B1 Revision Guide
B1 Revision – Healthy Bodies
Diet and Exercise
· Components in a balanced diet –
o Carbohydrates – the main source of energy.
o Fats – important for energy storage and forms the main part of cell membranes.
o Proteins – important for growth and repair.
o Vitamins and minerals – to keep healthy – eg vitamin A for good vision and calcium for bones.
o Water – maintains fluid levels to prevent dehydration.
o Fibre – indigestible and maintains a healthy digestive system.
· Malnutrition – occurs when a balanced diet is not maintained – can include being overweight or underweight, or lacking a particular vitamin or mineral (deficiency disease).
· Metabolism –
o Metabolic rate – the speed at which your body uses energy released from food in chemical reactions.
o Basal metabolic rate - the rate at which you use energy at rest.
o A higher muscle to fat ratio due to exercise increases metabolic rate.
o Metabolism decreases with age.
o Metabolic rate is affected by inherited factors.
· Cholesterol – a fatty substance that increase risk of diseases of the heart and blood vessels – the level of cholesterol depends on inheritance and the amount of fat in the diet.
· Pathogens are microorganisms (bacteria/viruses/fungi) that cause diseases.
· Bacteria and viruses spread through the air, food, water and by touch, as well as through the placenta when a woman is pregnant.
· Pathogens make us ill by releasing toxins (poisonous chemicals), causing symptoms such as headaches, fever and feeling sick.
· Bacteria can double in numbers rapidly
· Viruses enter your cells and use chemicals inside the cell to make copies of themselves before they burst out and infect other cells.
· Important discoveries about pathogens –
o Ignaz Semmelweiss – concluded that fewer women died of ‘childbed fever’ when doctors handling dead bodies washed their hands with chlorinated soap before delivering babies
o Louis Pasteur – proved that there were germs in the air that carried disease.
· Antiseptics – chemicals used to clean wounds to prevent entry of microorganisms into the body.
· Disinfectants – chemicals used on surfaces to kill pathogens.
Defence against Disease
· Some white blood cells ingest pathogens – they take them into the cell and digest them with enzymes.
· Other white blood cells make antibodies – chemicals that attach to pathogens and destroy them, or antitoxins that prevent toxins from poisoning the body.
· Specific antibodies are made for specific pathogens – so a flu antibody would destroy the flu virus, but not the measles virus.
· If you are infected with the same pathogen again, your white blood cells can produce the right antibodies much faster as they recognise the pathogen – this kills the pathogen before it causes symptoms, so you…