The menstrual cycle- Mr. panneh

this lecture was presented to the December 2016 Midwifery class of the school for Enrolled Nurses and Midwives- The Gambia.

1. THE MENSTRUAL CYCLE MR. ABDOU PANNEH ( RM,DHAF,NT , RN)

2. OBJECTIVES At the end of the lesson students should be able to Define menstrual cycle List the organs involve in menstrual cycle Describe different cycles involve State the stages of menstrual cycle

3. ORDER OF PRESENTATION Definition/Introduction List of organs involve List of hormones Different cycles Different stages of menstrual cycle

4. INTRODUCTION The term menstrual cycle technically refers to the cyclic changes that occur in sexually mature, non pregnant females and culminates in menses. Typically, the menstrual cycle is about 28days long, although it can be as short as 18 days in some women and as long as 40 days in others. The term menses is derived from a Latin word meaning month. It is a period of mild haemorrhage, which occurs approximately once each month, during which the uterine epithelium is sloughed and expelled from the uterus. Menstruation is the discharge of blood and elements of the uterine mucous membrane.

5. ORGANS ASSOCIATED WITH THE MENSTRUAL CYCLE Hypothalamus Anterior pituitary gland Ovary Uterus

6. HORMONES ASSOCIATED WITH THE MENSTRUAL CYCLE The hypothalamus produces: Gonadotropin releasing hormone ( GnRH ) The anterior pituitary gland produces: Follicle-stimulating hormone (FSH) Luteinising hormone (LH) The ovary produces: Oestrogen Progesterone

7. Pituitary Control Under the control/influence of the hypothalamus which produces gonadotrophin releasing hormone, the anterior pituitary gland secretes two hormones:

8. Follicle Stimulating Hormone This causes several Graafian follicles to develop and enlarge, one more than the others. Follicle-stimulating hormone stimulates the maturing ovum to secrete oestrogen. The level of FSH rises during the first half of the cycle. When oestrogen levels reach a certain level (i.e. very high) however, the production of FSH is stopped.

9. Luteinizing Hormone This is produced towards the end of the first half of the cycle when FSH levels begin to decline. As the LH rises and the FSH falls, the follicle ruptures and ovulation occurs. The corpus luteum develops under the influence of LH and produces some oestrogen and high levels of progesterone. LH is produced for 14days after which FSH reappears and the cycle begins again.

10. THE OVARIAN CYCLE The ovarian cortex contains 200,000 primitive primordial follicles at birth. From puberty onwards, certain follicles enlarge ( Graafian follicles) and one matures each month to liberate an ovum. During the normal 28days cycle a sequence of changes occurs in the ovary aimed at the production of a mature ovum, capable of being fertilized. This sequence also controls the quantity and quality of hormones necessary for the preparation of the uterus for reception of the ovum.

11. Oestrogen It is produced by the maturing ovarian follicle under the influence of FSH. During the cycle oestrogen causes proliferation (hyperplasia) of the uterine endometrium . This means that the cells of the endometrium increase in number and the endometrium becomes thicker.

12. Progesterone This is produced by the corpus luteum (after ovulation).Its effects are mainly evident during the second half of the cycle. It causes secretary changes in the lining of the uterus, when the endometrium develops tortuous glands and an enriched blood supply in readiness for the possible arrival of a fertilized ovum.

13. THE UTERINE CYCLE/PHASES OF THE MENSTRUAL CYCLE Proliferative/ Follicular phase The time between the ending of menstruation and ovulation is called the follicular phase, because of the rapid development of the ovarian follicle, or the proliferative phase, because of the rapid proliferation of the uterine mucosa. The length of the proliferative phase is variable but it is usually about 10 to 11 days. Stimulated by oestrogen, the endometrium increases in thickness (proliferates). The glands are straight and do not secrete. At the end of the proliferative phase the endometrium consists of three layers:

14. CONT’D A basal layer – this lies immediately above the myometrium , about 1mm in thickness. This layer never alters during the menstrual cycle. It contains all the rudimentary structures for building up new endometrium . A Functional layer – this contains tubular glands and is about 2.5mm thick. This layer changes constantly according to the hormonal influences of the ovary. A Layer of cuboidal ciliated epithelium – this covers the functional layer. It dips down to line the tubular glands.

15. Seceretory / Luteal Phase This follows ovulation (rupture of a mature follicle) at the end of the proliferative phase. The period after ovulation and before the next menses is called the luteal phase, because of the existence of the corpus luteum , or the secretary phase, because of the maturation of, and the secretion by uterine glands. The length of the luteal phase is fairly constant and usually lasts 14 days. Under the influence of progesterone and oestrogen (but mainly progesterone) produced by the corpus luteum , the functional layer thickens to 3.5mm and the endometrium is highly vascularised. Glands enlarge and become tortuous and secrete or store glycogen, mucin and other substances which can nourish a fertilized ovum. Blood vessels become more coiled (spiral arteries).

16. Menstrual phase The first day of menses is day 1 of the menstrual cycle, and menses typically last 4-5days. Endometrial growth ceases 5-6days before menstruation. High levels of LH stimulate a reduction in the production of progesterone. The withdrawal of progesterone causes the spiral arteries in the endometrium to shrink thus reducing the blood supply. This causes ischaemia and eventual sloughing of the functional layer. The functional layer is later discharged through the vaginal canal together with the unfertilized ovum and blood from the endometrium as menses.

17. QUESTIONS, CONTRIBUTIONS, CLARIFICATIONS & CONSTRUCTIVE CRITICISMS?????