How Our Body Defends Itself Against Infectious Diseases Flashcards Preview

Biology (B1) > How Our Body Defends Itself Against Infectious Diseases > Flashcards

Flashcards in How Our Body Defends Itself Against Infectious Diseases Deck (28):
1




WHAT ARE PATHOGENS?

A pathogen is a biological agent that causes disease or illness to its host

— they are microorganisms (bacteria and viruses)

2




HOW DO BACTERIA AND VIRUSES CAN MAKE US FEEL ILL

Bacteria released toxins and viruses that damage our cells

3




WHAT TYPE OF BLOOD CELL CAN DIGEST AND DESTROY PATHOGENS
( + the process)

WHITE BLOOD
CELL

1. The white blood cell surrounds the pathogen...
2. It then digests it

4




HOW DO WHITE BLOOD CELLS KILL VIRUSES

1. Your white blood cells make antibodies and memory cells

2. The antibodies attach to the measles virus and kills them

3. If the same virus returns to your body your memory cells know what antibodies to produce straight away

5




HOW ARE PATHOGENS USED IN VACCINATION

In vaccination, pathogens are introduced into the body in a weakened form.

The process causes the body to produce enough white blood cells to protect itself from the pathogens but without getting diseased.

6




WHAT IS BACTERIA (pathogens)

Bacteria are living cells and can multiply rapidly. They produce poisons and toxins

7




WHAT DISEASES CAN BE CAUSED BY BACTERIA (3)

• food poisoning
• typhoid
• whooping cough

8




WHAT ARE VIRUSES (pathogen)

Viruses can only reproduce inside host cells and they damage the cell when they do this. Once the cell bursts open, the viruses are passed out into the blood stream or airways

9




WHAT DISEASES CAN BE CAUSED BY VIRUSES (3)

• flu
• colds
• measles

10



WHAT HAPPENS WHEN PATHOGENS ENTER THE BODY

Once inside the body, pathogens reproduce
— viruses reproduce inside cells and damage them, while escaping to infect more cells

BUT the immune system destroys these pathogens
(White blood cells are important components of the immune system

11




WHAT CAN WHITE BLOOD CELLS DO
list 3

• engulf pathogens and destroy them

• produce anti bodies to destroy pathogens

• produce anti toxins that neutralise

12




WHAT IS ACTIVE IMMUNITY

Once you have been infected with a particular pathogen and produced anti bodies against it, some white blood cells remain

— if you become infected again with the same pathogen these white blood cells reproduce rapidly and the pathogens is destroyed - active immunity

13




WHO IS SEMMELWEISS AND WHAT DID HE DO

Semmelweiss reduced the number of deaths in hospitals from infectious diseases. 1948 be asked all doctors to keep washing their hands.

— demonstrated that hand washing could drastically reduce the number of women dying after childbirth
— he discovered that wards where babies were delivered only by mid wife's had lower death rates than a ward where babies were delivered by doctors

14




WHAT ARE ANTIBIOTICS

Antibiotics are a type of medicine that stops the growth of or destroys microorganisms

They work in two ways,
• bactericidal
• bacteriostatic

15




HOW DOES A BACTERICIDAL ANTIBIOTIC WORK

A bactericidal antibiotic kills the bacteria and interferes with the formation of the bacterium's cell wall or contents

E.g. penicillin

16




HOW DOES A BACTERIOSTATIC ANTIBIOTIC WORK

a bacteriostatic antibiotic stood bacterium from multiplying

17




WHAT ARE ANTIBIOTICS USED FOR

Treatment of an infection caused by bacteria

• targets microorganisms such as bacteria, fungi and paracites

• BUT is NOT affective against viruses

18




WHAT HAPPENS IF ANTIBIOTICS ARE OVERUSED

If antibiotics are over used there is a risk of the bacteria becoming resistant

19




WHAT ARE PAINKILLERS

pain killers relieve pain but does not cure diseases

— they block nerve impulses from the painful part of the body or blocks nerve impulses travelling to the part of the brain perceiving pain

20




WHAT IS MRSA

Meticillin Resistant staphylococcus Aureus

MRSA is a type of bacteria that's resistant to a number of widely used antibiotics, it can be known as a super bug

21




HOW DO BACTERIA STRAINS DEVELOP RESISTANCE TO ANTIBIOTICS

This happens because of natural selection
In large populations of bacteria, there may be some cells that are not affected by the antibiotic.

• these cells survive and reproduce, producing even more bacteria that are not affected by the antibiotic

22




MAIN STEPS IN THE DEVELOPMENT OF RESISTANCE ARE

1. Antibiotics kill individual pathogens of the non resistant strains

2. Resistant individual pathogens survive and reproduce

3. The population of the resistant pathogens increase

NEW ANTIBIOTICS MUST BE DEVELOPED FOR RESISTANT BACTERIA

23




WHAT DO VACCINATIONS DO

Vaccinations can make a person immune to diseases

24




WHAT DO VACCINES CONTAIN (4)

• live pathogens, treated to make them harmless
• harmless fragments of the pathogen
• toxins produced by pathogens
• dead pathogens

25




WHAT IS THE MMR VACCINE

Measles, mumps and Rubella

• it is given to children to protect them from diseases

26




ADVANTAGE AND DISADVANTAGE OF BEING VACCINATED

Advantage
✔️ if more people are vaccinated for a disease the chance of it spreading decreases

Disadvantage
✖️many believe that vaccinations like the MMR vaccine can lead to their children having autism

27




WHY DO SCHOOL AND COLLEGE LABORATORIES INCUBATE CULTURES AT NO MORE THAN 25 degrees

Because it would be dangerous to incubate (keep and grow) cultures at temperatures close to body temperature, as doing so would make it possible to allow the growth of pathogens harmful to the health

28




WHY ARE HIGH TEMPERATURES USED IN INDUSTRIAAL SITUATIONS

Because higher temperatures encourage faster growth