Answer:
The correct answer is: upper esophageal sphincter.
Explanation:
The alimentary canal is a very long tract responsible for the digestion of the food. It is composed of several organs with many different and important functions. The alimentary canal also has a few sphincters, which are muscular valves that open and close when needed for the food to pass or be retained.
The first sphincter is the upper esophageal sphincter. One particularity of this sphincter is that is one of the few sphincters in the body that opens and closes under our conscious control, which happens when we decide to swallow our food.
From the first to the last, the order of the sphincters in the gastrointestinal tract is: upper esophageal sphincter, lower esophageal sphincter or gastroesophageal sphincter, pyloric sphincter, ileocecal sphincter, and anus.
Soaring is a science when birds remain airborne and moving without flapping their wings. They are maintaining thrust and gliding downward but staying aloft
<h3 /><h3>Further explanation</h3>
Soaring birds is where the birds can maintain flight without wing flapping, because they using rising air currents. Many gliding birds are able to lock their extended wings by means of a specialized tendon. Some land birds such as vultures and certain hawks, sustain flight for long periods without flapping their wings.
For example soaring California Condor spreads its primary feathers so that each acts as a small, high-aspect-ratio wing. This reduces turbulence at the wingtips and helping the condor to stay aloft circling slowly in thermals.
Vultures have a low aspect ratio (ratio of length to width of the wing) which generally produce a lot of drag. Vultures overcome the problem of by flying with their primary feathers extended, creating slots between them. Each primary serves as an individual high-aspect-ratio wing. This high-aspect-ratio reducing wingtip turbulence and lowering the stalling speed of the wings. This helps vultures to circle in thermals, maintaining thrust by gliding downward, but staying aloft by sinking at a rate slower than the hot air rising.
<h3 /><h3>Learn more</h3>
- Learn more about Soaring birds brainly.com/question/4722417
<h3>Answer details</h3>
Grade: 9
Subject: biology
Chapter: animals
Keywords: birds
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