Nutrition and Digestion Flashcards
The basic unit of carbohydrates?
Simple sugars
Examples of monosaccharides:
Glucose
Fructose
Galactose
Examples of disaccharides:
Lactose
Maltose
Sucrose
Examples of polysaccharides:
Starch (a polymer of glucose)
Glycogen (tissues such as liver and muscles)
Why can’t our bodies digest cellulose?
Because our gut doesn’t make the enzyme needed to break down the cellulose molecule
What is the role of cellulose in our diet?
It forms dietary fibre/roughage which gives the muscles of the cell something to push against as the food is moved through the intestine
This keeps the gut contents moving, avoiding constipation and helping prevent diseases such as colitis and bowel cancer
An example of a fat:
Tristearin found in meat
C₅₁ H₉₈ O₆
The basic units of lipids?
3Fatty acids and 1glycerol (glycerine)
What causes kwashiorkor?
Symptoms:
Protein deficiency
A swollen belly, weight loss, flaky skin, poor muscle growth, and weakness
Use of Vitamin A in the body:
Effect of deficiency:
make a light-sensitive chemical in the retina; protects the surface of the eye
Night blindness; damaged cornea
Use of Vitamin B1 (thiamine) in the body:
Effect of deficiency:
Cell respiration
Beri-beri (weakening of muscles and paralysis)
Use of Vitamin B2 (riboflavin) in the body:
Effect of deficiency:
Cell respiration
poor growth, dry skin
Use of Vitamin B3 (niacin) in the body:
Effect of deficiency:
Cell respiration
Pellagra (dry red skin, poor growth and digestive disorders)
Use of Vitamin C in the body:
Effect of deficiency:
Needed to make fibres of connective tissue - sticks together cells in the lining surfaces of the body
Scurvy
Use of Vitamin D in the body:
Effect of deficiency:
Absorbs calcium and phosphate
Rickets, poor teeth
Test for Vitamin C:
Add 1cm³ of DCPIP solution to a test tube
Add a small amount of food sample (as a solution)
A positive test will show the blue colour of the dye disappearing
- If the Vitamin C solution is very concentrated it will take a few drops to remove the colour.
- If the Vitamin C solution is weakly concentrated then a lot of drops are needed to remove the colour.
Test for glucose (reducing sugar):
*Sucrose isn’t reducing sugar
Add Benedict’s solution into sample solution in a test tube
Heat at 60 – 70 °c in a water bath for 5 minutes
Take test tube out of the water bath and observe the colour
A positive test will show a colour change from blue (CuSO₄) to brick red (CuO)
Test for protein:
Sample: powdered egg white»_space;> dissolve
Add Biuret solution (CuSO₄ + KOH)
Positive test: blue to purple
Test for lipids:
The food sample is mixed with 2cm³ of ethanol and shaken until dissolved
The solution is added to a test tube that is ¾ filled with cold water
A positive test will show a cloudy layer at the top of the water and suspension of tiny droplets called an emulsion
Measuring the energy content of food:
Improvements:
Variables:
Measure the mass of your food sample
Add the measured amount of water to a boiling tube and place a thermometer in it to find the initial temperature
Place food sample on a mounted needle and set it alight using a burner
Place the burning sample underneath the boiling tube
Calculate the increase in temperature
Energy (J) = mass of water x c (4.2 J⁰C) x change in temperature
Improvements: repeat, test more foods, set up a barrier to reduce heat loss
Control: the mass of food, the SA of food
Define digestion:
Digestion is a mechanical and chemical process where large insoluble food molecules are broken down into small, soluble molecules that can be absorbed into the blood
Two layers of muscles in the oesophagus:
Circular muscles
Longitudinal muscles
Muscle movement to make the oesophagus narrow?
Circular contract
Longitudinal relax
Break down of carbohydrates:
Amylase (salivary gland, pancreas):
starch ➡ maltose
Maltase (wall of the small intestine):
maltose ➡ glucose
Break down of proteins:
Pepsin (stomach wall):
proteins ➡ peptides
Trypsin (pancreas):
proteins ➡ peptides
Peptidases (wall of the small intestine):
Peptides ➡ amino acids
Break down of lipids:
Lipases (pancreas):
lipids ➡ fatty acids and glycerol
pH requirement for protease:
Acidic - 2
The function of bile:
- Emulsification of large lipid globules into tiny droplets
- Neutralisation of acidic semi-digested food
Adaptations of the ileum:
- Length of the small intestine calls for a large SA which is aided by folds.
- The greatest increase is due to the large amounts of villi and microvilli
- Villi contain a network of blood capillaries (quick absorption) and lacteal (for products of fat digestion)
- Surface of the villi is made up of a single layer of epithelial cells (short diffusion distance)
- Mitochondria for active transport
- Villi are in constant motion: contact with the products of digestion and creates a steep conc. gradient for diffusion
- These blood capillaries join together leading up to the hepatic portal vein to the liver
Diseases that can be contracted due to obesity
CHD
Diabetes
How do you calculate BMI?
Mass in kg/(height in m)²
Some bacteria that are transmitted in food and cause diseases:
Salmonella typhi ➡ typhoid fever
Salmonella entrica ➡ salmonellosis
Listeria ➡ listeriosis
Clostridium botulinum ➡ botulism
Ways of food preservation:
Salting Pickling Pasteurization Canning UHT Irradiation Drying Freezing
Structure of teeth:
Enamel ➡ Dentine (cytoplasmic strands) ➡ Pulp cavity (blood vessels and nerves) ➡ Root (cement containing fibres attaching to the jawbone)
Ways to prevent tooth decay:
- Brushing your teeth (short bristles to reach crevices)
- Dental floss
- Flouride (strengthens the enamel)
- Healthy balanced teeth
- Avoid sugary drinks and sweets
How do the bacteria act on your teeth?
- Dental caries
- Periodontal disease - gums become inflamed and so sensitive that they bleed when brushed. can lead to loss of teeth
Plaque (invisible layer) ➡ 24 hrs ➡ (if left on the teeth ) tartar (hard deposit)
