All vertebrates possess a heart – a hollow muscular organ composed of cardiac muscle fibres. The function of the heart is to pump oxygen to all parts of the body. The evolution of the heart is based on the separation of oxygenated blood from deoxygenated blood for efficient oxygen transport. In fishRead more
All vertebrates possess a heart – a hollow muscular organ composed of cardiac muscle fibres. The function of the heart is to pump oxygen to all parts of the body. The evolution of the heart is based on the separation of oxygenated blood from deoxygenated blood for efficient oxygen transport.
In fishes, the heart was like a hollow tube. This evolved into the four-chambered heart in mammals.
Piscean heart:-Fish has only two chambers in its heart – one auricle and one ventricle. Since both the auricle and the ventricle remain undivided, only deoxygenated blood passes through it. The deoxygenated blood enters the gills for oxygenation from the ventricle. It has additional chambers such as sinus venosus and conus arteriosus.
Amphibian heart:- Amphibians, such as frogs, have three-chambered hearts, with two auricles and one ventricle. The auricle is divided into a right and a left chamber by an inter-auricular septum, while the ventricle remains undivided.
Additional chambers such as sinus venosus and conus arteriosus are also present. The oxygenated blood from the lungs enters the left auricle and simultaneously, the deoxygenated blood from the body enters the right auricle. Both these auricles empty into the ventricle, wherein the oxygenated and deoxygenated blood get mixed to some extent.
Reptilian heart:- Reptiles have incomplete four-chambered hearts, except for crocodiles, alligators, and gharials. They have only one accessory chamber called sinus venosus. The reptilian heart also shows mixed blood circulation.
Avian and mammalian hearts:- They have two pairs of chambers for separating oxygenated and deoxygenated bloods. The heart is divided into four chambers. The upper two chambers are called atria and the lower two chambers are called ventricles. The chambers are separated by a muscular wall that prevents the mixing of the blood rich in oxygen with the blood rich in carbon dioxide.
(a) Blood and lymph:- Blood- 1. Blood is a red-coloured fluid that contains RBCs. 2. It contains plasma, RBCs, WBCs, and platelets. It also contains proteins. 3. Blood transports nutrients and oxygen from one organ to another. lymph- 1. Lymph is a colourless fluid that lacks RBCs. 2. It contains plaRead more
(a) Blood and lymph:-
Blood-
1. Blood is a red-coloured fluid that contains RBCs.
2. It contains plasma, RBCs, WBCs, and platelets. It also contains proteins.
3. Blood transports nutrients and oxygen from one organ to another.
lymph-
1. Lymph is a colourless fluid that lacks RBCs.
2. It contains plasma and lesser number of WBCs and platelets. It lacks proteins.
3. Lymph plays a role in the defensive system of the body. It is a part of the immune system.
(b) Open and closed systems of circulation:-
Open system of circulation-
1. In this system, blood is pumped by the heart, through large vessels, into body cavities called sinuses.
2. The body tissues are in direct contact with blood.
3. Blood flows at low pressure. Hence, it is a slower and less efficient system of circulation.
4. The flow of blood is not regulated through the tissues and organs.
5. This system is present in arthropods and molluscs.
Closed system of circulation-
1. In this system, blood is pumped by the heart, through a closed network of vessels.
2. The body tissues are not in direct contact with blood.
3. Blood flows at high pressure. Hence, it is a faster and more efficient system of circulation.
4. The flow of blood can be regulated by valves.
5. This system is present in annelids, echinoderms, and vertebrates.
(c) Systole and diastole
Systole:-
1. It is the contraction of the heart chambers to drive blood into the aorta and the pulmonary artery.
2. Systole decreases the volume of the heart chambers and forces the blood out of them.
Diastole:-
1. It is the relaxation of the heart chambers between two contractions. During diastole, the chambers are filled with blood.
2. Diastole brings the heart chambers back into their original sizes to receive more blood.
(d) P-wave and T-wave:-
1. In an electrocardiogram (ECG), the Pwave indicates the activation of the SA node.
2. During this phase, the impulse of contraction is generated by the SA node, causing atrial depolarisation.
3. It is of atrial origin.
T-wave:-
1. In an electrocardiogram (ECG), the T-wave represents ventricular relaxation.
2. During this phase, the ventricles relax and return to their normal state.
3. It is of ventricular origin.
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 chambersRead more
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 – 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:
1 Systemic circulation
2 Pulmonary circulation
Systemic 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 pulmonary circulation.
