How does venoconstriction affect blood flow compared to vasoconstriction?
Both venoconstriction and vasoconstriction decrease flow.
Venoconstriction increases resistance and decreases flow, while vasoconstriction does the opposite.
Both venoconstriction and vasoconstriction increase flow.
Venoconstriction decreases resistance and increases flow, while vasoconstriction increases resistance and decreases flow.
The Correct Answer is D
A. Both venoconstriction and vasoconstriction decrease flow: While vasoconstriction of arterioles reduces blood flow by increasing resistance, venoconstriction does not primarily act to decrease flow. Instead, it mobilizes blood from the venous reservoir to the heart, increasing preload and cardiac output, which can enhance systemic flow.
B. Venoconstriction increases resistance and decreases flow, while vasoconstriction does the opposite: Venoconstriction primarily reduces venous compliance rather than increasing resistance in the arterial system. It shifts blood toward the central circulation, raising venous return, stroke volume, and ultimately cardiac output. Arteriolar vasoconstriction increases resistance and reduces flow to downstream tissues.
C. Both venoconstriction and vasoconstriction increase flow: This is partially true for venoconstriction because it increases venous return and can enhance cardiac output. However, vasoconstriction reduces blood flow in arterioles by increasing resistance, so the effect is opposite in the arterial system.
D. Venoconstriction decreases resistance and increases flow, while vasoconstriction increases resistance and decreases flow: Venoconstriction reduces the capacitance of veins, mobilizing stored blood toward the heart, which increases preload, cardiac output, and systemic blood flow. In contrast, vasoconstriction in arterioles raises resistance and limits blood flow to specific tissues. This reflects the fundamental difference between venous and arterial control of circulation.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is D
Explanation
A. Right subclavian artery → Right brachial artery → Ulnar artery → Digital arteries: This pathway skips the axillary artery, which is anatomically located between the subclavian and brachial arteries. It also omits the radial artery, which supplies the radial (lateral/thumb) side of the forearm, making the sequence incomplete.
B. Right subclavian artery → Ulnar artery → Deep palmar arch: The ulnar artery does not branch directly from the subclavian artery. The normal progression is subclavian → axillary → brachial → radial and ulnar arteries.
C. Right subclavian artery → Axillary artery → Brachial artery → Deep palmar arch: While this pathway includes the correct proximal sequence, it omits the radial artery. The deep palmar arch is primarily formed by the radial artery, so skipping makes the pathway anatomically inaccurate.
D. Right subclavian artery → Right axillary artery → Right brachial artery → Radial and ulnar arteries → Superficial palm: The subclavian becomes the axillary, then the brachial artery, which bifurcates into radial and ulnar arteries supplying the forearm and contributing to the palmar arches. The radial artery specifically supplies the radial side.
E. Right subclavian artery → Right axillary artery → Radial artery → Superficial palmar arch: This sequence incorrectly skips the brachial artery, which is the direct continuation of the axillary artery before bifurcating. The radial artery does not arise directly from the axillary artery.
Correct Answer is C
Explanation
A. They generally have thinner walls than veins: Arteries actually have thicker walls than veins to withstand higher pressure from the heart’s pumping action. Thin walls are a characteristic of veins, which transport blood under lower pressure.
B. They contain valves to prevent backflow: Valves are primarily found in veins, especially in the limbs, to prevent backflow of blood as it returns to the heart against gravity. Arteries generally do not require valves because the pressure from the heart ensures unidirectional flow.
C. They carry blood under high pressure: Arteries are uniquely structured to carry blood under high pressure generated by ventricular contraction. Their thick, elastic walls and smooth muscle allow them to absorb the pulsatile force and maintain blood flow throughout the systemic circulation.
D. They conduct blood toward the heart: This describes veins, not arteries. Arteries carry blood away from the heart.
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