Food and Digestion Flashcards
What is a balanced diet?
A balanced diet means eating the right types of food in the right amounts so that the body gets the nutrients it needs.
What are the seven nutrients?
- carbohydrates
- proteins
- fats
- vitamins
- minerals
- water
- fibre
What is carbohydrates function and nam a source?
- It is an immediate source of energy and you need lots of carbohydrates if you’re active and growing.
- Pasta, bread, rice, potatoes
What are lipids/fats used for? And name a source
- It is used for energy to make cell membranes. It is also used for energy if your body runs out of carbohydrates.
- fired bacon, nuts, dairy products
What is protein used for and name a source?
- It is for growth and repair and to make enzymes
- cooked salmon, nuts
What are minerals used for and name a source?
- They make body chemicals in small amounts
- white bread
- apples, nuts, cheese and milk which are all rich in calcium
What are vitamins for and name a source?
Vitamins in small amounts are used for cells to work properly and a source is kiwi
What is fibre for and an name a source
Fibre is to keep the bowels working properly and it helps to move food through your digestion
- chilli con carne
- fruit, vegetables, cereal, brown rice, brown bread, wholegrain bread
What is water used for?
It is used for chemical reactions to occur as water is where all the chemical reactions in your body take place and it is for transport
Which food has a high calorific content?
Fried bacon
Which food has a low caloric content?
Carrots and broccoli
What nutrient type do you think contributes most to the amount of calories a food has?
Fat
What food would you eat if you had an iron deficiency?
White bread, Burger King burger, chilli con carne, corned beef and brown bread
How do you test for starch.
Iodine
A dropping palette is used
In the test for starch what is the starting colour and what is the positive result.
Starting colour: brown
Positive result: black
How do you test for sugar and glucose?
It’s the benedicts test + warm water
The test tube used it put in hot water
What is the starting colour and the positive result for the test for sugar/glucose?
Starting colour: blue
Positive result: brick red
How do you test for protein?
Biuret (0.1M sodium hydroxide solution and 0.01M copper(II) sulfate solution) + warm water
The test tube used is put in hot water
How do you test for fats/lipids?
Alcohol
Two pipettes of alcohol + one pipette of water
Wait for the layers to separate
What is the starting colour and positive result for lipids and fats?
Starting colour: colourless
Positive result: the top layer goes cloudy
Name the parts of the digestive system
- tongue
- mouth
- salivary gland
- epiglottis
- trachea
- oesophagus
- gull bladder and bile duct
- liver
- pyloric sphincter
- large intestine
- appendix
- diaphragm
- stomach
- pancreas
- small intestines
- rectum
- anus
What is the stomach?
Muscular bag filled with gastric juice (a mixture of hydrochloric acid, mucus and enzymes e.g. protease breaks down proteins to amino acids). The stomach has a very strong lining to stop the strong acid from harming the stomach.It mechanically digests the food by churning it into a pulp called chyme. Food can be eaten in large quantities with gaps between meals but a steady flow of semi liquid food is allowed out of the stomach while large lumps of food cannot leave. Movement of food from the stomach into the duodenum is controlled by the small intestine which is a circle of muscle.
What is the mouth?
Your teeth help chop up food here. Saliva added here softens the food and has the enzyme amylase which is a type of carbohydrase which breaks down starch into sugar. Mastication happens here it is to crush down food inside your mouth; to chew food. This is mechanical chewing. It allows chemicals to get around everything. There is an enzyme called amalyse in the saliva which breaks down carbohydrates. The food mixes with saliva which contains mucus and lubricates the food making it easier to swallow.
What is the bile duct?
Bile is released here.
What is the gall bladder?
Bile is stored here.
What is the oesophagus?
A muscular tube which takes (semi-digested) food from the throat and pushes it down into the stomach. It moves food by waves of muscle contraction called peristalsis. The epiglottis covers the trachea to make sure food doesn’t enter.
What is the large intestine?
Water and body minerals are absorbed here and go back into the blood. The remains are formed into semi-solid faeces.
What is the liver?
Stores some nutrients, vitamins and minerals from digestion changes then from one form to another, and releases them into the blood according to the needs of the body. It also makes bile which removes toxins, breaks fat into tiny droplets and it neutralises the acid from the stomach so that the small intestine does not get harmed by the acid.
What is the rectum?
The end of the large intestine and the next part of the track is where the faeces are stored. Undigested food collects in the food, cellulose.
Herbivores have bacteria in their gut which can digest cellulose. Undigested food together with dead and living bacteria worn away from the gut lining is called faeces. Muscular contractions of the rectum forces the faeces out of the body through the anus.
What is the small intestine?
This is the site of maximum absorption.
Three liquids are added here bile, pancreatic juices and intestinal juice
-bile helps to neutralise the acid which was added to food in the stomach and is the best pH for enzymes to work. Bile also helps to break down fats.