Lymph:- 1. It is a colourless fluid that does not contain RBCs. 2. It contains plasma and lesser number of WBCs and platelets. 3. It helps in body defence and is a part of the immune system. 4. Its plasma lacks proteins. 5. It transports nutrients from the tissue cells to the blood, through lymphatiRead more
Lymph:-
1. It is a colourless fluid that does not contain RBCs.
2. It contains plasma and lesser number of WBCs and platelets.
3. It helps in body defence and is a part of the immune system.
4. Its plasma lacks proteins.
5. It transports nutrients from the tissue cells to the blood, through lymphatic vessels.
6. The flow of lymph is slow.
Blood:-
1. It is a red-coloured fluid that contains RBCs.
2. It contains plasma, RBCs, WBCs, and platelets.
3. It is associated with the circulation of oxygen and carbon dioxide.
4. Its plasma has proteins, calcium, and phosphorus.
5. It transports nutrients and oxygen from one organ to another.
6. The flow of blood in the blood vessels is fast.
Connective tissues have cells scattered throughout an extra-cellular matrix. They connect different body systems. Blood is considered as a type of connective tissue because of two reasons. 1 Like the other connective tissues, blood is mesodermal in origin. 2 It connects the body systems, transportsRead more
Connective tissues have cells scattered throughout an extra-cellular matrix. They connect different body systems. Blood is considered as a type of connective tissue because of two reasons.
1 Like the other connective tissues, blood is mesodermal in origin.
2 It connects the body systems, transports oxygen and nutrients to all the parts of the body, and removes the waste products. Blood has an extra-cellular matrix called plasma, with red blood cells, white blood cells, and platelets floating in it.
Describe the evolutionary change in the pattern of heart among the vertebrates.
All vertebrates possess a heart – a hollow muscular organ composed of cardiac muscle fibres. The function of the heart is to pump oxygen to all parts of the body. The evolution of the heart is based on the separation of oxygenated blood from deoxygenated blood for efficient oxygen transport. In fishRead more
All vertebrates possess a heart – a hollow muscular organ composed of cardiac muscle fibres. The function of the heart is to pump oxygen to all parts of the body. The evolution of the heart is based on the separation of oxygenated blood from deoxygenated blood for efficient oxygen transport.
In fishes, the heart was like a hollow tube. This evolved into the four-chambered heart in mammals.
Piscean heart:-Fish has only two chambers in its heart – one auricle and one ventricle. Since both the auricle and the ventricle remain undivided, only deoxygenated blood passes through it. The deoxygenated blood enters the gills for oxygenation from the ventricle. It has additional chambers such as sinus venosus and conus arteriosus.
Amphibian heart:- Amphibians, such as frogs, have three-chambered hearts, with two auricles and one ventricle. The auricle is divided into a right and a left chamber by an inter-auricular septum, while the ventricle remains undivided.
Additional chambers such as sinus venosus and conus arteriosus are also present. The oxygenated blood from the lungs enters the left auricle and simultaneously, the deoxygenated blood from the body enters the right auricle. Both these auricles empty into the ventricle, wherein the oxygenated and deoxygenated blood get mixed to some extent.
Reptilian heart:- Reptiles have incomplete four-chambered hearts, except for crocodiles, alligators, and gharials. They have only one accessory chamber called sinus venosus. The reptilian heart also shows mixed blood circulation.
Avian and mammalian hearts:- They have two pairs of chambers for separating oxygenated and deoxygenated bloods. The heart is divided into four chambers. The upper two chambers are called atria and the lower two chambers are called ventricles. The chambers are separated by a muscular wall that prevents the mixing of the blood rich in oxygen with the blood rich in carbon dioxide.
For more answers visit to website:
See lesshttps://www.tiwariacademy.com/ncert-solutions/class-11/biology/chapter-18/
Write the differences between: (a) Blood and Lymph (b) Open and Closed system of circulation (c) Systole and Diastole (d) P-wave and T-wave
(a) Blood and lymph:- Blood- 1. Blood is a red-coloured fluid that contains RBCs. 2. It contains plasma, RBCs, WBCs, and platelets. It also contains proteins. 3. Blood transports nutrients and oxygen from one organ to another. lymph- 1. Lymph is a colourless fluid that lacks RBCs. 2. It contains plaRead more
