Biology 1.1 & 1.2

Biology 1.1 & 1.2

1. Balanced Diet

   • A balanced diet it necessary to stay healthy
     • It provides the right balance of different you need and the right amount of energy
   • What makes up a healthy diet?
     • Fats and carbohydrates
       • Provide energy for your body chemistry to function correctly
       • Keep your body temperature at 37 degrees
       • Excessive fats and carbohydrates can lead to obesity
         • A common disorder in developed countries
         • Having a mass of at least 20% greater than the max recommended body mass
         • Overeating, lack of sufficient exercise, bad diet and hormonal problems
         • Can lead to arthritis, type 2 diabetes, high blood pressure, and heart disease
     • Protein
       • Build cells, grow new tissue, repair & replace cells
     • Mineral ions and vitamins
       • Small amounts
       • Healthy functioning of the body
       • Mineral salts containing things like sodium, calcium, potassium and chloride ions
         • Too much salt (sodium chloride) can cause high blood pressure & heart problems
     • Fibre
       • keeps everything running smoothly in your digestive system
   • Malnourishment
     • When a person's diet is not balanced
     • A malnourished person is not necessarily thin - an obese person could be malnourished if they only ate junk food as this is not providing them a balanced diet.
     • MALNOURISHMENT AND STARVATION ARE NOT THE SAME THING!!!!!!
   • Losing weight
     • A person loses mass when the energy content of the food taken in is lower than the amount of energy used by the body
   • Energy
     • Metabolism/Metabolic rate
       • How fast the chemical reactions in your body take place
         • This is your metabolism
         • These reactions are fuelled by energy
       • The amount of exercise you do makes your metabolism vary
     • Energy used by your body
       • Exercise increases the amount of energy used by your body
         • Athletes or people doing heavy manual labour need a higher energy (calorie) intake
           • The amount of fat and carbohydrates you eat should be adjusted

2. Defence against disease

   • Pathogens
     • Microorganisms that cause infectious disease
     • Bacteria
       • What they do
         • Very small cells
         • Rapidly reproduce
           • Cell division
         • Produce toxins
           • What makes you feel ill
       • Antibiotics
         • Help cure bacterial disease
           • Kill infectious bacteria
         • CAN'T TREAT VIRUSES
           • VIRUSES LIVE & REPRODUCE INSIDE THE CELLS
             • CAN'T TREAT THEM WITHOUT DAMAGING THE CELLS
         • Antibiotics like penicillin kill or prevent the growth of harmful pathogens
           • They kill the bacteria but not your own body cells
         • Different antibiotics target different bacteria
           • Specific bacteria should be treated by specific antibiotics
       • Antibiotic resistant strains
         • Overuse and inappropriate use has increased the rate of development of antibiotic resistant strains
           • Important not to over use antibiotics
         • Many strains mutate which causes stronger, more resilient strains of bacteria to survive as a result of natural selection
         • If infections are treated with antibiotics then resistant bacteria will survive
           • This means resistant bacteria can survive and reproduce to infect other people
             • This will then spread rapidly as people are not immune to it and there is no treatment
     • Viruses
       • NOT cells
         • Smaller than bacteria
         • They damage the cells in which they reproduce
           • They replicate by invading a cell and then using the cell's genetic machinery they reproduce themselves as copies of the original virus
             • The invaded cell then bursts releasing lots of new viruses
               • The cell damage is what makes you feel ill as your body fights back to make new 'good' cells to replace those destroyed by the virus
       • Can't be treated by antibiotics
     • Fungi
       • Biggest microorganisms
       • Live in colonies
       • Digest material externally
         • Absorb the nutrients from outside their cells
       • Can be useful or harmful
     • How our body deals with it
       • Has defense systems
         • Skin, hair, mucus stop pathogens entering the body
         • Skin helps as when you get a cut you get a scab over it (small sections of cells called platelets help the blood to clot
         • Tears contain a chemical which kills bacteria on the surface of the eyes
         • The stomach contains HCl acid which kills pathogenic bacteria
       • WHITE BLOOD CELLS
         • Ingesting
           • WBCs surround invasive microorganisms and break them up and ingest them
         • Produce antibodies
           • An antibody is created by WBCs when they encounter a 'foreign' antigen on a pathogen they don't recognise. They produce antibodies which lock onto the antigens of the pathogen
             • The antibodies produced are specific to that type of antigen - they will not lock onto any other type of antigen
             • ANTIGEN
               • All invading cells have unique molecules on their surface - these are antigens
         • One of the most important parts of the IMMUNE SYSTEM
           • Immune system
             • Kicks in when a pathogen gets inside your body
             • Produces specific antibodies to kill a particular pathogen
               • Does this quicker if you have been vaccinated
                 • Injected into you with a inactive or weakened form of a pathogen
                   • The body starts an immune response
                     • Lymphocytes produce antibodies to fight the pathogen
                       • The body remembers how to fight the infection so if you do get infected you can fight it off quicker
                         • CULTURING MICROORGANISMS
                           • You should sterilise everything - petri dish, innocullating loop (by passing through a flame) and agar jelly
                           • The lid of the petri dish should be secured by tape
                           • It should not be incubated over 25 degrees to stop harmful pathogens growing
         • Present throughout your body and always to hand
           • If your WBC count is low you are more susceptible to disease & infection
       • Produces antitoxins
         • These counteract the toxic effect of the toxins released by the pathogen. They are very specific chemicals

3. Nervous system

   • any changes in your surroundings is potentially a detectable stimulus for your sensory organs
     • sensory organs contain receptors that are sensitive to stimuli
     • The nervous system controls our REFLEXES
       • Receptor: sensitive to changes in conditions - stimulated by a stimulus
       • Sensory neurone: the nerve cell connected to the receptor - a message is sent down it by the receptor cell
       • Synapse: the junction between two neurones to keep the signal strong by diffusing chemicals - a message is passed onto it by the sensory neurone
       • Relay neurone: the nerve cell found in the spinal chord - a message is passed down the relay neurone by the synapse
       • Motor neurone: the nerve cell that sends the impulse to the effector - the relay neurone passes the message down the motor neurone
       • Effector: the organ affected by a nerve impulse as a response to a stimulus - the message is passed by the motor neurone to the effector

4. Internal conditions

   • Water content
     • lungs when we breathe out
     • skin when we sweat
     • kidneys in the urine
   • Ion content
     • skin when we sweat
     • kidneys in urine
   • Temperature
     • brain keeps our body at 37 degrees
   • Blood sugar levels
     • via insulin
       • diabetes
         • when your body cannot produce enough insulin to tell your body to reduce glucose
           • Pancreas - controls the use of 2 hormones
           • Insulin - hormone secreted by the pancreas
             • Causes liver to remove any glucose not needed after digestion
           • Glycogen - the liver converts soluble glucose into glycogen to store
           • Glucagon - second hormone secreted by the pancreas
             • tells the liver to convert glycogen back into glucose for use in respiration

5. Hormones

   • Menstrual cycle
   • Plant hormones
   • a hormone is a chemical messenger secreted by a gland carried to the effector cell by the blood