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What role does the liver play in the RAAS?
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The liver produces angiotensinogen, an inactive precursor of angiotensin.
What are the main stimuli that can activate the RAAS?
Dehydration, blood loss, and sodium deficiency.
Describe the role of the macula densa in the RAAS.
The macula densa, located in the distal convoluted tubule, acts as chemoreceptors that detect low sodium levels.
What are the primary functions of the Renin-Angiotensin-Aldosterone System (RAAS)?
The RAAS regulates blood pressure, blood volume, and sodium levels.
What role does the pituitary gland play in RAAS and what does it release as a result of angiotensin II?
The pituitary gland releases Antidiuretic Hormone (ADH) in response to angiotensin II.
How does the sympathetic nervous system respond to activation of the RAAS?
It increases heart rate and heightens alertness.
Name two direct actions of angiotensin II within the nephron.
Angiotensin II increases sodium reabsorption in the proximal convoluted tubule and stimulates aldosterone production.
Where are the baroreceptors that detect decreases in blood pressure located?
In the juxtaglomerular (JG) cells in the afferent arterioles of the kidney.
What is the overall effect of the RAAS on blood pressure, blood volume, and sodium levels?
The RAAS works to restore and maintain normal blood pressure, blood volume, and sodium levels.
Which enzyme converts angiotensin I to angiotensin II, and where is it produced?
Angiotensin-converting enzyme (ACE), produced in the lungs, converts angiotensin I to angiotensin II.
How does renin contribute to the RAAS?
Renin, released from kidneys, converts angiotensinogen to angiotensin I.
Which hormone increases water reabsorption in the distal convoluted tubule and collecting duct?
Antidiuretic Hormone (ADH) increases water reabsorption in these segments.
How does aldosterone affect sodium reabsorption?
Aldosterone increases sodium reabsorption in the distal convoluted tubule.
What immediate effect does angiotensin II have on blood vessels?
Angiotensin II causes vasoconstriction, which raises blood pressure.
What organ(s) produce renin, and under what conditions is renin released?
The kidneys produce renin, which is released when blood pressure is low or sodium levels decrease.
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