TRANSPORT IN ANIMALS

Key words

• Antigen
• Artery
• Bicuspid
• Blood
• Blood group
• Blood transfusion
• Capillary
• Coronary artery disease
• High blood pressure
• Immune
• Immunity
• Lymph
• Lymphatic
• Transport
• Tricuspid
• Stroke
• Surface area: volume ratio
• Valve
• Vein

By the end of this chapter, you will be able to:

1. Understand the principle of the surface area to volume ratio.
2. Know the need for a transport system, and identify the components involved in the transport system in mammals.
3. Describe the structure of the heart and know how it functions.
4. Understand how structure of blood vessels are related to their function by comparing arteries, veins, and capillaries.
5. Identify the major function of blood and relate the function to the components of blood.
6. Understand the causes and prevention of diseases associated with the heart (high blood pressure, coronary heart disease and stroke).
8. Understand the importance of knowledge of blood groups for blood transfusion.

Introduction

Animals have special systems for the efficient transport of materials around their bodies in this chapter you will learn the principles of how these transport systems operate. You will discover that the transport system consists of a number of tubes called vessels through which specific materials are distributed

The circulatory system in mammals consists of closed tubes and the heart which provides the motile force that moves the fluid (blood) into the tubes consisting of arteries, capillaries and veins

7.1 The concept of surface area to volume ratio

Activity 7.1 Investigating how surface area to volume ratio is affected by size

Key question

How does surface area to volume ratio vary with size?

 Figure 7.1: Surface area varies according to volume ratio

What you need

• Cubes of different dimensions i.e.  1cm x 1cm x 1cm , 20m 2cm x 2cm , 3cm x 3cm x 3cm/large Irish potato with a knife x and ruler .
• Calculator

What to do

1. In pairs, use the cubes provided to calculate the volume and total surface area of the cubes (remember a cube has 6 sides) / prepare your own cubes if they are not provided
2. Determine the surface area: volume ratio and fill in the table below.
3. Discuss and explain the biological significance of the calculated ratios in relation to transport in small and large animals

 Table 7.1: Table of results

1. Explain what happens to the ratio of surface area to volume with increasing size.
2. Diffusion of substances into and out of a cell occurs across the cell surface. Describe how increasing the size of a cell will affect the ability of diffusion to transport materials into and out of a cell.

The elephant is one of the largest mammals on land, it has increased its surface for radiating body heat by having large flat ears, it moves around as fans.

To overcome the problems arising due to small cell size, organisms became multicellular (many celled). Many celled organisms that have a small surface area compared to their volume have evolved various adaptive features to increase their effective surface area. These include:

• Flatness of the body
• Folding of membranes.
• Having a transport system to carry materials into and out of cells from the interior of the body
• Surface area to volume ratio influences
• Heat loss and gain
• gaseous exchange
• absorption across surface eg water in roots, food in the alimentary canal

7.2 Need for a transport system in animals

You have already learnt that materials can diffuse from one cell to another. This is very okay for unicellular organisms but it would be very slow to supply materials to all parts of the body of multicellular organisms. This, therefore, necessitates a transport system. In plants we have already seen it’s the vascular system and in higher animals it’s the circulatory system.

 The circulatory system consists of several components each with a specific function and is designed differently for its functions. In this activity, you are to review the components of the circulatory system in relation to their functions

Figure 7.2: Circulatory system

7.3 Components of the circulatory system

Activity 7.2 Finding out the components of the circulatory system

What you need

• Pictures, models, and charts of components of the circulatory system.

Key question

 What are the components of the circulatory system?

What to do

1. In pairs, discuss the components of the circulatory system using knowledge from science lessons learnt in primary school and knowledge obtained from Biology textbooks.
2. Record your findings.
3. Report your findings to the rest of the class.

7.4 Structure of the heart

The heart

Figure 7.3: a) External structure                        b) Internal structure

 The heart is a complex structure organ made out of special muscle called cardiac muscle. This muscle contract and relaxes without tiring. This means that it can do its work of pumping blood with its contents to the body without stopping.

 The heart is a single organ in the circulatory system with several chambers and valves and blood vessels attached. Each of these has a special function in the functioning of the heart. In this activity you are to study the structure of the mammalian heart to find its and how they are designed for particular functions.

