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Physiology Supplemental Cards > Female Physiology > Flashcards

Female Physiology Flashcards

1
Q

describe negative feedback loops

A
  • most common homeostatic control mechanisms
  • generally occurs at the hypothalamic level
  • physiologic ability to maintain stable internal environment despite external changes
  • occurs via continuous monitoring, regulation, and coordination of responses
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2
Q

describe positive feedback loops

A
  • only used for infrequent events that don’t require homeostatic control
  • ex. oxytocin in parturition (childbirth)
    • stimulates contractions, which stimulate additional oxytocin release
    • birth ends this stimulus
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3
Q

what is GnRH?

A
  • gonadotropin-releasing hormone
  • released from hypothalamus
  • part of pituitary-ovarian (HPO) loop
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4
Q

what are the trophic hormones of the HPO loop?

A
  • gonadotropins
    • FSH
    • LH
  • released from anterior pituitary
  • stimulate gonads
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5
Q

what are the target hormones in the HPO loop?

A
  • ovarian hormones
    • estrogens - generators of sexual activity
    • progesterone - progestational hormone
    • inhibins - peptide hormones
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6
Q

describe the HPO axis

A
  • feedback regulation of ovarian function
  • in the ovary, thecal cells provide androgens which stimulate the granulosa cells and produce the circulating estrogens
    • estrogens feedback inhibit GnRH, LH, and FSH secretion
  • inhibins from granulosa cells inhibit FSH secretion
  • LH stimulates thecal cells, while both LH and FSH stimulate granulosa cells
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7
Q

describe estrogens

A
  • natural estrogens - all estrogens are characterized by their basic 18-C skeleton, called an estrane skeleton
    • estradiol (E2) - predominant estrogen during reproductive years
    • estrone (E1) - during menopause and post-menopause
    • Estriol (E3) - during pregnancy
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8
Q

estrogens functions in female sexual maturation and development of ____

A

secondary sex characteristics

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9
Q

describe functions of estrogen

A
  • increases CNS excitability
  • stimulate endometrial proliferation and uterine growth
  • reduce rate of bone-reabsorption
  • alter plasma lipids
  • enhance blood coagulability
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10
Q

describe how estrogen alters plasma lipids

A

increases HDL and triglycerides, while decreasing LDL

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11
Q

at what point during the menstrual cycle is a woman considered the most fertile?

A
  • towards the end of the proliferative phase
  • around day 10-12 of the cycle
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12
Q

what hormone is being released for the first ~1/2 of the menstrual cycle? the second ~1/2?

A
  • first 1/2 = estrogen
  • second 1/2 = progesterone
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13
Q

describe hormonal changes during the menstrual cycle

A
  1. estrogen
    1. low point during menses, so the pituitary makes and secretes FSH and LH
  2. FSH and LH stimulate the growth of several preovulatory (premordial) ovarian follicles
  3. E2 increase inhibits FSH and LH release (~day 7)
    1. allows dominant secondary follicle to survive/grow on its own
  4. building up to ovulation, FSH and LH have accumulated in anterior pituitary due to prolonged high levels of estrogens that predominate follicular phase
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14
Q

interactions between ___ and ___ cells result in estradiol synthesis and secretion

A

theca and granulosa cells

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15
Q

prior to ovulation, ___ acts predominantly on the ___ cells surrounding the developing follicles, to enhance production of adrogenic hormones, which cross over the basement membrane of the follicle to ___ cells, which are predominantly under the influence of ___

A
  • LH
  • theca cells
  • granulosa cells
  • FSH
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16
Q

what causes the LH surge?

A

E2 levels reach a tipping point threshold, briefly flipping the gonadotrophic feedback from negative to positive

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17
Q

describe the progestational effects of progesterone

A
  • under the influence of progesterone, uterus begins to change its character, creating a highly vascularized bed for a fertilized egg
  • the corpus luteum produces progesterone until about 10 weeks gestation, if a pregnancy occurs
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18
Q

if the egg is not fertilized and/or implantation does not occur, the circulating levels of hormones decline with the degeneration of the ___ to ___ and the shedding of the lining of the uterus. what is the name for the bleeding that results?

A
  • corpus luteum
  • corpus albicans
  • menses
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19
Q

describe how the HPO axis is a reproductive axis

A
  • following ovulation, granulosa cells converts enzymatic activity from predominantly estrogen (E2)-producing to progesterone (P)-producing as the corpus luteum develops
  • the enhanced blood supply to the corpus luteum cyst enables delivery of large amounts of circulating steroid precursors and abundant production of progesterone
20
Q

describe progestins

A
  • synthesized in ovary, testes, and adrenal cortex from cholesterol
  • all progestins are characterized by their basic 21-C skeleton
  • ex. progesterone
21
Q

describe progesterone

A
  • the most important natural progestin in humans
  • while all steroid hormones are derived from cholesterol, progesterones serve as a precursor to synthesis of all esterogens, androgens, and adrenocortical steroids
22
Q

describe the physiological effects of progesterone

A
  • progestational effects - prepares the uterus for implantation, plays a role in the secretory mechanism of the breast
  • increases fat deposition
  • decrease CNS excitability (anticonvulsant)
  • increases body temperature (thermogenic)
  • decreases PCO2 during pregnancy
23
Q

HPO axis changes throughout a woman’s lifetime

unlike a male who makes sperm throughout life, a female’s total supply of gametes are determined ___

A

at birth

24
Q

HPO axis changes throughout a woman’s lifetime

during childhood, a critical body weight must be reached for puberty to occur, likely due to ___

