glucagon; Glucagon promotes release of glucose/ breakdown of glycogen by liver cells; Glucagon is secreted when blood glucose levels are low/raises blood glucose levels; B cells of the pancreas produce insulin; Insulin promotes glucose uptake/ storage of glycogen by liver/body/muscle cells; Insulin secreted when blood glucose levels are high/ lowers blood glucose levels; Negative feedback mechanism;