What role does the macula densa play in GFR?

What role does the macula densa play in GFR?

As part of the body’s blood pressure regulation, the macula densa monitors filtrate osmolarity; if it falls too far, the macula densa causes the afferent arterioles of the kidney to dilate, thus increasing the pressure at the glomerulus and increasing the glomerular filtration rate.

What do macula densa cells respond to?

In response to elevated sodium, the macula densa cells trigger contraction of the afferent arteriole, reducing flow of blood to the glomerulus and the glomerular filtration rate.

How does macula densa stimulate renin?

Macula-Densa Control of Renin Release The macula densa participates in the regulation of renin release from juxtaglomerular granular cells. Renin secretion depends on NaCl delivery to and reabsorption by the macula-densa cells at the end of the TAL.

Do macula densa cells stimulate renin release?

Macula densa cells can sense variations in tubular fluid composition, including salt content and metabolites such as succinate. PGE2 via paracrine signaling causes increased renin synthesis and release from adjacent juxtaglomerular cells and activation of the renin-angiotensin system (RAS).

What is the function of juxtaglomerular cells?

The juxtaglomerular apparatus functions to maintain blood pressure and to act as a quality control mechanism to ensure proper glomerular flow rate and efficient sodium reabsorption. The urethra extends from the bladder to the surface of the body. It consists of an epithelium-lined lumen and a smooth muscle layer.

What is a granular layer?

Medical Definition of granular layer : the deeper layer of the cortex of the cerebellum containing numerous small closely packed cells.

How is the macula densa related to GFR?

The macula densa ◦ Regulation of GFR You might want to read the nephron overview and glomerular filtration entries. As the distal proximal tubule rises from the renal medulla, it makes close contact with the glomerulus. The cells on the side of the tubule facing the glomerulus have a distinct appearance and constitute the macular densa (Figure 1).

Which is part of the tubule has a macula densa?

The cells on the side of the tubule facing the glomerulus have a distinct appearance and constitute the macular densa (Figure 1). These cells sense the NaCl content of the tubule and make changes to GFR appropriately. Figure 1: The macula densa is a region of specialised cells lining the distal convoluted tubule.

How is adenosine secreted by macula densa cells?

Macula-densa cells may signal granular cells to inhibit renin release by secreting adenosine and/or ATP across the basolateral membrane in response to increased sodium delivery [96, 101, 102]. The precise mechanism of this effect is not clear. Adenosine stimulates granular cell A 1 and A 2 receptors.

How are prostaglandins released from the macula densa?

Function. Second, macula densa cells release prostaglandins, which triggers granular juxtaglomerular cells lining the afferent arterioles to release renin into the bloodstream. (The juxtaglomerular cells can also release renin independently of the macula densa. They are also triggered by baroreceptors lining the arterioles,…