2:Reproductive and menstrual physiology

The _ axis regulates production through coordinated hormone signaling

HPO

The hypothalamus releases __ __ initiating hormonal communication

Pulsatile GnRH

The pituitary gland responds by releasing _ and _, which stimulate ovarian function

FSH and LH

The ovaries produce _ and _, influencing ovulation, menstruation, and feedback regulation

FSH and LH

Clinical principle:

• normal _ function depends on communication between all three levels of HPO axis

• Disruption at any point can result in irregular _, _, or _

Reproductive

Menses, infertility, anovulation

GnRH is released in a __ pattern that:

• stimulates normal _ and _ secretion

• regulates ovarian hormone production through change in pulse __ and __

pulsatile

LH and FSH

frequency and amplitude

clinical implications of GnRH secretion:

• disrupted pulsatility can impair __ and __

• commonly seen with __, significant __ __, excessive __, and chronic __

ovulation and fertility

stress, weight loss, exercise, illness

clinical pearl for GnRH secretion:

• pulsatile GnRH __ gonadotropin release, whereas continuous GnRH __ it

stimulates

suppresses it

FSH promotes maturation of __ __ by:

• stimulating growth of developing __

• activating __ cells within the follicles

• increasing __ production as follicles mature

ovarian follicles

follicles

granulosa

estrogen

clinical implications of FSH:

• elevated FSH may indicate diminished ovarian __ or __

• low FSH suggests __ or __ dysfunction

reserve/failure

hypothalamic or pituitary

clinical pearl of FSH:

• FSH helps select the __ follicle that ultimately ovulates

dominant

LH functions:

• triggers release of the __ follicle (ovulation)

• transforms the ruptured follicle into the __ __

• stimulates __ production after ovulation

mature

corpus luteum

progesterone

clinical hallmark:

• midcycle __ surge occurs approximately _-_ before ovulation

LH

24-36

clinical implication LH:

absence of LH surge results in __ and __

anovulation and infertility

clinical pearl LH:

home ovulation predictor detect the __ surge

LH

Follicular phase:

• estrogen provides primarily __ feedback

• __ supports follicular development

negative

FSH

midcyle:

• sustained high estrogen creates __ feedback

• __ surge triggers ovulation

positive

LH

luteal phase:

• __ restores negative feedback

• supports __ preparation for implantation

progesterone

endometrial

clinical relevance of hormonal feedback in HPO axis:

• disruption of feedback may cause __ menses or __

irregular

anovulation

follicular phase (Day _ → _)

1 to ovulation

Follicular phase: FSH promotes __ growth and selection of __ follicle

follicular

dominant

ovulation occurs ~Day _

14

ovulation: sustained high __ triggers __ surge

mature __ is released from the dominant follicle

estrogen

LH

oocyte

Luteal phase:

corpus luteum produces __

progesterone prepares __ for possible implantation

hormone levels __ if pregnancydoes not occur

progesterone

endometrium

fall

hormone patterns vary by cycle phase and influence __, __, and __ interpretation

fertility

symptoms

laboratory

the __ changes throughout the cycle in response to ovarian hormones

endometrium

menstrual phase:

declining __ and __ trigger shedding of the functional endometrium

marks __ of new menstrual cycle

estrogen and progesterone

beginning

proliferative phase:

rising __ stimulates rapid endometrial __

endometrial __ increases in preparation for possible pregnancy

estrogen, regrowth

thickness

secretory phase:

__ transforms the endometrium into a __ environment

__ become active and support potential implantations

progesterone

receptive

glands

hormonal disruption can alter __ development and contribute to abnormal uterine __

endometrial

bleeding

ovulation represents the release of a mature __ from the dominant follicle

oocyte

timing of ovulation:

• usually occurs approximately _-_ hrs after _ surge

• occurs about _ days before next menstrual _

• timing varies with cycle _

24-36 LH

14; period

length

mechanism of ovulation:

• sustained high __ triggers the _ surge

• _ causes rupture of dominant follicle

• the oocyte is released into the _ tube

estrogen; LH

LH

fallopian

clinical significance of ovulation:

• defines the __ window of the menstrual cycle

• failure to ovulate is a common cause of __

• ovulatory dysfunction often presents as irregular __

fertile

infertility

menses

the fertile window occurs __ ovulation (not after)

before

why can pregnancy occur before ovulation?

