What is the primary purpose of high-density lipoprotein (HDL) cholesterol in the body?
Transporting cholesterol to peripheral tissues
Facilitating the formation of atherosclerotic plaques
Transporting cholesterol from peripheral tissues to the liver
Providing a structural component for cell membranes
The Correct Answer is C
A. Transporting cholesterol to peripheral tissues: This is the primary function of low-density lipoprotein (LDL), which delivers cholesterol to cells for membrane synthesis or hormone production. When LDL levels are excessive, they contribute to lipid deposition in the arterial walls. HDL serves the opposite function by removing excess lipids from the periphery to prevent accumulation and subsequent vascular damage.
B. Facilitating the formation of atherosclerotic plaques: HDL actually prevents the formation of plaques by inhibiting the oxidation of LDL and removing cholesterol from foam cells within the arterial intima. High levels of HDL are associated with a reduced risk of coronary artery disease. It is the atherogenic particles, like LDL and VLDL, that are responsible for the progression of atherosclerotic lesions.
C. Transporting cholesterol from peripheral tissues to the liver: This process is known as reverse cholesterol transport and is the most vital function of HDL. HDL particles collect excess cholesterol from the blood and tissue walls and return it to the liver for excretion in bile or recycling. This mechanism is fundamentally cardioprotective because it reduces the amount of lipid available to form dangerous arterial obstructions.
D. Providing a structural component for cell membranes: While cholesterol itself is a vital structural component of all cell membranes, HDL is a transport vehicle rather than a structural building block. The cholesterol carried by HDL is destined for removal or processing in the liver. Cell membranes integrate free cholesterol directly into their lipid bilayers to maintain fluidity and stability rather than using HDL particles.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is B
Explanation
A. A parasternal heave is a visible or palpable lift of the chest wall usually associated with right ventricular hypertrophy or enlargement. Aortic regurgitation primarily affects the left side of the heart, leading to left ventricular dilation and hypertrophy due to chronic volume overload. While late-stage heart failure can affect the right side, it is not a classic finding for aortic insufficiency.
B. Widened pulse pressure is a hallmark of aortic regurgitation caused by the combination of an increased stroke volume and a rapid drop in diastolic pressure. During diastole, blood flows backward from the aorta into the left ventricle, significantly lowering the diastolic value. This creates a large gap between the systolic and diastolic numbers, often manifesting as a "water-hammer" pulse.
C. A systolic ejection click is more frequently associated with aortic stenosis or a bicuspid aortic valve during the opening of the valve. Aortic regurgitation is characterized by a high-pitched, blowing diastolic decrescendo murmur heard best at the left sternal border. The sound is produced by the turbulent backflow of blood, rather than the abrupt opening of a narrowed or stiffened valve.
D. A split S2 occurs when the aortic and pulmonic valves close at slightly different times, which can be a normal physiological finding during inspiration. While various valvular pathologies can cause fixed or paradoxical splitting, it is not the defining clinical sign for aortic regurgitation. The focus in regurgitation is on the characteristic diastolic murmur and the peripheral vascular signs of high stroke volume.
Correct Answer is D
Explanation
A. Iron deficiency anemia is typically characterized by a microcytic, hypochromic profile, meaning the mean corpuscular volume would be significantly decreased. In this state, the red blood cells are smaller than normal due to the lack of iron available for hemoglobin synthesis. While common in pregnancy, it would not present with a normal MCV
B. Folate deficiency anemia is a type of megaloblastic anemia that results in an increased mean corpuscular volume, or macrocytosis. Folate is essential for DNA synthesis during erythropoiesis, and its absence causes red blood cell precursors to grow large without dividing properly. A patient with folate deficiency would typically show an MCV well above 100 fL.
C. Vitamin B-12 deficiency anemia, much like folate deficiency, causes macrocytic changes in the blood count. This results in large, immature red blood cells and an elevated MCV due to the impairment of nucleic acid metabolism. Since there is a "normal" MCV (normocytic), B-12 deficiency is an unlikely diagnosis for this specific clinical presentation.
D. Hemolytic anemia is a normocytic anemia, meaning the red blood cells that remain in circulation are of normal size, but their total number is reduced due to premature destruction. In pregnancy, this can occur due to autoimmune processes, infections, or mechanical factors. Because the bone marrow's production of cells is initially normal in size, the MCV remains within the standard physiological range.
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