Keeping Healthy (nutrition) Flashcards
What is a nutrient?
Nutrients are molecules which the body needs for many functions.
What is a balanced diet?
If we eat a balanced diet, we are eating different foods and nutrients in the correct amounts.
What are the impacts of an unbalanced diet?
- suffer from malnutrition
- lack of fibre -> constipation
- lack of protein -> poor growth and repair
- too much carbohydrate -> overweight/bad teeth
What is protein?
- The main structures of our bodies are made of protein
- we need protein for growth and repair
- many immune and digestive functions rely on proteins
- a test with Biret solution turns purple
- e.g. meat, milk, cheese, eggs, nuts
What are carbohydrates?
- carbohydrates give us energy
- starches turn blue or black in a test with Iodine solution
- e.g. bread, rice, pasta
- sugars give a red precipitate in a test with Benedict’s solution
- e.g. sweets, cakes
What are fats?
- contain about twice the energy of carbohydrates and protein
- also used in cell membranes
- test with Ethanol, gives a white emulsion
- e.g. butter, oils, cheese
What is fibre?
- used in cellulose (cell wall of plants)
- we cannot digest it
- keeps our intestines clean and healthy
- unblocks the intestine
- e.g. whole meal foods, fruit and veg
What causes obesity?
Too many calories
What causes heart disease?
Too much saturated fat
What causes high blood pressure?
Too much saturated fat/salt
What causes diabetes?
Too many sugary foods
What causes deficiency diseases?
Lack of a particular nutrient
What causes rickets?
Lack of vitamin D
What causes scurvy?
Lack of vitamin C
What causes anaemia?
Lack of iron
What is digestion?
The process by which food is broken down into smaller molecules so that it can be absorbed by the body.
What parts of the body are used in digestion?
- Gullet/oesophagus
- stomach
- small intestine
- large intestine (colon)
- rectum
What is the gullet/oesophagus?
- when you swallow, the trachea is closed
- the muscles in the wall of the gullet contract when they are above the food
- this pushes food to the stomach, through a process called peristalsis
What is the stomach?
In the stomach, food is churned up by highly concentrated Hydrochloric acid of pH 1-2
The muscles inside the stomach are able to withstand this constant exposure to acid.
What is the small intestine?
- nutrients in food are made up of molecules
- large molecules are broken down by digestive enzymes and absorbed through the wall of the small intestine
- contains ~1kg of bacteria
- lines with Villi
What are villi?
- a villius is a hair-like structure
- thin
- good blood supply
- give the small intestine a large surface area, which helps with absorption
What is the large intestine?
- Food that cannot be digested in the small intestine is squeezed through here
- the water is removed
- Any solid material that is left becomes faeces
- about 60% of faeces is dead bacteria
- contains the appendix, which is an evolutionary artefact. When pathogenic bacteria in the intestines are killed, some beneficial bacteria may hide here (just a theory)
What is the rectum?
- faeces are stored here
- deposited by anus
- process called egestion
- ingestion -> egestion transit time is approximately 24-28 hours
- the guy is 8 metres long
What is absorption?
- only small, water soluble molecules can be absorbed through the small intestine
- these are vitamins, minerals and sugars (glucose, sucrose, etc.)
- fats, proteins and starches need to be broken down properly
- this is done by digestive enzymes
What are digestive enzymes?
A digestive enzyme is a chemical (protein) that breaks down large protein, carbohydrates and fat molecules into smaller molecules that can be absorbed by the body via the small intestine.
What are the three main digestive enzymes and what do they do?
- amylase breaks down starches into glucose
- lipase breaks down fats into fatty acids and/or glycerol
- protease breaks down proteins into amino acids
