Assertion : WBCs accumulate at the site of wounds by diapedesis.
Reason : It is the sqeezing of leucocytes from the endothelium.
Assertion: In most of the mammal RBCs are devoid of nucleus.
Reason: Red colour is filled in the entire cytoplasm of RBCs, iron containing complex protein called haemoglobin
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Assertion: In lymphatic system, lymph is known as tissue fluid.
Reason: It comprises of plasma proteins, RBCs and WBCs.
Assertion: Type 'O' blood group individuals are called 'universal donors'.
Reason: RBCs of 'O' blood group consists both 'A' and 'B' surface antigens.
Assertion (A) : Blood coagulates in uninjured blood vessels.
Reason (R) : Uninjured blood vessels release an anticoagulant heparin.
Assertion: Fibrins are produced by the conversion of inactive fibrinogens in the plasma,
in the presence of enzyme thrombin.
Reason: Plasma without fibrinogen and blood corpuscles is called serum.
Assertion: The clotting process can occur in the absence of all cellular elements except platelets.
Reason: Activated platelets release vitamin K.
Assertion : Prothrombinase enzyme act as antiheparin.
Reason : Heparin prevent coagulation of blood in blood vessels.
Assertion : Blood is coloured in the insects.
Reason : Insect blood has no role in O2 transport.
Assertion : When there is a fall in the blood pressure due to loss of blood volume, this is compensated by vasoconstriction of veins.
Reason : Veins hold the extra amount of blood which can be shifted to the arteries as required.
Assertion: Sympathetic nerves can increase the strength of ventricular contraction neural
signals.
Reason: To increase the cardiac output parasympathetic neural signals synergistically act with sympathetic neural signal.
Assertion: Open circulatory system is more efficient than closed circulatory system.
Reason: In closed circulatory system rather than in open circulatory system, the blood flow is slow.
Assertion: In amphibians and reptiles, double circulation is incomplete.
Reason: Unlike in birds and mammals, in amphibian and reptiles, the left atrium receives oxygenated blood and right atrium receives deoxygenated blood.
Assertion: Left atrium possesses the thickest muscles.
Reason: Left atrium receives blood from the lungs.
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
Assertion: Atria act as primer pumps that increase the ventricular pumping.
Reason: Through the atria about 80 percent of the blood flows directly into ventricles.
Assertion : Heart of fish contains only deoxygenated blood.
Reason : Oxygenated blood does not return back to the heart in fishes
Assertion : Closed circulatory system is more effective than open type.
Reason : The closed circulatory system considerably enhances the speed, precision and efficiency of circulation.
Assertion : Heart valves resemble swing doors in action.
Reason : Valves are present in the heart chamber, at the opening of the heart into large arteries and veins.
Assertion : Blood pressure is arterial blood pressure.
Reason : It is measured by sphygmomanometer.