 Activity 7.3 Discussing the structure of the heart

 Key question

 How is the structure of the heart related to its functions?

What you need

• Diagram of the heart model of a mammalian heart / fresh or preserved mammalian heart.
• Computer connected to the Internet / Biology textbooks.
• Knife.
• Dissecting board.
• Cotton wool.

Figure 7.4: External features of the heart

What to do

1 In pairs, discuss and describe the structure and function of the mammalian heart referring to diagrams and a model of the heart.

2 Draw and label the external parts of a mammalian heart adding short notes relating to function of each part. Cut a longitudinal section through the heart and display it on the dissection board

 3. Make a well labeled drawing of the longitudinal section through the heart.

4. Describe how blood circulates in the heart.

5. Share your findings with other groups and with the whole class.

7.5 Circulation of blood in mammals

In the next Activity 7.4, you are going to design a model of the circulatory system to show how blood flows / circulates in the human body.

Activity 7.4 designing a model of the circulatory system

Key question

How can one design a model of the circulatory system?

What you need

• Manila paper
• Red and blue markers
• Clear rubber tubing 0.5 diameter
• Cultured solutions, blue and red
• A balloon Cellotape
• Computer with Internet connection

What to do

1. In groups design a model or animation to illustrate blood flow circulates in the human body following what you observed in the mammal internet / Biology textbook and present to the class

2. Explain your model to the rest of the class

7.6 Types of blood vessels

 In the circulatory system there are three types of blood vessels: arteries, veins and capillaries. They differ in size, structure and function.

Activity 7.5 comparing the structures of different types of blood vessels

 In this activity you are to research on the structure of each blood vessel and how its structure relates to its function.

 Key questions

 (i) How do arteries, veins and capillaries differ structurally?

 (ii) How is the structure of each blood vessel related to its function?

What you need.

• Biology textbooks
• Charts on blood vessels

What to do

1. In pairs research on structure of arteries, capillaries and veins.
2. Record your findings in form of a table or models or diagrams to show how the structure is related to the function in each of the vessels.
3. Present your findings to the rest of the class.

  7.7 Components of blood

Figure 7.5: Components of blood

 Activity 7.6 Researching on the components of blood and their functions

 Key question what are the components of blood and their functions?

What you need

• Textbooks of Biology / computer connected on internet.
• Notebooks / writing pads.
• Pens
• Manilla papers

What to do

1.  In groups of 3 or 5 make a research on the components of blood and their functions.
2. Name the different components of blood.
3. State the functions of each of the components of blood in mammals.
4. State the major functions of blood in a mammal and relate each function to the components of the blood that carries it out.
5. Present your findings in summary form in a table to the rest of the class.

7.8 Heart diseases

Activity 7.7 Discussing and researching on the heart diseases

Key question what are the diseases that affect the heart?

 What you need

• Biology textbooks / medical journals on the heart / computer connected on internet
• Notebooks / writing pads
• Pens
• Manilla papers
• Markers

 What to do

1. In groups research, on the diseases associated with the heart in the Biology textbooks / medical journals / computer connected to internet.
2. What are the diseases that are associated with the heart? For each of the diseases you have discovered discuss how they came about.
3. How can these diseases be prevented, controlled and treated?
4. Write a report about the diseases associated with the heart indicating clearly the causes, prevention, control and treatment.
5. Present your findings to the rest of the class.

Activity 7.8 visiting a health facility to find out the causes and prevention of high blood pressure, coronary heart disease and stroke

Key questions

(ii) What are the causes of high blood pressure, coronary heart disease and stroke?

(ii) How can these diseases be prevented?

What you need

• Notebooks

What to do

1. Your teacher will organize a trip to a health facility for the class to find out the causes and prevention of high blood pressure, coronary heart disease and stroke.
2. When the health worker is presenting, take note of the key facts and later write a report on the causes and their prevention
3. Present your report to the class for discussion.

7.9 Blood groups and blood transfusion

 Figure 7.6: A person donating blood

Activity 7.9 Discussing blood groups and blood transfusion

Key questions

• What are the types of blood groups?
•   How can blood be transfused?

