Biology Unit 2

Biology Unit 2

1. Microorganisms and disease

   • Symptoms can be caused by cell damage or by toxins
   • Malaria symptoms caused by cell damage
   • E-coli releases toxins
   • Microorganisms reproduce quickly inside the body
   • Bacteria make copies of themselves
   • Viruses need other cells to reproduce

2. The immune system

   • Fights of invading microbes
   • Responses always involve white blood cells
   • White blood cells can engulf and digest the microorganisms
   • Antibodies recognise foreign microorganisms
     • Sends out correct antibody to fight the antigen on the microbe
   • Antibodies are proteins specific to a particular antigen

3. Vaccination

   • Use a safe version of a dangerous microorganism
   • First infection- takes a while for white blood cells to respond
   • Immunisation- infecting with dead or inactive microorganisms
   • Memory cells remember antigens
   • If live microorganisms appear AGAIN the body can make antibodies more quickly to kill the microorganism more quickly
   • Prevents epidemics
   • Have different effects on different people

4. Antimicrobials

   • Can inhibit or kill bacteria, fungi and viruses
   • Antibiotics are one type
   • Clear up infections
   • Microorganisms can evolve and become resistant
   • Always finish antibiotic course
     • More courses of antibiotic- leaves only the resistant microbes

5. Drug Trials

   • Tested in a lab first
   • developed using lab grown human cells
     • Can't predict how it will effect a living human
   • Test on humans = clinical trial
     • Blind trial- patients don't know if they have the placebo or drug
   • First on healthy volunteers
     • Then ill people
   • Placebo's are used
     • Not ethical on very ill patients
   • Double blind trial- even scientist doesn't know what they are giving the patient
   • Open label trials- all parties are aware of what is being used

6. The circulatory system

   • Arteries- blood away from the heart- thick walls for the high pressure
   • Veins- back to heart- thin walls big lumen
   • Capillaries- one cell thick

7. heart rate and blood pressure

   • Pulse rate used to measure your heart rate
   • Heart rate in BPM
   • Blood pressure- the pressure of blood against artery wall
     • Two values
       • HIgher= pressure when heart contracts
       • Lower= pressure when heart relaxes
     • Average healthy lower- 60-100 BPM
   • High blood pressure increases risk of heart disease
     • Build up of fatty deposits increase blood pressure
       • if deposit breaks through inner lining of the artery a blood clot could form around it
         • if a coronary artery becomes blocked it cuts off the blood and oxygen supply to part of the heart and this part dies.

8. Heart disease

   • Poor diet
     • Cholesterol makes most of fatty deposits
     • High blood cholesterol is linked to eating foods with high saturated fats e.g. fatty meats and cheese
     • Salt increases risk- it increases blood pressure
   • Smoking
     • carbon monoxide and nicotine increase risk
       • CO reduces amount of oxygen in the blood
         • If the heart doesn't get enough oxygen- heart attack
   • Stress
     • + BP = +risk of heart disease
   • Illegal drugs
     • + heart rate =+ risk of heart disease
       • Same as excessive alcohol

9. Homeostasis

   • Maintaining a constant internal environment

10. Controlling water content

    • Inputs- water can be gained from drink, food and respiration
    • Outputs- sweating, breathing, faeces and urine
    • Kidneys help balance substances in the body
      • Filter small molecules from the blood
        • Reabsorb- all the sugar and as much salt and water as the body requires
    • Urine isn't always the same
      • External temperature
        • Effects how much you sweat- more sweat= water loss so kidneys will reabsorb more water back into the blood
          • Small amount of concentrated urine
      • Exercise- makes you hotter- sweat to cool down
      • Intake of fluids and salts- eating too much salt/not enough water=concentrated small amount of urine

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