Digestion Flashcards
Define Ingestion
the taking in of substances into the body through the mouth
Define digestion (mechanical)
the breakdown of food into smaller pieces without chemical change to the food molecules
Define digestion (chemical)
the breakdown of large insoluble molecules into smaller soluble molecules
Define absorption
the movement of small food molecules and ions through the wall of the intestines into the blood
Define egestion
the passing out of food that has not been digested or absorbed through the anus
Role of fat - storage
Long-term energy storage
Insulate the body
Stored around vital organs
Store certain fat soluble vitamins
Difference between alimentary canal and the digestive system
Alimentary canal: begins at the mouth ends at the anus
Digestive system: alimentary canal+ teeth+ salivary glands+ liver+ gall bladder+ pancreas
Importance of chemical digestion in the alimentary canal
large insoluble molecules are broken down into smaller soluble molecules that can be absorbed and used by cells
Digestion of starch in the alimentary canal
Starch- salivary amylase
Starch- pancreatic amylase
Maltose- maltase
glucose
Function of the pharynx
contracts by muscular action to swallow bolus or push bolus to the oesophagus
Function of the mouth cavity
Mechanical and chemical digestion
Function of the epiglottis
flap which closes over the windpipe
Function of the oesophagus
force food down through peristalsis
Function of the sphincter muscle
Prevents food from passing back
Function of the liver
Sore excess glucose
Breaks down excess amino acids
Function of the colon
Absorb water
Compact indigestible residue into semi-solid faeces
Function of the gall bladder
Store bile
Function of bile
Neutralize stomach acid
Turn large fat globules to small fat droplets which increases the surface area for lipase
Function of the salivary glands
Secrete saliva with water and mucus to soften and lubricate food
Contain salivary amylase
What is a bolus?
Masticated food rolled by tongue into the pharynx into the oesophagus
Function of the stomach
MD and CD
Churn and mix food with gastric juice
Some absorption
HCl destroy bacteria found in food
Contains pepsin
Function of the pancreas
Secrete bicarbonate ions into the duodenum to completely neutralise and acids not neutralised by the bile
Function of the small intestine
Absorption by villi
Absorption of water
CD and MD
Starch to Maltose to glucose
Adaption of the villi
Finger-like projection: extended surface area
Micro-villi: increase surface area
Dense network of capillaries: absorption of digested nutrients
Single central lacteal: absorption of fat-soluble vitamins
Single layer of epithelial cells: faster diffusion of nutrients, may mitochondria for active transport of nutrients
