B3 Digestive System Flashcards
Tissue
A group of cells with similar structures and functions working together
Organs
Collections of tissues performing specific functions
Organ system
Group of organs working together to form organisms
Muscular tissue: function
Able to contract to bring about movement
Glandular tissue: function
Able to produce and release substances such as enzymes and hormones
Epithelial tissue: function
Covers the outside of the body and internal organs - protective layer
What is digestion?
Large food molecules are broken down into smaller ones which can be absorbed into the bloodstream
- Starch -> Glucose
- Proteins -> Amino Acids
- Lipids -> Fatty Acids and Glycerol
What are the organs in the digestive system? (in order)
- Mouth
- Oesophagus
- Stomach
- Small Intestine
- Large Intestine
- Anus
Food does not go through here but is still part of the digestive system - Liver
- Pancreas
What happens in the mouth?
Food is chewed by teeth and mixed with saliva
How is the mouth adapted for absorption?
Food is broken down into smaller pieces by teeth and enzymes in saliva start to break down starch
What happens in the oesophagus?
Food is pushed down into the stomach
How is the oesophagus adapted for absorption?
Stretchy and muscular -> pushes food down even when you’re upside down - Peristalsis
What happens in the stomach?
Food is churned with acids and enzymes
How is the stomach adapted for absorption
- Acids kill bacteria -> Walls protected by mucus
- Enzymes break food into smaller pieces
What happens in the small intestines?
- Enzymes finish breaking down most food
- Food is absorbed through the walls into the bloodstream
How are the small intestines adapted for absorption?
Villi on the wall gives it a large surface area -> faster rate of diffusion
What happens in the large intestines?
Water is absorbed from undigested food
How are the large intestines adapted for absorption?
Contains millions of bacteria which break down undigested food
What happens in the anus?
Waste gets excreted
How is the anus adapted for absorption?
You can control the muscles which open and close it
What happens in the liver?
Bile is produced which:
- Neutralises food exiting the stomach (acidic)
- Break down fat into smaller pieces to increase surface area for lipase to work
What do carbohydrates contain?
Carbon, hydrogen, oxygen
What are simple carbohydrates?
Contains one or two sugar units -> glucose (1) or sucrose (2)
What are complex carbohydrates?
Long chains of simple sugars bonded together like starch or cellulose
Where can carbohydrates mainly be found?
Bread, potatoes, rice, and pasta
What is glucose used for?
Cellular respiration
What are lipids?
It is an energy store in the form of solid fats or liquid oil
What do lipids contain?
Carbon, hydrogen, oxygen. They are insoluble in water
Lipids in the nervous system and cell membrane
They are important because they act as hormones
What are lipids made out of?
3 fatty acids joined to a glycerol
Where can lipids be mainly found?
Olive oil and corn oil, butter, cream, and cheese
What do proteins contain?
Carbon, hydrogen, oxygen, nitrogen
Where can proteins mainly be found?
Meat, fish, pulses, and cheese
What are proteins made of?
Long chains of amino acids. Different amino acids give them different functions.
What is a polymer?
Large molecule made of smaller molecules joined together. The smaller molecules are called monomers.
What reagent is used to test for glucose?
Benedict solution
What reagent is used to test for protein?
Biuret solution
What reagent is used to test for lipids?
Ethanol
What reagent is used to test for starch?
Iodine
How do you test for protein?
Add biuret to food sample. If positive, the colour will turn purple
How do you test for lipids?
Add ethanol to food sample. If positive, the colour will turn milky white (no lipids = clear solution)
How do you test for glucose?
Add benedict to food sample. Place in a beaker of hot water. If positive, the colour will turn: Blue -> Green -> Yellow -> Orange -> Brick Red (intensity)
How do you test for starch?
Add few drops of iodine to food sample. If positive, the colour will turn from orange to blue or black
How are proteins used in our bodies?
They act as:
- Structures like muscles and tendons
- Hormones such as insulin
- Antibodies which destroy pathogens
- Catalysts in the form of enzymes
Where and what are proteins made from?
Made in the ribosomes. Made of amino acids
What is a catalyst?
A chemical which speeds up a reaction. They are never used up and can be reused
What are enzymes and what are they made up of?
Biological catalysts which speed up reactions in the body. They are large arrangements of proteins with a specific shape and active site.
What do enzymes do to a reaction?
Speeds up a reaction but it does not get involved with the reaction.
What can enzymes do? (not as a catalyst)
- Build larger molecules from smaller ones
- Changing one molecule into another
- Breaking down larger molecules into smaller ones
Why are enzymes specific?
They have different shapes and active sites. The shape of an active site is complementary to the shape of its specific substance.
Why do we need enzymes in digestion?
To break down molecules in our food so they can be absorbed into our bloodstream through diffusion
How does a reaction start to take place?
When the reactants collide with enough energy to start the reaction
How can the rate of reaction increase?
- Increase temperature/pressure
- Increase surface area of reactants
- Increase concentration of reactants
- Add a catalyst
What are the factors affecting enzymes?
Temperature and pH scale
Enzymes in relation with temperature
As the temperature increases, the enzymes work faster. Once past the optimum temperature, they become denatured. At colder temperatures, they work slower but don’t denature
What happens to the rate of reaction when the temperature of an enzyme reaches too high?
Shape changes from the temperature -> becomes denatured
What does it mean for enzymes to become denatured?
Their shape is changed due to temperature or pH level, therefore they can no longer catalyse reactions.
Enzymes in relation with pH level
Each has their own pH tolerance. At a too high or low pH level from optimum causes them to denature
What does bile do?
- Neutralise the stomach acid as food leaves the stomach
- Emulsifies fat to form droplets that increase surface area
Where is bile produced and stored?
Made in the liver. Stored in the gallbladder
What does the pancreas do?
Releases enzymes into the small intestines
Where is amylase produced?
- Salivary Glands
- Pancreas
Where is amylase used?
- Mouth
- Small Intestines
Where is protease produced?
- Stomach
- Pancreas
- Small Intestines
Where is protease used?
- Stomach
- Small Intestines
Where is lipase produced?
- Pancreas
- Small Intestines
Where is lipase used?
Small intestines
