OCR 21st Century B2

Keeping Healthy
1. Homeostasis
  1. Receptor (detect changes in the environment)
    1. Processing Centre (coordinate responses automatically)
      1. Effector (produce the response)
        Negative feedback- A system where any change results in actions that reverse the origional change
        water levels are controlled by balancing gains from drinks, food and respiration and losses through sweating, breathing, faeces and the excretion of urine
        A balanced water level is important for maintaining the concentration of cell contents at the correct level for cell activity
        the kidneys balance water levels by producing dilute or concentrated urine as a response to the concentration of blood plasma, which is affected by external temperature, exercise level and intake of fluids and salt.
        They do this through the secretion of the hormone ADH into the bloodstream through the pituitary gland
        alcohol results in the production of a greater volume of more dilute urine, due to ADH suppression, which can lead to dehydration
        Ecstasy results in a smaller volume of less dilute urine, due to increased ADH production.
    2. High Level of water
      1. Co-ordinates the response
        counteracts the change (less ADH secretion), levels decrease
    3. Low level of water
      1. Co-ordinates the response
        counteracts the change (more ADH secreted), levels increase
Resisting Infection
1. symptoms of an infectious disease caused by...
  1. poisins or toxins made by the microorganism
  2. damage done to cells when microorganisms reproduce
    1. in suitable conditions such as those inside a human body, microorganisms (e.g. bacteria and viruses) can reproduce rapidly to produce very large numbers
      1. warmth
      2. moisture
      3. nutrients
      4. Can divide every 20 minutes
2. Immune System
  1. White Blood Cells
    1. Phagocytes- engulfing and digesting
    2. Lymphocytes- Attack specififc microorgansisms as their receptors recognsie particular antigens
      1. Produces antibodies to fight the invading microrganisms
        Marks the microorganisms so phagocytes can engulf it
        Bind to and neutralise viruses and toxins
        Memory cells remain in the blood once the infection is clear and they are able to rapidly mass produce the necessary antibodies should familiar antigen arrives in the system once again.
        They do so before you are affected by the symptoms and so you are "immune".
        Some can even attach to bacteria and kill them directly
Vaccines & Antibiotics
1. provide protection from microorganisms by establishing memory cells that produce antibodies quickly on reinfection
  1. dead or inactive form of pathogen injected
    1. White blood cell still produce antibodies
      1. memory cells remain
    2. Safe form of disease-causing microorganism
      1. Never be completely safe
        1 in 4 Meningitis vaccinations develop a painful swelling at injection site
        1 in 50 have a fever
        Genetic differences cause different side effects
        Individuals have varying degrees of side effects to them
  3. To prevent epidemics of infectious diseases, it is necessary to vaccinate a high percentage of a population.
    1. More vaccinated= Less risk of spreading (less people to pass on the disease)= Less chance of epidemic
2. chemicals used to kill, or inhibit, bacteria, fungi and viruses
  1. Antimicrobials
    1. Microorganisms develop random mutations in their DNA. This can lead to the organisms being less affected by an antimicrobial
      1. It survives within the host and then reproduces, passing on the resistant gene
        =SUPERBUGS
        we should only use antibiotics when necessary and always complete the course
  2. antibiotics are a type of antimicrobial that attacks ONLY bacteria without harming your own body cells
3. Development & Testing
  1. new drugs and vaccines are first tested for safety and effectiveness using human cells grown in the laboratory and then animals to test if it works well in whole animals
    1. human trials may then be carried out
      1. 1. on healthy volunteers to test for safety
        2. on people with the illness to test for safety and effectiveness
        Open-label- the patient and doctor both know the treatment. no other available treatment and slim chance of recovery
        Blind trial- the volunteers do not know which group they are in but the researchers do. researchers may subconsciously give away clues, this is called observer bias; it can make the results unreliable.
        Double-blind trial- both the volunteers and the researchers do not know which group they are in This removes the chance of bias and makes the results more reliable. But double-blind trials are more complex to set up.
        Placebo-The patient will not benefit from taking a fake drug and will not get better despite believing they will. This is not fair to the patient.
      2. Long term human trials- ensure that the drug is safe and works. It's important that there are no adverse effects when used for a long time
Heart Disease
1. The first pump carries deoxygenated blood to your lungs, where it offloads carbon dioxide and obtains oxygen. It then delivers oxygenated blood back to your heart.
  1. The second pump delivers oxygenated blood to every part of your body. Blood needing more oxygen is sent back to the heart to begin the cycle again.
    1. Arteries- take oxygentaed blood from the heart to the rest of your body. The thick muscle/elastic outer wall can withstand the high pressure created by the puming heart
      1. Veins- return de-oxygenated blood to the heart. The thin layer of muscle and elastic fibres allows the vein to be squashed when you move. This pushes the blood back to the heart. The valves prevent blood from flowing backwards as it moves against gravity.
      2. Capillaries- are tiny blood vessels (only one cell thick) that carries blood through the tissue between arteries and veins
  2. The muscle cells in the heart need a constant supply of oxygen and nutrients, and for their waste products to be removed. So the heart requires its own blood supply in order to keep beating. Blood vessels called the coronary arteries supply blood to the heart muscles.
    1. If this coronary artery is cut off, the cells are starved of nutrients and they die, causing a heart attack
      1. The clot/embolism is caused by the build up of fatty deposits. These deposits can be caused by sat fats in foods.
        A High Blood Pressure damages the smooth lining of the artery.
        This allows fatty deposits to build up
        Thye restrict the blood flow and further increase the blood pressure
  3. Beats per minute= pulse rate
2. Blood Pressure
  1. Given as two numbers. e.g. 120/80. the higher value when the heart is contracting and the lower value when the heart is relaxed
    1. blood pressure measurements record the pressure of the blood on the walls of the artery
      1. ‘Normal’ measurements for factors such as heart rate and blood pressure is given within a range because individuals vary. The 'normal' BP is 80-110/60-80
3. Lifestyle factors that can increase the risk of heart disease
  1. Poor Diet
    1. Cholesterol= fatty deposits that clog the arteries
      1. High Cholesterol= High risk of Heart Disease
  2. Stress
    1. If stressed, the heart beats faster, thus increasing the blood pressure
  3. Smoking
    1. Carbon Monoxide
      1. Reduces the amount of Oxygen the blood can carry.
        If the heart doesn't get oxygen, it's cells will die= Heart Attack
    2. Nicotine
      1. heart contracts more often, thus increasing blood pressure
        Regular moderate excersise burns fat, preventing it from building up in arteries. Regular excersises strengthens the heart muscle, thus decreasing the risk of heart disease.
  4. Drugs
    1. Ecstacy and Cannabis increase the heart rate and therefore the blood pressure
  5. Alcohol
    1. Increase the risk of high blood pressure.
      1. Heavy drinking weakens the heart muscle. This can cause herat failiure
4. epidemiological and large scale genetics studies identify these lifestyle risk factors
  1. looks at similarities between those who died of heart disease
  2. Involves large scale genetic studies to identify the genetic risk factors (looks for genetic similarities)

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OCR 21st Century B2

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	Created by Pritesh Patel about 8 years ago