chapter-1 class 10 notes science
Answers
Explanation:
Functioning of Heart
1. Impure blood from the body enters the right auricle through inferior & superior vena cava
2. From the auricle the blood is pumped into right ventricle passing through tricuspid valve
3. Now the ventricle contracts and pump blood into pulmonary artery.
4. The pulmonary artery bifurcates and branches into each lungs
5. In the lungs the blood gets oxygenated and is collected by pulmonary vein.
6. Pulmonary vein carries blood to the left auricle.
7. The left auricle contracts to pump blood intoIt is a muscular organ, that function non-stop throughout the life of an individual. It is mesodermal in
origin & consist of Cardiac muscles. It never gets tired or undergo fatigue.
Heart of Different Vertebrates
• In Fishes: The heart is two chambered, one Auricle & one Ventricle
• In Amphibians: [e.g. Frog] the heart is three chambered, it contains two Auricles & one
Ventricle. Due to a single Ventricle, the heart pumps only mixed blood.
• In Reptiles: The hear is imperfectly four chambered.
• In Birds & Mammal: The heart is perfectly four chambered. In this case there is no mixing of
blood.
The Human Heart
The heart is hollow muscular organ, located in the centre of thoracic cavity, slightly towards the left.
It is protected by a double membrane called Pericardium. The space between the two walls are filled
with pericardial fluid. The heart is four chambered, the upper two chambers are Auricles and the
lower two are Ventricles.
• Right Auricle; deals with impure blood. It receives impure blood from various parts of body
through two major veins, the superior vena cava, & the inferior vena cava.
• Left Auricle; deals with pure blood. It receives pure blood through pulmonary vein.
• Right Ventricle; receives impure blood from the right Auricle. Right ventricle pumps blood to
the pulmonary artery, which takes it to the lungs for purification.
• Left Ventricle; left ventricle receives pure blood from left auricle .It pumps the pure blood to
Aorta , the main artery ,which takes it to the whole body
. left ventricle through bicuspid valve.
8. From the left ventricle the pure blood is pumped into aorta, which carries it to various parts.
Pulmonary and Systemic Circulation
Pulmonary Circulation: It deals with the purification of deoxygenated blood. It involves pumping of
impure blood from right ventricle to lungs, through pulmonary artery and returning of pure blood
from lungs to left auricle through pulmonary vein.
Systemic Circulation: It deals with the supply of pure blood to all the parts of body ,it includes the
pumping of pure blood from left ventricle to all parts of body through aorta ,and return of impure
blood from all the parts of body to right auricle ,through superior & inferior vena cava.
Double Circulation: A circulatory system in which the blood travels twice through the heart in one
complete cycle of the body is called double circulation. It includes both pulmonary and systemic
circulation.
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