Biology revision

Health
1. Diet
  1. Carbohydrates - slowly release energy and glucose ( bread , paste , potatoes ) produces sugars when digested.
  2. Fats ( lipids ) - quick rushes of energy ( chocolate, sweets, chips ) produces fatty acids and glycerol when digested.
  3. Vitamins - vitamins A , D , E and K are all fat soluble vitamins( fruits , citrus fruits , vegetables ) .
    1. Protiens - used for growth and repair , also to build muscles( meat , fish , beans ) , produces amino acids when digested.
    2. Fibres - to help with digestion ( rice , potatoes , breakfast cereals ).
  4. Minerals - iron/calcium ( fruits , water , vegetables).
  5. Water - removes body toxins.
2. Key words
  1. Malnourished - not having enough to eat or having to much to eat.
  2. Metabolic rate - refers to the rate of which the chemical reactions take place in cells.
  3. Deficiency - when you have to little of something.
  4. Obesity - when a person is severely over weight.
Deficiency Diseases
1. Scurvy - is a condition caused by a prolonged deficiency of vitamin C ( ascorbic acid ) in the diet . vitiman C plays a major part in the forming of your collagen , and a major cmponent of connective tissue. Symptoms of scurvy are fatigue , loss of appetite , nausea/diarrheoa and the loss of hair follicles
2. Rickets - is a defective mineralization of bones before epiphyseal ( the rounded end of a long bone) closure of immature mammels due to deficiency or impaired metabolism of vitamin D, phosphores ( non-metalic chemical element ) or calcium leading to potential fractures and/or deformities.rickets occurs in adults but is mainly found in children.
3. Deficiency diseases can be passed on to offspring if they inherit the diseases factors.
Disease
1. Key words
  1. Infectious disease - disease which can be passed from one individual to another.
  2. Microorganism - beacteria , viruses and other organisms that can only be seen using a microscope.
    1. White Blood Cells - help to defend your body against pathogens by ingesting them, making anti-bodies and anti-toxins.
  3. Pathogen - Microorganism which causes disease.
  4. Bacteria - Microorganism that can cause disease.
  5. Viruses - microorganisms that takes over cells and reproduce rapidly , causing disease.
2. Pathogens
  1. Pathogens make you ill by nesting inside your body and reproducing , this is why you're ill . they attack your body from the inside producing toxins that can be harmful to your body, they reproduce by damaging and destroying your cells.
    1. Pathogens can enter your body through cuts , scratches , needles e.g HIV/AIDS or heatitis.
    2. Your skin acts as a barrier . it prevents bacteria and viruses from reching the tissues beneath that can be infected.
    3. If you damage or cut your skin , you bleed. your blood forms a clot, which dries into a scab. stopping pathogens getting into into the wound.
  2. when you cough , sneeze or talk you expel tiny droblets full of pathogens from your breathing system. other people breath in the droplets along with the pathogens that they contain, so they pick up the infection e.g flu , tuberculosis , or the common cold.
    1. Eating raw or uncooked food, or drinking water containing sewage can spread disease e.g diarroea or salmonella. You get these by taking large amounts of microorganisms straight to your gut.
      1. Your lungs produce a sticky substance ( mucus ) this helps the pathogens stick to it and then you swallow it and your stomach acid ( hydrochloric acid ) kills the microorganisms.
  3. Some diseases are spread by direct contact of the skin e.g impetigo and some sexually transmitted diseases like genital herpes.
The Nervous System
1. key words
  1. Axon - long thin projection carrying impulses all around the body.
    1. Dendrites - branched fibres , that pick up information ariving from receptors or other nuerons.
  2. Myelin sheath - isulates the axon and makes transmissions faster.
    1. Cell Body - the cell body contains the necleus and cytoplasm, like most animal cells.
2. Nerves
  1. The synapse - nervous impulses can be transmitted from one nueron to another. These happen at junctions called synapses. Nuerons are not in contact with each other.
    1. There is a gap between the sensory and relay nuerons called a synaptic cleft.
    2. when a nerve impulse arrives at the end of a sensory nuerone, it triggers the movment of nuerotransmitter molrcules towards the membrane.
      1. These diffuse . they bind with receptors on relay nurone triggering another impulse. meanwhile , the nuerotransmitters are absorbed back into the sensory nuerone to be reused.
      2. stimulis -> receptor -> sensory nuerones -> relay nuerones -> motor nuerones -> effectors -> response

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Biology revision

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