-pancreatic juice contains enzymes e.g. lipase, carbohydrase, protease which helps to digest the food further
-intestinal juice also has the enzymes lipase, carbohydrase and protease. Finally the nutrients are small enough to pass through the lining and into the blood
What is the pancreas?
They make lots of enzymes e.g. lipase, carbohydrase and protease which help to digest the food further when released into the small intestine. This is the part of the body which produces the most enzymes. The pancreas secretes more NaHCO3 and many enzymes including amylase as salivary amylase would have been denatured by the acid in the stomach.
Absorb
The diffusion of particles into the body
Amylase
Enzymes found in saliva that breaks down carbohydrates
Amino acids
Product of digestion of protein
Bile
Alkaline, brownish-yellow fluid that is secreted by the liver, stored in the gallbladder. It is used to emulsify fats and break fats into smaller droplets so that they can be absorbed or broken down into fatty acids and glycerol. Bile also neutralises the acid on the food so that the small intestine is not harmed also so that the enzymes can work in the best possible conditions. Bile contains NaHCO3 and bile salts but no enzymes.
Denature
Process where the shape of an enzyme is changed so it no longer works. Heat and pH changes can denature enzymes
Digestion
The process where food is converted into smaller substances that can be absorbed by the body.
Emulsify
Break a large droplet into lots of smaller ones (usually fats and oils)
Enzyme
Substance in the body that chemically breaks up food into smaller substances. Each type of nutrient needs a specific enzyme
Fatty acids
Product of digestion of lipids
Glycerol
Product of digest of lipids
Gut
The entire length of tubing between the mouth and anus
Hydrochloric acid
Acid found in the stomach to kill bacteria
Lipase
Enzyme that breaks down fat
Lipids
Fats
Microvilli
Tiny ‘spikes’ on the villi to provide a larger surface area for absorbing nutrients
Peristalsis
A wavelike contraction of muscles to help move food down the oesophagus
Protease
Enzymes that break down protein
Saliva
Fluid produced by mouth. Contains amylase to start chemical digestion
Starch
Type of carbohydrate
Villi
Tiny ‘spikes’ on the small intestine to provide a larger surface area for absorbing nutrients
Visking tubing
Tubing that acts in a similar way to the small intestine. Used in experiments modelling digestion.
A young healthy person would need more ———
carbohydrates
Weight-lifters need to build large muscles. To do this they need to eat a diet with a lot of —— in it
protein
What are capillaries?
Small blood vessels
Where are villi found in
In your small intestine
What do villi do?
They absorb nutrients more quickly that a flat surface because they have a greater surface area. Villi also have very thin walls so digested food can diffuse foo into your blood quickly. Also they have a good blood supply.
Where are capillaries and what do they do?
There are capillaries in the centre of the villi and they collect nutrients to carry them to cells all over your body. Cells use glucose and fat for energy and protein and fat for growth and repair.
Group A: 5cm cubed starch and 5cm cubed of enzymes
What test would you do to know if there is starch in the visking tube and explain what results you would get?
The iodide test and the result would be positive so it would turn black
Group A: 5cm cubed starch and 5cm cubed of enzymes
If you tested the inside of a visking tube for glucose , what test would you do and what results would you expect to get?
The benedicts test and it would turn the colour brick red this is because the enzymes break up the starch into glucose.
Group A: 5cm cubed starch and 5cm cubed of enzymes
Starch is a big molecule that doesn’t fit through the intestine wall. If you tested the ‘blood’ (water) around the visking tube for starch what do you think the results would be and why?
The starch wouldn’t be in the ‘blood’ around the visking tube because the molecules are too big so enzymes break it up into glucose which is able to get through the the intestine wall
Group A: 5cm cubed starch and 5cm cubed of enzymes
If you tested the ‘blood’ (water) for glucose/ sugar what do you think the result would be and why?
It would be positive and it would turn the colours brick red this is because the big starch molecules can’t fit through the small intestine wall so enzymes break the starch molecules apart and it becomes glucose which can fit through the small intestine wall and be absorbed.
What type of enzyme is starch broken down by and what does it become?
It gets broken down by carbohydrase and it becomes glucose
What is glucose used for?
Energy
What type of enzyme is protein broken down by and what does it become?
The enzyme is protease and they become amino acids
What are amino acids for?
They build cell components
What sort of enzyme are lipid/fat molecules broken down your and what do they become?
They are broken down by an enzyme called lipase and they become fatty acids and glycerol
What are fatty acids used for? And what is glycerol used for?
Fatty acids are used to make cell membranes and glycerol is for energy?
Do glucose vitamins and minerals need enzymes to fit through the small intestine?
Glucose vitamins and minerals are small enough molecules to fit through the small intestine without needing an enzyme to break them down.
Does fibre have an enzyme?
No, fibre is too large to fit through the small intestine and it is too big to fit through the small intestine but humans do not have an enzyme to break it down so fibre is used instead to prevent constipation.
