Question 1

Explain double circulation in human

Accepted Answer

The heart receives deoxygenated blood from different parts of the body, and it pumps this blood to the lungs. The oxygenated blood from the lungs returns to the heart, which is pumped again into different parts of the body by the heart. Thus, the blood passes twice through the heart making one complete round through the body. This is called double circulation.Pulmonary and systemic circulationThe pulmonary circulation pertains to lungs. The blood flows from the right ventricle to the lungs. Pulmonary veins collect oxygenated blood from the lungs and carry it back to the heart (left auricle). The systemic circulation pertains to the major circulation of the body. The aorta receives the blood from the left ventricle and sends it to the various parts of the body. Veins collect the deoxygenated blood from the body parts and pour it back into the right auricle.

Question 2

Describe double circulation in human beings. Why is it necessary?

Accepted Answer

Explanation-The heart receives deoxygenated blood from different parts of the body, and it pumps this blood to the lungs. The oxygenated blood from the lungs returns to the heart, which is pumped again into different parts of the body by the heart. Thus, the blood passes twice through the heart making one complete round through the body. This is called double circulation. The two circuits involved in double circulation are:1. Pulmonary circulation: Pulmonary circulation pertains to the lungs. The blood flows from the right ventricle to the lungs. Pulmonary veins collect oxygenated blood from the lungs and carry it back to the heart (left auricle). 2. Systemic circulation: Systemic circulation pertains to the major circulation of the body. The aorta receives the blood from the left ventricle and sends it to the various parts of the body. Veins collect the deoxygenated blood from the body parts and pour it back into the right auricle.Significance of double circulation: The separation of oxygenated and deoxygenated blood allows a more efficient supply of oxygen to the body cells. Blood is circulated to the body tissues through systemic circulation and to the lungs through pulmonary circulation.

Question 3

Draw a standard ECG and explain the different segments in it.

Accepted Answer

Answer-Electrocardiogram is a graphical representation of the cardiac cycle produced by an electrograph. The diagrammatic representation of a standard ECG is shown below.                                     A typical human electrocardiogram has five waves &#8211; P, Q, R, S, and T. The P, R, and T-waves are above the base line and are known as positive waves. The Q and S-waves are below the base line and are known as negative waves. The P-wave is of atrial origin, while the Q, R, S, and T-waves are of ventricular origin. (a) The P-wave indicates atrial depolarisation. During this wave, the impulse of contraction is generated by the SA node. The PQ-wave represents atrial contraction.(b) The QR-wave is preceded by ventricular contraction. It represents the spread of the impulse of contraction from the AV node to the wall of the ventricle. It leads to ventricular depolarisation.(c) The RS-wave represents ventricular contraction of about 0.3 sec.(d) The ST-wave represents ventricular relaxation of about 0.4 sec. During this phase, the ventricles relax and return to their normal state.(e) The T-wave represents ventricular relaxation.

Question 4

What would be the consequences of the deficiency of haemoglobin in the human body?

Accepted Answer

Deficiency of hemoglobin in the human body will result in anaemia.  Hemoglobin is present in red blood cells which carry oxygen to cells of the body. A decrease in its amount will result in a decrease in the oxygen-carrying capacity of blood. The person may suffer from breathlessness and fatigue which may be a symptom of anaemia.

Question 5

Identify the correct order of blood flow through the heart, entering from the vena cava.

Accepted Answer

Both vena cava passes the deoxygenated blood to the right atrium. Blood from right atrium enters right ventricle and pulmonary arteries carry deoxygenated blood from right ventricle to lungs for oxygenation. Two pulmonary veins come from each lung and pass O$_2$-rich blood to left atrium. Blood enters left ventricle from the left atrium. The left ventricle pumps blood into the aorta which in turn branches and delivers blood to the major body regions and organs. So, the correct sequence is C.

Question 6

What is meant by double circulation? What is its significance?

