Renal Physiology Part 2 Flashcards
(21 cards)
What are the two regions of the kidney?
: The outer renal cortex and the inner renal medulla.
What are cortical nephrons?
Nephrons with glomeruli in the outer cortex and short loops of Henle that only penetrate a short distance into the medulla.
What percentage of nephrons are cortical nephrons?
The majority of nephrons.
What are juxtamedullary nephrons?
Nephrons with glomeruli located deep in the renal cortex near the medulla, having long loops of Henle that extend deep into the medulla.
What percentage of nephrons are juxtamedullary nephrons?
About 20–30% of all nephrons.
What is the key function of juxtamedullary nephrons?
Responsible for the reabsorption of water and concentration of urine.
What is the juxtaglomerular apparatus (JGA)?
A structure that regulates the function of each nephron and is located next to the glomerulus.
What are the three types of cells in the juxtaglomerular apparatus?
• Macula densa (in the thick ascending limb)
• Juxtaglomerular (granular) cells
• Extraglomerular mesangial cells
What is the function of macula densa cells?
They detect sodium concentration in the distal tubule and help regulate glomerular filtration and renin release.
What do juxtaglomerular (granular) cells do?
They produce and secrete renin, which is crucial for blood pressure and sodium regulation
Where are juxtaglomerular cells located?
In the media of the afferent arterioles as they enter the glomeruli.
What is the role of renin in the body?
Renin initiates the renin–angiotensin system, which helps regulate blood pressure and sodium balance.
What type of cells make up the macula densa?
Modified tubular epithelial cells.
Where is the macula densa located?
In the wall of the last portion of the distal straight tubule, where it contacts the afferent and efferent arterioles of its own nephron.
What is the primary function of the macula densa?
To detect sodium chloride (NaCl) levels in the distal tubule and regulate GFR via the tubuloglomerular feedback loop.
What happens when the macula densa detects high sodium chloride levels?
It signals the adjacent afferent arteriole to constrict, reducing blood flow into the glomerulus and lowering GFR.
How does high NaCl affect glomerular filtration rate (GFR)?
High NaCl causes vasoconstriction of the afferent arteriole, which decreases GFR.
What happens when the macula densa detects high sodium chloride levels?
It signals the adjacent afferent arteriole to constrict, reducing blood flow into the glomerulus and lowering GFR.
What happens when sodium levels are low at the macula densa?
The macula densa reduces sodium reabsorption, releasing nitric oxide and prostaglandins to vasodilate the afferent arteriole and increase renin release.
What is the effect of nitric oxide and prostaglandins released by the macula densa?
They dilate the afferent arteriole and stimulate renin secretion from juxtaglomerular cells.
What system is activated when renin is released due to low sodium?
The renin–angiotensin–aldosterone system (RAAS), which helps restore blood pressure and sodium balance.
