Food and Nutrition Flashcards
what is the test for starch
take a tile with the pieces of food on it and add a few drops of iodine solution
if the starch is present the iodine solution will turn from yellow to blue and black
what is the test for sugars
put a 2cm depth of crushed food liquid in a test tube. add an equal volume of benedicts solution. shake well and put the test tube in boiling water for 2-3 minutes.
the blue solution will change colour as a precipitate is formed, it could go yellow or green meaning a trace, or orange to brick red if sugar is present.
what is the experiament to measure the energy content in foods
put 20cm cubed of water into a boiling tube and clamp it. record the temperature of the water as your initial temperature.
weigh the piece of food and record this as the initial mass. attatch the food onto the mounted needle.
light the bunsen burner and set fire to the food until it starts burning.
hold the burning food under the boiling tube until it stops burning. after this record the final temperature of water and the final temperature of mass.
what is the equation to work out how many energy content is in our food
energy released/J = volume of water/cm cubed x temperature rise/degrees C x 4.2
how much energy is used to heat 1cm cubed of water up by 1degreeC
4.2J
what is peristalsis
peristalsis is a wave of muscular contraction, where in sequential order the muscles in your oesophagus push the food down.
what happens in the stomach
the stomach produces hydrochloric acid which kills pathogen and makes the stomach wall the right PH level for protease enzyme (pepsin) to work. Pepsin starts the break down of protein into amino acids. Nothing happens to carbohydrates or lipids in the stomach because the acidity level is too high.
what happens at the small intestine
at the duodonem - the start of the small intestine, bile sent from the liver is used to neutralise the acid levels. Bile also emulsifies fats into tiny droplets. the enzyme amylase made in the pancreas is sent to here where it continues to break down starch into maltose and also the enzyme maltase produced in the pancreas breaks maltose into glucose. the enzyme lipase made by the pancreas breaks down the small droplets of fat into glycerol and fatty acids. The other protease enzyme trypsin also made in the pancreas finishes the break down of protein into amino acids.
why does the small intestine have villi
the small intestine is covered in villi to increase its surface area. having a large surface area allows food and substances to diffuse much quicker and easier. glucose, fatty acids, glycerol and amino acids all diffuse from the lumen into the blood capillaries to be used around the body. they have a very short diffusion distance from the lumen to the blood vessels.
why does the blood move away quickly after the substances have diffused into it
so the concentration gradient remains the same and diffusion always occurs and equilibrium is never reached.
what happens at the large intestine
any food that hasnt been digested eg fibre passes into the large intestine. water is absorbed back into the body while food becomes a solid waste called faeces. faeces is stored in the rectum and removed through the anus. this removal is called egestion.
what is the lacteal
the lacteal is inside the villi and its where insoluble lipids go that are too big to diffuse into blood capillaries.
what does the gall bladder do
the gall bladder stores bile made in the liver and then transports it through the common bile duct into the duodonem.
what does the pancreas do
the pancreas makes enzymes like: trypsin, amylase, maltase and lipase. the enzymes move across the pancreatic duct into the duodonem.
what does the liver do
produces bile
what do the teeth do
our teeth cause the mechanical break down of food to increase the surface area. increasing the surface area makes it easier to swallow and gives more places for enzymes to break it down.
what does the tongue do
the tongue detects soluble chemicals and rolls chewed food into a pellet or bolus for swallowing
what do the salivary glands do
the salivary glands produce the enzyme amylase to start the break down of starch into sugar.
what does the oesophagus do
the oesophagus moves each food bolus down from the mouth to the stomach using peristalsis
what are 7 things should you have for a healthy diet
carbohydrates, lipids, proteins, vitamins, minerals, water, dietary fibre
what health issues can be caused from too much fat
it could lead to obesity and increases the risks of heart disease and diabetes.
what is the process called where substances diffuse from small intestine into blood capillaries
absorption
what happens after the blood capillaries take the substances away from the small intestine and what is the process called
the process is called assimilation and its where the capillaries take glucose, amino acids and fatty acids to use around the body.
what is glucose used for
a source of energy
what is amino acids used for
to build new cytoplasm and tissue cells
what are fatty acids used for
to build new cell membranes
explain the digestion of carbohydrates
first the mouth starts a mechanical breakdown of starch to increase the surface area giving it more places for enzymes to break it down and making it easier to swallow. then the tongue rolls the food into a bolus to make it easier to swallow. the salivary glands start to produce the enzyme amylase which starts the breakdown of starch into maltose. the bolus moves down your oesophagus using peristalsis-a wave of muscular contraction into your stomach. the stomach has too much acid for the enzymes to work on the starch. Bile made in the liver and stored in the gall bladder moves into the duodoenum to neutralise the acidic conditions. in the small intestine, more amylase from the pancreas continues breaking down starch into maltose. the enzyme maltase also made in the pancreas breaking down the maltose into glucose. the glucose then diffuses through the villi into the blood capillaries to be used as energy in the body.
explain the digestion of lipids/fats
first the mouth starts a mechanical breakdown of starch to increase the surface area giving it more places for enzymes to break it down and making it easier to swallow. then the tongue rolls the food into a bolus to make it easier to swallow. the bolus moves down your oesophagus using peristalsis-a wave of muscular contraction into your stomach. the stomach has too much acid for the enzymes to work on the lipids. Bile made in the liver and stored in the gall bladder moves into the duodenum to neutralise the acidic conditions. the bile also emusifies the fat into very small droplets. lipase sent from the pancreas through the pancreatic duct breaks down the small droplets of fat into glycerol and fatty acids. these diffuse through the villi into the blood capillaries where the fatty acids are used to build new cell membranes.
explain the digestion of protein
first the mouth starts a mechanical breakdown of starch to increase the surface area giving it more places for enzymes to break it down and making it easier to swallow. then the tongue rolls the food into a bolus to make it easier to swallow. the bolus moves down your oesophagus using peristalsis-a wave of muscular contraction into your stomach. in the stomach the enzyme pepsin is produced which starts to break down protein into amino acids. then in the small intestine, the enzyme trypsin finishes breaking protein down into amino acids. Trypsin is made in the pancreas and was sent to the small intestine throw the pancreatic duct. amino acids diffuse through the villi into the capillaries where they are used in tissue cells and for cytoplasm around the body.
