 Welcome to the juxtaglomerular apparatus. The juxtaglomerular JG apparatus is a structure in the kidneys. It's a specialized region of a nephron where the afferent arterial and the distal convoluted tubule, DCT, come into direct contact with each other. The JG apparatus as a whole works to regulate filtrate formation and systemic blood pressure. In this diagram we can see the afferent arterial, afferent arterial, DCT, glomerulus, and proximal convoluted tubule. The specialized cells of the afferent arterial at this region are called juxtaglomerular JG cells. These cells contain the enzyme renin and function as mechanoreceptors to sense blood pressure. Let's zoom in to see the JG cells up close. The specialized cells of the DCT at the point of contact with the afferent arterial are the macula densa cells. These cells function as chemoreceptors to sense changes in the solute concentration and flow rate of the filtrate. Here's a close-up of the macula densa cells. Now let's examine the functions of these cells using specific examples. When systemic blood pressure decreases, there is a decreased stretch of the JG cells which leads to their release of renin. Renin release causes the activation of the renin angiotensin mechanism, which ultimately leads to an increased blood pressure. Now here's another example. When filtrate has low osmolality or decreased flow rate, the macula densa cells sense this, which leads to vasodilation of the afferent arterial and stimulation of the JG cells to release renin. This will return filtrate flow rate and osmolality to normal. And in our last example, when filtrate has increased osmolality or increased flow rate, the macula densa cells sense this, which leads to the vasoconstriction of the afferent arterial. This will return osmolality and flow rate of the filtrate to normal. Review Let's complete this sentence with the missing terms related to the juxtaglomerular apparatus. Juxtaglomerular cells function to act as blank receptors, whereas macula densa act as blank receptors. Juxtaglomerular cells function to act as mechanoreceptors, whereas macula densa act as chemoreceptors. Let's try another one. JG cells contain the enzyme blank. JG cells contain the enzyme renin. Here's one more. As a result of the increased osmolality of the filtrate, the macula densa will cause the blank of the afferent arterioles. As a result of the increased osmolality of the filtrate, the macula densa will cause the vasoconstriction of the afferent arterioles. In conclusion, the juxtaglomerular JG apparatus is a structure in the kidneys. They regulate the function of each nephron. The system as a whole regulates filtrate formation and systemic blood pressure. Congratulations! You have completed the Juxtaglomerular Apparatus video.