 What you need

• Computer with internet / Biology textbooks / Science journals.
• Notebooks / Writing pads.
• Pens
• Manilla papers
• Markers

What to do

1. In groups, make a research to find out the different blood groups and how they are transfused.
2. What are the different types of blood groups?
3. What should be considered before transfusing blood into a person?
4. Make a write up of the different blood types and explain how the blood groups react during transfusion.
5. What is meant by the term compatible and incompatible when transfusing blood?
6. Present your findings to the rest of the class.

Activity 7.10 Finding out how blood groups and blood transfusion relate

Key questions

(i) What is a blood group?

(ii) What is blood transfusion?

What you need

1. Notebooks
2. Pens
3. Video on blood groups and blood transfusion
4. Health worker

What to do

1 Watch a video or listen to a health worker from the blood bank talking about blood groups and their relation to blood risks involved. Transfusion, importance of blood transfusion and the possible

2. In pairs compile a short report on the benefits and risks of blood transfusion including compatible blood groups.

7.10 Blood and body defense

Activity 7.11 Researching and discussing blood defense and immunity

 Key question

i) What is immunity?

(ii) What are the different types of immunity?

 What you need

• Pens
• Manila papers
• Markers
• Computer connected to internet / Biology books / medical journals on immunity and disease
• Notebooks / writing pads

What to do

1. In groups research on how blood defends the body.
2. What are the different methods the blood uses to defend itself?
3. What is immunity?
4. Discuss the different types of immunity experienced by a human body.
5. What diseases are currently being immunized against in Uganda?
6. Make a table to show the different diseases immunized, what causes them.
7. The types of immunization and the age of immunization.
8. Make a write-up of your findings and present them to the rest of the class.

Activity 7.12. Finding out the role of blood in body defense

 Key question

What is the role of blood in body defense?

 What you need

• Biology textbooks / computer with internet
• Notebooks
• Pens
• Manila papers
• Markers

Figure 7.7: A baby being immunized

What to do

1.  In groups, research and describe the role of blood in the defense of the human body.
2. Research and describe how the immunity is weakened by infections like HIV.
3. Write a summary of your findings on Manila paper.
4. Report your findings to the rest of the class.

7.11 Structure and function of the lymphatic system

Figure 7.8: Lymphatic system

 The Lymph is also known as tissue fluid. It is formed at the arterial end of the capillary network. This is due to the high pressure created by blood being forced into the small capillaries which have gaps between the cells that make their walls. The pressure forces the fluid into the gaps. The fluid is made up of plasma because the other materials have large molecules that cannot pass through the small gaps in the capillary.

 As the plasma moves into the tissue cells, the blood remaining behind becomes more concentrated. As blood moves forward it begins to pull fluid back by osmosis at the venous end of the capillary.

Not all the fluid in the tissue cells go back, some remain as tissue fluid and is picked by another system of vessels called the lymphatic vessels. These pick the fluid and it is now called the lymph.

An alternative circulatory system in the body to the blood circulatory system is the lymphatic system in which a fluid called lymph flows. This system is important in body defense against disease. In activity 7.13, you are going to research on the structure and function of the lymphatic system.

Activity 7.13 Investigating the structure and function of the lymphatic system

 Key question

How is the structure of the lymphatic system adapted for its functions?

What you need

• Biology textbooks Notebooks

What to do

1. In groups, research on the process of the formation of lymph and its flow around the body and the function of the lymphatic system in maintaining a healthy body.

2. Make a report of your findings to the class.

Chapter Summary

In this chapter, you have learnt the:

• Surface area to volume ratio varies with size .Small animals have larger surface area to volume ratio than large animals.
• The transport system in animals consists of a pumping organ the heart , blood vessels : -arteries , veins and capillaries , blood cells white blood cells , red blood cells and platelets . Each of these has a structure designed to perform a specific function.
• Blood plays the role of transport and defense in the body.
• Diseases associated with the blood circulatory system include blood pressure, coronary artery disease and stroke.
• Blood transfusion is necessary for patients without enough blood but requires knowledge of blood groups and their compatibility.
• Blood defends the body from disease by using white blood cells and antibodies.
• Immunity is weakened by various infections including HIV
• Lymph is formed from blood and is important in maintaining a healthy body.