Short notes on the circulatory system 

Circulatory system: transports nutrients, water, oxygen & removes waste gases via blood.

Organs of the circulatory system: heart, blood, blood vessels (arteries, veins, capillaries).

Heart: muscular pump that moves blood to all body parts.

  • Location: between lungs, slightly left of chest midline; protected by ribcage.
  • Size: about the size of a fist.

Structure of the heart: 4 chambers.

  • Upper chambers: 2 auricles (atria) – receive blood from the body.
  • Lower chambers: 2 ventricles – pump blood out to the body.
  • Divided lengthwise into right & left sides.

Blood flow: right atrium → right ventricle → pulmonary artery (to lungs); left atrium → left ventricle → aorta (to body).

Functions of the heart: Pumps blood containing oxygen & nutrients to all cells.

  • Receives impure blood (with carbon dioxide) from the body & pumps it to the lungs for purification.

Heartbeat & pulse:

  • Heart makes a rhythmic pumping movement called the heartbeat.
  • The movement can be felt as a pulse at the wrist or neck.
  • Normal adult pulse rate: 60–100 beats per minute (average 72 bpm).

Measuring your own pulse (Activity):

  • Extend left wrist, palm up.
  • Find a point ~1 inch above the base of the palm with your right hand’s first two fingers.
  • Feel the pulse (pumping movement).
  • Count the beats for 30 seconds and multiply by 2 → your pulse rate.

Blood: red fluid in blood vessels; colour due to hemoglobin.

    - Components:

  • Red Blood Cells (RBCs)
  • White Blood Cells (WBCs)
  • Platelets

Functions of Blood: Transport O₂ & CO₂ (RBCs carry O₂ from lungs → body & bring CO₂ back).

  • WBCs fight germs & protect against infections.
  • Platelets cause blood clotting at cuts/wounds.
  • Carries nutrients from digestive system to body.
  • Removes waste for excretion.
  • Helps maintain body temperature.

Blood Vessels: thin muscular tubes that form a network for blood flow.

  - Types:

  • Arteries
  • Veins
  • Capillaries

Info buzz: Not all animals have red blood; octopus has blue blood.


Arteries

  • Carry oxygenated (pure) blood away from the heart to body tissues.
  • Have thick, elastic walls.
  • Branch into arterioles forming a network.
  • Largest artery: aorta.

Veins

  • Carry deoxygenated (impure) blood back to the heart (except pulmonary vein).
  • Contain valves to prevent backflow.
  • Divide into venules forming a network.
  • Largest veins: vena cavas (superior & inferior).

Capillaries

  • Thinest blood vessels; form a network between arteries & veins.
  • Connect arterioles to venules, enabling exchange of oxygen & nutrients.
Heart function:  the heart works continuously throughout life without rest; we must take care of it for a healthy life.

Lifestyle tips
  • Eat a balanced diet rich in iron & calcium.
  • Avoid sitting long on computers or TV.
  • Go for morning walk or exercise ≥30 minutes.
  • Avoid vehicles for short distances; walk, jog, cycle or play outdoor games.
  • Do yoga, jogging, swimming or any activity to stay active & healthy.

Mental health: stay happy & relaxed; avoid tension & polluted surroundings.

Diet: avoid junk & fried food.

Yoga for heart: regular yoga improves circulation, reduces stress & enhances lung function.

Beneficial yoga poses(illustrated):
  •   Tadasana (mountain pose).
  •   Vrikshasana (tree pose).
  •   Trikonasana (triangle pose).
  •   Dhanurasana (bow pose).
  •   Virabhadrasana (warrior pose).

F. Answer the following questions


1. What is the function of circulatory system? Name the main organs of the circulatory system.
Ans: The circulatory system transports oxygen, nutrients, water, and also removes waste products throughout the body. 
The main organs of the circulatory system are:
(1) Heart – the muscular pump that drives blood flow.
(2) Blood vessels – the network of arteries, veins, and capillaries that transport blood to and from tissues.

2. How many types of blood vessels are there? Name them.
Ans: There are 3 types of blood vessels:
(a) Arteries – carry blood away from the heart.
(b) Veins – bring blood back to the heart.
(c) Capillaries – tiny vessels where exchange of gases & nutrients occurs.

3. Explain the structure of heart. Draw a labeled diagram.
Ans: The heart is a muscular pump with four chambers that separate oxygen‑rich and oxygen‑poor blood:
(1) Right atrium: receives deoxygenated blood from the body via superior & inferior vena cava.
(2) Right ventricle: pumps the blood to the lungs through the pulmonary artery for oxygenation.
(3) Left atrium: receives oxygenated blood from the lungs via pulmonary veins.
(4) Left ventricle: pumps oxygen‑rich blood to the entire body through the aorta.
Valves – tricuspid, pulmonary, mitral, aortic – ensure one‑way flow.

4. Write the functions of blood in human body.
Ans: Blood performs several functions:
(1) Transport of oxygen & nutrients.
(2) Removal of waste products.
(3) Regulation of body temperature.
(4) Protection via immune cells (WBCs) and clotting (platelets).

5. What is the difference between arteries and veins?

Answer: The differences between arteries and veins are as follows:

  • Arteries
  1. Carry blood away from heart
  2. Thick, elastic walls
  3. Usually oxygen-rich blood, except pulmonary artery
  • Veins
  1. Carry blood toward heart
  2. Thinner walls, have valves
  3. Usually oxygen-poor blood, except pulmonary veins

6. Write some ways to keep the heart healthy and strong.

Answer: The following are some ways to keep the heart healthy and strong:
(1) Eat a healthy balanced diet rich in iron and calcium.
(2) Avoid sitting long on computer or TV; stay active.
(3) Do morning walk or exercise for at least 30 minutes.
(4) Walk or ride bicycle instead of using vehicles for short trips.
(5) Do yoga, jogging, cycling, swimming or outdoor games.
(6) Stay away from polluted surroundings.Stay happy, relaxed and avoid tension.
(7) Avoid junk and fried food.