286037
Assertion: Blood exhibits coagulation or clotting in response to an injury or trauma.
Reason: Uninjured blood vessels release an anticoagulant heparin.
1 Both (A) and (R) are correct but (R) is not the correct explanation of(A)
2 (A) is correct but (R) is not correct
3 (A) is not correct but (R) is correct
4 Both(A) and (R) are correct and (R) is the correct explanation of (A)
Explanation:
(b) When an injury is caused to a blood vessel, bleeding starts which is stopped by bluod clotting. At the site of injury blood platelets release platelet factor - III and injured tissues release thromboplastin. The two combine to form prothrombinase enzyme which converts prothrombin to thrombin. The latter stimulates formation of fibrin thread or clot. Blood contains an anticoagutant heparin which prevents blood clotting in uninjured vessels.
NCERT Page-281 / N-196
BODY FLUIDS and CIRCULATION(NCERT)
286038
Assertion: In the human heart, there is no mixing of oxygenated and deoxygenated blood.
Reason: Presence of valves in the heart allows the movement of blood in one direction only.
1 Both (A) and (R) are correct but (R) is not the correct explanation of(A)
2 (A) is correct but (R) is not correct
3 (A) is not correct but (R) is correct
4 Both(A) and (R) are correct and (R) is the correct explanation of (A)
Explanation:
(a) In the human heart, there is no mixing of deoxygenated and oxygenated blood due to the presence of inter - atrial and inter - ventricular septum.
These septa completely divide the atria and ventricles into right and left and thus avoid mixing of blood. As the heart muscle contracts and relaxes, the valves open and shut, letting blood flow into the ventricles and atria at alternate times. This heart valve minimises any obstruction and allows blood to flow smoothly and freely in one direction. It closes completely and quickly, not allowing any blood to flow back through the valve. The heart has 4 valves: the mitral valve and tricuspid valve, which control blood flow from the atria to the ventricles and the aortic valve and pulmonary valve, which control blood flow out of the ventricles..
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BODY FLUIDS and CIRCULATION(NCERT)
286037
Assertion: Blood exhibits coagulation or clotting in response to an injury or trauma.
Reason: Uninjured blood vessels release an anticoagulant heparin.
1 Both (A) and (R) are correct but (R) is not the correct explanation of(A)
2 (A) is correct but (R) is not correct
3 (A) is not correct but (R) is correct
4 Both(A) and (R) are correct and (R) is the correct explanation of (A)
Explanation:
(b) When an injury is caused to a blood vessel, bleeding starts which is stopped by bluod clotting. At the site of injury blood platelets release platelet factor - III and injured tissues release thromboplastin. The two combine to form prothrombinase enzyme which converts prothrombin to thrombin. The latter stimulates formation of fibrin thread or clot. Blood contains an anticoagutant heparin which prevents blood clotting in uninjured vessels.
NCERT Page-281 / N-196
BODY FLUIDS and CIRCULATION(NCERT)
286038
Assertion: In the human heart, there is no mixing of oxygenated and deoxygenated blood.
Reason: Presence of valves in the heart allows the movement of blood in one direction only.
1 Both (A) and (R) are correct but (R) is not the correct explanation of(A)
2 (A) is correct but (R) is not correct
3 (A) is not correct but (R) is correct
4 Both(A) and (R) are correct and (R) is the correct explanation of (A)
Explanation:
(a) In the human heart, there is no mixing of deoxygenated and oxygenated blood due to the presence of inter - atrial and inter - ventricular septum.
These septa completely divide the atria and ventricles into right and left and thus avoid mixing of blood. As the heart muscle contracts and relaxes, the valves open and shut, letting blood flow into the ventricles and atria at alternate times. This heart valve minimises any obstruction and allows blood to flow smoothly and freely in one direction. It closes completely and quickly, not allowing any blood to flow back through the valve. The heart has 4 valves: the mitral valve and tricuspid valve, which control blood flow from the atria to the ventricles and the aortic valve and pulmonary valve, which control blood flow out of the ventricles..