Tag: regulation of the menstrual cycle

• Corpus luteum secretes large quantity of progesterone and small quantity of estrogen.
  
• In the absence of fertilization, the corpus luteum degenerates resulting in decreased level of progesterone and estrogen.
  
• This causes disintegration of the endometrium leading to menstruation, marking a new cycle.
  

So, the correct option is 'Constriction of uterine blood vessels leading to sloughing of uterine epithelium'.

Progesterone levels are higher when the women are pregnant and even the levels are normal during nonpregnancy time. The progesterone levels fall when women reach to menopause stage.

Progesterone and estrogen are necessary to prepare the uterus for menstruation, and their release is triggered by the hypothalamus. Estrogens are a group of sex hormones that promote the development and maintenance of female characteristics in the human body. During the menstrual cycle, estrogen produces an environment suitable for the fertilization, implantation, and nutrition of an early embryo. Progesterone prepares the body for pregnancy by causing the uterine lining to thicken. If a woman is not pregnant, the corpus luteum disappears.

Hormone prepares the body for ovulation before menstrual phase can begin. The pituitary gland releases two hormones, FSH (Follicle Stimulating Hormone) and LH (Luteinizing Hormone). LH stimulates the follicle to manufacture and secrete estrogen. When the amount of estrogen produced in your body reaches a certain level, it causes the pituitary gland to release a surge of LH. The LH surge is what triggers the almost-ripened egg to become fully matured and break through the follicle and the process is known as ovulation.

Estrogens are a group of sex hormones that promote the development and maintenance of female characteristics in the human body. They play an essential role in the growth and development of female secondary sexual characteristics, such as breasts, pubic and armpit hair, and the regulation of the menstrual cycle and reproductive system. Estrogen enhances and maintains the mucous membrane that lines the uterus. It increases the size of the endometrium as well as enhancing blood flow, protein content, and enzyme activity. 

Progesterone belongs to a group of steroid hormones called progestogens. It is mainly secreted by the corpus luteum in the ovary during the second half of the menstrual cycle. It plays important roles in the menstrual cycle and in maintaining the early stages of pregnancy. Progesterone, a hormone secreted by the female reproductive system that functions mainly to regulate the condition of the inner lining (endometrium) of the uterus. When a woman has her menstrual period, her progesterone level is usually low during the first few days.

Luteinizing hormone (LH) and follicle-stimulating hormone (FSH) are called gonadotropins because stimulate the gonads - in males, the testes, and in females, the ovaries. They are not necessary for life but are essential for reproduction. These two hormones are secreted from cells in the anterior pituitary called gonadotrophs. Most gonadotrophs secrete only LH or FSH, but some appear to secrete both hormones.

Menstruation is the shedding of the lining of the uterus (endometrium) accompanied by bleeding. The menstrual cycle is regulated by hormones. Luteinizing hormone and follicle-stimulating hormone, which are produced by the pituitary gland, promote ovulation and stimulate the ovaries to produce estrogen and progesterone. The follicular phase ends when the level of luteinizing hormone increases dramatically (surges). The surge results in the release of the egg (ovulation) and marks the beginning of the next phase.

So the correct option is 'Corpus luteum'