The normal pathway of the conduction system is which one of the following?
SA node - AV node - bundle of his - bundle branches - Purkinje fibers.
SA node - bundle of his -AV node - bundle branches - Purkinje fibers.
SA node - AV node - bundle branches - Ventricles - Purkinje fibers.
AV node-SA node - a bundle of his - bundle branches - Purkinje fibers.
The Correct Answer is A
This pathway represents the normal sequence of electrical impulses that coordinate the contraction and relaxation of the heart chambers.
The electrical signal originates from the sinoatrial (SA) node, which is often referred to as the natural pacemaker of the heart. It is located in the right atrium and generates the electrical impulses that initiate each heartbeat. From the SA node, the electrical signal travels to the atrioventricular (AV) node, which is located at the junction between the atria and ventricles.
After passing through the AV node, the electrical impulse travels through the bundle of His (also known as the atrioventricular bundle) and divides into the right and left bundle branches. These branches continue the conduction pathway and deliver the electrical signal to the Purkinje fibers.
The Purkinje fibers spread the electrical impulse rapidly throughout the ventricles, stimulating the contraction of the ventricular muscle and allowing for efficient pumping of blood out of the heart.
Therefore, the correct sequence of the normal conduction pathway in the heart is:
A. SA node - AV node - bundle of His - bundle branches - Purkinje fibers.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is B
Explanation
Disseminated Intravascular Coagulation (DIC) is a condition characterized by widespread activation of the coagulation system, leading to both excessive clot formation and consumption of clotting factors and platelets. This process can result in both bleeding and thrombosis.
The manifestations mentioned in option B are commonly seen in DIC:
Decreased platelet counts: DIC leads to platelet consumption and destruction, resulting in low platelet counts (thrombocytopenia).
Increased D-dimer: D-dimer is a fibrin degradation product, and its levels are increased DIC due to the breakdown of fibrin clots.
Increased prothrombin time (PT): DIC can lead to the depletion of clotting factors, resulting in prolonged prothrombin time, indicating impaired coagulation.
The other options mentioned do not represent the typical clinical manifestations of DIC:
A. Decreased hematocrit, increased platelet counts, and increased D-dimer in (option A) are incorrect because While platelet counts and D-dimer are increased in DIC, decreased hematocrit is not a characteristic finding.
C. Decreased Antithrombin III, increased platelet counts, and increased fibrinogen in (option C) is incorrect because: Decreased Antithrombin III can be seen in DIC, but increased platelet counts and fibrinogen levels are not specific to DIC.
D. Decreased D-dimer, increased platelet counts, and increased hemoglobin in (option D) is incorrect because Decreased D-dimer and increased hemoglobin are not typical findings in DIC, while increased platelet counts can be seen in some cases.
Correct Answer is B
Explanation
Lactate is a by-product of anaerobic metabolism that accumulates when there is insufficient oxygen supply to meet cellular metabolic demands. In the context of severe tissue hypoxia, such as in septic shock, the body may resort to anaerobic metabolism, leading to increased lactate production and elevated lactate levels in the blood.
Elevated lactate levels, typically above 4.0 mmol/L, are indicative of tissue hypoxia and inadequate oxygenation at the cellular level. Higher lactate levels, such as 9.0 mmol/L, suggest more severe tissue hypoxia and increased anaerobic metabolism.
A. Partial thromboplastin time (PTT) 64 seconds in (option A) is incorrect because: PTT is a laboratory test that evaluates the intrinsic pathway of the coagulation cascade. While coagulation abnormalities may occur in septic shock, PTT alone does not specifically indicate severe tissue hypoxia.
C. Potassium 2.8 mEq/L (2.8 mmol/L) (option C) is incorrect because Low potassium levels (hypokalemia) can be a concern in septic shock, but it does not directly indicate severe tissue hypoxia.
D. PaCO2 58 mm Hg in (option D) is incorrect because: PaCO2 refers to the partial pressure of carbon dioxide in arterial blood and is a measure of the respiratory status. While an elevated PaCO2 can be a sign of respiratory acidosis, it is not specific to severe tissue hypoxia.
Therefore, in a critically ill patient with septic shock, an elevated lactate level, such as 9.0 mmol/L, indicates severe tissue hypoxia and inadequate oxygenation at the cellular level
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