Chapter 7: Transport systems in animals

7.1 Overview (ESG8V)

Introduction (ESG8W)

In this chapter, learners will be introduced to the circulatory system in humans. The chapter starts with an introduction of different types of circulatory systems found in animals.

Learners will then spend some time studying the pulmonary and systemic circulatory systems; the internal and external structure of the heart; the cardiac cycle and the different types of blood vessels. A brief overview of the lymphatic circulatory system follows. The chapter concludes with an overview of some diseases that affect the cardiovascular system, as well as their treatments.

There are two important practicals in this chapter. In the first practical investigation, learners will need to dissect an animal heart in order to examine the structure of the heart. In the second investigation, learners will evaluate the effect of exercise on heart-rate. This activity should be conducted in the form of a scientific experiment, with an hypothesis, method, analysis of results and conclusion.

All living organisms require oxygen and nutrients, and a method of removing carbon dioxide and waste products. However, the circulatory system is not limited to the delivery of nutrients, gas exchange, and waste removal. Hormones, too, rely on the circulatory system to reach target organs, and the immune system depends on the transport of white blood cells and antibodies. This chapter discusses transport systems found in mammalian systems, with a focus on transport systems found in humans.

There are open and closed circulatory systems. In an open circulatory system blood enters a cavity, in a closed circulatory system blood remains in vessels.
A double closed circulation system consists of the pulmonary and systemic circulatory systems.
The direction of blood flow is significant. In the systemic circulatory system oxygenated blood is transported to the body and deoxygenated returns to the heart. In the pulmonary circulatory system, deoxygenated blood is sent to the lungs, and oxygenated blood is returned to the heart.
Specialised cells (sinoatrial node) send signals to the atrioventricular node to cause the atria and ventricles to contact and control the cardiac cycle and heart rate.
The structure of blood vessels such as arteries, veins and capillaries are suited to their function.
The lymphatic system transports lymph around the body and returns fluid to the blood circulatory system.
The lymphatic system also plays an important role in immunity.
Conditions and diseases of the heart and circulatory system include high and low blood pressure, heart attacks and strokes. Treatments include stents, valve replacements, bypass surgery, pacemakers, and heart transplants.

TEACHERS RESOURCE:

The following website has interactive activities that summarise different material covered in this chapter. The different activities are best done when the relevant material is covered:

End of chapter exercises

Table of Contents

7.2 Circulatory systems in animals