Digestion Flashcards
What are carbohydrates used for?
Store of Energy
Fuel for Respiration (glucose is a carb)
What are Proteins used for?
Growth and repair of cells/tissues
Fuel for respiration
What are Lipids used for
Thermal insulation
Store of energy
Fuel for respiration
What is water used for?
Regulating temperature
Used to transport substances in blood plasma
What is fibre used for?
It is mainly cellulose
Helps movement of food through small intestine
Prevents constipation and bowel cancer
Protein –>
(Peptides) –> Amino acids
Carbohydrates (Starch) –>
(Maltose) –> Glucose
Lipids –>
Glycerol + Fatty acids
Which enzyme breaks down protein into peptides, where is it made and where does it act?
Protease - Pepsin made in Stomach
Acts in stomach
Which enzyme breaks down peptides into amino acids, where is it made and where does it act?
Protease - Trypsin made in Pancreas
Acts in small intestine
Which enzyme breaks down starch into maltose, where is it made and where does it act?
Carbohydrase- Amylase made in pancreas and salivary glands
Acts in mouth and small intestine
Which enzyme breaks down maltose into glucose, where is it made and where does it act?
Carbohydrase - Maltase made in Pancreas
Acts in small intestine
Which enzyme breaks down Lipids into fatty acids and glycerol, where is it made and where does it act?
Lipase made in Pancreas. Acts in the small intestine.
Bile (not an enzyme) emulsifies lipids. Bile is made in the liver and acts in the small intestine.
What are the functions of bile?
To neutralise stomach acid (optimum pH for enzymes)
To emulsify lipids (increase surface area for digestion)
How is the small intestine adapted for diffusion?
Large Surface Area - Folds in walls, many villi and microvilli.
Short diffusion distance - Villi walls are once cell thick, each villus has its own set of capillaries.
High concentration gradient - Capillary network and lacteals removing absorbed molecules.
Why doesn’t amylase work in the stomach?
The enzyme is denatured as the stomach acid is too acidic, not the right pH.
Why might someone with Anaemia feel tired?
Lack of iron, less haemoglobin made, less oxygen carried, less aerobic respiration, less energy
What is the purpose of digestion?
To break down large ,insoluble molecules into into smaller ,soluble molecules that can be absorbed into the blood stream.
What can we do to improve limitations of the Energy Content in a food sample practical?
(Paper 2)
Incomplete burning of the food sample - Relight it until it no longer lights up
Heat energy is lost to the surroundings - Whilst heat lost means that the energy calculation is not very accurate, so long as the procedure is carried out in exactly the same way each time (with the same distance between food sample and boiling tube), we can still compare the results
Describe the Energy content in a food sample practical. (Paper 2)
Use the measuring cylinder to measure out 25cm3 of water and pour it into the boiling tube
Record the starting temperature of the water using the thermometer
Weigh the initial mass of the food sample
Set fire to the sample of food using the bunsen burner and hold the sample 2cm from the boiling tube until it has completely burned and won’t ignite.
Record the final temperature of the water and calculate temperature change.
Repeat the process with different food samples
e.g. popcorn, nuts, crisps
How is the small intestine adapted for absorption?
Large Surface Area - Many microvilli
Short diffusion distance - Villi’s walls are one cell thick.
Steep Concentration Gradient - The villi are well supplied with a network of blood capillaries that transport glucose and amino acids away from the small intestine in the blood
A lacteal runs through the centre of the villus to transport fatty acids and glycerol away from the small intestine.
In which part of the small intestine are digested food molecules absorbed?
Ileum
In which part of the small intestine does chemical digestion occur?
Duodenum
Which enzymes are made in the pancreas?
Trypsin, lipase, maltase and amylase
What is iron used for?
Forms part of haemoglobin which binds to oxygen
What is the deficiency disease for iron?
Anaemia
What is calcium used for?
Needed to form bones and teeth
What is the deficiency disease for calcium?
Rickets (weak bones)
What is vitamin A used for?
Making a chemical in the retina and also protects the surface of the eye
What is the deficiency disease for vitamin A?
Night blindness and damaged cornea
What is vitamin C used for?
Needed for cells and tissue to stick together
What is the deficiency disease for vitamin C?
Scurvy
What is vitamin D used for?
Needed to absorb calcium and phosphate ions from food
What is the deficiency disease for vitamin D?
Rickets, caused by weak bones (lack of calcium)
Source of carbohydrate
Bread, potatoes
Source of protein
Meat, eggs
Source of lipids
Butter, cooking oil
Source of iron
Red meat, spinach
Source of calcium
Milk, cheese
Source of vitamin A
Fish liver oil, carrots
Source of vitamin C
fruit, vegetables
Source of vitamin D
milk, oily fish
Where is bile made, stored and used?
Made in the liver, stored in the gall bladder and used in small intestine
What process allows food to move through the gut?
Peristalsis
What is peristalsis?
Muscles push food through the alimentary canal.
Circular and longitudinal muscles contract and relax.
Source of dietary fibre
Fruits, vegetables
Describe the organs that make up the human alimentary canal
Mouth
Oesophagus
Stomach
Small Intestine (duodenum and ileum)
Large intestine (colon and rectum)
Pancreas
Describe the energy requirements of males compared to females
Males require more energy as they have larger proportion of muscle than fat
Describe the energy requirements of young people compared to older people
Amount of energy increases towards adulthood as it is needed for growth.
Children require more energy than adults. Energy needs of adults decrease as they age.
Describe the energy requirements of an active person compared to a less active person
Active person requires more energy for movement as muscles are contracting more and respiring faster.
Describe the energy requirements of a pregnant woman
Energy requirements increase as energy is needed to support the growth of the developing fetus, as well as the larger mass that the mother needs to carry around. Extra calcium and iron are also needed in the diet to help build the bones, teeth, and blood of the fetus
Describe the energy requirements of a breast-feeding woman
Energy requirements increase and extra calcium is still needed to make high-quality breast milk
