Where would a pressure drop occur to cause retrograde flow in the downstream artery?

Where would a pressure drop occur to cause retrograde flow in the downstream artery?

• A. Distal
• B. Through
• C. Proximal
• D. Across

Answer: (C)

Flow follows the pressure gradient: blood moves from higher pressure to lower pressure. To cause retrograde flow in the downstream artery, the pressure just upstream of that artery must be lower than the pressure inside the downstream segment. So a pressure drop occurring proximal to the downstream artery lowers the upstream pressure while leaving the downstream segment relatively higher, creating a gradient that drives flow backward through the downstream artery toward the proximal (lower-pressure) site. If the drop happened downstream, the downstream pressure would be even lower, not promoting retrograde flow in that segment.

Flow follows the pressure gradient: blood moves from higher pressure to lower pressure. To cause retrograde flow in the downstream artery, the pressure just upstream of that artery must be lower than the pressure inside the downstream segment. So a pressure drop occurring proximal to the downstream artery lowers the upstream pressure while leaving the downstream segment relatively higher, creating a gradient that drives flow backward through the downstream artery toward the proximal (lower-pressure) site. If the drop happened downstream, the downstream pressure would be even lower, not promoting retrograde flow in that segment.