B7.2 & B7.3 - Human Nutrition Flashcards
Digestive system & Digestion
Ingestion
The taking of substances into the body (food and drink)
Digestion
The breakdown of food
Absorption
The movement of nutrients from the intestines into the blood
Assimilation
Uptake and use of nutrients by cells
Egestion
The removal of undigested food from the body as faeces
Physical/mechanical digestion
Breakdown of food into smaller pieces without chemical change to the food molecules
What does physical digestion do?
Increase the surface area of food for the action of enzymes in chemical digestion
Chemical digestion
The breakdown of large insoluble molecules into small soluble molecules
What is the role of chemical digestion?
Producing small soluble molecules that can be absorbed
What does the amylase do?
break down starch into simple reducing sugars (maltose and glucose)
What do proteases do?
break down protein to amino acids
What do lipase do?
break down fats and oils to fatty acids and glycerol
Where is the amylase secreted (produced)?
Salivary glands and Pancreas
Where does the amylase act?
duodenum
where is the protease secreted (produced)?
Pancreas
where does the protease act?
duodenum
where is the lipase secreted (produced)?
Pancreas
where does the lipase act?
duodenum
what is the function of hydrochloric acid in gastric juice?
-kill harmful microorganisms in food
-provide an acidic pH (optimum pH) for optimum enzyme activity of proteases in the stomach
what is bile?
alkaline mixture that neutralises the acidic mixture of food and gastric juices entering the duodenum from the stomach, to provide a suitable pH for enzyme action in the small intestine
what is the role of bile?
emulsifying fats and oils to increase the surface area for chemical digestion
defaecation
some excretory materials added to egested substances and expelled from the body as faeces during defaecation
process of salivary glands
three pairs that produce saliva and pour it into the mouth through salivary ducts
process of oesophagus
muscular tube which helps food move to stomach by peristalsis. (connects the mouth and stomach)
process of liver
(produces bile), which helps to neutralise acidic chyme and also emulsifies fats. Important in assimilation
process of stomach
muscular bag which stores food for a short time, and mixes food with acidic digestive juices to form the creamy liquid called chyme
(Churns food up with its muscular walls.
Produces the protease enzyme, pepsin.
produces gastric juice containing hydrochloric acid,
to kill bacteria in food (because it has a low pH which denatures the enzmes in the harmful microorganisms),
and to give an acid pH for the enzyme pepsin to work (optimum pH is 2)
process of gall bladder
(stores bile) before pouring it into the duodenum through the bile duct
process of duodenum
first part of the samll intestine, where semi-liquid food is mixed with pancreatic juice and bile
process of pancreas
produces pancreatic juice that contains enzymes, mucus, and hydrogen carbonate which neutralises acidic chyme. This is then poured into the small intestine through the pancreatic duct
(produces protease, amylase, and lipase enzymes.
Releases these enzymes into the small intestine)
process of mouth
food enters the alimentary canal. It is converted to a bolus of food. It’s produced by teeth, tongue, and saliva during mastication. It gets food ready for swallowing
(salivary glands in the mouth produce amylase enzyme in the saliva, teeth break down food)
process of ileum
longest part of the small intestine, where digested food is absorbed into the blood and lymphatic system
process of large intestine
It is wider than the small intestine. The colon is part of the large intestine. It reabsorbs water from gut contents; also absorbs some vitamins and minerals
(where excess water is absorbed from the food)
process of rectum
stores faeces before expelling them at a convenient time
(last part of large intestine
where the faeces, made up mainly of indigestible food, are stored before they are passed out through the anus)
process of anus
exit for faeces defaecation is controlled by two anal sphincters. constipation is the inability to expel the faeces, it can result if theres not enough fiber in the diet. The faeces become too dry and hard to pass easily out of the rectum
process of small intestine
produces protease (trypsin), amylase, and lipase enzymes to complete digestion.
Where nutrients are absorbed out of the alimentary canal, into the body
Where most of the water is absorbed into the body.
Has 2 parts - Duodenum & Ileum
