Normal pupils are dilated or contracted due to the control of muscles around the pupils.
The pupil is a hole in a person's eye. Muscles around the pupil contract and relax to control the range of light entering the eyes. This is a reflex reaction, and human beings have easily completed the regulation function without special brain regulation. In microscopic expression, pupil size can also be used as a reference value. When a woman sees a mother with a child in her arms and a man sees a picture of a naked woman, her pupils will also be dilated, because psychology will affect them. Therefore, no matter what actions people take, their pupils will unconsciously expand with the language.
Normal pupils are different from postmortem pupils, and the postmortem pupils are maximized.
When people or animals die, the pupil is not controlled by the muscles around the pupil, and there is no nerve to control it. So the pupil is completely dilated and dilated. Usually, the signal of sympathetic nerve will lead to muscle tension and pupil dilation. Sometimes, atropine and other drugs are used to dilate pupils before testing and treating vision. Eating toxic substances will dilate the pupils. At this time, it is precisely because of the paralyzing effect of drugs that the muscles are temporarily out of control, the pupils are dilated, and the vision is blurred.
It will recover naturally after a period of time, and the pupil dilation at the time of death should be combined with no breathing to make a comprehensive judgment. You will see that sometimes doctors judge whether a person is dead, not by listening to heart sounds first, but by opening people's eyelids to see if the pupils have spread.
Pupils are dilated not just because people are dead. If the patient has dilated pupils for various reasons and is not treated and corrected in time, it may cause cerebral hemorrhage and force brain tissue to die. Therefore, it is necessary to check the physical indicators in time after cerebral hemorrhage, and you should not abuse drugs to affect your health.