Digestive System Amd Excretory System Flashcards
What is mechanical digestion
Breakdown of food into smaller pieces without chemical change to the food molecule
Chemical digestion
The breakdown of large insoluble molecules into small soluble molecules
Mouth
Mechanical digestion: teeth che food to break into smaller pieces for larger SA to volume ratio
Chemical digestion: salivary amylase break down starch
Starch —> maltose
Oesophagus
Passes blooded of food by peristalsis from mouth to stomach
Stomach
1) contract muscular walls; churn to break up the food by mechanical digestion
2) produces protease enzyme for breakdown protein
3) produces HCl - maintain pH level for enzyme action and kills bacteria by acidic conditions which denature enzyme - product amino acid
pH in stomach 2-3 acidic
Small intestine
Chemical digestion ; protease, amylase, lipase
—> pancreas secreted into small intestine
pH 8 alkaline
Lipid digestion. Starts here
Liver
Makes bile to be secreted into the small intestine
1) neutralize the acid in the stomach to provide a suitable pH to work
Neutralize acidic food from stomach
2) emulsifiers fats increasing surface area so enzyme can digest the more quickly
Ileum
Lined with villi to increase surface area which absorption can take place
1) thin walls
Speed up the rate of diffusion of molecules into the blood
2) rich blood supply
Helps carry absorbed molecules away from intestine - always low concentration of food molecules in the blood maintain high conc gradient
3) increase. Length
Increase SA
4) SURFACE area
Villi increase surface area means digested food can be absorbed into the blood stream faster
Large intestine
Indigestible food passes through large intestine consist of the colon, rectum and anus remaining salts and water are absorbed
Faecas stored in the rectum before removed
Glomerulus
Filter small solute from the blood
Proximal convuluted tubules
Reabsorb water, ion and nutrients: removes toxins and adjust filtrate pH
Descending loop of Henles
Aqua poring allows water to pass from the filtrate into the interstitial fluid
Ascending loop of henle
Reabsorb Na+ and Cl- from the filtrate into the interstitial fluid
Distal convoluted tubules
Selectively secrete and reabsorb different ions to maintain blood pH and electrolyte balance
Collecting duct
Reabsorb solutes and water from the filtrate
Removes from the blood
Most urea
Excess H2O
Excess salts
Reabsorb into the blood
All glucose
Most H2O
Some salts