Activity 1 - The chemical cascade of blood clotting

Using the SOLO hexagon cards on blood clotting below first match the images to the descriptions and then arrange them into an order which explains the process of blood clotting.

Activity 2 - What happens if blood clots form in coronary arteries?

Watch this video of a blood clot in coronary arteries and answer the questions below.

Teachers notes

The activities one this page are each free standing but cover some of the simple ideas about blood clotting and immunity. In total they should take about 1 hour, activity three is really shorter than the others.

The SOLO hexagons can be approached by different students in different ways. The simplest is to pair the images and the descriptions. Better students will be able to arrange the cards in a logical sequence. The best students will realise that there are a couple of different possibilities for a correct order.

Extra activity - video narration

Explain the process of blood clotting by narrating the Video prompts of blood clotting

Model answers for the blood clotting activity

Heart attack video questions - model answers

• Heart attack video questions - model answers

This page contains model answers for the two activities on the blood clotting activities page.

Activity 1- Answer these questions while watching the video

“What happens during a Heart Attack?

Watch the video and answer the questions below.

Click here for the video link

1. Why is John in mortal danger, ‘just to keep him in the game’?

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John has "heart disease" - fat build up on his coronary arteries.

His heart has to work harder to pump the blood. The blood is flowing faster than normal.

The plaques of fat lining the walls of his coronary arteries are in danger of bursting. If they do burst this could be fatal.

2. What is a plaque on the inside of John’s coronary artery made from?

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The plaque build up is made of fats

3. What happens when the plaque bursts? In simple terms.

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A blood clot forms around the burst plaque in John's coronary artery. This blocks the flow of blood

4. List four symptoms of a heart attack.

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• Pain in his chest - like indigestion

• Pain in his left arm

• Rapid heart rate

• Difficulty breathing

• Dizziness

Activity 2 – Questions to answer following some research/thought?

Look up information about clotting of blood and the structure of the heart to answer these questions.

1. What happens when the plaque bursts? Give details of blood flow and blood clotting.

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The cells which burst around the plaque release clotting factor

This causes prothrombin to become thrombin

Fibrinogen becomes insoluble fibrin

Erythrocytes become more and more trapped in the growing blood clot around the fibrin

The blood flow in the coronary artery is reduced

2. Explain why a blood clot in a coronary artery can cause the heart to stop beating.

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The reduced blood flow in the coronary artery reduces the oxygen to muscles of the heart and these can not do aerobic respiration so they stop beating

3. What other problems occur in the rest of the body as a result of reduced heart function and a slower flow of blood?

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Fluid can build up in the lungs, breathing becomes difficult.

The brain is starved of oxygen and this causes dizziness

Activity 4 - Distinguish between antigens and antibodies

Use the following slides to introduce antigens and antibodies Antigens & antibodies

Questions

1. What is an antigen?

An antigen is a chemical which stimulates the production of an antibody when it is inside the body. Usually proteins, antigens are found on the surface of cells.

2. Which type of cells have antigens on their surface?

All cells have antigens on their surface. Eukaryote and prokaryote cells.

The human body does not normally produce antibodies to its own cells.

3. How many different types of lymphocyte are there?

There is a very large variety of lymphocytes.

4. How many different types of antibody can one type of lymphocyte produce?

Each type of lymphocyte can only produce one type of antibody.

5. What is an antibody made out of?

Antibodies are made of protein. They all have a Y shaped structure but the antibody binding site is different in different antibodies.

HIV & AIDS

Guiding Questions

What does HIV do to the body? How does it lead to AIDS? Why is AIDS called a syndrome?

How does the HIV damage to T-cells affect the number of B-lymphocytes which make antibodies?

A Summary of the effect of HIV infection

HIV is a virus which Infects helper T-cells (white blood cells)

With infection the HIV replicates using the metabolism of the helper T-cell

This replications kills the helper T-cells and their number declines.

As a consequence, B-lymphocytes are not activated during other infections

B-lymphocytes do not make as many antibodies

Opportunistic infections grow in the body.

AIDS is defined by:

• HIV infection and a very low helper T cell count, or

• HIV infection with opportunistic infections is called AIDS

Activity 2: Further details about methods of transmission of HIV

The different methods of transmission of HIV each carry their own risk. The extent to which individuals in different societies can minimize or eliminate each of these risks could be considered.

This animation Transmission and Prevention of HIV describes the common and less common ways in which HIV can be transmitted from one person to another.

Warning: the video covers some information about sexual intercourse and homosexuality.

Activity 3 - The social implications of AIDS - discussion

1. Students are each given two or three sticky notes each.

2. Students are asked to write something they know about the implications of HIV or AIDS in society.

3. The sticky notes are collected and re-distributed at random (so that individuals don't get embarrassed)

4. The class is split into two equal sized groups

5. The groups are asked to organise their post-it notes onto the scale; Strongly Agree, Agree, Unsure, Disagree strongly disagree.

6. For each statement the group needs to have a justification why they agree or disagree. Where students are unsure they should agree on a question which will help to find out missing knowledge.

Consideration could be given to some of the following points;

• the severe problems in sub-saharan Africa.

• the different ways HIV can be transmitted.

• the cost of treatment.

• the stigma attached to being HIV positive.

• the affects of HIV infection on friends and family.

• views held by different types of people.

• the moral obligation of those with the technology & wealth to help other poorer societies.

Teachers notes

The first activity uses two videos to introduce HIV and AIDS. Each video is only 3 or 4 minutes long and students could watch them twice if necessary.

There is a worksheet on which students answer questions about the information in the two videos.

Activity 2 is beyond the IB syllabus but valuable information for young people. Personally I would include this in my lesson. The information in the film is factual and not judgemental and if would help to set the scene for Activity 3.

Activity 3 is a debate, based on an activity on the AVERT website. It provides a clear structure to explore student opinions and ideas about HIV and AIDS in a way which allows students to ask questions without fear of embarrassment.

Ground rules for this type of lesson are worth mentioning to students. These can be simple such as:

• Care about others.

• Don't ask personal questions.

• Don't answer a question if you don't feel happy about it. (say, "I don't think that is a good question")

• Remember that discussion which happen during this lesson may not be appropriate outside of the class.

There is a great animation which links transcription and translation to the HIV life cycle on DNAtube here: Animation of HIV lifecycle it was considered too complex for SL Biology.