NCAM217 MATERNAL LEC 2C menstruation

MENSTRUATION:

30-60 cc of blood

epithelial cells and mucus are being discharged.

•Purpose: to bring an ovum to maturity and renew a uterine tissue bed that will be responsible for the ova’s growth should it be fertilized.

It is the process that allows for conception and implantation of a new life.

Physiology of Menstruation

hypothalamus, the pituitary gland, the ovaries, and the uterus.

Graafian follicle.

After an upsurge of LH from the pituitary, prostaglandins are released and the Graafian follicle ruptures. The ovum is set free from the surface of the ovary, a process termed ovulation.

Effects of ESTROGEN to the body:

-Inhibits production of FHS.

- Causes hypertrophy and hyperplasia of myometrium

- Stimulates the growth of ductile structures of the breast

- Increases quantity and pH of cervical mucus causing it to become watery and can be to a distance of 10-13 cm. (Spinnbarkeit test of dilation)

Effects of PROGESTERONE in the body:

- Inhibits production of LH.

- Facilitates transport of fertilized ovum through the fallopian tubes.

- Causes fluid retention

- Decreased hemoglobin and hematocrit levels

- Increased basal body temperature after ovulation because of the presence of

progesterone

THE MENSTRUAL CYCLE

On the third day of the menstrual cycle, serum estrogen level is at lowest which stimulates the hypothalamus to produce follicle stimulating hormone releasing factor (FSHRF).

2. FSHRF is responsible for stimulating the anterior pituitary gland (APG) to produce the FSH which will act on one immature oocyte inside. a primordial follicle, stimulating its growth.

3. In view of the FSH, estrogen is now going to be produced in an increasing amount inside the follicle, which is found in the ovary. Once estrogen is present the primordial follicle is now termed Graafian follicle. The GF is the structure therefore that contains high amounts of estrogen.

4. Estrogen in the GF will cause the cells in the uterus to proliferate (grow rapidly); increasing its thickness to about eight fold. This is called Proliferative/follicular phase.

5.Once ovulation has taken place, the GF which contains increased amount of progesterone will turn to Corpus Luteum which is yellow appearance

6.Progesterone causes the gland of the uterine endothelium to become corkscrew or twisted in appearance. This is the hormone of pregnancy because it prevents uterine contractions. Once the fertilized ovum developed finger-like projections called TROPHOBLAST around the blastocyst, the trophoblasts are the ones that will implant high on the anterior or posterior surface of the uterus.

MENSTRUATION IMPORTANT

IMPORTANT:

• Despite the variability of a woman’s cycle (23-35 days), ovulation occurs exactly 2 weeks before the next menstruation. The first 14 days of the cycle is variable. Thus, ovulation occurs not on the 14th day of the cycle but 14 days prior to the first day of the next menstrual cycle unless a pregnancy occurs.

• First day of the cycle is the first day of menstruation and one menstrual cycle is from the first day of the menstrual period till the first day of the next cycle.

FERTILIZATION

Fertilization (also referred to as conception and impregnation) is the union of an ovum and a spermatozoon. This usually occurs in the outer third of a fallopian tube, the ampullar portion

•Usually only one of a woman’s ova will reach maturity each month. Once the mature ovum is released, fertilization must occur fairly quickly because an ovum is capable of fertilization for only 24 hours (48 hours at the most).

•After that time, it atrophies and becomes nonfunctional. Because the functional life of a spermatozoon is also about 48 hours, possibly as long as 72 hours, the total critical time span during which sexual relations must occur for fertilization to be successful is about 72 hours (48 hours before ovulation plus 24 hours afterward).

•As the ovum is extruded from the graafian follicle of an ovary with ovulation, it is surrounded by a ring of mucopolysaccharide fluid (the zona pellucida) and a circle of cells (the corona radiata)

Capacitation

is a final process that sperm must undergo to be ready for fertilization. This process, which happens as the sperm move toward the ovum, consists of changes in the plasma membrane of the sperm head, which reveal the sperm-binding receptor sites.

Hyaluronidase (a proteolytic enzyme)

is released by the spermatozoa and dissolves the layer of cells protecting the ovum. One reason that an ejaculation contains such a large number of sperm is probably to provide sufficient enzymes to dissolve the corona cells. Under ordinary circumstances, only one spermatozoon is able to penetrate the cell membrane of the ovum. Once it penetrates the cell, the cell membrane changes composition to become impervious to other spermatozoa.

• Immediately after penetration of the ovum, the chromosomal material of the ovum and spermatozoon fuse to form a zygote.

• Because the spermatozoon and ovum each carried 23 chromosomes (22 autosomes and 1 sex chromosome), the fertilized ovum has 46 chromosomes.

• If an X-carrying spermatozoon entered the ovum, the resulting child will have two X chromosomes and will be female (XX).

• If a Y-carrying spermatozoon fertilized the ovum, the resulting child will have an X and a Y chromosome and will be male (XY).

Implantation

Once fertilization is complete, a zygote migrates over the next 3 to 4 days toward the body of the uterus, aided by the currents initiated by the muscular contractions of the fallopian tubes. During this time, mitotic cell division, or cleavage, begins.

Implantation, or contact between the growing structure and the uterine endometrium, occurs approximately 8 to 10 days after fertilization.