B3 Organisation and the digestive system Flashcards
Mouth
Teeth grind the food into smaller pieces. Salivary glands produce saliva containing amylase
Oesophagus/gullet
muscular tube which moves ingested food to the stomach
Peristalsis
The relaxing and contracting of the muscles
Stomach
Muscular walls pummel the food. Food is mixed with enzyme pepsin. Contains hydrochloric acid
Amylase
Helps convert starch to glucose
Pepsin
Breaks down proteins
Hydrochloric acid in the stomach
creates optimal pH 2 condition for protease enzymes and kills bacteria
Small intestine
produce protease, amylase and lipase enzymes to complete digestion. This is where the food is absorbed out of the digestive system into the blood
Adaptations of small intestine
covered in villi to increase surface area, has a good blood supply and short diffusion distances to the blood vessels
Large intestine
Where excess water is absorbed from the food
Liver
Where bile is produced
Function of bile
neutralises stomach acid and emulsifies fats
Emulsify
breaking up fat globules into smaller droplets
Pancreas
Produces protease, amylase and lipase enzymes and releases these into the small intestine
Rectum
where the faeces are stored before they pass out of the anus
Gall bladder
where bile is stored before it is released into the small intestine
what do proteins contain?
carbon, hydrogen, oxygen and nitrogen.
what are carbohydrates and fats made up of?
carbon, hydrogen and oxygen.
Carbohydrates
Carbohydrates provide energy. There are two types - simple and complex. All carbs are made up of units of sugar
simple carbohydrates
they are sugars, like glucose and lactose. They are a fast acting source of energy, like biscuits or energy bars
complex carbohydrates
they are a source of slow release energy, like rice and pasta.
examples of complex carbohydrates
Cellulose, starch and glycogen are complex carbohydrates. They are long chain of sugars joined together.
Lipids
They are the most efficient energy store in the body. When combined with other molecules, lipids are very important in the cell membrane, as hormones, and in the nervous system
What are lipids made up of?
three molecules of fatty acids joined to a molecule of glycerol. The glycerol is always the same but the fatty acids vary.
Protein
Molecules that contain carbon, hydrogen, oxygen and nitrogen and are made up of long chains of amino acids. They are used for building the cells and tissues of the body and to form enzymes
what is protein made up of?
Proteins are made up of long chains of amino acids.
Contain carbon, hydrogen, oxygen and nitrogen
what do proteins do?
they act as…
structural components of tissues such as muscles and tendons, hormones such as insulin, antibodies, and enzymes
reagent
a chemical that indicates the presence of a substance, usually by changing colour
Starch test
add a few drops of iodine to food solution
brown-orange to blue-black
Lipid test
Add ethanol to the food to dissolve the fat then add water.
Colourless to white emulsion
Sugar test
Add Benedict’s reagent to the food and boil in a water bath.
Blue (minimum) to brick red (maximum)
Protein test
Add Biuret reagent to the food.
blue to purple
Enzymes
large protein molecules which catalyse chemical reactions.
What are enzymes made up of?
long chains of amino acids folded to produce a uniquely shaped active site
Active site
the part of the enzyme to which a specific substrate can attach or fit on to
Lock and key theory
model which compares the specificity of enzymes with a key and its lock
Metabolism
the sum of all the reactions in a cell or in the body
affect of temperature on enzyme action
the rate of enzyme-controlled reactions increases as the temperature increases, however this only true for humans up to about 40 degrees c.
what happens to the enzyme if it is too hot?
the long amino acid chains begin to unravel, and as a result, the shape of the active site changes.
denature
to change the shape of an enzyme’s active site. Denatured enzymes no longer work.
effect of pH on enzyme action
A change in pH affects the forces that hold the folded chains in place and changes the shape of the molecule. Different enzymes work best at different pH levels
carbohydrases
enzymes that break down carbohydrates into simple sugars
proteases
enzymes that catalyse the breakdown of proteins to amino acids
lipases
enzymes that catalyse the breakdown of lipids to fatty acids and glycerol
effect of pH RP
place drops of an amylase, buffer and starch solution into the iodine on the spotting tile at intervals and record the time taken for the disappearance of starch (when the iodine remains the original colour)
stomach protease enzymes
work best in acid conditions. The stomach produces hydrochloric acid, which maintains a low pH
pancreas and small intestine enzymes
work best in alkaline conditions
What is a tissue?
a group of cells with similar structure and function working together
What is an organ?
collections of tissues
