E-Note (Basic Science – JSS2)
Topic: Circulatory System I
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Meaning of Circulatory System
- The circulatory system is the body system that
carries blood, oxygen, food, and wastes around the body.
- It is made up of:
- Blood
– the fluid that carries materials.
- Heart
– the pump that pushes blood.
- Blood vessels
– the tubes through which blood flows.
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Composition of Blood and Their Functions
- Plasma
– liquid part, carries food and waste.
- Red Blood Cells (RBCs) Also called erythrocyte– carry oxygen using
haemoglobin.
- White Blood Cells (WBCs) Also called
leucocyte– fight germs and protect the body.
- Platelets
– help in clotting blood when there is a wound.
Functions of Blood:
- Transport oxygen, food, and waste.
- Protect the body from diseases.
- Regulate body temperature.
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Blood Vessels
- Arteries
– carry carry blood to the heart; have valves.
- Capillaries – very tiny vessels where food, oxygen, and waste are exchanged.
- Veins- blood away from the heart; thick walls.
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Blood Groups and Blood Test
- Four main blood groups: A, B, AB, O.
- Group O
= Universal Donor (can give blood to anyone).
- Group AB
= Universal Recipient (can receive blood from anyone).
- Blood test is important before transfusion to avoid death from wrong blood gro
Topic:
Circulatory System (2)
1️⃣ The Heart
– Structure and Functions
- The heart is a strong muscular organ in
the chest, slightly to the left.
- It has four chambers:
- Right Atrium
→ receives blood from the body.
- Right Ventricle
→ pumps blood to the lungs.
- Left Atrium
→ receives blood from the lungs.
- Left Ventricle → pumps blood to the rest of the body.
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Functions of the Heart:
- Pumps blood round the body.
- Supplies oxygen and nutrients to tissues.
- Removes waste products like carbon dioxide.
2️⃣ Circulation of Blood
Blood moves in two main ways:
- Pulmonary Circulation
- Blood flows from the heart → lungs → heart.
- Purpose: to collect oxygen and release carbon
dioxide.
- Systemic Circulation
- Blood flows from the heart → body → heart.
- Purpose: to supply oxygen and nutrients to the
whole body.
👉 Key Points:
- Arteries
carry blood away from the heart.
- Veins
carry blood to the heart.
- Capillaries
connect arteries and veins and allow exchange of materials.
3️⃣ Diagram
of Blood Circulation
(Teacher’s note: Students should
draw this in class)
Pathway:
Body → Right Atrium → Right Ventricle → Lungs → Left Atrium → Left Ventricle →
Body
4️⃣ Effects
of Poor Blood Circulation
If blood does not circulate well:
- Body tissues lack oxygen.
- Person may feel weak, dizzy, or faint.
- Organs may fail.
- In severe cases, it can cause death.
5️⃣ Diseases
of the Circulatory System
- Hypertension (High Blood Pressure)
- Blood pushes too hard against vessel walls.
- Can damage heart, brain, or kidneys.
- Heart Attack
- When blood supply to the heart is blocked.
- Can be fatal if not treated quickly.
- Stroke
- When blood supply to the brain is cut off.
- Can cause paralysis or death.
👉 Prevention:
- Exercise regularly.
- Eat balanced diet (less salt, less fat).
- Avoid smoking and alcohol.
- Rest well and avoid stress.
✍️ Quick Revision Questions
- Mention the four chambers of the heart.
- Differentiate between pulmonary and systemic
circulation.
- What will happen if blood does not circulate properly?
- State two diseases of the circulatory system and give
one way to prevent them.
🩸 Objective Questions
1. The circulatory system is responsible for:
A. Carrying only oxygen in the body
B. Carrying blood, food, oxygen, and waste around the body
C. Helping the body to breathe in air
D. Producing food in plants
2. The three main parts of the circulatory system are:
A. Heart, lungs, stomach
B. Blood, kidney, liver
C. Blood, heart, blood vessels
D. Arteries, capillaries, brain
3. Which component of blood carries oxygen using haemoglobin?
A. White blood cells
B. Plasma
C. Platelets
D. Red blood cells
4. The part of blood that helps to clot wounds is called:
A. Plasma
B. Red blood cells
C. Platelets
D. White blood cells
5. Which of the following is NOT a function of blood?
A. Carrying food and oxygen
B. Regulating body temperature
C. Fighting diseases
D. Breaking down food in the stomach
6. Arteries are different from veins because arteries:
A. Carry blood to the heart
B. Carry blood away from the heart
C. Have thinner walls than veins
D. Contain valves to stop backflow
7. The universal donor blood group is:
A. A
B. B
C. AB
D. O
8. Why is a blood test important before transfusion?
A. To make blood taste sweet
B. To know the blood group and avoid wrong transfusion
C. To increase blood circulation
D. To produce more red blood cells
✅ Answers
1. B
2. C
3. D
4. C
5. D
6. B
7. D
8. B
Objective Questions on Circulatory System (2)
Instruction: Choose the correct option (A–D).
- The human heart is located in the ______.
A. Stomach
B. Chest
C. Neck
D. Brain - How many chambers are found in the human heart?
A. 2
B. 3
C. 4
D. 5 - Which chamber of the heart pumps blood to the body?
A. Right atrium
B. Left atrium
C. Right ventricle
D. Left ventricle - Blood flows from the heart to the lungs and back in
______ circulation.
A. Pulmonary circulation
B. Systemic circulation
C. Arterial circulation
D. Capillary circulation - Which blood vessel carries blood away from the heart?
A. Arteries
B. Veins
C. Capillaries
D. Nerves - What happens if blood does not circulate properly?
A. Person becomes stronger
B. Organs get more oxygen
C. Person may feel weak or faint
D. Heart beats normally - A disease caused by very high blood pressure is called
______.
A. Stroke
B. Hypertension
C. Heart attack
D. Malaria - Which of these is a good way of preventing heart
diseases?
A. Eating too much fatty food
B. Smoking
C. Regular exercise
D. Drinking alcohol
✅ Answers
- B. Chest
- C. 4
- D. Left ventricle
- A. Pulmonary circulation
- A. Arteries
- C. Person may feel weak or faint
- B. Hypertension
- C. Regular exercise
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