The mitral and tricuspid valves close after the ventricles are filled with blood because the
Chordae tendineae relax, which allows the valves to close.
Increased pressure in the ventricles pushes the valves to close.
Trabeculae carneae contract, which pulls the valves closed.
Reduced pressure in the atria creates a negative pressure that pulls the valves closed.
The Correct Answer is B
The mitral and tricuspid valves are located between the atria and ventricles in the heart, and they open and close to allow blood to flow in one direction through the heart. During diastole, when the heart is relaxed and filling with blood, the mitral and tricuspid valves are open to allow blood to flow from the atria into the ventricles.
Once the ventricles are filled with blood, they begin to contract during systole to pump the blood out to the lungs (right ventricle) and the rest of the body (left ventricle). As the ventricles contract, the pressure within them increases, which causes the mitral and tricuspid valves to be pushed closed by the blood within the ventricles. This closure prevents the backflow of blood into the atria during ventricular contraction (systole).
The chordae tendineae are thin, fibrous cords that connect the mitral and tricuspid valves to the papillary muscles within the ventricles. These structures help to anchor the valves in place during ventricular contraction, and prevent them from prolapsing (bulging back into the atria) and causing regurgitation (backflow of blood).
The trabeculae carneae are muscular ridges within the ventricles that help to increase the force of ventricular contraction, but they do not play a direct role in closing the mitral and tricuspid valves. Similarly, the reduced pressure in the atria during ventricular contraction is due to the fact that blood is being pumped out of the atria and into the ventricles, rather than the atria "pulling" the valves closed.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is {"dropdown-group-1":"A"}
Explanation
Clubbing is a medical condition characterized by bulbous enlargement of the distal portion of a digit (usually a finger, but sometimes a toe) due to soft tissue proliferation and increased bone deposition. The affected digit takes on a rounded or "club-like" appearance, and the angle between the nail and nail bed (known as the Lovibond angle) increases to greater than 180 degrees.
Clubbing is commonly associated with a variety of medical conditions that interfere with oxygenation of the blood, including lung diseases such as chronic obstructive pulmonary disease (COPD), interstitial lung disease, and bronchiectasis; heart diseases such as congenital heart defects and cyanotic heart disease; and gastrointestinal diseases such as inflammatory bowel disease and cirrhosis.
The exact mechanism underlying clubbing is not fully understood, but it is thought to involve a combination of vascular, inflammatory, and neurogenic factors. Hypoxia (low oxygen levels) is believed to play a central role in the development
of clubbing, leading to the release of growth factors and cytokines that promote soft tissue and bone proliferation.
Clubbing is typically diagnosed based on physical examination findings, including the Lovibond angle and the presence of nail bed fluctuation (when the nail bed feels spongy or compressible). It is important to identify and treat any underlying medical conditions that may be contributing to clubbing, as these can have significant implications for the patient's health and quality of life.
Correct Answer is C
Explanation
Hyperventilation refers to an increased rate and depth of breathing, which results in excessive elimination of carbon dioxide (CO2) from the body. Carbon dioxide is an acidic gas that helps regulate the pH of the blood. When too much CO2 is lost through hyperventilation, it causes a decrease in the partial pressure of carbon dioxide in the blood (PaCO2), leading to a condition called hypocapnia.
Hypocapnia can cause symptoms such as lightheadedness, dizziness, and tingling in the fingers and toes.
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