Which of the following mechanisms directly regulates the constriction or dilation of the afferent arteriole to control GFR?

Question

BlackTom AI · Accepted Answer

Question restatement: Which mechanism directly regulates the constriction or dilation of the afferent arteriole to control GFR?

Option 1: Tubuloglomerular feedback. This is the intrinsic renal mechanism in which the macula densa cells sense NaCl delivery in the distal tubule and adjust afferent arteriole tone to modify GFR accordingly. If NaCl delivery is high, the afferent arteriole constricts to reduce GFR; if it’s low, it dilates to raise GFR. This direct local control of the afferent arteriole is precisely what tubuloglomerular feedback describes.

Option 2: Renin-angiotensin-aldosterone system. The RAS is a systemic hormonal mechanism that primarily increases efferent arteriolar constriction via angiotensin II and can influence GFR indirectly. However, it is not the direct mechanism that governs afferent arteriole constriction in response to tubular flow; its main effect is on efferent tone and overall blood pressure regulation.

Option 3: Sympathetic nervous system. Sympathetic activation can constrict renal arterioles, including the afferent, thereby reducing GFR during stress or hypovolemia. While this does alter afferent tone, it is a neural regulatory pathway rather than the intrinsic, direct tubuloglomerular feedback mechanism that responds to tubular flow and NaCl delivery. Some texts acknowledge neural influence, but it is not the primary direct mechanism described for local control of the afferent arteriole in response to tubular signaling.

Option 4: Glomerular basement membrane. The glomerular basement membrane is part of the filtration barrier, not a mechanism regulating arteriolar tone. It determines what gets filtered, but it does not constrict or dilate the afferent arteriole to control GFR.

In summary, option 1 provides the direct, intrinsic mechanism that links tubular flow to afferent arteriolar tone and thereby regulates GFR, whereas the other options describe regulatory influences that are either indirect, neural, systemic, or structural rather than direct arteriolar regulation.

Which of the following mechanisms directly regulates the constriction or dilation of the afferent arteriole to control GFR?单项选择题

类似问题

What was the world's first widely adopted biodiversity policy?

The aim of the Paris Agreement is to ensure that the earth’s preindustrial temperature is not exceeded by more than º Celsius.

The IPCC's mission is to Blank ______.

Why have most international agreements for environmental protection been based on the honor system?

As was exhibited with the Montreal Protocol and the encouragement of reduced CFC production, trade can be an effective tool to compel compliance with international treaties.

The Stockholm Declaration and UNEP were the result of the Blank ______ first conference on the Human Environment in 1972.

更多留学生实用工具

智能学习助手

风格化写作助手

论文查重助手

文献引用助手

课堂转译助手

课堂笔记助手

Quiz搜索助手

学校历年真题

智能刷题助手

智能匹配练习

希望你的学习变得更简单