Course: Science and Elementary Technology, Topic: UNIT 11:Circulatory System

General

UNIT 11:Circulatory System
2.What is happening in picture A? How about picture B?
3. Discuss the consequences of poor health care shown on picture A and B
11.1 Main function of human circulatory system
Find out
1. The main function of circulatory system.
Activity 11.1 Investigating the function of human
circulatory system
1. Research in library text book or search engine on human
circulatory system
2. Write down your findings

The main functions of the human circulatory system include
• Transport oxygen to blood cells.
• Transport digested food nutrients to the cells of the body.
• Transport carbon dioxide from cells to excretory organs.
• Transport hormones to the glands.
11.2 Organs of the human circulatory system
Find out
1. The main organs of the human circulatory system.
Identifying organs of the human
circulatory system
1. Use a chart of blood circulation and name main organs of
circulatory system.
2. Watch the video on human blood circulation using the link:
The circulatory system in human beings is made up of three main organs:
• The heart - This is a muscular organ that pumps blood to all
parts of the body.
• Blood vessels -These are tubes that carry blood around the
body. They are of different types depending on what they do.
• Blood - This is the transport fluid in the body.
Structure of the human heart
Activity 11.3 Drawing the structure of the human
heart
1. Research from library text book about the heart structure.
2. Draw the diagram of the human heart in your notebook.
3. Label the various parts of the human heart.
The human heart is a muscular organ that pumps blood to all parts of
the body. It is divided into four chambers:
• Two chambers are on the upper side of the human heart. They are
called Auricles or atria (singular-atrium).
• Two other chambers are located on the lower side of the human
heart. They are called ventricles.
• The heart also has blood vessels. Example, vena cava, pulmonary
artery,aorta and pulmonary vein.

Note : Further, the human heart chambers are separated by valves
on both the left and right sides. Valves prevent the blood from flowing
backwards.
Separating the left side of the heart from the right side is a muscular wall
called septum.

Remember!
The division of the heart into four chambers is important as it
ensures that oxygenated and deoxygenated blood do not mix.

11.3 The process of human blood circulation
a ) Blood vessels
Activity 11.4 Identifying different types of blood
vessels in human beings
1. Observe the picture below of human blood circulation. Name the
parts labelled a, b and c.
2. Trace the path of blood from the heart to the lungs and to all
parts of the body and back using the picture above.
3. Watch the video on human blood circulation using the link:

4. Try to trace the path of blood from the heart or other body parts.
• How does blood flow from the heart to other body parts?
Which vessels are involved in the process?
• How does blood flow from the other body parts back to the
heart? Which vessels are involved in the process?

5. Draw a diagram to represent the path of blood from the heart
to the lungs and to all parts of the body and back. Compare your
diagram to the one in the picture in (1) above. Are they similar?

The blood vessels are interconnected to allow transportation of blood
to all parts of the body. There are three major blood vessels:
• Arteries - carry blood from the heart to all parts of the body.
The main artery is the aorta.They lack valves , have thick
elastic wall and narrow lumen and carry blood at high
pressure.
• Veins - carry blood from all parts of the body to the heart.
The main vein is the vena cava. They have thinner walls
than the arteries but with wider lumen. They have valves
which prevent blood from flowing backwards. Blood in the
vein flow at much low pressure than in arteries.
• Capillaries - act as a link between arteries and veins. They
form a network within tissues. They are very thin -They have
tiny holes called pores which allow movement of materials in
and out. Further, they connect arteries and veins.

b) Blood circulation
The heart pumps blood to all parts of the body.
• The blood leaves the heart and flows to the body parts through
arteries. The blood returns to the heart from the body parts through
veins.
• The steps involved in blood circulation are as follows:
• Deoxygenated blood from all parts of the body flows through
the vena cava into the right auricle (RA) and finally into the right
ventricle.
• The walls of the right ventricle then pumps the blood into the lungs
through the pulmonary artery for oxygenation.
• In the lungs, oxygen is added to the blood and carbon dioxide is
removed. The blood is now said to be oxygenated.
• The oxygenated blood then flows to the left auricle through
pulmonary vein and finally into the left ventricle.
• The walls of the left ventricle (which are thicker and more muscular)
then pump the blood to all parts of the body through the aorta.
• Once the blood circulates to all parts of the body, it flows back to
the heart through vena cava and the cycle repeats itself.
11.4 Components of human blood
Find out
1. The various components of human blood.
2. The importance of the various components of human blood.
Activity 11.5 Investigating the components of human
blood.
1. Research in library text book or search engine on
components of human blood.
2. Write your findings in exercise note book.
Blood is the red fluid found in our bodies. It has four main components:
a) Plasma - This is the main component of blood. This part is mainly liquid.
b) Red blood cells - Red blood cells help to carry oxygen from the lungs to all body organs. They contain a red colouring matter called
haemoglobin.

