11.1+Defence+against+infectious+disease

11. Human Physiology AHL - 11.1 Defence against infectious disease - 11.2 Muscles and movement - 11.3 The kidney - 11.4 Reproduction - Physiology AHL Labs


 * Assessment statements** (IBO notes added to some point to clearly indicate what needs to be understood and what does not)
 * 11.1.1 || Describe the process of blood clotting. Limit this to the release of clotting factors from platelets and damaged cells resulting in the formation of thrombin. Thrombin catalyses the conversion of soluble fibrinogen into the fibrous protein fibrin, which captures blood cells. ||
 * 11.1.2 || Outline the principle of challenge and response, clonal selection and memory cells as the basis of immunity. ||
 * 11.1.3 || Define active and passive immunity. ||
 * 11.1.4 || Explain antibody production. Limit the explanation to antigen presentation by macrophages and activation of helper T-cells leading to activation of B-cells which divide to form clones of antibody-secreting plasma cells and memory cells. ||
 * 11.1.5 || Describe the production of monoclonal antibodies and their use in diagnosis and in treatment. Production should be limited to the fusion of tumour and B-cells, and their subsequent proliferation and production of antibodies. ||
 * 11.1.6 || Explain the principle of vaccination. Emphasize the role of memory cells. The primary and secondary responses can be clearly illustrated by a graph. ||
 * 11.1.7 || Discuss the benefits and dangers of vaccination. ||

This intro on the immune system from Hank is amusing and informative. It does go into greater detail than you need in some areas, but none the less it is a good introduction. media type="custom" key="24773410"
 * Starter**

Log in to the [|DCS Bridge] to obtain your workbooks and supporting resources
 * Workbooks and Worksheets **

An alternative set of notes from [|i-Biology] can be found here: media type="custom" key="23684940"

Steven Taylor ( [|i-Biology] ) has a great presentation to view and take notes from before starting your notebook media type="custom" key="23684942"
 * Presentations and tutorials **

The khan academy video tutorials covers: B Lymphocytes (B cells): Overview of B cells (B lymphocytes) and how they are activated and produce antibodies media type="custom" key="23684946" Macrophages are covered in detail (you need only an outline understanding) in Professional Antigen Presenting Cells (APC) and MHC II complexes media type="custom" key="23684948" Helper T Cells: Introduction to helper T cells and their role in activating B cells media type="custom" key="23684952"

Your knowledge of leukocytes only needs to extend to phagocytes, macrophages, b-cells, helper t-cells and memory cells. That said an idea of the basic types of leukocytes is helpful. This HHMI slideshow does a good job of outlining them (click on the image to view the slideshow).

This [|animation helps you to visualise blood clotting], but it is too simple and needs additional information for the DP Bio level of understanding.

Use [|click4biology] to review and complete your notes

Build your own workbook. First sub-divide it into sections reflecting the different assessment statements (as grouped below). Don't just add in the numbers include the descriptors too. Next complete the suggested activities and add notes to each section as specified.
 * Approach**

//**N.B. Immunity is a very complex area. For the DP Bio course you are must gain a certain depth of understanding, as specified by the assessment statements. It is strongly suggested that when using resources and developing your understanding you are very aware of what is required of you.**//

__11.1.1 (starter)__
 * 1) You have 3 mins to decode the assessment statement and present your understanding of blood clotting in a simple flow chart.
 * 2) Compare your example to the classes' and amend as necessary.
 * 3) Add the amended flowchart to your notes.

__11.1.2 and 11.1.4__ Interesting extra: why B-cells and T-cells? All lymphocytes are made in the bone marrow. B-cells (B for bone marrow) mature in the bone marrow, whilst T-cells are released and migrate, via the blood to the thymus gland (T for thymus) where they mature.
 * 1) Your task is to develop a personalised set of notes.
 * 2) Use a selection of resources, but recommended starting points are your textbooks, i-Biology presentation, the click4biology notes and the Khan academy videos on B Lymphocytes and macrophages.
 * 3) Use the list of key questions below as guidance your notes should address each point, though you do not have to refer to them specifically or in order
 * 4) Copy and paste in to your notes key images (screen print/copy if necessary).
 * 5) For each image add relevant notes.

