Human Bio Immunity

pathogen

Any microorganism that can cause disease, such as bacteria, viruses, fungi, or parasites.

bacteria structure

single-celled prokaryotic organisms- key components include a cell wall, cell membrane, cytoplasm, nucleoid (containing DNA), ribosomes, and sometimes structures like flagella, pili, and capsules e.g. tetanus

bacteria replication method

primarily reproduce asexually through a process called Binary fission. This involves a single cell dividing into two identical daughter cells

virus structure

Non-living particles, as they cannot reproduce by themselves, Contain DNA or RNA, Some are surrounded by a protein coat and/or a lipid envelope, Some viruses have protein spikes on their surface e.g. COVID-19

virus replication method

Viruses enter host cells in the body. The virus adds it’s DNA to the cells DNA. This tricks the cell into making more virus particles which can leave the cell to infect more cells.

fungi structure

Fungi cannot move so they make spores that act like seeds, These spores can be harmful to humans if they are ingested, similar in structure to animal and plant cells, grow in soil and decaying plant matter to get nutrients e.g. ringworm

fungi replication method

Reproduce by spreading spores, which can cause infections when they come into contact with the skin or lungs.

Parasite structure

Parasites are organisms that live off other organisms called hosts to survive, Parasites are often spread through contaminated water, food, waste and soil. Can be unicellular or multicellular, In humans they mostly affect the intestines or the skin.

parasite replication method

Some parasites spread through insects that act as ‘vectors’ or carriers, eg. malaria

Transmission by direct contact

Directly touching an infected person or coming into contact with their body fluids

Transmission by indirect contact

touching an object the infected person has touched such as a door knob e.g. STIs and HIV

transmission by contaminated food and waste

The spread of a pathogen through consuming food or drink contaminated with a pathogen. The pathogen then enters the body through the digestive tract. e.g. salmonella

Airborne transmission

The spread of a pathogen through tiny droplets that are emitted when coughing or sneezing. The droplets can fall and settle on food or utensils or they may remain airborne to be breathed in by others. e.g. influenza

Vectors

The spread of a pathogen via an animal such as insects, ticks or mites. Some transfer pathogen directly, others spread it to food or water which is then ingested. e.g. Malaria by mosquitoes

Good hygiene practices

• Wash your hands often with soap and water

• Use alcohol based sanitisers

• Cough or sneeze into your elbow or a tissue

• Wear a mask to prevent droplet spread

• Wear gloves when cleaning up bodily fluids such as blood

• Clean surfaces with disinfectant

• Use tongs, pliers or tweezers

• Never share personal articles

Hygiene hypothesis

In the late 1990’s Dr Erika Mutius compared the rates of allergies and asthma in East and West Germany. Her initial hypothesis was that East German children, who grew up in ‘dirtier’ and less healthy conditions would have more allergies. However, what she found was the opposite, children in polluted areas had less allergies, while children in ‘cleaner’ West Germany had more allergic reactions and high incidence of asthma.

Hygiene hypothesis results

When environments are too clean, there are fewer pathogens, and children are less likely to get sick. Early exposure to a variety of microbes teaches the immune system to differentiate between harmful and harmless substances and not to ‘overreact’.

Inflammation

the body’s response to any damage or infection of tissues.

Inflamation purpose

• Reduce the spread of pathogens, destroy them and prevent entry of additional pathogens.

• Remove damaged tissue and cell debris.

• Begin the repair of damaged tissue.

signs of inflammation

• Redness

• Swelling

• Heat

• Pain

immune response

If a microorganism enters the body, the body can defend itself by producing antibodies.

self antigens

cells that belong to our body

non-self antigens

Cells that don’t belong to our bodies like microorganisms

Natural immunity

occurs without any human intervention

Artificial immunity

results from giving an injection of an antigen or antibodies

Passive immunity

antibodies produced by someone else

Active immunity

antibodies that are produced by yourself

antibody

a protein produced by the body's immune system to help fight off foreign substances like bacteria and viruses

Vaccination

the introduction of ‘weakened’ pathogens to the body, so that the body produces antibodies and develops immunity, without having to suffer the disease itself.

vaccination methods

syringes, fine spray, skin patches and ingestion of food.

vaccination start dates

When an infant is 2 months old and most are complete by 10 years of age. Later in life, secondary vaccinations called boosters are required for higher, longer-lasting immunity

Herd Immunity

When large proportions of the population are immunised

Herd immunity necessity

The more people vaccinated, the less chance of disease transmission, also protects the most vulnerable people in our society.

Factors affecting vaccinations

• Health issues

• Social factors

• Cultural factors

• Economic factors

Vaccinations- health issues

Allergic reactions – some people can have a reaction to the medium of the vaccine

Preservatives – perceived reactions to certain chemicals that are used as preservatives

Vaccinations- Social factors

• Ethical concerns – moral or religious objection to: Use of animal or human tissue to produce vaccines, Testing on animals

• Informed consent – trials on people not fully aware of the risks

• Lack of availability – not accessible to everyone

• Peer pressure to vaccinate

Vaccinations- Cultural factors

Religious beliefs – some religions that rely on faith healing are opposed to vaccines. Other religions may be opposed to methods used to produce vaccines

Vaccinations- Economic Factors

• Cost – vaccines may be too expensive for some people to afford

• Commercialisation – companies profiting from or exploiting the sale of a vaccine.

Reasons to vaccinate

• Helping create herd immunity

• Following the advice of health professionals

• Negative side effects are rare

• Reduced health care of treating the sick

Antibiotics

used to treat bacterial infections only, some work by changing the structure of the cell wall or membrane, while others stop the bacteria from reproducing

Multi-resistant

bacteria that are resistant to many antibiotics- developed through the overuse of antibiotics

antivirals

Used to treat viral infections, work by inhibiting the viruses development inside the body.

Antiseptics

Don’t cure bacterial or viral infections, but they can be used to slow or prevent the growth of infections on your body surfaces, e.g. savlon

Disinfectant

Used to prevent microbe growth on non-living surfaces such as benchtops e.g. dettol