Menstrual Cycle: human females menstruation,Human Reproduction

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Menstrual Cycle: human females menstruation,Human Reproduction

family planning stage |

Menstrual Cycle:

The reproductive cycle in the female primates (e.g, monkeys, apes andi human beings) is called menstrual cycle. 
 
The first menstruation begins at puberty and is called menarche
In human females, menstruation is repeated at an average interval of about 28/29 days, and the cycle of events starting from one menstruation till the next one is called the menstrual cycle. 
 
One ovum is released (Ovulation ) during the middle of each menstrual cycle. The major events of the menstrual cycle are shown in FigurA.2
 
 The cycle starts with the menstrual phase, when  menstrual flow occurs and it lasts for 3-5 days. 
 
The menstrual flow results due to breakdown of endometrial lning of the uterus and its  blood vessels which  liquid that comes out through vagina.
 
 Menstruation only occurs if the released ovum is not fertlisedLack of menstruation may be indicative of pregnancy.
Causes lack of menstruation:
  • Stress
  • Poor health
  • Weakness
 
 However. it may also be caused due to some other underlying causes like sresspoor health etc. 
 
The menstrual phase is followed by the follicular phase. Duringi this phase, the primary follicles in the ovary grow to become a fully mature Graafian olllcle and simultaneously the endometrium of uterus regenerates through prollferation
Test your brain
1 : What is mensuration cycle?
2 : Due to breakdown of which parts cause  Mensuration cycle?
3 : How many days does menstruation occur?
4 : What is menarche?
5 : At which is does first  menstruation occur?
6 :  Lack of  mensuration cycle what may be cause?
 
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These changes in the uterus are induced by changes in the levels of pituitary and ovarian hormones( figure A.2). 
 
The secretion of gonadotropins (LH and FSH) increases gradually during the follicular phase, and stimulates follicular development as well as secretion of estrogens by the growing follicles. 

Diagarammatic  presentation of various events during a menstrual cycle (A.2)
Diagarammatic  presentation of various events during a menstrual cycle (A.2) 
 
Both LH and FSH attain a peak level of the middle of cycle about 14 days). 
Rapid secretion of LH leading to its maxinuum level during the mid-cycle called LH surge induces rupture of Graafian follicle and thereby the release of ovum (Ovulation ). 
 
The ovulation (ovulatory phase) is followed by the luteal phase during which the remaining parts of the Graafian follicle transform as the corpus luteum (Figure A.2). 
 
The corpus luteum secretes large amounts of progesterone which is essential for maintenance of the endometrium. 
Such an endometrium is necessary for implantation of the fertilised ovum(gametGamet) and other events of pregnancy.
 During pregnancy all events of the menstrual cycle stop and there is no menstruation
 
Test  your brain
 
 1: When do LH and FSH have peak level during  menstruation cycle?
 2 :What is menopause?
 3 : Write the main function of endometrium  layer  during mensuration cycle?
 4 : In the absence of fertilization what happens of Corpus luteum?
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In the absence of fertilisation, the corpus luteum degenerates, This causes disintegration of the endometrium leading to menstruation, marking a new cycle
 
In human beings, menstrual cycles ceases around 50 years of age: that is termed as menopause
 
 Cyclic menstruation is an indicator of normal reproductive phase and extends between menarche and menopause.


All topic of Human Reproductive systems below:

1: MaleReproductive Systems

2:FemaleReproductive systems

3:Gametogenesis

4:Menstruation

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