What is the function of fibrin?
Fibrin creates the framework of a blood clot.
Fibrin, released from platelets, attracts other platelets.
Fibrin stimulates cell division.
Fibrin activates prothrombin.
Fibrin dissolves blood clots after tissue repair is complete.
The Correct Answer is A
Choice A rationale
Fibrin is a crucial protein in the coagulation cascade. It is formed from fibrinogen by the enzyme thrombin. Fibrin polymerizes to form a mesh-like network that traps red blood cells and platelets, creating the structural framework of a stable blood clot, effectively sealing off damaged blood vessels and preventing further blood loss.
Choice B rationale
While platelets are involved in coagulation, fibrin itself is not released from platelets to attract other platelets. Platelets release various factors like ADP and thromboxane A2 to aggregate. Fibrin's role is structural, forming the clot framework after platelet plug formation.
Choice C rationale
Fibrin does not directly stimulate cell division. Its primary role is in hemostasis and clot formation. Cell division, or mitosis, is regulated by growth factors and signaling pathways independent of fibrin's direct action, although clot removal is part of wound healing.
Choice D rationale
Fibrin is a product of prothrombin activation, not an activator of prothrombin. Prothrombin is converted into thrombin by prothrombinase, and thrombin then acts on fibrinogen to produce fibrin, which then forms the clot. The sequence is critical for proper coagulation.
Choice E rationale
Fibrin is the main component of a blood clot and needs to be dissolved for tissue repair to be complete. However, fibrin itself does not dissolve blood clots. Fibrinolysis, the process of clot dissolution, is mediated by plasmin, an enzyme that degrades fibrin.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is B
Explanation
Choice A rationale
The radial artery is a major artery in the forearm, running along the thumb side. It is a common site for pulse palpation and arterial blood gas sampling due to its superficial location. However, it typically terminates by contributing to the deep palmar arch, not forming the superficial palmar arch directly.
Choice B rationale
The superficial palmar arch is a vascular arcade formed primarily by the superficial branch of the ulnar artery, with a contribution from the radial artery. This arch is located just beneath the palmar aponeurosis and gives rise to the common digital arteries, supplying blood to the fingers.
Choice C rationale
Common digital arteries originate from the superficial palmar arch and run distally along the metacarpals. They then bifurcate into proper digital arteries, which supply the individual digits. These are branches of the arch, not the arch itself.
Choice D rationale
The brachial artery is a continuation of the axillary artery and is the main arterial supply to the arm. It typically bifurcates into the radial and ulnar arteries in the cubital fossa, well before reaching the hand to form palmar arches.
Choice E rationale
The ulnar artery is the larger terminal branch of the brachial artery, descending along the medial side of the forearm. Its superficial branch is the primary contributor to the superficial palmar arch, making it a key vessel in the hand's vascular supply.
Correct Answer is A
Explanation
Choice A rationale
Vaccination works by introducing attenuated (weakened) or inactivated forms of pathogens, or specific pathogen components (antigens), into the body. This exposure triggers the immune system to mount a primary immune response, leading to the production of antibodies and memory cells without causing the actual disease, thus providing future protection.
Choice B rationale
Antibiotics are antimicrobial drugs that directly kill or inhibit the growth of bacteria. They are not involved in stimulating the body's immune system for long-term immunity; instead, they provide a direct therapeutic intervention against bacterial infections.
Choice C rationale
Vaccination aims to increase the body's resistance to disease, not its susceptibility. By priming the immune system with harmless forms of pathogens, vaccines enhance the body's ability to quickly and effectively combat future infections, thereby reducing susceptibility.
Choice D rationale
Vaccination does not suppress the immune system's natural response; rather, it activates and enhances it. The purpose of a vaccine is to stimulate a controlled immune response that leads to the development of immunological memory, preparing the immune system for real pathogen exposure.
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