Female Reproductive Physiology

Role of the human female

• The female human has the following roles in reproduction – Production of the egg – Ovulation – Implantation of the egg – Pregnancy – Birth – lactation

Hypothalamus

Anterior Pituitary

GnRH

Estrogens / Progestins

LH and FSH

Ovaries

ovary has three zones

The functional unit of the ovaries is the single ovarian follicle

Thecal CellLH

cAMP

DNA transcription

Via PKA

cholesterol

pregnenolone

Granulosa CellFSH

cAMP

DNA transcription

Via PKA

Enzyme(aromatase)

• The granulosa cells do not have the enzymes to convert progesterone into androstenedione so instead must receive androstenedione from the thecal cell.

• there is an interaction between the thecal and granulosa cells in order to produce estrogens.

LH FSHLDL

via cAMP

Cholesterol

Pregnenolone

Androstenedione

Thecal Cell

Estradiol

Granulosa Cell

INTO THE BLOOD

via cAMP

During the Follicular Phaseestradiol.

LH

FSH

LDL

via cAMP

Cholesterol

Pregnenolone

Androstenedione

Thecal Cell

Estradiol

Granulosa CellINTO THE BLOOD

Progesterone

Cholesterol

Pregnenolone

Progesterone

via cAMP

LHLuteal phase

Negative and Positive Feedback In females, the hypothalamic-pituitary axis is controlled by both negative and positive feedback, depending on the phase of the menstrual cycle

Progesterone

Collagenaseprostaglandins

Hyperemia

Swelling of follicle

Breakdown of wall

Stigma degeneration

Rupture and

ovulation

EstrogensEstrogen is the word defining the family of sex hormones that include estradiol, estriol and estrone. They are secreted in varying amounts by the ovary but all have similar effects (though different potencies).

Estrogens (at Puberty)

­ Size of Reproductive

organs

Initiation of Breast

development

Vaginal Epithelium

Infection -resistant

Epiphyseal Fusion

Histological Changes in Uterine cells

Estrogen(> puberty)

­ no. and activity Of ciliated cells

At oviduct

­ Protein synthesis

Further breast development

Ovarian and Menstrual

function

Subcutaneous Fat deposition

ProgestinsTwo hormones that come under the umbrella of progestins are released by the ovary, progesterone and 17--hydroxyprogesterone. The former is secreted in a much greater amount and it is convention to put both under the name progesterone.

Progesterone

Uterine endometrium

Ovulation

Alveoli cells Or breast

↓Uterine excitability During pregnancy

Puberty and Menopause

• At Puberty: – GnRH activity increases – Eventually leads to ovarian activity – Increased estrogen levels stimulate

reproductive organ development. • At Menopause

– Cessation of the ovarian cycle – Decreased estrogen secretion.

Endocrinology of Pregnancy

In order to understand pregnancy you must accept the fetus, placenta and mother all as one unit. This section will discuss the hormone interactions within this unit and the reasons underlying these changes.

Human Chorionic Gonadotropin It is produced by the embryo prior to implantation and after implantation is secreted by the syncytiotrophoblast cells in the intravillous space.hCG can be detected in the serum or urine 7-8 days before the expected menses and is the earliest detector of pregnancy. In fact some can now measure hCG levels 2 days after fertilization has taken place.

hCG Corpus Luteum

EstrogensProgesterone

Male Fetus

Corpus Luteum

Placenta

Progesterone Progesterone

Up to 6 Weeks 6-12 weeks More than 12 weeks

The Placenta• The placenta is a

specialized organ – Controls exchange between

maternal and fetal blood

• Capillaries from umbilical cord embed in placenta – Called placental villi – Allow for the exchange of

blood.• allow nutrient uptake, waste

elimination, and gas exchange via the mother's blood supply.

Progesterone-

Endometrial cells Of uterus

And Inhibition of myometrium.

Maintains pregnancy

Cervical Plug?? Final breast

development

Estrogens

Prepare body for Parturition(myometrium) Development

Of Breast

Inhibits Milk production

(with progesterone)

Initiator of Parturition ???

Human Placental Lactogen (hPL)

Growth Hormone Effects ??? On breast

Decreases maternal Insulin sensitivity

More glucose available For fetus

Example:LMP = 31 May 2011

+1 year = 31 May 2012-3 months = 31 February 2012+7 days = 7th February 2012

labor

Diet/Nutrition

• demand for carbohydrates, proteins, iron, calcium (Vit D), folate (neural), Vitamin K (clotting factors)

Insulin and glucose levels

• Must supply adequate levels of glucose to fetus

• Mother develops hyperglycemia between meals and when sleeping – Increases as pregnancy continues

• Increase of placental hormones increase insulin resistance – Insulin levels rise

ParathyroidGland

PTH

Calcium forfetus

Calcium formilk

• Pituitary- increases in size by 100% predisposing for Sheehan's syndrome

Parturition

Role of oxytocin

Smooth muscle cell

Oxytocin

IP3 & DAG Ca2+

Contraction

Delivery of the fetus, occurs approximately 40 weeks after the onset of the last menstrual period.

The mechanism of parturition is unclear, although roles for estrogen, progesterone , cortisol, oxytocin, prostaglandins, relaxin, and catecholamines have been proposed.

Initiation of Parturition

There is still much controversy and discussion over the mechanisms involved in the initiation of the birthing process. It may be due to a decrease in progesterone levels, an increase in circulating CRH or an increase in estrogen levels, or all three.

CRH

Hypothalamus

Placenta

Posterior Pituitary

Uterus

Fetus

oxytocin

oxytocin

pgs

Neural reflex

oxytocinContractions

of uterus

STRESS