Organisms Exchange Substances with their Environment (Exchange) Flashcards
Ingestion
Taking in food
Physical digestion
Breaking large food pieces into small pieces mechanically (teeth/stomach muscles/churning) increase surface area
Chemical digestion
Breakdown of large insoluble molecules to small soluble molecules using enzymes/hydrolysis
Absorption
Taking in the products of digestion, from the lumen of the small intestine into the blood stream
Assimilation
The process by which nutrients fro foods are taken into the cells of the body after the food has been digested and absorbed
Egestion
Removal of faeces form the body
Breakdown of starch
- Mouth with Salivary amylase = Maltose
2. Small intestine with Pancreatic amylase = maltose
Breakdown of Protein
- Stomach with Protease = Amino acids
2. Small intestine with Protease = Amino acids
Breakdown of Maltose
- Small intestine with Maltase = Glucose
Breakdown of Lipids
- Small intestine with Lipase = Monoglyceride + 2 fatty acids
Carohydrate digestion
Amalyse hydrolyses alternate glycosidic bonds of starch molecule. Then maltose is hydrolysed into the monosaccharide a-glucose by maltase
Membrane-bound disaccharidases
Disaccharidases that are attached to the membrane to further increase area that enzymes can work
Lipid digestion
Hydrolysed by lipases to produce a monoglyceride and fatty acids. Pancreas, Ester bond, Micelles, Bile salts, Emulsification
Micelles
Are the products of lipase digestion that remain in association with the bile slats to form structures
Emulsification
Two immiscible liquids, one of which is dispersed as small droplets within the other, is produced
Bile salts
Are biological detergents that the liver normally secretes into the duodenum to solubilise ingests fats
Protein digestion
Hydrolysed by peptidases, Endo = middle, Exo = terminal
Endopeptidase
First protease to work on proteins, (hydrolysis of peptide bonds between amino acids in the centre of a protein). Makes more terminal amino acids available
Exopeptidase
Second protease to work on proteins, (hydrolysis of peptide bonds at terminal amino acids). Releasing single amino acids and dipeptides
Dipeptidases
Hydrolyse the bond between the two amino acids of a dipeptide. Are membrane-bound, part of the epithelial cells lining the ileum
Membrane bound dipeptidases
Dipeptidases that are attached to the membrane to further increase area that enzymes can work
Ileum
The last part of the small intestine
Food digested in the ileum
Starch, maltose, protein, triglycerides
Absorbtion of glucose (1)
Sodium ions are co-transported by facilitated diffusion with glucose. Amino acids are also co-transported by facilitated diffusion with Na+ ions. Co-transported proteins on the membrane are involved. CHANNEL PROTEINS
Absorbtion of glucose (2)
Na+ ion are actively pumped out of the epithelial cells across the plasma membrane into capillaries. From a low concentration to a high concentration ATP is used. Energy needed for active transport. CARRIER PROTEINS
Absorption of glucose (3)
The amino acids or glucose pass out of the cell to the capillaries by facilitated diffusion
Microvilli
Tiny finger-like projections from the cell-surface membrane of some animal cells
Chylomicrons
Contains triglycerides, cholesterol, and other lipids, leave epethelial cell in exocytosis
Lacteals
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Facilitated diffusion
Passive transport of molecules across a membrane, with the help of transmembrane proteins
Lactose Intolerance
Not able to hydrolyse lactose
Water potential in lumen of SI falls
Water moves out of epithelial cells and capillaries to capillaries
Eventually move to large intestine
Unbroken lactose causes what
Bloating, diarrhoea and cramps
Bacterial fermentation causes what
Methane to form