A

leptin

25
Q

HPO axis changes throughout a woman’s lifetime

if leptin levels are inadequate, the hypothalamus becomes less sensitive to ___ and a rhythmic pulsatile release of ___ begins, triggering the anterior pituitary to release ___ and ___, thus increasing ovarian release of estrogens

A
  • estrogen
  • GnRH
  • FSH and LH
26
Q

HPO axis changes throughout a woman’s lifetime

at puberty, an increase in ___ secretion contribute to bone growth, breast development, pubic and ancillary hair growth, and ___

A
  • estrogen
  • menarche (first menses and start of endometrial cycle)
27
Q

T or F:

ovulation begins with menarche

A

false

adult cyclical ovarian pattern is usually achieved 2-4 years post-menarche

28
Q

HPO axis changes throughout a woman’s lifetime

describe perimenopause

A
  • can vary from 1-10 years preceding onset of menopause
  • large fluctuation of gonadotropins and estradiol levels
  • believed to be due to the loss of inhibins
29
Q

HPO axis changes throughout a woman’s lifetime

describe menopause

A
  • permanent cessation of menstruation cause by a loss of ovarian follicular activity
  • at onset, FSH levels are markedly elevated
  • Estrone (E1) is the predominant circulating estrogen since the ovaries no longer secrete progesterone and estradiol
  • in postmenopausal women, E1 is formed from testosterone by aromatase enzyme in adipocytes
30
Q

describe early pregnancy (months 1-2)

A
  • upon implantation, trophoblast cells from the implanting conceptus begin secreting human chorionic gonadotropin (hCG)
    • supports corpus luteum
  • hCG bypasses HPO axis control and prompts the corpus luteum to continue expressing estrogens and progesterone, preventing menstruation
  • uterine control is taken over by the developing embryo
31
Q

describe pregnancy (months 2-3)

A
  • placenta takes over production of progesterone and estrogen by ~8 weeks
  • corpus luteum degenerates and ovaries become inactive until after childbirth
    • if placental hormones are inadequate after hCG levels wane, then the endometrium degenerates and the pregnancy is absorbed
32
Q

what are the pro-gestational effects of progesterone in pregnancy?

A
  • prevents uterine contractions
  • moderates maternal immune response to preserve pregnancy
  • stimulates lobular-alveolar development in mammary glands
  • suppressing actual milk synthesis until near childbirth
33
Q

the principal estrogen formed during pregnancy is?

A

estriol (E3)

34
Q

what can be monitored as an index of the fetus condition?

A

maternal urine estriol excretion

35
Q

describe the 3 hormones involved in parturition (childbirth)

A
  • estrogen
    • induces uterine oxytocin receptor expression
  • oxytocin
    • causes contractions during parturition (+ feedback) and induces release of placental prostaglandins
  • relaxin
    • peptide hormone secreted by the placenta to relax the cervix and pelvic ligaments to ease birth
36
Q

hormones involved in breast development and lactation:

describe prolactin

A
  • stimulates development of milk glands
  • is said to be under “predominant inhibitory control”
    • prolactin inhibitory factor (PIF) is continuously produced and secreted by the hypothalamus
    • only when prolactin is needed does the hypothalamus stop production/secretion of dopamine (PIF), allowing the anterior pituitary to secrete prolactin
37
Q

hormones involved in breast development and lactation:

estrogen

A
  • stimulates development of milk ducts
  • stimulates prolactin release, but helps block milk production
38
Q

hormones involved in breast development and lactation:

progesterone

A
  • stimulates development of milk glands
  • blocks stimulation of milk production by prolactin
39
Q

describe lactation

A
  • secretion of milk from the mammary gland
  • after birth, prolactin stimulates milk production
  • milk ejection is promoted by oxytocin in response to suckling of the breast (+ feedback)
  • first fluid released after birth is colustrum
40
Q

T or F:
oral infections, such as gum disease, have been linked to preterm birth

A

true

41
Q

if dental work is required during pregnancy, when is the ideal time for this to happen? why?

A
  • 2nd trimester
  • fetal organ development occurs during the first trimester, so it is best to avoid all potential risks at this time if possible
  • 3rd trimester is not ideal because it may be difficult for the patient to lie in a reclined position
42
Q

hormonal changes during the menstrual cycle:

when E2 is sufficient (~day 13), an ___ surge triggers changes that allow the follicle to rupture, aka ___

A
  • LH surge
  • ovulation
43
Q

describe ovulation

A
  • takes place 28-48 hours after onset of LH surge and 10-12 hours after LH reaches its peak
  • ovulatory mechanism includes the release of metalloproteinases that weaken the ovarian wall
  • blood flow to the area stops and the follicle wall thins and ruptures allowing egg to be released
44
Q

describe how birth control pills function to prevent ovulation

A
  • constant low levels of estrogen and progesterone
  • this inhibits GnRH, FSH, and LH secretion and therefore follicular development and ovulation
45
Q

describe the luteal phase

A
  • begins at ovulation and lasts ~14 days
  • remaining ovarian cells become the corpus luteum and produce some E2 as well as high amounts of progesterone
46
Q

what prevents a second ovulation event during the menstrual cycle?

A
  • elevated progesterone (and estrogens) in the blood (released by the corpus luteum) inhibit pituitary release of LH and FSH, preventing a second ovulation event
47
Q

name, in order, the phases of the uterine cycle

A
  • follicular phase:
    • menses: day 0-7
    • proliferative phase: day 7-14
  • luteal phase:
    • secretory phase: day 14-28

Physiology Supplemental Cards (3 decks)

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