◄UNIT 10: Sustainable waste managementUNIT 12 :Respiratory System►

UNIT 11:Circulatory System

  • UNIT 11:Circulatory System

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    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.
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    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.

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    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.

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    • 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.

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    • 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.

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    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:

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    • 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:

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    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.

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    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.

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    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.

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    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

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    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

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    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.

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    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

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    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.

    ◄UNIT 10: Sustainable waste managementUNIT 12 :Respiratory System►