[Draft] T9.3 Human Infection & Response + Drug Development

Year 9 Topic 3 @ SGS

Disease

Disease

Caused by pathogens such as bacteria, viruses, protists or fungi.

Pathogens

Microorganisms which cause disease

Spread of Pathogens

Direct Contact, Water or Air

Toxins

Created by bacteria in our body, making us feel ‘ill’

Viruses

Live & reproduce inside the cell, causing damage

Prevention of Disease

• Basic hygiene

• Destroying vectors (carriers)

• Isolating the infected individuals

• Vaccination

Measels

Viral disease that can be fatal, spread by inhaling droplets from sneezes or coughs

Symptoms of Measels

Fever and red skin rash

Prevention of Measels

Vaccination during childhood

HIV (Human Immunodeficiency Virus)

Viral disease which attacks the immune cells, spread by sexual contact or exchange of bodily fluids.

AIDS (Acquired Immune Deficiency Syndrome)

Advanced stage of HIV. The body is too weak to fight other infections or cancers

Symptoms of HIV

Initially causes a flu-like illness

Treatments of HIV

Antiretroviral drugs

Salmonella

Food poisoning spread in unhygienic food

Symptoms of Salmonella Toxins

Fever, Cramps, Vomiting, Diarrhoea.

Prevention of Salmonella

Poultry vaccinations

Gonorrhoea

Sexually Transmitted Disease, caused by bacteria

Symptoms of Gonorrhoea

Thick, yellow or green discharge from penis or vagina & pain during urinating

Treatments of Gonorrhoea

Antibiotics or barrier contraception (Condoms)

Malaria

Caused by a protist involved in the life cycle of a mosquito

Symptoms of Malaria

Fevers, Vomiting, Diarrhoea. Can become fatal

Prevention of Malaria

Preventing vectors (mosquitoes) from breeding and using bug nets

Human Defence Systems

• Skin

• Nose

• Trachea & Bronchi

• Stomach

Skin

Physical barrier that secretes antimicrobic substances

Nose

Traps particles that could contain pathogens

Trachea & Bronchi

Secrete mucus which traps pathogens. Cilia waft the mucus to the throat

Stomach

Acid that kills the majority of pathogens

Immune System Reactions

• Phagocytosis

• Antibody production

• Antitoxic production

Phagocytosis

Process of white blood cells engulfing and destroying pathogens

Antibody Production

Producing specific antibodies that bind onto antigens of the pathogen.A

Antitoxin Production

Counteract the effects of the toxins produced by the bacteria

Vaccination

Injection of dead or inactive microorganisms to stimulate the production of antibodies

Benefits of Vaccination

• Can control lots of common communicable diseases effectively

• Large outbreaks of disease (epidemics) can be prevented if a high percentage of people are vaccinated

Downsides of Vaccination

• Their efficacy is not guaranteed

• You could have bad side effects to the vaccine

Antibiotics

Medicine that kills bacteria, not viruses, in the body

Resistant Bacteria

Bacteria mutations can cause resistance to certain antibiotics, so it becomes ineffective

Preventing Resistant Bacteria

• Avoiding over-prescription/usage of antibodies

• Using the full course of antibodies

Painkillers

Alleviate symptoms, but does not treat the disease/pathogen

Examples of Painkillers

Paracetamol, Ibuprofen, Codeine, Aspirin

Example of Antibiotics

Penicillin

Importance of Plants in Medicine

Many chemicals derive from plants. Eg. Digitalis - Foxglove, Aspirin - Willow

Pre-clinical Testing

Drugs are tested on human cells & tissues in the lab, and live animals.

Clinical Testing

• Drug is tested on healthy adults, who volunteer.

• Dosage is gradually increased, and those with the illness are introduced to find the optimum dosage.

Double Blind Trial

One group is given a placebo to see the actual effects of the drug, without the patients or doctors from knowing.

Peer Review

Results are peer reviewed before publication to prevent false claims

Monoclonal Antibodies

Genetically identical antibodies that target only one antigen

Production of Monoclonal Antibodies