First Term Lesson Note for Week Ten
Class : Primary Six
Subject : Basic Science
Topic : The Human body (circulatory system)
Duration : 40 Minutes
Period : Single Period
Reference Book :
Basic Science for Primary Schools, Book 6.
Lagos State Unified schemes of work for Upper Primary, (Primary 4 – 6).
Online Resources
Instructional Material : Chart showing the human heart and the circulatory system..
Learning Objectives : By the end of the lesson learners will be able to :
i. Define the Human heart
ii. State the functions of the heart
iii. Mention the types of blood circulation
Previous Knowledge :
Learners are familiar with the topic in their previous classes.
Content :
The Human Heart
The heart is the muscular organ that pumps blood round the body. It contains four chambers namely:
- Right auricle
- Left auricle
- Right ventricle
- Left ventricle
The major difference between the auricles and the ventricles is that the walls of the ventricles are thicker and more muscular than those of the auricles.
Functions of the Heart
The functions of the heart include the following:
i. ) The major function of the heart is to pump blood to all parts of the body.
ii. ) It also keeps blood in continuous flow round the body.
Blood Vessels : These are tubes through which blood moves round the body.
These vessels are; arteries, veins, and capillaries and they have various functions in the body.
- Arteries carry blood away from the heart to all parts of the body.
- Veins carry blood towards the HEART from all parts of the body.
- Capillaries join arteries to the veins.
Arteries: These are blood vessels that carry blood away from the heart. That is, blood flows from the heart to all parts of the body through arteries.
Veins: These are blood vessels that carry blood from other parts of the body to the heart.
Capillaries: They are the tiny network of blood vessels that connect the veins to the arteries. They carry blood between arteries and veins.
Blood Circulation
The circulatory system is the route by which blood moves round the body. It is made up of the heart blood, and blood Vessels.
Functions of the blood circulatory system
The blood circulatory system in the human body has several functions. These are :
Transport
- The blood system carries oxygen, absorbed into the blood in the lungs, to all the living cells in all parts of the body.
- The blood system carries food substances, after digestion, from the alimentary canal to all the living cells in the body.
- The blood system carries the white blood corpuscles to all parts of the body where they defend the body against infection.
- The blood system carries antibodies all round the body. The antibodies defend the body against infection.
- The blood system carries waste products, such as carbon dioxide, urea, water and excess salts from living cells where they are produced to the parts of the body, such as the lungs and kidneys where they are removed.
- Defense of the body against infection
When disease-causing organisms enter the human body, the white blood cells attack and swallow them, or produce chemicals called antibodies that kill the disease-causing organisms. - Blood clotting
By clotting at the point of an injury, the blood protects the body against further loss of blood. - Distribution of heat
Some parts of the body, e.g. the muscles produce more heat than others. The blood circulatory system distributes heat evenly throughout the body.
There are two types of blood circulation in the body. These are:
Pulmonary circulation and Systemic circulation.
Pulmonary Circulation· This is one in which blood flows from the heart to the lungs and back to the heart.
Systemic Circulation: This is one in which blood is pumped from the heart to the other parts of the body and back to the heart.
The right auricle and ventricle contains blood with less oxygen and more carbon dioxide. The left auricle and ventricle contains blood with more oxygen that comes from the lungs.
The heart is filled with blood, as a result of the relaxation of the involuntary muscles of the heart called cardiac muscle. When the muscles of the heart contract, it (the heart) pumps blood out through the right and left ventricles into the pulmonary arteries and aorta respectively.
The blood in the pulmonary arteries goes to the lungs and the blood in the aorta goes to other parts of the body.
The presence of valves prevent the blood from flowing back to the heart.: When the heart is relaxed, blood returns to the heart from the veins through vena-cava to the right auricles and through the pulmonary veins to the left auricles. The blood that moves into the body cells is more oxygenated because the blood flows by the indication of the arrows.
Functions of the arteries and veins.
The arteries carry blood away from the heart and the veins carry blood towards the heart.
Functions of the capillary blood vessels
If blood were to flow all the time within the blood vessels, it would not be of much use to the body.
The capillaries have thin walls through which the liquid part of the blood can diffuse out of the blood vessels to reach the living cells in the various organs.
In this way, the capillaries make it possible for the cells of the body to be supplied with food, water, oxygen and all other essentials.
They are also useful in the removal of waste products from the cells
Differences between arteries and veins
| Arteries | Veins |
| They carry blood away from the heart | They carry blood towards the heart. |
| They have thick elastic walls | They have thin, not very elastic walls. |
| They carry blood that contains oxygen | They carry blood that does not contain oxygen. |
| Pressure of blood in the vessels is high | Pressure of blood in the vessels is low. |
| They do not have valves. | They have valves to prevent the back-flow of blood. |
| Pulse is detectable | Pulse is not detectable |
Presentation Steps :
Step 1 : Revises the previous lesson with the learners by asking questions orally.
Step 2 : Introduces the new topic by defining circulatory system and identify the blood vessels
Step 3 : Describe the human heart and state it functions
Step 4 : Describe the blood vessels, identify types and state their functions.
Evaluation :
1. Define human heart
2. State the functions of the heart
3. Mention the types of blood circulation
4. List the blood vessels
5. Mention two differences between the arteries and veins
Conclusion :
Teacher goes over the topic once again to enhance better understanding
Assignment :
Answer these questions
1. List the things that make up the human blood.
2. Name the four chambers that make up the human heart.
3. Describe the paths along which blood circulates round the human body.
4. Describe the functions of the human heart.