• sperm can survive in cervical mucus for up to _ days

• the oocyte remains viable for only about _ hrs after release

therefore intercourse occurring several days before ovulation can still result in conception

5

24

clinical application of the fertility window:

• _ patients attempting pregnancy

• understanding natural family __ methods

• evaluating _ concerns and cycle _

counseling

planning

fertility/timing

ovulation determines __, but sperm survival extends the _ window

fertility

fertile

in the early follicular phase, there is low _ and _ meaning _ begins

estrogen and progesterone

menstruation

in the late follicular phase there is rising _ and this results in endometrial _

estrogen

growth

during ovulation there is a _ surge and this causes release of _

LH

oocyte

in the luteal phase _ predominates and this results in endometrial _

progesterone

stabilization

in the late luteal phase there can be _ pregnancy, there is _ withdrawal and this means _ begins again

no

progesterone

menstruation

_, _, and _ patterns are largely explained by predictable hormonal changes throughout the cycle

symptoms, fertility, and bleeding

__ occurs when the normal ovulatory sequence is disrupted

anovulation

anovulation can occur from:

• inadequate _ pulsatility prevents _ surge

• without _ surge, the dominant follicle does not release a _

• _ does not occur and _ _ does not form

GnRH/LH

LH/oocyte

ovulation/corpus lutem

common causes of anovulation:

• _ _ _ (most common)

• significant weight _ or excessive _

• chronic _ or systemic _

• _, _, or _ disorders

polycystic ovarian syndrome

loss/exercise

stress/illness

hypothalamic, pituitary, endocrine

clinical consequences of anovulation:

• irregular or absent _ cycles

• abnormal uterine _

• _ or _

menstrual

bleeding

subfertility/infertility

normal cycle:

_ → _ surge → _ → _ _ → _

GnRH → LH surge → ovulation → corpus luteum → progesterone

anovulatory cycle:

_ disruption → no _ surge → no _ → no _ _

GnRH disruption → no LH surge → No ovulation → no corpus luteum

clinical applications of putting physiology into clinical practice

• abnormal uterine __

• _ and _

• _ eval

• endocrine disorders such as _

bleeding

amennorhea and oligomenorrhea

infertility

PCOS

when menstrual cycles become abnormal, begin by asking:

• is the patient _

• is _ occurring normally

• where might _ axis be disrupted?

pregnant

ovulation

HPO

_ test remains the first diagnostic step

pregnancy

menstrual history helps determine cycle _, _, and _ patterns

associated symptoms may suggest _ or _ causes

frequency, regularity, and ovulatory

endocrine/systemic

laboratory eval (when indicated):

• _ - evaluate thyroid dysfunction

• _ - assess for hyperprolactinemia

• _ and _ - help localize hypothalamic, pituitary, or ovarian dysfunction

TSH

prolactin

FSH and LH

common misconceptions

• assuming ovulation always occurs on day 14 instead of approximately 14 days _ next menses

• confusing ovarian phases (_, _, _) with endometrial phases (_, _, _)

• failing to recognize that anovulation results in inadequate _ production

• overlooking the importance of GnRH _ in maintaining normal ovulatory cycles

• assuming abnormal bleeding is simply a normal variation without considering underlying _ dysfunction

before

ovarian: (follicular, ovulatory, luteal) vs. endometrial (menstrual, proliferative, secretory)

progesterone

pulsatility

physiologic

HPO axis regulates _ function through coordinated hormonal signaling

reproductive

GnRH _ is required for normal FSH and LH secretion

pulsatility

the _ surge triggers ovulation and marks transition to the _ phase

LH

luteal

_ production depends on successful ovulation

progesterone

disruption of hormonal feedback can result in _, irregular _, and abnormal _

understanding normal reproductive physiology provides the foundation for evaluating _ and _ disorders

anovulation, cycles, bleeding

menstrual/fertility