There is such a group of magical creatures on Earth:
They are beautiful, lively, gentle, cute...
About 23,000 ml of blood will be lost regularly in a lifetime!
Fold contract 70 listen to fat house happy water, on average, every month to shed a bottle of "Yakult".
(Source: giphy)
Menstruation allows women to experience a process of wound healing and tearing every month.
All of this is related to fertility.
The uterus is responsible for fertility, and on the surface of the uterus, there is a layer of "membrane" that changes periodically, that is, the endometrium.
The inner membrane is like a soft bed, and only "thick" enough can it successfully wrap the fertilized egg.
Every month, the endometrium is working hard to prepare for the acceptance of sperm eggs.
There are 2 fates that greet the endometrium:
Successfully received the landing of the fertilized egg, maintained its thickness, and gradually evolved into part of the placenta;
Eggs that fail to successfully wait for fertilization, as the level of estrogen in the body decreases, collapse violently, and then peel off and bleed.
After peeling, the inner membrane thins again, waiting for the start of the next "thickening" cycle [1].
endometrium
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"The endometrium is like a house that is constantly being built, tearing down and rebuilding when no one is staying until someone moves in."
Under normal circumstances (not pregnant), hormone ebb and flow in the female body, this membrane is also "thick and thin", constantly resetting until pregnancy or menopause.
The flaking inner membrane and the blood that flow when this automatic "crack" occurs, forming a menstrual period.
Menstruation is a phenomenon that occurs only in a few mammals: it is limited to human females, primates, and a few other mammals.[2]
Compared with other species, human menstrual phenomena are the most regular, frequent, and significant.
In fact, the emergence of menstruation is the result of the game between lives.
A fertilized egg whose genes are provided by half of the father and the other half by the mother. Its genotype is not the same as that of its mother.
In other words, the purpose of the embryo and the mother is not the same:
The embryo wants to suck all the possible nutrients from the mother and grows desperately; the mother wants to have a healthy body that can successfully conceive.
Screening the quality of the embryos: For those embryos that are not good enough, they will leave the mother with the exfoliation of the endometrium, that is, spontaneous abortion.
If the embryo fails in the process of rooting in the uterus, the highly aggressive cells left behind can cause damage to the mother.
Therefore, the development process of embryos is very similar to that of cancer cells, so there are also articles that believe that the invasion of cancer is the process of repeating the embryo implantation [3].
To minimize this risk, periodic endometrial spallation can achieve a "zeroing" effect:
The unqualified, dead embryos are excreted along with the highly aggressive embryonic cells and endometrium, preparing a new and healthy environment for the next pregnancy.
Cyclical changes in the endometrium are usually regular, and if an abnormality occurs, it usually means some kind of "procedural abnormality" in the body.
"For example, whether the level of hormone secretion is normal during the menstrual cycle, whether the level of endometrial degeneration is coordinated, and whether the body can repair the hemostasis in time after menstrual bleeding, abnormal changes in blood glucose and blood pressure...
Abnormalities have also been observed during the normal menstrual cycle without pregnancy, suggesting a risk of pregnancy-related complications, including miscarriage, preeclampsia, and preterm birth [6]. ”
In each menstrual cycle, the body is adapting to and balancing the changes in uterine and hormone levels as much as possible, and thus can achieve a certain sense of correction.
Menstruation, in another sense, is the "rehearsal" of human pregnancy.
The benefits of this protective effect far outweigh the blood loss and associated energy loss caused by menstruation, and are evolutionarily advantageous to the mother, particularly in the areas of protection from placental invasion, protection of the mother from embryonic influence, and protection of the uterus for future pregnancy[5].
Although women have evolved a seemingly stupid "physiological process" of periodic blood loss, throughout the evolutionary process, the presence of menstruation does protect women themselves.
If we say that pregnancy and feeding, a purely altruistic act from a biological point of view, many mothers forget themselves because they love their children.
Then the existence of menstruation is the "cry" of the body to protect itself.
Either way, your body won't forget to love you.
Reviewer
Liu Juan | deputy chief physician of the Department of Gynecology of the Third Affiliated Hospital of Guangzhou Medical University
bibliography
[1] Critchley HOD, Maybin JA, Armstrong GM, Williams ARW. Physiology of the Endometrium and Regulation of Menstruation. Physiol Rev. 2020 Jul 1;100(3):1149-1179. doi: 10.1152/physrev.00031.2019. Epub 2020 Feb 7. PMID: 32031903.
[2] Jarrell J. The significance and evolution of menstruation. Best Pract Res Clin Obstet Gynaecol. 2018 Jul;50:18-26. doi: 10.1016/j.bpobgyn.2018.01.007. Epub 2018 Feb 8. PMID: 29530426.
[3] Valerie K. Harris, ... Amy M. Boddy, in Ecology and Evolution of Cancer, 2017
[4] Pavlicev M, Norwitz ER. Human Parturition: Nothing More Than a Delayed Menstruation. Reproductive Sciences. 2018;25(2):166-173. doi:10.1177/1933719117725830
[5] D. Emera, R. Romero, G. Wagner.The evolution of menstruation: a new model for genetic assimilation: explaining molecular origins of maternal responses to fetal invasiveness. Bioessays, 34 (1) (2012 Jan), pp. 26-35
[6] Rabaglino MB, Post Uiterweer ED, Jeyabalan A, Hogge WA, Conrad KP. Bioinformatics approach reveals evidence for impaired endometrial maturation before and during early pregnancy in women who developed preeclampsia. Hypertension.
2015;65(2):421-429
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