Analogy: towels soak up water faster when they are covered in absorbent fibres
Fact: the inside wall of your small intestine are covered with tiny fingers called villi.
Analogy: when there is a big height difference you slide faster
Fact: glucose is taken in quickly when the amount in your intestine is much bigger then the amount in your blood
Specialisation: your blood keeps taking nutrients away so the concentration difference stays high
Analogy: the narrower the river the quicker you can get across
Facts: a thin layer of cells let’s nutrients through to your blood faster
Specialisation: your blood vessels reach into narrows fingers of tissue, so they are close to the cells tat take nutrients.
Describe what villi look like?
Tiny finger-like projections
Name two minerals what they are in and what they are used for:
- Calcium is found in milk and is needed for strong bones and teeth
- iron is found in meat and it is needed for healthy blood
What nutrients do you get energy from?
Carbohydrates and fats
What is your basic energy requirement (BER) and how do you calculate it?
Your BER per day is the energy you need to stay alive you calculate it like this:
5.4 x 24hrs x Body mass(kg)
How do you calculate the total amount of energy you need every day?
Daily BER + energy used for daily activities (kj)
What could happen if you Takenaka more energy than you use up?
You will put on weight and over time this could lead to obesity and obesity could lead to health problems such as heart disease.
What could happen if you don’t get enough food to eat?
This would be called starvation. Starvation can cause slow growth in children and irregular periods in women.
What happens if you don’t get enough vitamins or minerals?
This could cause deficiency diseases. For example, not getting enough vitamin C can cause scurvy. This is a deficiency disease that causes problems with skin and gum.
What is chemical digestion?
Chemical digestion uses enzymes. Enzymes are biological catalysts, this means they speed up chemical reactions in your body.
What is the gullet?
This links the mouth to the stomach.
What type of organisms are bacteria?
Unicellular organisms
Is it normal to have loads of bacteria in your gut?
Yes
What do the bacteria do?
- they make enzymes that help digest food
- they make useful vitamins
- they help to stop harmful bacterial growing in your intestines. Harmful bacteria can make you ill.
How does iodine break up starch in a warm + neutral condition?
It works as normal.
How does iodine work when it’s breaking up big starch molecules in a cold + neutral condition?
It works slightly slower
How does iodine break up starch molecules in a warm + acid condition?
It deforms so it can’t do its job
How does the iodine break up starch in a boiled + neutral condition?
It deforms and it can’t do its jobs
What is mucus used for in the oesophagus and small intestine?
Lubrication
Anus:
Any undigested food passes out of the anus as faeces.
Muscular contractions of the rectum forces the faeces out of the body through the anus.
Mastication
To crush down food inside your mouth; mechanical digestion
Allows the chemicals to get around everything
Mechanical digestion
- breaking down lathe lumps of food into a slurry
- involves chewing (mastication) and the churning action of the stomach and the intestine
chemical digestion
- the breaking down of large molecules into smaller molecules that can pass through the lining of the small intestine into the blood
- this process involves enzymes, which are secreted by several parts of the gut and require the right temperature and pH to work
What enzyme does the stomach produce?
It produces an enzyme called pepsin (type of protease) which only works in acidic conditions which catalysts the breakdown of protein into smaller proteins and amino acids. HCl provides the correct pH for pepsin to work in and kills most of the bacteria on the food.
Small intestine
Duodenum
- where most of the chemical digestion (using enzymes) takes place involving digestive juices from 3 sources
- the walls secrete enzymes and also sodium carbonate (NaHCO3), this neutralises the acid from the stomach so that the enzyme can work
Small intestine
Ileum
-function is to absorbs small molecules formed by digestion
Well adapted for absorption:
-large surface area (300m squared)
-very long (8m) and has folded lining
-lining is covered by finger-like projections called villi
-each cell on the surface of the villi has a “brush border” of even smaller projections called microvilli
-good transport systems
-digested food into blood capillaries
-blood from the gut is carried to the liver, which controls the amount of food in the blood
-thin lining, allows food molecules to diffuse quickly across the lining
Small intestine
Colon
Main function is to reabsorb nutrients.
Evaluation - checklist for good experiments
Fair test
Other factors that could affect the outcome are controlled.
Evaluation - checklist for good experiments
Reliable
Repeats are done and averages are taken.
Evaluation - checklist for good experiments
Realistic values
A situation that is likely to occur in real life is tested.
Evaluation - checklist for good experiments
Conclusion
Your evidence full supports the conclusion you’ve drawn.
Evaluation - checklist for good experiments
Range and intervals
Enough values were tested to see any patterns.
Evaluation - checklist for good experiments
Right variables
The experiment tests the right thing.
Evaluation - checklist for good experiments
Precision
Measurements are taken (to a high enough resolution, more digits).
can enzymes be used again and again?
yes
what does gut bacteria do?
- create nutrients
- breaks down food that the body can’t
what metal do we have a lot of in our body?
calcium
