MENSTRUAL CYCLE & HORMONAL CONROL MECHANISM
Definition:
Menstrual cycle is a term that describes the sequence of events that occurs in in
the body as it prepares for the possibility of pregnancy each month.
It is the time from the first day of menstrual period until the first day of the next
menstrual period.
It is the manifestation of series of cyclic changes taking place in the uterus.
Simultaneously, cyclic changes also take place in the ovaries, and these constitute
the ovarian cycle.
Every person’s cycle is slightly different, but the process is the same.
Control:
The normal menstrual cycle is the result of highly coordinated hypothalamic-
pituitary-ovarian (HPO) axis with complex hormonal feedback loops that lead to
the formation of a dominant follicle, ovulation and, in the absence of fertilization,
shedding of the endometrial lining at regular interval.
These hormones cause the lining of the uterus to thicken thus preparing it for
implantation peradventure there is fertilization. It also cause the ovaries to release
an egg (ovulation).
Length in Days:
Each cycle lasts 28 days averagely but may vary between 21-35 days (40days) and
is still be normal. The first day of a cycle is the first day of a menstrual period while
the last day is that of the following period. The menstrual period also known as
MENSES is characterized by shedding of blood. The days between periods is
known as the menstrual cycle length. Most people have their period (bleed)
between three and seven days. A period is normal if it’s anywhere between three
and seven days. While on the shorter end of the range, some people have a
menstrual period for three days and this is ok.
1
, To understand the menstrual cycle it is necessary to know the structure of the
uterus. The wall of the uterus is made up of three layers:
1. The outermost layer or perimetrium is made up of peritoneum.
2. The main thickness of the wall is made up of smooth muscle. This is the
myometrium.
3. The innermost layer is called the endometrium. It is the layer which undergoes
changes during the menstrual cycle.
PHASES OF MENSTRUAL CYCLE
The menstrual cycle is usually divided into 4 phases on the basis of changes taking
place in the uterine endometrium: Menstrual, Proliferative, Ovulatory and Luteal
(Corpus Luteum) Phases.
2
Definition:
Menstrual cycle is a term that describes the sequence of events that occurs in in
the body as it prepares for the possibility of pregnancy each month.
It is the time from the first day of menstrual period until the first day of the next
menstrual period.
It is the manifestation of series of cyclic changes taking place in the uterus.
Simultaneously, cyclic changes also take place in the ovaries, and these constitute
the ovarian cycle.
Every person’s cycle is slightly different, but the process is the same.
Control:
The normal menstrual cycle is the result of highly coordinated hypothalamic-
pituitary-ovarian (HPO) axis with complex hormonal feedback loops that lead to
the formation of a dominant follicle, ovulation and, in the absence of fertilization,
shedding of the endometrial lining at regular interval.
These hormones cause the lining of the uterus to thicken thus preparing it for
implantation peradventure there is fertilization. It also cause the ovaries to release
an egg (ovulation).
Length in Days:
Each cycle lasts 28 days averagely but may vary between 21-35 days (40days) and
is still be normal. The first day of a cycle is the first day of a menstrual period while
the last day is that of the following period. The menstrual period also known as
MENSES is characterized by shedding of blood. The days between periods is
known as the menstrual cycle length. Most people have their period (bleed)
between three and seven days. A period is normal if it’s anywhere between three
and seven days. While on the shorter end of the range, some people have a
menstrual period for three days and this is ok.
1
, To understand the menstrual cycle it is necessary to know the structure of the
uterus. The wall of the uterus is made up of three layers:
1. The outermost layer or perimetrium is made up of peritoneum.
2. The main thickness of the wall is made up of smooth muscle. This is the
myometrium.
3. The innermost layer is called the endometrium. It is the layer which undergoes
changes during the menstrual cycle.
PHASES OF MENSTRUAL CYCLE
The menstrual cycle is usually divided into 4 phases on the basis of changes taking
place in the uterine endometrium: Menstrual, Proliferative, Ovulatory and Luteal
(Corpus Luteum) Phases.
2
