The menstrual cycle is a monthly process controlled by hormones that prepares the body for potential pregnancy. If pregnancy does not occur, the thickened uterine lining breaks down and is expelled as menstruation. Key events include maturation of a follicle and ovulation around day 14 when an egg is released. If the egg is fertilized, the corpus luteum maintains progesterone production to sustain the uterine lining. Without fertilization, progesterone levels drop and menstruation begins, starting a new cycle. Menstrual cramps are caused by prostaglandins released during breakdown of the uterine lining, causing muscle contractions and restricted blood flow.

1. THE MENSTRUAL CYCLE
Candidate should be able to describe the menstrual cycle

2.  When a female reaches puberty she usually has a
menstrual period every month.
 The start of periods is known as menarche.
 Menarche doesn't happen until all the parts of a girl's
reproductive system have matured and are working
together.
 This event occurs until the woman reaches menopause

4.  This ‘period’ is apart of a cyclical process which prepares
the woman's body for the development of a fertilized egg.
 The process is controlled by several hormones.
 What is a hormone?
 A chemical substance produced by an endocrine gland to
coordinate one or more specific processes in the body.

5.  The process is controlled by several hormones.
 GONADOTROPIN-RELEASING HORMONE GnRH
 FOLLICLE STIMULATING HORMONE FSH
 LEUTENIZING HORMONE LH
 LUTEOTROPPIC HORMONE
 OESTROGEN
 PROGESTERONE

6.  Each month, the ovary releases an egg cell. It travels
down the fallopian tube towards the uterus.

7. The egg matures when FSH
from the pituitary gland
reaches the ovary.
The mature egg is
surrounded by a fluid and
a jacket of cells known as
the Graafian follicle.

8. Graafian Folllicle

9. OVULATION
 The mature Graafian follicle moves toward the surface of
the ovary and ruptures releasing the egg(ovum) from the
follicle and the ovary.
 This process, ovulation occurs about the 14th
day after
the beginning of the menstrual period.
 When the ovum is released it enters the oviduct and
passes along the oviduct to the uterus

10.  After ovulation, the pituitary gland secretes lutenizing
hormone (LH).
 LH changes the remains of the follicle into the corpus
luteum/yellow body.
 Corpus luteum produces the hormone progesterone.
 Progesterone further thickens the uterus lining and
increases blood supply

11.  If fertilization does occur the corpus luteum enlarges and
continues to produce progesterone. The lining of the
uterus thickens and blood supply increases.
 Progesterone also causes the breast to enlarge.
 These are pregnancy changes, progesterone is also known as
the ‘pregnancy hormone’.
 Both oestrogen and progesterone slow down FSH
production when their concentrations become high. Thus
no more eggs develop. *negative feedback *

12.  If fertilization does not occur the corpus luteum
degenerates to ordinary ovary tissue and the
progesterone level falls.
 The lining of the uterus breaks down and the egg dies.
 Lining along with blood passes out the vagina as the
menstrual period.
 Cycle continues with increased FSH production and egg
development.
 Cycle lasts approximately 28days

13. Normal Menstrual Cycle
What is the mean duration of the MC?
Mean 28 days (only 15% of )
♀
Range 21-35
What is the average duration of menses?
3-8 days
What is the normal estimated blood loss?
Approximately 30 ml
When does ovulation occur?
Usually day 14
36 hrs after the onset of mid-cycle LH surge

15. Menstrual Cramps
 Menstrual cramps are pains in the abdominal (belly) and
pelvic areas that are experienced by a woman as a result
of her menstrual period.
 Menstrual cramps can range from mild to quite severe.
Mild menstrual cramps may be barely noticeable and of
short duration - sometimes felt just as a sense of light
heaviness in the belly. Severe menstrual cramps can be so
painful that they interfere with a woman's regular
activities for several days.

16. What causes menstrual cramps
 When the old uterine lining begins to break down,
molecular compounds called prostaglandins are released.
These compounds cause the muscles of the uterus to
contract. When the uterine muscles contract, they
constrict the blood supply to the endometrium.
 This contraction blocks the delivery of oxygen to the
tissue of the endometrium which, in turn, breaks down
and dies. After the death of this tissue, the uterine
contractions literally squeeze the old endometrial tissue
through the cervix and out of the body by way of the
vagina.