Key questions/points:
 * Describe the affect of antibodies have upon pathogens
 * What are pathogens?
 * What can stimulate an immune system reaction (i.e. create a 'challenge')?
 * What is the role of macrophages in the immune response?
 * What does APC stand for?
 * What is the role of helper T-cells?
 * What is clonal selection?
 * What is the role of B-cells in immunity? What do they produce?
 * What is the difference between plasma cells and memory cells? what different roles do they perform?
 * What is the difference between an antigen and an epitope?
 * How does polyclonal selection differ from clonal selection?
 * __Outline__ the cytotoxic response and the role of killer T-cells
 * __Outline__ the role of phagocytic lymphoctyes

__11.1.3__
 * 1) You simply have to know and be able to distinguish between the two below types of immunity.
 * 2) Add the definitions to your notes (and remember them).
 * 3) For completeness of knowledge additionally differentiate between natural and artificial immunity. Add these definitions to your notes too.

Definitions - below are the accepted IBO definitions, record them, learn them, better add them to your flash card pile.
 * Active immunity is immunity due to the production of antibodies by the organism itself after the body’s defence mechanisms have been stimulated by antigens.
 * Passive immunity is immunity due to the acquisition of antibodies from another organism in which active immunity has been stimulated, including via the placenta, colostrum, or by injection of antibodies.

__11.1.5__ How are monoclonal antibodies artificially produced? Re-read the assessment statement Watch the [|Sumanas animation] Restrict your notes to answering:
 * where are the B-cells harvested from?
 * what is the name of the tumor cell used?
 * why are tumor cells used?
 * what is formed by the fusion of tumor and B-cells?
 * After screening what happens?

You need to be familiar with one example of diagnosis and use. Investigate one instance of each and take notes. You are not limited to the suggested examples, but you might find them very useful guidance: > __Detection/Diagnosis__
 * detection of antibodies to HIV [|UCSF (you need to produce a simple outline)], [|Virtual lab using the ELISA test from HHMI]
 * detection of a specific cardiac isoenzyme in suspected cases of heart attack
 * detection of human chorionic gonadotrophin (HCG) in pregnancy test kits [|Sumanas animation]

> __Treatment__
 * targeting of cancer cells with drugs attached to monoclonal antibodies
 * emergency treatment of rabies
 * blood and tissue typing for transplant compatibility
 * purification of industrially made interferon

__11.1.6__
 * 1) What does a vaccine consist of? watch the [|McGraw-Hill animation] to find out.
 * 2) Sketch a graph (texts, i-Biology and click4biology are all useful resources) showing time on the x-axis and response to disease (antibody concentration on the y-axis. Add to your graph lines to show a primary and secondary response to a given pathogen.
 * 3) Annotate your graph to explain the shape/patterns you have drawn. Include the terms: vaccination, infection, primary response, secondary response, memory cells.
 * 4) Remember you need to "Explain the **principle** of vaccination with reference to memory cells". If your notes don't do this then add to them. Use a textbook to help you in this.

__11.1.7__ Use the below to create a series of notes - expand on each point, add a sentence or two of further detail. The TOK points will form the basis of a class discussion in groups you will be assigned a question to answer and the other groups will be given an opportunity to criticise/ask questions.

Resources: [|weighing up the risks from the NHS] (useful for some points)

__The benefits - not limited too, but includes__
 * total elimination of diseases
 * prevention of pandemics and epidemics
 * decreased health-care costs
 * prevention of harmful side-effects of diseases

__The dangers - not limited too, but includes__
 * possible toxic effects of mercury in vaccines
 * possible overload of the immune system
 * possible links with autism //N.B. recent studies have eliminated have shown that there is NO EVIDENCE of a link between autism and the MMR vaccine//

__Other considerations__
 * parents have to balance perceived risk of the vaccine and disease, plus the societal benefit of epidemic prevention
 * pandemics are becoming an increased risk due to the proliferation of international travel
 * smallpox is a case study for how international cooperation can be effective in combating disease

__TOK - possible points for research and discussion__
 * risk assessment: how can risk be assessed accurately? how is perception of a risk different to the actual risk?
 * what is a double-blind trial and why are they so useful in the development and testing of drugs?
 * public hysteria has been the result of poorly understood scientific findings communicated again poorly (with and without intention), should the media be censored more strongly? should scientific findings be witheld to prevent hysteria?
 * should governments impose compulsory vaccination upon the populace?