The Anatomy and physiology of uterus and the menstrual cycle by Nurse Abdulrazaq Maryam from the University of Ibadan.
The Anatomy and Physiology of Uterus
The uterus is a muscular hollow pear-shaped organ located in the pelvic cavity with the bladder located anterior to it and the rectum located posterior to it.
It weighs abt 30 to 40g. It has 3 part macroscopically, the fundus, the body and the cervix.
The fundus is the doom shaped part of the uterus located above d entrance of the uterine tube.
The body is the main part.
The cervix is the lower part which protrudes inside into the vagina.
The wall of the uterus has 3 part, perimetrium, myometrium, endometrium.
The perimetrium is the peritoneum covering the uterus. It folds over the bladder to form the vesicouterine pouch and fold over the rectum to form the rectouterine pouch or pouch of Douglas. It folds over the fundus twice to form the broad ligament.
The myometrium is the muscle layer containing blood vessels and nerves.
The endometrium is the innermost layer consisting of columnar epithelia with mucus-secreting goblet cells. It is divided into 2 part, the functional and the basal layer. The functional layer is the part shed during menstruation while the basal layer help in regeneration of the functional layer.
The Anatomy and Physiology of Uterus ……
Blood supply to the uterus is by uterine arteries which are branches of the iliac arteries.
Venous drainage is by uterine veins which drain into the iliac veins.
Lymph from the uterus drains into the aortic lymph node.
Nerve supply is by both sympathetic and parasympathetic nerve.
Function: implantation of the fertilized ovum, provide abode 4 Fertilized ovum, provide nourishment for the embryo.
Supporting structure in the uterus includes broad ligament, pubocervical ligament, transverse cervical ligament, round ligament and uterosacral ligament.
The Anatomy and Physiology of Uterus continued.
It is a series of event that occurs in the female reproductive system in an average of every 28 days (26-30 days) throughout the childbearing age.
This series of events occur as a result of changes in the level of some hormones secreted by a negative feedback mechanism.
The stages involved include menstrual phase, proliferative phase and secretory phase which are numbered for convention purpose.
*Menstrual phase*: it takes about 4 days. When the ovum is not fertilized, the corpus luteum starts to degenerate. The progesterone and oestrogen level falls and the functional level of the endometrium which is dependent on a high level of this hormone is shed during menstruation. The menstrual flow consists of endometrial tissue, blood, unfertilized ovum, endometrial cells and glands, calcium and some elements.
Proliferative phase: it takes about 10 days, due to fall in d level of these ovarian hormones, there will be a production of FSH. This will stimulate an ovarian follicle to mature, the follicle will now start to produce oestrogen. The oestrogen will now assist in the development of the functional layer of the endometrium for the reception of fertilized ovum. Therefore, the endometrium thickens and become very vascularized and rich in mucus-secreting goblet cells. Increase in the level of oestrogen leads to increase the level of LH. Increase LH stimulate ovulation.
Secretory phase takes about 14 days. After ovulation, there would be a development of corpus luteum from the ruptured follicle. The corpus luteum produces progesterone and Oestrogen. The progesterone act on the endometrium making it produce an increasing amount of watery mucus. This is believed to assist the passage of sperm through the uterus to the uterine tubes where the ovum will be fertilized. Also, watery mucus will be produced by the cervix too. If fertilization doesn’t occur, it causes the cycle to take place again.
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