Nutrition in humans Flashcards
The mouth, stomach and duodenum all use what to break down food?
Enzymes
What happens in the ileum?
Digested food is absorbed
What happens in the colon?
Remaining water is absorbed
Where is faeces stored?
The rectum
What is peristalsis?
Behind the food circular muscles contract and radial muscles relax, squeezing the gut. Around the food radial muscles contract and circular muscles relax, expanding the gut
Sources of carbohydrates?
Starch in plants (potatoes, rice, wheat and millet), sugars in fruit and veg (sucrose and fructose) and processed food/drink (coca-cola, sweets and biscuits)
Function of carbohydrates?
Source of energy
Sources of proteins?
Meats, fish, cheese, eggs, beans, peas and nuts
Functions of proteins?
Growth and repair; Helps to form enzymes
Sources of lipids?
Meat, butter, cheese, milk, eggs, oily fish, olive oil, corn oil, rapeseed oil and margarine
Functions of lipids?
- Essential to form cell membrane
- Used for long-term energy store
- Thermal insulation
- Protection from mechanical damage
Sources of vitamin A?
Fish liver oils, livers, butter, margarine and carrots
Function of vitamin A?
Makes light-sensitive chemicals in retina
Sources of vitamin C?
Fresh fruit and veg
Functions of vitamin C?
Makes fibres of connective tissues in blood vessels and skin; Helps stick cells together
Sources of vitamin D?
Fish liver oils and sunlight
Function of vitamin D?
Helps bones grow by taking up calcium salts and phosphates
Sources of calcium?
Dairy products, fish, bread and veg
Function of calcium?
Makes teeth and bones
Sources of iron?
Red meat, liver, eggs and spinach
Function of iron?
Makes haemoglobin
Sources of fibre?
Fruit, veg and wholegrain plant matter
Function of fibre?
Provides something for the gut muscles to push against
Sources of water?
Water
Functions of water?
A solvent for chemical reactions; Transfers heat efficiently
Digestive action of amylase?
Starch to maltose
Digestive action of maltase?
Maltose to glucose
Sources of amylase?
Salivary glands and pancreas
Source of maltase?
Wall of small intestine
Where amylase acts?
Mouth and small intestine
Digestive action of pepsin?
Proteins to peptides
Digestive action of trypsin?
Proteins to peptides
Digestive action of peptidase?
Peptides to amino acids
Source of pepsin?
Stomach wall
Source of trypsin?
Pancreas
Source of peptidase?
Wall of small intestine
Where pepsin acts?
Stomach
Where trypsin acts?
Small intestine
Where peptidase acts?
Small intestine
Digestive action of lipase?
Lipids to glycerol and fatty acids
Source of lipase?
Pancreas
Where lipase acts?
Small intestine
Where is bile produced?
Liver
Where is bile stored?
Gall bladder
What does bile do?
Neutralises stomach acid and emulsified lipids
Why does the ileum have a large surface area?
To maximise absorption
What do epithelium cells contain?
Contain many mitochondria for active transport and have many microvilli to further increase surface area
What do capillaries do?
Absorb nutrients into blood stream
What does lacteal do?
Absorbs fat products and tiny fat droplets into the lymphatic system
Why does each villi contain a muscle fibre?
To constantly move it so it remains in contact with the contents of the ileum and maintains a steep concentration gradient
Describe an experiment to measure the energy content of a food?
- Weigh the food sample; 2. Measure 20cm cubed of water into a boiling tube and clamp it with a thermometer inside and record the temperature; 3. Spear the sample on the end of a mounted needle and light it; 4. Hold the burning food underneath the boiling tube, relighting it if it goes out, until the food will no longer burn; 5. The final temperature of the water is measured; 6. Energy in J per g = (final temp - initial temp)x20x4.2/mass of sample
