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I found the same in this book, published just over 100 years ago. The book appears to be the result of some pretty rigorous study, so I expect it is a reliable source. On page 294, it refers to the gizzard as an involuntary sphincter, and again on page 302 it refers to the grinding of food in poultry as involuntary. In fact it says that because poultry ...


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Involuntary. The gizzard, like our stomachs, works unconciously. However, chickens do choose to peck up stones to help along the process, whether that is by instinct or otherwise. (I raised chickens a long time but a proper reference is below) This book on commercial poultry raising says involuntary


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This is called achalasia. According to UpToDate, the mechanism for this diseases are generally unknown. What is known, however, is that the esophagus has a neural system called the myenteric plexus and if these ganglion cells in the esophagus are damaged in any way (e.g. physically, followed by Wallerian degeneration, or the primary process of degeneration ...


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Frequency of tremor typically remains constant for the person. Levadopa (sinemet) does not change the frequency. Typically the tremor frequency will be in the range from 3Hz to 7Hz. There is a common phrase when dealing with PWP (Person With Parkinson's Disease). If you have seen one PWP, you have seen one PWP. Currently I am part of a study by the ...


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Our muscles are not limited to 7 hertz. You provide two examples yourself. I can provide a third: world's fastest clapper: 804 claps in 1 minute (video here), which is an average of 13.4 claps/sec -- though, you can see his pace changes so at times he's doing more than that. What about a non world-record holding example? I can provide one of those as ...


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According to the book, Principles of Animal Locomotion by R. McNeil Alexander, oscillatory movements in animals are limited by an organism's nature in general to minimize metabolic energy costs. The energy capacity, inertial, compliant, and dissipative forces involved in the muscles, tendons, skeleton, and non-actuating load all enter into this cost ...



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