Remember!
Blood that contains oxygen is called oxygenated blood. It is scarlet
or bright red in colour. Blood that has lost oxygen and has more
carbon dioxide is called deoxygenated blood. It is dark-red in colour.
c) White blood cells
White blood cells help to fight and kill disease - causing germs. They are therefore responsible for body immunity.

d) Platelets
Blood platelets are responsible for clotting of blood, they therefore
help to stop bleeding in case of injury. They also help during healing
of wounds.
Self –Test 11.1
1. What makes up the circulatory system?
2. Describe the process of blood circulation using a flow diagram.
3. What is the significance of the organisation of the heart into
four chambers and further left and right sides?
4. Complete the table below.
5. Differentiate between arteries and veins.
6. What is blood made of? What are their functions?
11.5 Caring for and health of circulation system
Find out
1. What to do in order to keep our blood circulatory system healthy.
2. How to take care of the human heart.

Activity 11.6 Researching how to keep the blood
circulation system healthy
1. Visit the library. Find out from textbooks about practices that help
to keep the human heart healthy. You can also use the Internet.
2. Write your findings in a exercise book.
3. Do the same with the rest of the parts that make up the human
circulatory system (blood vessels and blood).
Table 11.1 below shows some ways of observing hygiene of the human
heart, blood and blood vessels:
Table 11.1: Hygiene of the human heart, blood and blood vessels

Remember!
We should avoid all activities that may lead us into getting infected
with HIV and AIDS.
11.6 Diseases or conditions of the circulatory system
Find out
1. The diseases that affect the circulatory system.
2. The causes, signs and symptoms of diseases that affect the
circulatory system.
3. How to avoid diseases of circulatory system.
Activity 11.7 Investigating common diseases of
circulatory system
1. Research in library textbook or search engine on disease that
affect circulatory system.
2. Write your findings in a exercise book.
The diseases that affect the circulatory system include: high blood
pressure, heart attack, stroke, atherosclerosis and deep-vein
thrombosis (DVT)
Table 11.2 Diseases of the circulatory system, their signs and symptoms
and prevention and control measures

11.7 Blood pressure measurement
Find out
Normal measurement of blood pressure
Activity 11.8 A visit to health centre
1. Go to a nearby health centre .
2. Observe how the nurse measures your blood pressure.
3. Ask the nurse what normal blood pressure is.
4. Discuss and interpret your blood pressure.
• Blood pressure is the amount of force exerted against the walls of
arteries as blood flows through them.
• It is measured using an instrument called sphygmomanometer/
blood pressure meter.
• The normal blood pressure is 120/80mmHg.
Note: Any value lower than 120/80mmHg is considered low blood
pressure. Any value higher than 120/80mmHg is high blood pressure.
UNIT TEST 11
1. Name the organs that make up the human circulatory system.
2. Blood leaves the heart to the rest of the body through ______
and returns to the heart through the _____________.
3. The __________ prevents blood from flowing backwards in
veins.
4. The main artery is the _________ while the main vein is the
________.
5. Draw and label the parts of the circulatory system. Using arrows,
show how blood circulates in the body.
6. Name the three types of blood vessels in human circulatory
system.
7. Arteries do not have valves. Why?
8. Compare and contrast heart rate during rest and during
exercise.
9. How would you ensure that your blood is functioning properly?
10. Why is it important to check our blood pressure regularly?
11. Blood carried by the arteries are under____________ pressure
while that carried by veins is under _________________ pressure.
(high, low)
12. The main function of white blood cells is__________________
while platelets help during ________________ process.
13. Oxygen is carried in blood in form of________________

Use the diagram below to answer questions 14-17

14. Which of the following statements is correct? The blood vessel
mark W carries:
A. Blood from the lungs
B. Blood to the lungs
C. Blood to the body organs
D. De-oxygenated blood
15. The blood vessel marked X is the __________
16. Which one of the following statements is not correct about the
blood vessel marked Y?
A. Carries deoxygenated blood
B. Is the major artery in the circulatory system
C. Carries blood from the heart to the body organs
D. Is the aorta
17. The blood vessel marked Z is _____________. It is the largest
vein in the body.

Science and Elementary Technology

General

UNIT 11:Circulatory System

UNIT 11:Circulatory System

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