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प्रश्न
Draw a neat and well-labeled diagram showing T.S. of the ovary and describe the menstrual cycle in human females.
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उत्तर
T.S. Ovary
In Human females, at the start of the puberty period, the menstruation is repeated at an average interval of about 28 / 29 days and the cycle of events starting from one mensuration till the next one is called mensuration cycle. It is a monthly flow of blood from the uterus it lasts about 25 days.
PHASES OF MENSTRUATION CYCLE
Changes during the menstrual cycle can be divided into four phases. Menstrual phase b. Proliferative phase c. Ovulatory phase d. Post ovulatory or secretory phase or luteal phase
a. Menstrual Phase (bleeding or destructive phase):
This phase extends from the 1st to the 4th day of the menstrual cycle. Menstruation occurs in the absence of fertilization. During this phase, bleeding occurs as the endometrium of the uterus is sloughed off. The menstrual flow consists of the secretion of endometrial glands, cell debris, and unfertilized ovum along with 35 to 45 ml of blood.
b. Proliferative phase: This phase extends from the 5th to the 13th day of the menstrual cycle.
Changes in the ovary: During this phase, the primordial follicle of the ovary develops into the Graafian follicle. Theca internal cells of the follicle secrete female sex hormone estrogen. Only one follicle develops in one cycle.
Changes in the uterus: Oestrogen secreted by follicular cells of ovary stimulate endometrial glands. This causes the repair of the endometrium. The endometrial cells proliferate and the thickness of endometrium grows to about 3mm to 5mm.
c. Ovulatory phase: During this phase, ovulation takes place. It usually occurs on the 14th day of the cycle. Due to LH secreted by the pituitary, the Graafian follicle bursts and releases the ovum in the abdominal cavity. It passes through the fallopian tube. On its way, if it happens to meet sperms, it is fertilized. If it remains unfertilized then ovum degenerates.
d. Secretory phase/Luteal phase: This phase extends from the 15th to the 28th day of the menstrual cycle. Changes in the ovary: After ovulation, the ruptured follicle develops into a yellow body called corpus luteum. Corpus luteum remains active till the placenta starts the secretion of HCG (Human chorionic gonadotropin). If the ovum is not fertilized, corpus luteum degenerates and transforms into a whitish scar called corpus Albicans.
Changes in Uterus: Corpus luteum formed in ovary secretes progesterone. It causes further growth of endometrial glands. If fertilization occurs, the embryo is implanted in thickened endometrium.
APPEARS IN
संबंधित प्रश्न
Complete the following by filling in the blanks 1 to 5 with appropriate words:
The human female gonads are ovaries. A maturing egg in the ovary is present in a sac of cells called ______ (1). As the egg grows larger, the follicle enlarges and gets filled with a fluid and is now called the ______ (2) follicle. The process of releasing the egg from the ovary is called ______ (3). The ovum is picked up by the oviducal funnel and fertilization takes place in the ______ (4). In about a weak the blastocyst gets fixed in the endometrium of the uterus and this process is called ______ (5).
Briefly describe the secretory phase of the menstrual cycle.
Follicle stimulating hormone : Development of oocyte : : Luteinizing hormone : ____________
Read the following passage and answer the question that follows:
Rahini and her parents were watching a television programme. An advertisement flashed on the screen which was promoting the use of sanitary napkins. Rahini’s parents suddenly changed the channel, but she objected to her parents and explained the need and importance of such an advertisement.
What is first menstruation called? When does it occur?
The endometrium in the female is the lining of ______.
The Corpus luteum grows during menstruation.
Given below is a flow chart showing ovarian changes during menstrual cycle. Fill in the spaces giving the name of the hormones responsible for the events shown.
Write a short note on Proliferative Phase.
Write a short note on Secretory Phase.
Give a reason for the following:
The second half of the menstrual cycle is called the luteal phase as well as the secretory phase.
