The Menstrual Cycle

What happens if fertilisation doesnt occur?

corpus luteum stops producing progesterone and oestrogen and endometrium starts to shed

Menstruation? Proliferative phase? Secretory phase? How many days do these each take?

menstruation- loss of lining 5 DAYS proliferative phase-build up of lining 9 DAYS secretory phase-lining becomes secretory 14 DAYS

Hypothalamus?

-controls the pituitary gland -regulator of homeostasis -produces and secretes gonadotrophin-releasing hormone GnRH which moves to the pituitary gland where it stimulates the production of 2 more hormones (LH and FSH)

Why do midwives need to understand menstruation?

-diagnose pregnancy -work out EDD -work out fertile period

Describe the luteal phase

-follicle slows oestrogen production -become corpus luteum which eventually degenerates -releases progesterone and oestrogen which stops release of LH and FSH -also prepares uterus to receive oocyte

Role of follicle-stimulating hormone?

-gonadotrophic hormone -stimulates growth of ovarian follicles before release of egg

Describe the follicular phase

-hypothalamus releases GnRH once a month -stimulates anterior pituitary to release FSH & LH -FSH stimulates growth of primordial follicle (one furthest along in its development) -follicle produces oestrogen -make pituitary release more LH which stimulates more oestrogen production -oestrogen goes to endometrium and breasts -LH triggers oocyte inside follicle to start dividing by meiosis -mature follicle pushes against ovary wall, ruptures and ejects oocyte- THIS IS OVULATION

Role of prolactin? PRL

-initiates milk synthesis in females and functions related to growth, metabolism, reproductive and parental behaviours

Role of luteinizing hormone? LH

-it is a gonadoptrophic hormone -regulates function of ovaries and testes -testes- stimulates production of testosterone -ovaries- stimulates follicles to make oestrogen and stimulates corpus luteum to make progesterone

Describe how the levels of the hormones change during menstruation (what happens on the graph)

-low oestrogen- cycle begins -FSH levels grow, which causes oestrogen levels to grow -rise in oestrogen causes big peak of LH and FSH -after ovulation, peak in progesterone

PROGESTERONE (7 THINGS)

-mainly produced by corpus luteum but also produced ovaries, adrenal glands and placenta -acts on tissues affected by oestrogen -regulates lining of endometrium -makes tissue soft or secretory -makes cervical mucous thick -resets thermoregulation -production stopped if fertilisation doesn't occur

Name each phase of the menstrual cycle? (4 phases)

-menstruation day 1-5 -follicular phase day 6-13 -fertile period day 14-16 -secretory phase day 17-28

What are the two cycles called within the menstrual cycle?

-ovarian cycle- associated with maturation of ovum -uterine cycle- associated with preparation of uterine lining for pregnancy

What is the function of the female reproductive tract?

-produce ovum and transport them to site of fertilisation -provide site for implantation of fertilised ovum

Define hormone (5 points)

-secreted by endocrine tissue -affects only target cells -bind to cell receptors -release is pulsatile -excreted by kidneys and broken down by liver

OESTROGEN (7 THINGS)

-secreted by the ovaries -stops FSH being produced -stimulates pituitary to release LH -Promotes development and maintenance of female reproductive structures including breasts -control secondary sex characteristics like fat distriubtion, voice pitch and pelvic shape -reduce blood cholesterol -prepares uterus for ovulation and fertilisation -thins cervical mucous to allow sperm in

describe the secretory phase?

-simultaneous with ovulation -under the influence of progesterone and oestrogen secreted by corpus luteum -functional layer of endomterium thickens to 3.5mm and becomes spongy -blood supply yo area increases -these conditions last for 7 days awaiting fertilised egg

describe the proliferative phase

-simultaneous with the follicular phase and lasts until ovulation -formation of new layer of endometrium -at completion of this phase, endometrium consists of three layers -basal layer- 1mm thick -functional layer- on top of basal layer, contains tubular glands 2.5mm thick -layer of cuboidal ciliated epithelium

Role of oxytocin?

-stimulates uterine contraction -milk ejection -influences reproductive and sexual functions

How many eggs mature at each menstrual cycle?

1000 eggs

How many eggs is a female born with? And how many do you have left by puberty?

2 million 300-400,000

How many cycles do you have in your lifetime?

400 cycles

What hormones are released by the posterior pituitary gland?

ADH- kidney oxytocin- uterus

Name the three parts of the pituiatry gland

anterior, intermediate and posterior

Menstruation?

cyclical shedding of uterine lining

What day is the egg released?

day 14

What will happen if you are born with fewer eggs?

early menopause

How long does this maturation take??

final rapid maturation takes 14 days BUT the growth from primordial to maturity takes a year which means the follicle that ovulates actually started its growth to maturity 10-12 cycles before

The ovarian cycle splits into two, what are the 2 phases called?

follicular phase and luteal phase

How are the two cycles coordinated?

hormone levels

What is the pituitary gland affected by?

low blood pressure because it already has a low blood supply as its tucked away in the brain

What is the menstrual cycle?

name given to the female reproductive cycle of changes in the ovaries and uterus occurs monthly controlled through hormone regulation

What happens if fertilisation does occur?

progesterone from corpus triggers more thickening of endometrium and secretion of nutrients for embryo until its implanted itself in lining

What hormones are released by the anterior pituitary gland?

prolactin- breasts LH and FSH- ovary and testes