Extraglomerular mesangial cells are located in the junction between the afferent and efferent arterioles. The hypersensitivity of vagal afferent nerves causes refractory or idiopathic cough. Prostaglandins normally dilate the afferent arterioles of the glomeruli. The loss of afferent signals induces functional changes in dorsal horn neurons. Often tumor cells secrete growth factors which activate receptors close to primary afferent neurons. Their antiemetic effect due to blockade of 5HT3 receptor on vagal afferent in the gut. That is, each brain region has its own unique set of afferent and efferent projections. The walls of the afferent arteriole contain specialized smooth muscle cells that synthesize renin. Cutaneous receptors are at the ends of afferent neurons. A feedback response to the medulla is triggered via the afferent vagus nerve. These impulses are transmitted to the brain through afferent neurons. TRPA1 is co-expressed with TRPV1 on nociceptive primary afferent C-fibers in humans. This electric current creates action potentials within the connected afferent neurons. The JGA is located between the thick ascending limb and the afferent arteriole. The olfactory nerve is special visceral afferent (SVA).