Accepted Answer

Double circulation is a process during which blood passes twice through the heart during one complete cycle. This type of circulation is found in amphibians, reptiles, birds, and mammals. However, it is more prominent in birds and mammals as in them the heart is completely divided into four chambers &#8211; the right atrium, the right ventricle, the left atrium, and the left ventricle.The movement of blood in an organism is divided into two parts:(i) Systemic circulation(ii) Pulmonary circulationSystemic circulation involves the movement of oxygenated blood from the left ventricle of the heart to the aorta. It is then carried by blood through a network of arteries, arterioles, and capillaries to the tissues. From the tissues, the deoxygenated blood is collected by the venules, veins, and vena cava, and is emptied into the left auricle.Pulmonary circulation involves the movement of deoxygenated blood from the right ventricle to the pulmonary artery, which then carries blood to the lungs for oxygenation. From the lungs, the oxygenated blood is carried by the pulmonary veins into the left atrium.Hence, in double circulation, blood has to pass alternately through the lungs and the tissues.Significance of double circulation:The separation of oxygenated and deoxygenated blood allows a more efficient supply of oxygen to the body cells. Blood is circulated to the body tissues through systemic circulation and to the lungs through the pulmonary circulation.

Question 7

Explain double circulation with a schematic diagram?

Accepted Answer

Double circulation is the most efficient way of circulation. Here, in humans, the four-chambered heart, arteries, veins, and capillaries all have a vital role to play. Blood gets pumped out of the heart. This blood goes to different organs and then blood again comes back to the heart. All this happens in a very systematic way through the different arteries and veins carrying oxygenated and deoxygenated blood.In double circulation, there are two pathways in which blood flows. They are:1) Pulmonary pathway   2) Systemic pathway.The pulmonary circulation or pathway carries the deoxygenated blood from the right side of the heart to the lungs.  Exchange of oxygen and carbon dioxide takes place in the lungs and the blood is now oxygenated (with oxygen). Through the systemic circulation, oxygenated blood travels from the left side of the heart to the other areas of the body. At various organ sites, exchange of gases, nutrients, and waste through lymph occurs. This deoxygenated blood again goes back to the right side of the heart. The pulmonary circuit and the systemic circuit work together. This ensures that deoxygenated blood goes to the lungs through the pulmonary artery while the oxygenated blood from the aorta reaches the different organs and tissues.

Question 8

Given below is a diagram of a smear of human blood. Study the same and answer the questions that follow:a. Name the parts 1, 2, 3 and 4 indicated by guidelines.b. Mention two structural differences between the parts labelled '1' and '2'.c. What is the main function of the parts labelled 1, 2 and 3 respectively?d. What is the life span of the part labelled '1'?e. Name a soluble protein found in '4' which helps in the clotting of blood.

Accepted Answer

a) 1) Red blood corpuscles, 2) White blood corpuscles, 3) Platelets, 4) Blood plasma.b) RBCs lack nucleus whereas, WBCs have a nucleus. RBC has a biconcave shape while the shape of WBC is irregular.c) Functions:- 1) RBCs- Its main function is to carry oxygen from the lungs to the body tissues and also carry carbon dioxide as a waste product away from tissues to lungs. Haemoglobin protein in RBCs helps in carrying oxygen.2) WBCs- Its main function is to fight infection by preventing the entry of foreign particles.3) Platelets:- Its main function is to prevent bleeding by clotting blood.d) The life span of RBC is 120 days.e) Fibrinogen is the soluble plasma protein that helps in blood clotting.

Question 9

What prevents backflow of blood inside the heart during contraction?

Accepted Answer

Hint - Flow of blood in the heart is unidirectional in both right and left part of the heart.  This unidirectional flow is maintained by flaps like structure.Part 1 - Heart Heart is the blood-pumping organ that pumps blood throughout the body with the help of blood vessels of the circulatory system. The heart is divided into two halves: right and left. Both the halves have 1 atrium (upper chamber) and 1 ventricle (lower chamber) each.Part 2 - ValvesThe atrium and ventricle have valves in between the chambers to prevent the backflow of the blood.Between the right atrium and the right ventricle, the Tricuspid valve is present.Between the left atrium and the left ventricle, the Bicuspid valve is present.The semilunar valve is present between the ventricles and the pulmonary artery and the systemic aorta.Part 3 - ConclusionThe four valves present in the heart prevents the backflow of blood inside the heart.The thick muscular wall of ventricles (especially left ventricle) helps in sending blood to the entire body with pressure. The wall of atria is thinner than ventricles because they have to pump blood just to the ventricles and not to the body. Final step -  The Valves in heart prevent the backflow of blood inside the heart.

Question 10

Ventricles have thicker walls than auricles. Give reasons.

Accepted Answer

Because ventricles have to do more work as compare to atria. Ventricles pump blood into various organs and the pressure of blood flowing in them is more than that of articles.