4. Why does human heart has different chambers that are not connected to each other? - Different chambers in human heart are not connected to each other in order to prevent mixing of oxygenated and deoxygenated blood. - Complete separation of chambers ensures that deoxygenated blood goes to various parts of body. This increases the efficiency of supply of oxygen to the body to meet the high-energy requirements.  5. Describe the flow of blood through human heart.
- Blood is received from various body parts into the right atrium by superior and inferior vena cava, when the chambers is relax.
- From right auricle blood flows to right ventricle.
- From right ventricle blood is transported to lungs for purification by pulmonary artery.
- After purification, blood comes back to heart in the left auricle / atrium through pulmonary vein.
- From left atrium blood moves to left ventricle.
- From left ventricle blood is
pumped out to all the body parts through aorta. 6. Give a flow chart of blood circulation through human heart.  7. Name the following blood vessels which
i. Brings deoxygenated blood into the right atrium from upper body parts -
ii. Brings deoxygenated blood into the right atrium from lower body parts -iii. Takes deoxygenated blood from right ventricle to lungs.
iv. Brings oxygenated blood from lungs to left atrium -.
v. Largest artery that takes oxygenated blood from left ventricle to all body parts -
vi. Supply blood to heart muscles. i. Superior vena cava.
ii. Inferior vena cava.
iii. Pulmonary artery.
iv. Pulmonary vein.
v. Aorta.
vi. Coronary arteries. 8. Name the chambers of heart that carries
i. Oxygenated blood.
ii. Deoxygenated blood. i. Oxygenated blood - left atrium and left ventricle.
ii. Deoxygenated blood - right atrium and right ventricle 9. Tabulate the changes taking place in heart when-
i. Both atria and ventricles are relaxed
ii. Atria contracts
iii. Ventricles contracts. | Events | Changes | | Both atria and ventricles are relaxed | -Deoxygenated blood flows from body parts to the right atrium through vena cava.
- Oxygenated blood flows from lungs to left atrium through pulmonary vein | | Atria contracts | -Deoxygenated blood from right atrium moves to right ventricle.
- Oxygenated blood from left atrium moves to left ventricle | | Ventricles contracts | - Deoxygenated blood from right ventricle moves to the lungs through pulmonary artery.
- Oxygenated blood from left ventricle moves to the body parts through aorta. |
10. Compare the number of chambers in the heart of following animals
(i) Fish
(ii) Amphibians
(iii) Reptiles
(iv) Birds | Animal | Number of Chambers in heart | | Fish | 2 | | Amphibians | 3 | | Reptiles | 3 Som etimes 31/2 | | Birds and Mammals | 4 | 11. What is the importance of separation of oxygenated and deoxygenated blood in the heart of living organisms? Separation of oxygenated and deoxygenated blood allows a highly efficient supply of oxygen to the body. This is specially useful in animals that have high energy needs like birds and mammals, which constantly use energy to maintain their body temperature. 12. Give two examples of animals which can tolerate some mixing of oxygenated and deoxygenated blood in their hearts. How do these animals manage their energy requirements? Amphibians and most
reptiles have three-chambered heart. They can tolerate some
mixing of oxygenated and deoxygenated blood.These animals can afford
such mixing because their body temperature depends on the
temperature in the environment and they do not use energy to
constantly maintain it. Their energy needs are therefore less.
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