Multiple Choice
In which step of urine formation is the glomerulus primarily involved?
389
views
25. The Urinary System
Renal Physiology Step 1: Glomerular Filtration
Problem 4
Textbook Question
The glomerular filtration rate is regulated by all of the following, except
(a) Autoregulation
(b) Sympathetic neural control
(c) Cardiac output
(d) Angiotensin II
(e) The hormone ADH
Verified step by step guidance1
Step 1: Understand what the glomerular filtration rate (GFR) is — it is the rate at which blood is filtered through the glomeruli of the kidneys, a key factor in kidney function and fluid balance.
Step 2: Review the mechanisms that regulate GFR: Autoregulation (intrinsic kidney mechanisms that maintain stable GFR despite blood pressure changes), Sympathetic neural control (nervous system influence on blood vessel constriction), Angiotensin II (a hormone that constricts blood vessels and affects filtration), and ADH (antidiuretic hormone, which primarily regulates water reabsorption, not directly GFR).
Step 3: Analyze the role of cardiac output — while cardiac output affects overall blood flow and pressure, it does not directly regulate GFR; instead, GFR is regulated more locally within the kidney.
Step 4: Compare each option to identify which one does not directly regulate GFR. Autoregulation, sympathetic control, angiotensin II, and ADH all have roles related to kidney function or blood flow affecting GFR, but cardiac output influences systemic circulation rather than directly controlling GFR.
Step 5: Conclude that the correct answer is the option that does not directly regulate GFR, which is cardiac output.
Verified video answer for a similar problem:This video solution was recommended by our tutors as helpful for the problem above
Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Glomerular Filtration Rate (GFR)
GFR is the rate at which blood is filtered through the glomeruli of the kidneys, reflecting kidney function. It depends on the balance of hydrostatic and oncotic pressures in glomerular capillaries and is crucial for waste removal and fluid balance.
Recommended video:
3:15
Glomerular Filtration Rate
Regulation Mechanisms of GFR
GFR is regulated by intrinsic mechanisms like autoregulation (myogenic response and tubuloglomerular feedback) and extrinsic factors such as sympathetic nervous activity and hormones like angiotensin II. These mechanisms adjust afferent and efferent arteriole tone to maintain stable filtration.
Recommended video:
3:02Internal Regulation - The Myogenic Mechanism
Role of Hormones in Kidney Function
Hormones like angiotensin II influence GFR by constricting arterioles, while ADH primarily regulates water reabsorption in the collecting ducts, not GFR directly. Understanding which hormones affect filtration versus water balance is key to answering the question.
Recommended video:
1:00The Kidneys Example 1
Related Videos
Related Practice