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Chapter 6

The Circulatory System

Class 8 - Concise Biology Selina

Multiple Choice Questions

Question 1

The vein which brings oxygenated blood to the heart from the lungs:

  1. Renal vein
  2. Superior Vena Cava
  3. Pulmonary vein
  4. Coronary Vein


Pulmonary vein

Reason — Pulmonary vein are the blood vessels which carry oxygenated blood from lungs to the heart.

Question 2

The path which the blood flows through during pulmonary circulation is:

  1. RA → RV → Pulmonary arteries → Lungs → Pulmonary veins → LA
  2. LA → LV → Pulmonary veins → Lungs → Pulmonary arteries → RA
  3. LA → LV → Aorta → Body → Vena Cavae → RA
  4. RA → RV → Vena Cavae → Body → Aorta → LA


RA → RV → Pulmonary arteries → Lungs → Pulmonary veins → LA

Reason — Pulmonary circulation is the movement of blood from the heart to the lungs for oxygenation, then back to the heart again. At first, blood flows from the right side of the heart to the lungs and then returns to the left side of the heart (pulmonary circulation).

Short Answer Questions

Question 1

In which organ of our body does blood get oxygenated ?



Question 2

Which side of the heart (left or right) contains oxygenated blood ?


The left side of the heart contains oxygenated blood.

Question 3

Name the following :

(a) Three kinds of blood vessels

(b) Two types of blood circulation in the human body

(c) The membranous structure which divides the heart into a right and a left portion

(d) The structure responsible for starting electrical impulses that cause the heart to contract and relax in order to keep pumping blood

(e) The scientist who identified different types of blood groups


(a) Arteries, Veins, Capillaries.

(b) Pulmonary circulation, Systemic circulation

(c) Septum

(d) SA node (Sinoatrial Node)

(e) Karl Landsteiner

Question 4

Define the terms :

(a) Circulatory system

(b) Blood

(c) Lymph

(d) Artificial pacemaker


(a) Circulatory System — The circulatory system comprises of the heart, blood and blood vessels which circulates blood throughout the body, thereby helping in the transport of nutrients, oxygen and carbon dioxide.

(b) Blood — Blood is the circulating fluid contained in the heart and in the blood vessels such as arteries, veins and capillaries of the circulatory system.

(c) Lymph — Lymph is the fluid contained within the lymph vessels and lymphatic organs. It is also a part of immune system and its main function is defence against germs.

d) Artificial Pacemaker — Sometimes a mechanical device called an artificial pacemaker is placed surgically in humans if their SA node is damaged or if the electrical conduction system of the heart has problems.

Long Answer Questions

Question 1

Differentiate between the following pairs on the basis of what is indicated within the brackets:

(a) Pulmonary artery and pulmonary vein (kind of blood)

(b) Artery and vein (direction of blood flow)

(c) Closed and open vascular system (definition)

(d) Bicuspid and tricuspid valve (location)

(e) Blood and lymph (composition)


(a) Difference between Pulmonary artery and Pulmonary vein

Pulmonary arteryPulmonary vein
Pulmonary artery carries deoxygenated bloodPulmonary vein carries oxygenated blood.

(b) Difference between Artery and Vein (direction of blood flow)

Artery carries blood from the heart to various parts of the body.Vein carries blood from different parts of the body to the heart.

(c) Difference between Closed and Open Vascular system (definition)

Closed Vascular SystemOpen Vascular System
In Closed Vascular System, blood flows inside the body through blood vessels in a closed manner.In Open Vascular System, blood flows through open spaces in the body without blood vessels.

(d) Difference between Bicuspid and Tricuspid valve (location)

Bicuspid ValveTricuspid Valve
Present between left auricle and left ventricle.Present between right auricle and right ventricle.

(e) Difference between Blood and Lymph (composition)

Non-cellular fluid part of blood is Plasma. It makes up 55-60% of the blood.Non-cellular part of Lymph is made up of mostly water (about 94%) and the remaining 6% is made up of proteins, fats, carbohydrates, enzymes, antibodies, etc.
Cellular part of blood consists of red and white cells and platelets. They make up 40-45% of the blood.Cellular part of Lymph contains only leukocytes (mostly lymphocytes). Platelets and red blood cells are absent.

