साइनोएट्रियल (SA) नोड, जिसे अक्सर प्राकृतिक पेसमेकर कहा जाता है, मानव शरीर के किस अंग में स्थित होता है?

Which digestive hormone inhibits both gastric secretion and motility, stimulates insulin release, and is secreted mainly when fat is present in the duodenum?

The repeated sequence of gradual onset of apnoea followed by gradual restoration of respiration is called ________.