Nutrition in Humans Flashcards
function of carbohydrates
provides energy
function of lipids
provide energy, act as an energy store and provide insulation
function of VITAMIN A
found in liver. helps to improve vision and keep skin and hair healthy
function of VITAMIN C
prevents scurvy. healthy immune system
function of VITAMIN D
Found in eggs and sunlight. needed for calcium absorption
function of calcium
needed to make bones and teeth
function of iron
needed to make haemoglobin for healthy blood
function of water
- every bodily function relies on water.
- we need a constant supply to replace water loss through urinating, breathing and sweating
function of fibre
aids movement of food through gut
how does amount of energy needed vary for different people?
- activity level= more active needs more energy
- age= children and teenagers need more energy as they are growing
- pregnancy= pregnant women need more energy for their babies to develop
function of mouth
- salivary glands in mouth produce AMYLASE enzyme in the salvia
- teeth break down food
function of oesophagus
muscular tube that connects the mouth and stomach
function of liver
where bile is produced
function of gall bladder
where bile is stored
function of large intestine
aka colon. where excess water is ABSORBED from the food.
function of rectum
last part of large intestine. where faeces are stored before being excreted.
function of stomach
- pummels food with its muscular walls
- produces the protease enzyme PEPSIN
- produces hydrochloric acid for 2 reasons:
- to kill bacteria
- to give the optimum pH for the protease enzyme to work (pH 2)
function of pancreas
produces protease, amylase and lipase enzymes. releases them into the small intestine
function of small intestine
produces protease, amylase and lipase enzymes to complete digestion.
also where nutrients are absorbed of the alimentary canal into the body.
how is the small intestine adapted for the absorption of food?
- very long= so there’s time to break down and absorb all the food before it reaches the end.
- really big SA for absorption because walls of small intestine are covered in millions of villi.
- each cell on the surface of a villus has its one microvilli (tiny projections that increase the SA even more)
- villi have a single permeable layer of surface cells and a very good blood supply to assist quick absorption.
how is food moved through the gut?
- PERISTALSIS.
- there is muscular tissue all the way down the alimentary canal.
- it’s job is to squeeze balls of food (boluses) through the gut, otherwise it would get clogged. this squeezing, which is waves of circular muscle contractions, is called peristalsis.
what do digestive enzymes do?
break down BIG MOLECULES (eg starch, proteins and fats) into small molecules so they can pass through the walls of the digestive system.
what do amylase and maltase do?
- AMYLASE converts STARCH into MALTOSE.
- MALTASE converts MALTOSE into GLUCOSE.
what does protease do?
converts PROTEINS into AMINO ACIDS
what does lipase do?
converts LIPIDS into FATTY ACIDS and GLYCEROL.
what does bile do?
neutralises stomach acids and emulsifies fats.
where is bile produced and stored?
produced in liver and stored in gall bladder before it’s released into the small intestine.
how does bile neutralise stomach acid?
- the hydrochloric acid in the stomach makes the pH too acidic for enzymes in the small intestine to work properly.
- bile is ALKALINE- it neutralises the acid and makes conditions alkaline.
- the enzymes in the small intestine work best in alkaline conditions.
how does bile emulsify fats?
- it breaks the fat into tiny droplets.
- this gives a much bigger SA of fat for the lipase enzyme to work on which speeds up digestion.
