Circulatory system

Class: JSS2

Subject: Basic Biology

Topic: Circulatory System

OBJECTIVES 

By the end of the lesson, student should be able to;

Define Circulation

Define the heart

Understand the blood vessels

State importance of circulatory system

Day 1

Introduction 

Higher organisms e.g. man, require blood to carry materials to and from different parts of their body. There is need for organisms to transport oxygen from the lungs to other living cells within the organisms and also, dissolved food materials absorbed in the villi to other parts of the body which need them. Circulation is therefore the process by which absorbed food materials are carried through arteries, capillaries and veins to all parts of the body where they are utilized for body functioning. Materials which are transported by blood in human body are water, salt, hormones, oxygen, digested food, etc. Waste materials are also removed from the body through blood circulation.

Day 2

The heart

The heart pumps blood to all parts of the body through the circulatory system. The heart is a muscular organ that lies in the chest cavity and is almost conical in shape. It is made up of four chambers. These four chambers include two upper chambers which are the right atrium and left atrium; and two lower chambers, the right ventricle and the left ventricle. Blood enters the heart at the atriums and leaves from ventricles. The heart is constantly beating, contracting and relaxing. There are about 70 to 75 beats per minute although this beating rate may vary with individuals. Beating rate is faster in children than in adults.

Interior view of the heart (Credit: aspiruslibrary.org)

Day 3

Blood vessels 

There are channels or routes through which blood passes to different parts of the body. There are three types of blood vessels; the arteries, veins and capillaries.

Arteries:  These are the blood vessels that carry oxygenated blood away from the heart to all parts of the body except the pulmonary artery.

Veins:  These are blood vessels that carry oxygenated blood to the heart from all parts of the body except the pulmonary vein.

Capillaries:  These are tiny networks of blood vessels that connect arteries to veins. Blood flows out from the heart through arteries to all parts of the body, through capillaries and then into the veins and back to the heart where circulation continues.

Day 4

Importance of circulatory system

Helps in excretion of waste products from the body.

Digested food materials like glucose, amino acids, fatty acids and glycerol are carried from the intestine to the tissues where they are stored or used up, water and oxygen are also carried by the blood.

Protection of the body against diseases e.g. white blood cells.

Regulation of the body temperature: the blood helps in the distribution of heat produced in muscle and organs like liver, to other parts of the body.

Helps in blood clothing in wounds e.g. blood platelets.

Sustain life by supplying nutrients to cells.

Day 5

Home Work

Define circulatory system

What is the heart?

Explain the blood vessels

What are the importance of circulatory system?