(a) Blood and lymph:-
Blood-
1. Blood is a red-coloured fluid that contains RBCs.
2. It contains plasma, RBCs, WBCs, and platelets. It also contains proteins.
3. Blood transports nutrients and oxygen from one organ to another.
lymph-
1. Lymph is a colourless fluid that lacks RBCs.
2. It contains plasma and lesser number of WBCs and platelets. It lacks proteins.
3. Lymph plays a role in the defensive system of the body. It is a part of the immune system.
(b) Open and closed systems of circulation:-
Open system of circulation-
1. In this system, blood is pumped by the heart, through large vessels, into body cavities called sinuses.
2. The body tissues are in direct contact with blood.
3. Blood flows at low pressure. Hence, it is a slower and less efficient system of circulation.
4. The flow of blood is not regulated through the tissues and organs.
5. This system is present in arthropods and molluscs.
Closed system of circulation-
1. In this system, blood is pumped by the heart, through a closed network of vessels.
2. The body tissues are not in direct contact with blood.
3. Blood flows at high pressure. Hence, it is a faster and more efficient system of circulation.
4. The flow of blood can be regulated by valves.
5. This system is present in annelids, echinoderms, and vertebrates.
(c) Systole and diastole
Systole:-
1. It is the contraction of the heart chambers to drive blood into the aorta and the pulmonary artery.
2. Systole decreases the volume of the heart chambers and forces the blood out of them.
Diastole:-
1. It is the relaxation of the heart chambers between two contractions. During diastole, the chambers are filled with blood.
2. Diastole brings the heart chambers back into their original sizes to receive more blood.
(d) P-wave and T-wave:-
1. In an electrocardiogram (ECG), the Pwave indicates the activation of the SA node.
2. During this phase, the impulse of contraction is generated by the SA node, causing atrial depolarisation.
3. It is of atrial origin.
T-wave:-
1. In an electrocardiogram (ECG), the T-wave represents ventricular relaxation.
2. During this phase, the ventricles relax and return to their normal state.
3. It is of ventricular origin.
For more answers visit to website:
See lesshttps://www.tiwariacademy.com/ncert-solutions/class-11/biology/chapter-18/
What is meant by double circulation? What is its significance?
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 chambersRead more
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 – 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:
1 Systemic circulation
2 Pulmonary circulation
Systemic 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 pulmonary circulation.
For more answers visit to website:
See lesshttps://www.tiwariacademy.com/ncert-solutions/class-11/biology/chapter-18/
What is the difference between lymph and blood?
Lymph:- 1. It is a colourless fluid that does not contain RBCs. 2. It contains plasma and lesser number of WBCs and platelets. 3. It helps in body defence and is a part of the immune system. 4. Its plasma lacks proteins. 5. It transports nutrients from the tissue cells to the blood, through lymphatiRead more
Lymph:-
1. It is a colourless fluid that does not contain RBCs.
2. It contains plasma and lesser number of WBCs and platelets.
3. It helps in body defence and is a part of the immune system.
4. Its plasma lacks proteins.
5. It transports nutrients from the tissue cells to the blood, through lymphatic vessels.
6. The flow of lymph is slow.
Blood:-
1. It is a red-coloured fluid that contains RBCs.
2. It contains plasma, RBCs, WBCs, and platelets.
3. It is associated with the circulation of oxygen and carbon dioxide.
4. Its plasma has proteins, calcium, and phosphorus.
5. It transports nutrients and oxygen from one organ to another.
6. The flow of blood in the blood vessels is fast.
For more answers visit to website:
See lesshttps://www.tiwariacademy.com/ncert-solutions/class-11/biology/chapter-18/
Why do we consider blood as a connective tissue?
Connective tissues have cells scattered throughout an extra-cellular matrix. They connect different body systems. Blood is considered as a type of connective tissue because of two reasons. 1 Like the other connective tissues, blood is mesodermal in origin. 2 It connects the body systems, transportsRead more
Connective tissues have cells scattered throughout an extra-cellular matrix. They connect different body systems. Blood is considered as a type of connective tissue because of two reasons.
1 Like the other connective tissues, blood is mesodermal in origin.
2 It connects the body systems, transports oxygen and nutrients to all the parts of the body, and removes the waste products. Blood has an extra-cellular matrix called plasma, with red blood cells, white blood cells, and platelets floating in it.
For more answers visit to website:
See lesshttps://www.tiwariacademy.com/ncert-solutions/class-11/biology/chapter-18/