Dark spot
macula densa
decrease
macula densa
macula densa
Correct Answer: changes in solute content of the filtrate
macula densa cells
macula densa
In the kidney, the macula densa is an area of closely packed specialized cells lining the wall of the distal tubule at the point of return of the nephron to the vascular pole of its parent glomerulus glomerular vascular pole. The cells of the macula densa are sensitive to the ionic content and water volume of the fluid in the tubule. If low water volume is detected by these cells, they will produce molecular signals that promote renin secretion by other cells of the juxtaglomerular apparatus. The release of renin is an essential component of the renin-angiotensin-aldosterone system (RAAS), which regulates blood pressure and volume. http://en.wikipedia.org/wiki/Macula_densa
Elachista densa was created in 1981.
Raphitoma densa was created in 1884.
When the macula densa in the distal tubules of the kidney sense a decrease in fluid volume, the renin-aldosterone system is activated. Aldosterone is the hormone responsible for sodium retention, causing water to be conserved.
Renin can be upregulated in two ways: Macula densa cells in the early distal tubule of the nephron communicates with the juxtaglomerular cells of the afferent arteriole in the kidney. When the macula densa cells detect low levels of sodium, it will communicate that to the juxtaglomerular cells and in turn that will stimulate the production of renin. This is the glomerular tubular feedback system. The second way it can be stimulated is by the somatic nervous system directly. When the baroreceptors detect a drop in pressure they will stimulate your SNS and inhibit your PNS. This has several cardiovascular effects in addition to stimulating renal nerves that will upregulate more renin from the juxtaglomerular cells.