The final step in the formation of a blood clot is:
The formation of prothrombin activator.
The conversion of prothrombin to thrombin by prothrombin activator.
The conversion of fibrinogen to fibrin by thrombin.
Tissue damage.
The Correct Answer is C
The conversion of fibrinogen to fibrin by thrombin is the final step in the formation of a blood clot.
Fibrin is a protein that forms a net-like structure that traps platelets and other blood cells, making the clot stronger and more durable.
Choice A is wrong because the formation of a prothrombin activator is the first step in the formation of a blood clot.
A prothrombin activator is a complex of enzymes that converts prothrombin to thrombin.
Choice B is wrong because the conversion of prothrombin to thrombin by the prothrombin activator is the second step in the formation of a blood clot.
Thrombin is an enzyme that converts fibrinogen to fibrin.
Choice D is wrong because tissue damage is not a step in the formation of a blood clot, but a trigger for the clotting process.
When blood vessels are injured, they release substances that activate platelets and clotting factors.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is C
Explanation
The thymus gland is an essential part of the immune system that produces and matures T cells, a type of white blood cell that defends the body from infections.
Thymosins also regulate immune cell production and inhibit aging.
Choice A is wrong because thyroxines are hormones produced by the thyroid gland, not the thymus gland.
Thyroxines control metabolism and affect growth and development.
Choice B is wrong because melatonins are hormones produced by the pineal gland, not the thymus gland.
Melatonins control circadian rhythms and sleep cycles.
Choice D is wrong because prostaglandins are not hormones, but lipid compounds that have hormone-like effects.
Prostaglandins control inflammation, blood pressure, muscle contraction, and other functions.
Correct Answer is C
Explanation
The sinoatrial (SA) node is the natural pacemaker of the heart.
It generates electrical impulses that cause the heart’s chambers to contract, setting the heart rate.
The SA node typically generates 60–100 heartbeats per minute when a person is at rest.
Choice A is wrong because Purkinje fibers are part of the electrical conduction system of the heart that carries impulses to the ventricles.
They are not the primary source of impulses.
Choice B is wrong because the AV bundle (also called bundle of His) is another part of the electrical conduction system of the heart that connects the atria and the ventricles.
It is not the natural pacemaker of the heart.
Choice D is wrong because an atrioventricular node is a relay station between the atria and the ventricles that delays the electrical impulses from the SA node.
It can act as a backup pacemaker if the SA node fails, but it is not the normal pacemaker of the heart.
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