Question 2

Write important role/roles of each:

(a) Pericardial fluid

(b) Aorta

(c) Vena cavae


(a) Pericardial fluid — Pericardial fluid protects the heart from shocks, jerks or any mechanical stress.

(b) Aorta — Aorta carries oxygenated blood from the heart to all parts of the body through its branches.

(c) Vena cavae — The two Vena Cavae veins (Superior Vena Cava and Inferior Vena Cava) bring deoxygenated blood from all the different parts of the body to the right auricle of the heart.

Question 3

Name any four heart-related conditions that occur commonly in humans. Briefly explain the cause and symptoms of each of them.


The four heart related conditions common to humans along with their cause and symptoms are given below:

  1. Palpitations — When the heart beats too hard or too fast or sometimes even skips a beat, it is called Palpitations. Palpitations are often caused due to stress or anxiety. Sometimes, certain types of food may also cause Palpitations.
  2. Hypertension — This is a condition that occurs when blood flows through the blood vessels with a force greater than normal. This is also called High Blood Pressure. Hypertension can also strain the heart, damage blood vessels and increase the risk of heart attack or stroke.
  3. Heart attack — A heart attack is a sudden interruption of blood supply to the heart. It usually occurs due to a blood clot that prevents the flow of oxygen rich blood to the cardiac muscle. As, a result a part of the cardiac muscle dies and causes a permanent damage to the heart. Some common symptoms of a heart attack include uncomfortable pressure, tightness or squeezing pain in the centre of the chest, discomfort or pain spreading beyond the chest to the shoulders, neck, jaw, teeth or one or both arms, shortness of breath , dizziness, sweating and nausea.
  4. Cardiac Arrest — A cardiac arrest occurs when the heart suddenly stops pumping blood around the body. In cardiac arrest, a person suddenly loses consciousness and stops breathing or may have abnormal breathing. Some people experience chest pain, shortness of breath, or nausea before a cardiac arrest occurs. zgThe common cause of cardiac arrest is coronary artery disease wherein the walls of the arteries thicken as a result of fat or plaque deposition. Less common causes include major blood loss, lack of oxygen, low potassium levels, heart failure and intense physical exercise.

Question 4

Give the functions of lymph.


Functions of lymph are —

  1. Drainage — It drains away excess tissue fluid and metabolites and returns proteins to the blood from tissue spaces.
  2. Absorption — Fats in the intestine are absorbed through lymph vessels (or lymphatics).
  3. Defence — Lymphocytes and monocytes of the lymph function to defend the body. The lymphatics also remove bacteria from the tissues.

Question 5

Explain — (a) Universal donor (b) Universal recipient


(a) Universal donor — The blood of O group can be given to all the groups. Hence, a person with O blood group is called a universal donor.

(b) Universal recipient — The blood of AB group can only be given to AB group, but a person with AB type of blood can receive blood from all types, and is therefore called a universal recipient.

Question 6

During surgical operations or during accidents, the patient may be given blood from outside to save his life. What is the technical name of this process ? Briefly explain the precautions to be observed and taken in this process.


This process is known as blood transfusion. The following precautions are to be observed for blood transfusion:

  1. Checking the compatibility of the donor's blood group with that of the recipient.
  2. It should be made sure clinically that the blood of the donor is free from any infections.
  3. The donor's hemoglobin level is checked.

Question 7

Given alongside is a diagram of the human heart showing its internal structure. Label the parts marked 1 to 6, and answer the following questions.

Given alongside is a diagram of the human heart showing its internal structure. Label the parts marked 1 to 6, and answer the following questions. Which type of blood is carried by the blood vessel marked 2? Name the main artery which takes the blood from heart to different parts of the body? Which chamber of the heart receives deoxygenated blood from the body? The Circulatory System, Concise Biology Solutions ICSE Class 8.

(a) Which type of blood is carried by the blood vessel marked 2?

(b) Name the main artery which takes the blood from heart to different parts of the body?

(c) Which chamber of the heart receives deoxygenated blood from the body?


The parts marked 1 to 6 are labelled below:

  • 1 → Left pulmonary artery

  • 2 → Superior vena cava

  • 3 → Left pulmonary vein

  • 4 → Right auricle

  • 5 → Left ventricle

  • 6 → Right ventricle

(a) Deoxygenated blood is carried by the blood vessel marked 2 (Superior vena cava).

(b) Aorta

(c) Right auricle