Topic: The special role of blood

Target group

7th‑grade students of elementary school

Core curriculum

5. Circulatory system. Student:

3) presents the role of the main blood components (red and white blood cells, platelets, plasma);

4) lists the blood groups of the AB0 and Rh system and presents the social significance of blood donation.

General aim of education

Students describe the composition and functions of blood and blood groups.

Key competences

• communication in foreign languages;

• digital competence;

• learning to learn.

Criteria for success
The student will learn:

• to show the connection between the build of the elements of blood and their functions;

• to explain the meaning of blood types;

• to assess the social role of donating blood.

Methods/techniques

• activating

  • discussion.

• expository

  • talk.

• programmed

  • with computer;

  • with e‑textbook.

• practical

  • exercices concerned.

• exposing

  • exposition.

Forms of work

• individual activity;

• activity in pairs;

• activity in groups;

• collective activity.

Teaching aids

• e‑textbook;

• notebook and crayons/felt‑tip pens;

• interactive whiteboard, tablets/computers;

• „Blood” - milk with a fat content of 2%, stained with food coloring in red;

• „Antibodies” and „serum” - water and vinegar;

• tubes;

• pipette;

• watch glasses.

Lesson plan overview

Before classes

• The teacher prepares for the study „blood” and „serum” of hypothetical people.

• „Blood” is milk with a fat content of 2%, dyed with food coloring in red (you can add some green dye, the red will become deeper). The teacher spills „blood” on three watch glasses for each subject (ie, three slides for eight people, see Table 1). „Serum” is water or vinegar. Test tubes with „sera” should be signed.

• Table 1.

  Persons	Antibodies and serum
  	Anti‑A	anti‑B	anti‑D
  Bożena	water	vinegar	vinegar
  Andrzej	vinegar	water	vinegar
  Jan's son	vinegar	vinegar	vinegar
  Adam's son	water	vinegar	vinegar
  Jola	water	water	water
  Oliwia	vinegar	water	water
  Teresa	vinegar	water	vinegar
  Marcin	vinegar	vinegar	water

Introduction

• The teacher explains the aim of the lesson and together with students determines the success criteria to be achieved.

Realization

• The teacher asks pupils to read the passage entitled „Blood components and their role”, then they compiled a table showing the individual components of the blood and their functions.

• The students, working in pairs, check each other's tables. Based on the comments of colleagues, they correct any errors.

• The teacher exchanges blood group, discusses the importance of antibodies and antigens and conditions of transfusion. Pupils analyze illustrations of „Antigens and antibodies” and „Table of compliance of blood groups”.

• The teacher asks students to carry out the recommended interactive exercise themselves.

Summary

• The teacher briefly presents the most important issues discussed in class. He answers the additional questions of the proteges and explains all their doubts. Students complete notes.

Homework

• Imagine that you have the opportunity to interview an academic - a specialist in the field of today's lesson. What questions would you like to ask him? Write them down.

The following terms and recordings will be used during this lesson

Terms

Texts and recordings

The special role of blood

Blood is a connective tissue which transports nutrients, respiratory gases, products of metabolism and hormones, participates in thermoregulation and in defense mechanisms of the body. It consists of liquid plasma and morphotic elements suspended in it. Water is the main component of plasma. It transports the dissolved organic and inorganic compounds throughout the entire body. One of the substances transported by plasma is the carbon dioxide - gas which dissolves in water.

Blood transfers also morphotic elements of blood, that is cells: red blood cells – erythrocytes, white blood cells – leukocytes and cell fragments – platelets. Among blood cells, the highest in number are erythrocytes, which are characterized by a big surface for binding oxygen. Their shape resembles concavoconcave discs, which gives them elasticity and allows them to squeeze through really narrow spaces. Fully grown erythrocytes do not have a karyon, and that is why they can fit more haemoglobin particles. Haemoglobin is a protein which gives the red blood cells their colour and which can bind oxygen and carbon dioxide particles. Haemoglobin can also permanently connect with carbon monoxide, but then it loses the ability to transport oxygen. This is why carbon monoxide is a strong toxin.

Leukocytes, white blood cells, are the most diverse group of cells, where each type of cells has different function. Leukocytes have no colour, have karyon and are able to move in an amoebic way. Platelets, also known as thrombocytes, are fragments of cells that participate in blood clotting processes.

There are 4 main blood types among humans: A, B, AB, O. The presence of a particular blood type is decided by the presence of proteins – antigens on the surface of the erythrocytes. A person with an A type blood has erythrocytes with antigens A. B type blood has antigens B on the surface of the erythrocytes, whereas erythrocytes of AB type blood have both types of antigens (A and B). Erythrocytes without antigens are in the case of an O type blood. In addition, in plasma there are 2 types of antibodies: anti‑A and anti‑B. They cause the red blood cells to be glued together. Anti‑A antibodies bind erythrocytes that have A antigen, anti‑B antibodies bind erythrocyte that have B antigen. O type blood plasma has both types of antibodies, whereas in the plasma of an AB type blood there are no antibodies. In addition, on the surface of erythrocytes there may be rhesus factor. If it exists, we have RhIndeks górny +⁺ blood type, e.g. ORhIndeks górny +⁺(O+, positive), if there is no rhesus factor– the blood type is RhIndeks górny -^-, e.g. ORhIndeks górny -^- (O-, negative). Around 85% of Polish people and nearly all Chinese and Japanese people have Rh+ blood.

Blood is a life‑giving liquid, called also the gift of life. It is given to the sick who lost some blood because of an accident or a surgery. Blood transfusion is sometimes needed if a person has low red blood cell count, for example in case of anaemia. In order for a transfusion to be successful, both the donor’s and the recipient’s blood type have to match.

Lack of possibility to conduct a transfusion of a specific blood type when someone’s life is in danger can be a serious obstacle to fully help such person. This is why blood donation is crucial in saving people’s lives. Blood from a donor is processed, which allows for the blood to be stored in form that allows it to be used when needed. Blood donation points can be found in every city. The biggest blood donation events are organized by Polish Red Cross (PCK). One form of blood donation takes place in special ambulances that drive around cities and towns.

• Blood is composed of plasma and morphological elements of blood.

• Plasma is a water solution which includes organic and inorganic compounds.

• Morphological elements of the blood are composed of the blood cells: erythrocytes, leukocytes and platelets.

• Platelets participate in the blood clotting process.

• Antigens that are present on the surface of erythrocytes decide on which four blood types we belong to: A, B, AB, O.

• Knowledge about the blood type and rhesus factor is important during blood trasfusion.

• Donating blood saves lives of many people.