igcse bio_ blood donation

8/13/2019 IGCSE Bio_ Blood Donation

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Blood donation


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Successful Outcomes

Describe why people might need a blood

transfusion

Explain how blood is donate and transfused

Explain the blood grouping system and why it

is important to get the correct donor blood

Describe how blood clots


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History of blood transfusions

1818, Dr James Blundell

performed the first

successful blood

transfusion into apatients who was

haemorrhaging

(bleeding severely).


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Haemophilia patients treated with a

blood transfusion

1840, first haemophiliac

treated successfully

with a blood

transfusion.(haemophilia is an

inherited disease where

blood does not clot so if a

person is cut, they could

bleed to death)


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Further history

1901, human blood groups were discovered

and so transfusions became safer.

Around 1911, anticoagulant was added to

refrigerated blood so it kept for longer.

World War II- blood banks set up

1950- blood stored in plastic bags instead ofglass bottles.


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Blood donation

People can give blood 3

times a year.

Blood is warmed before

it is transfused into apatient.


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What are blood groups

Each blood group has red blood cells with certain

proteins on their surface called agglutinins (a

type of antigen), and these are different shapes.

The plasma of the blood of each blood group has

antibodies against agglutinins, but it will not have

antibodies against its own agglutinins.

If you receive blood which is the wrong group,your antibodies will react with the donated red

blood cells and cause them to clump together.


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Blood groups and their agglutinins and

antibodies

Blood group Agglutinins

(antigens) on the

surface of the

red blood cells

Antibodies in

plasma

A Type A Anti B

B Type B Anti A

AB Type A and B noneO none Anti A and anti B


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Who can donate to who?

People with blood group O can donate to anyone

as their red blood cells so not have antigens that

recipient plasma antibodies could react to.

People with AB blood can receive any type as

they do not have antibodies to react with the

antigens

People with group A blood cannot receive bloodgroup B and vice versa as it would coagulate.


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What does it mean if I am

blood group O positive?

You are also classified according to whether

your blood has a D protein.

If it does you are rhesus positive and if not

rhesus negative.

If you are rhesus negative you cannot receive

blood from a rhesus positive person as your

blood would make antibodies against the D

protein.


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anticoagulants

Our blood will naturally clot in case we cutourselves.

In fact, we need vitamin K to help our blood to

clot (easy to remember Kfor Klotting).Bacteria in our gut make this vitamin but wecan get it in foods such as green vegetablesand cranberries.

Chemicals called anticoagulants must beadded to blood kept in a bag to stop clotting.


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People who might need to take

anticoagulants

People who have narrowed arteries due to

fatty deposits.

Smokers and alcohol drinkers have an

increased risk of blood clots forming.

Drugs such as aspirin, warfarin, and heparin

reduce blood clotting and are give to people

who have heart disease or have suffered a

stroke.


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questions

Who might need a blood transfusion?

What is added to bags of donated blood to stopthe blood clotting?

Why cant people with blood group A receivedonor blood from a person with group B blood?

Why are people with blood group O calleduniversal donors?

Why are people with blood group AB describedas universal recipients?

igcse bio_ blood donation

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