digestive system Flashcards
what does the alimentary canal do?
forms a tube through the centre of the body
food is… from this canal for the purpose that the food can be…
ingested, digested, absorbed, egested
assimilated
what makes up the small intestine?
duodenum and ileum
what makes up the large intestine?
the colon and the anus
what is ingestion?
taking food in through the mouth and swallowing
what is digestion?
breaking down large insoluble molecules in food into smaller pieces and smaller soluble molecules
what is absorption?
the movement of small soluble molecules out of the gut and into the blood by diffusion and active transport
what is egestion?
passing out undigested food through the anus
what is assimilation?
building larger biological molecules from the small soluble molecules, in all cells
what is the first structure in the alimentary canal?
the mouth
where does ingestion take place?
the mouth
what also happens in the mouth?
digestion
what is an example of mechanical digestion in the mouth?
- food is broken up into smaller pieces in the mouth by chewing
- this increases the surface area for enzymes and also prevents discomfort when swallowing
what is an example of chemical digestion in the mouth?
- saliva is released into the mouth by the salivary glands
- makes the food easier to swallow
- contains amylase
what does amylase break down starch to?
starch-> maltose
what happens when amylase reaches the stomach?
amylase works best at a neutral pH so it is denatured when it reaches the stomach and stops working
what happens before swallowing?
the food is shaped into a ball by the tongue and moved towards the back of the mouth
what is the ball of food called?
a bolus
what is the epiglottis and what does it do?
a flap which blocks the food from entering the trachea
what is the oesophagus?
a long tube that connects the mouth to the stomach
what process occurs in the oesophagus?
peristalsis
what is peristalsis?
- two sets of muscles push the food down the oesophagus
- the circular muscles contract behind the bolus pushing it along
- when the longitudinal muscles contract, they make the oesophagus wider and the circular muscles relax
what do the gastric glands in the stomach wall secrete?
the enzyme pepsin