First line of defence (innate immunity): This is like a moat and castle walls, preventing invasion by foreigners. There are physical and chemical barriers to infection.
Second line of defence (innate immunity): If the foreign materials breach the first line of defence, an infection forms. This is the inflammation (heated battle) where invaders are being killed indiscriminately.
Third line of defence (active immunmity) : The last line of defence is the active, specific response by trained killer cells (ninjas!) that recognise their targets and actively seek them out and destroy them. They may be proteins or pathogens that have taken over the reproductive capacity of the cell (prions and viruses, for example), so the infected cell must be destroyed.
How do cells communicate? In this area of study students focus on how cells receive specific signals that elicit a particular response. Students apply the stimulus-response model to the cell in terms of the types of signals, the position of receptors, and the transduction of the information across the cell to an effector that then initiates a response. Students examine unique molecules called antigens and how they elicit an immune response, the nature of immunity and the role of vaccinations in providing immunity. They explain how malfunctions in signalling pathways cause various disorders in the human population and how new technologies assist in managing such disorders.
Outcome 2 On completion of this unit the student should be able to apply a stimulus-response model to explain how cells communicate with each other, outline immune responses to invading pathogens, distinguish between the different ways that immunity may be acquired, and explain how malfunctions of the immune system cause disease.
In Area of Study 2: How do cells communicate? we study cellular signals (signalling molecules, signal transduction and apoptosis); responding to antigens (including antigens, innate and adaptive immunity and the lymphatic system) and the immune system (including diseases of the immune system and cancer immunotherapy). The following links are some resources for study in these topics.
Chapter 6: Cellular Signals
Chapter 7: Responding to antigens
Chapter 8: Immunity, immune malfunctions and immunotherapy
Sir Gustav Nossal at the Gene Technology Access Centre
On Tuesday 29th April, eight VCE Biology students attended the “Body at War” program for World Immunology Day at the Gene Technology Access Centre. The students joined with about eighty other students from government and independent schools to learn about the history, discovery and use of vaccinations against diseases such as smallpox and polio.
Students were welcomed by Prof. Phil Hodgkin, who spoke about the long history of immunology, including the famous scientists who have discovered how diseases can be prevented using vaccination. They then had the great privilege of hearing Sir Gustav Nossal, scientist and former Australian of the Year, speak about the progress of eradicating infectious diseases from across the world over the past two decades. They then rotated through three different workshops; learning about the bodies immune response through a computer game, identifying diseased mouse tissue using staining and microscopy and then simulating a Streptococcus pneumoniae diagnosis.
Students have been very fortunate to be invited to this special program, as only up to 10 students from selected schools were able to attend this free event. They also had the opportunity to work with working scientists in small groups and hear from three young scientists about their journey into research and career prospects for scientists.
Prior to attending the session, it was useful to know about pathogens, or disease causing agents. These range in size from the smallest sub-microscopic particles (prions) to multicellular organisms.
- Prions (BSE or mad-cow disease)
- Viruses (influenza, herpes, chicken-pox)
- Bacteria (tuberculosis, tetanus, Staphylococcus, Salmonella)
- Protozoans (malaria, amoebas)
- Fungus (athlete’s foot, Candida)
- Worms (tapeworm, nematodes)
- Ticks and mites
You can find out more about pathogens and the immune system here:
It will also be useful to watch the “Life on Us” program at 8.30pm Sunday night on SBS One. This two-part series has powerful imagery showing various microscopic pathogens that inhabit the human body – you can watch a short promotional video here.