Digestion Flashcards
What is digestion?
The breakdown of large insoluble food molecules into smaller, more soluble molecules that can be diffused into the blood
What does the mouth do in digestion?
It’s where food enters the alimentary canal and digestion begins
What’s the oesophagus do?
Muscular tube that moves ingested food to the stomach
What does the stomach do?
Muscular organ where digestion continues
What does the pancreas do?
Produce digestive enzymes
What does the liver do?
Produced bile
What does the large intestine (rectum) do?
Where faeces are stored until ready to leave the body
What does the small intestine (duodenum) do?
Where food is mixed with digestive enzymes and bile. Digestion is completed and digested food is diffused into the bloodstream
What does the gall bladder do?
Stores bile before releasing it into the duodenum
What des the salivary glands do?
Produces saliva containing amylase
What are the first 3 steps to the digestion process?
- food enters the digestive sustem through the mouth. This process is called ingestion
- once in mouth, food is chewed to form a ball of food called a bolus
- this passes down the oesoghagus and into the stomach
What process is food moved through the tubes of the digestive system called?
Peristalsis
What is peristalsis?
- muscles in the gut wall are involved, circular muscles and longitudinal muscles work together to produce wave like contractions
- these have a squeezing action that pushes the bolus through the gut
What happens after peristalsis in the gut?
Food is digested through mechanical and chemical processes
What is mechanical digestion?
Chewing in the mouth
Churning in the stomach
What is chemical digestion?
Involves enzymes, (proteins that function as biological catalysts) form part of digestive juices produced in glands
What do all organs in the digestive system have?
Epithelial tissue, which covers the stomach inside and out
What does the epithelial tissue allow the stomach to do?
Protects the stomach, helps keep its structure and allows substances to be exchanged through it
What does the stomach produce? What does it do?
Produce hydrochloric acid
Kills harmful microorganisms that may have been swallowed with food
Where do enzymes in the stomach work best?
In acidic conditions- at a low pH 1-6
Where does the food go after it has been in the stomach?
Food travels to the small intestine
Where do the enzymes in the small intestine work best in?
Alkaline conditions pH8-14
What is bile? Where is it produced and stored?
A substance produced by the liver and stored in the gall bladder
What two effects does Bile have in the small intestine?
1) . Neutralises the acid - providing alkaline conditions needed in the small intestine
2) . Emulsifies fat - providing a larger surface area over the enzymes can work
What is absorption?
The movement of digested food molecules through the wall of the intestine into the blood and lymph l
Which region is digested food absorbed?
Small intestine
What does the small intestine have for absorption?
Large internal surface area for absorption to happen quickly and efficiently
What are villi?
Tiny finger shaped structures that increase the surface area.
What 3 features do Villi have?
1) . Wall just one cell thick - ensures there is only a short distance for absorption to happen by diffusion
2) . Network of blood capillaries- transports digested food eg glucose away from the intestine in the blood
3) . Internal structure a lacteal - transports fatty acids and glycerol from the small intestine in the lymph
What does the remaining material of ‘digested food’ consist of after absorption?
Water, bacteria (living&dead), cells from the lining of the gut and indegestable substances eg cellulose from plant cell walls
What does the large intestine do?
Abosrb most of the remaining water
What does the remaining mateial leave as it has been going through the large intestine?
Leaves a semi sold waste material called feaces
Where do the faeces get stored?
In the rectum
What is Egestion?
When the faeces passes out of the body through the anus
What are enzymes?
A biological catalyst that helps to speed up chemistry reactions
What is the area within the enzyme called?
A active site
What are the smaller molecules that fit into the active site called? What does it do?
Substrate
A chemical reaction takes place
What do the active site and substrate molecules have? How do they fit?
Have complementary shapes which fit together like a lock and key
What is amylase? What does it catalyse the breakdown of and what into?
Type of carbohydrase, catalyses the break down of starch into sugar
Where does amylase work?
Mouth and small intestine
What does lipase catalyse the breakdown of and what into?
Catalyse the breakdown of fats and oils, into fatty acids and glycerol
Where does lipase work?
Small intestine
What does protease catalyse the breakdown of and what into?
Catalyses the breakdown of proteins into amino acids
Where does protease work?
Stomach and small intestine
What happens to the enzyme if it changes shape?
The active site may no longer work, the enzyme has been denatured
What two things can enzymes become denatured by?
High temperature and extreme pH
What is enzyme activity like with temperature upto 37degrees?
Its gradually increases
What happens to enzymes when temperature rise above 40degrees?
The rate of reaction falls rapidly
What does heat energy do to the structure?
Damages the enzyme structure, this changes the shape of the active site wich dentaures the enzyme
What does the optimum pH for an enzyme depend on?
Depends on where it normally works
What happens to the enzyme if the pH is different to its optimum?
Damges the enzymes structure, which leads to the enzyme changing the shape of its active site which denatures the enzyme
What is protease used for in industry?
Used to pre-digest proteins during the manufacture of baby foods
What is lipase used in industry?
In biological detergents with protease to break down stains into small water soluble substances
What is carbohydrase used in industry?
Convert starch into syrup which is relatively cheap and then into sugar syrup in sports drinks
What is isomerase used in industry?
Convert glucose syrup into fructose syrup so it can be used in smaller amounts in slimming foods
What do enzymes in industry allow companies to do?
Reduce the need for expensive equipment as enzymes allow reactions at normal room temperature and pressures
What are the benefits of enzymes in industry?
Cuts costs
Better for the environment since it reduces the amount of fuel and equipment needed
What are the disadvantages of enzymes in industry?
Are expensive to produce and can be denatured
What is the test for sugars?
Benedicts test
- if sugar is present it will change from blue to green, or yellow to brick red depending on amount of sugar present
What is the test for starch?
Iodine solution
- if starch is present it will change from browny orange to black or blue-black
What is the test for proteins?
Biuret test
- if protein in present it will change from blue to pink or purple
What is the test for lipids?
Sudan III
- if lipids are present, mixture will separate into two layers, top layer will be red
- (if nothing is present no red layer will form)
