Why do pupils dilate after death? Please, 3Q

The contraction of the pupil is due to the tension of the muscles around the pupil, and the pupils will dilate when a person dies, because the muscles that control the expansion and contraction of the pupils after the death of the person lose their innervation, and after the muscles are relaxed, the pupils will be dilated, and the muscles will of course not be tense, so they will be enlarged.

When a person dies, the visual function gradually loses, the light sensitivity deteriorates, and in order to maintain a clear vision, the pupils will naturally dilate, just like we see things in the dark, and the pupils will become very large, but we usually don't notice it.

After death, the pupil loses nerve control, and the muscles that control the dilated pupils are dominant, so the pupils are dilated

This is one of the manifestations of brain death, with dilated pupils and loss of light reflexes; After death, the pupils are dilated and fixed, and indeed they are often used as an important test for judging death. Specifically, if the diameter of the pupil is greater than 5 mm, the size of the pupil will not change if the eye is irradiated with a flashlight, etc. (the pupil will be narrowed during the prenatal examination). For some reasons, such as poisoning, the pupils are constricted or dilated during life, and in general, these signs will disappear after death.

With one exception, after death from organophosphate poisoning, the narrowed pupils are preserved, which is also a feature of poisoning with this type of poisoning. At present, in medicine and law in China, breathing and cardiac arrest are still the criteria for judging death. However, the academic community has been recommending the use of brain death.

The concept of brain death refers to death caused by the irreversible suspension of the function of the whole brain (including the cerebellum and brainstem).

Pupil dilation is one of the characteristics of human death, and the dilated pupils of humans before death are mainly due to the nerves after death

Because after brain death, there will be dilated pupils and the light reflex will disappear, unless the pupils of poisoning death will continue to remain unchanged.

Because before people die, all their consciousness has been blurred, and the spirit has collapsed, that is, what people usually call the human spirit has been dispersed, then it is not so concentrated from the eyes, so the pupils will look dilated.

The pupillary sphincter is innervated by the third pair of cranial nerves, the oculomotor nerve, and mydriasis indicates that the cranial nerve reflex is lost, so mydriasis can be used as one of the bases for brain death.

Will 1After death, the pupil will undergo obvious changes, which are divided into early changes and late changes. The changes in the early years of death are mainly diasal dilation, because the tone of the pupil sphincter decreases after death, and the pupil is unable to maintain the shape of the pupil contraction, which causes the pupil to gradually dilate, and the reflexes associated with the pupil are also lost, such as the pupil.

2.The pupillary changes in the late post-death period are mainly depigmented, at which time the iris tissue also begins to necrosis, and the iris cells are lysed, so that a large amount of pigment in the cells is removed, and the anterior chamber is filled with pigment granules.

Under normal physiological conditions, the pupil is innervated by the pupillary sphincter and is used to regulate the light entering the eye. The pupils are dilated when the light is dark and the pupils are constricted when the light is strong.

After death, the pupil sphincter is lost, so the pupil will be dilated.

Pupil dilation is used to determine death.

Categories: Healthcare.

Analysis: The human pupil is mainly innervated by two groups of muscles: the pupillary sphincter, whose contraction causes the pupil to constrict; The pupil is dilated, and its contraction causes the pupil to dilate.

The pupillary sphincter is innervated by the third cranial nerve oculomotor nerve (parasympathetic), and the pupillary greateris muscle is innervated by the sympathetic nerve. After death, brain activity stops, causing cranial nerves to stop excitating (i.e., parasympathetic function decreases), resulting in sympathetic nerve action being manifested in the dilation of the pupil. The dilated pupils when a person is frightened or have violent mood swings are also the result of sympathetic excitation.

Mydriasis is an important basis for judging the loss of brain function or the loss of life center function, and it is also an important basis for declaring death. Dilated pupils mean death means that the pupils are dilated to the edges, do not respond to light, and are not simply dilated at this point before the patient can be considered dead.

In some cases, mydriasis does not necessarily indicate complete death. In severe poisoning, deep coma, patients may develop body pigmentation, muscle rigidity, and autonomic dysfunction in a vegetative state close to brain death, with tendon relaxation starting from the pupils, and dilated pupils without reflexes. But it only shows that the pupils are dilated, not a complete death, and there are indeed cases of life-saving.

In medicine, the judgment of death is a comprehensive judgment of pupils, heartbeat, and breathing, relying on one or the other alone, and it is not rigorous.

The pupillary sphincter is innervated by the third pair of cranial nerves, the oculomotor nerve, and mydriasis indicates the loss of cranial nerve reflexes, so mydriasis is usually regarded as an important basis for clinical death.

NHK : In certain specific circumstances. In fact, people are not completely dead.

The pupils have begun to dilate. Magnify. For example.

Patient after deep poisoning. or in a coma. The brainstem is close to death.

or have entered a vegetative state. The body shrunk. Muscle rigidity.

This time. The patient's autonomic function has been slowly lost. The sphincter that controls the pupil.

Start relaxing. The pupils gradually dilate. There will be no reflection.

No luster. After the official death of the human body. In addition to dilated pupils.

The cornea also loses moisture. and become cloudy. Over time.

The turbidity will deepen. Normally. 6-12 hours after death is mildly turbid.

12-24 hours. The cloudiness still deepens. But this time.

It should be possible to see through the pupil. 48 hours later. The pupils may become severely cloudy.

I can no longer see through the pupils. See this time. That's what 1 person said.

The corpse's gray pupils.

When a person dies, the muscles stiffen and contract, and because the pupil sphincter controls the size of the pupil, the pupils are dilated when the person dies.