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Reproductive Physiology > Pregnancy, Parturition and Lactation > Flashcards

Pregnancy, Parturition and Lactation Flashcards

1
Q

what is the zona pellucida of the ovum? what does this trigger in the sperm?

A

a mucus mesh of 3 glycoproteins around the egg

sperm undergo the acrosomal reaction triggered by sperm binding to one of the glycoproteins

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2
Q

what intracellular event causes the acrosomal reaction and what does the acrosome contain?

A

rise inintracellular calcium triggers exocytosis of the acrosome
contains hydrolytic enzymes that dissolve the zona pellucida

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3
Q

what part of the sperm enters the oocyte and how?

A

the cytoplasmic portion of the sperm head and tail enter

the cell membranes of the sperm and oocyte fuse

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4
Q

what is a cortical reaction?

A

a calcium/ IP3 dependant process that prevents other sperm from entering by hardening the zona pellucida

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5
Q

other than the cortical reaction, what other event is prompted by the increase in oocyte calcium?

A

a second meiotic division with expulsion of a second polar body

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6
Q

what happens to the contents of the sperm when they enter the oocyte?

A

the sperm head condenses and becomes the male pronucleus. the cytoplasmic portion of the tail degenerates

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7
Q

what event leads to the formation of the zygote?

A

the fusion of the male and female pronuclei

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8
Q

where does fertilization typically occur? how long does it take for the embryo to be implanted?

A

in the fallopian tube

4-7 days

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9
Q

what facilitates sperm transport in the female reproductive tract?

A

flagella motility
uterine, cervix and fallopian tube contraction in response to oxytocin released in the female orgasm and prostaglandins in male seminal fluid

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10
Q

what maintains pregnancy at the early stage before the placenta develops?

A

the corpus luteum produces hormones to maintain pregnancy

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11
Q

what does the placenta develop from?

A

trophoblasts and adjacent cells

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12
Q

what is human chorionic gonadotropin produced by? what is its function?

A

syncytiotrophoblasts by the blastocyst

sustains the corpus luteum even without maternal LH

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13
Q

what is HCG used for clinically? what else does it stimulate in the mother and fetus?

A

measured in urine for pregnancy tests
immunosupressive agent, promotes placental development and stimulates the testes of the male fetus to produce testosterone (male sex development)

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14
Q

what provides the fetus with nutrition?

A

early weeks: endometrial decidua

later: nutrition provided by diffusion through the placenta

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15
Q

what does the placenta produce?

A

steroid hormones, amines, polypeptides, proteins and glycoproteins

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16
Q

what is the most important placental peptide hormone?

A

HCG

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17
Q

what is human somatomammotrophins related to and what is their purpose?

A

related to growth hormone

contribute to conversion of glucose to fatty acids and ketones. also promote mammary gland development in the mother

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18
Q

what happens to steroid hormones in the mother during pregnancy?

A

estrogens and progesterone rise rapidly and remain elevated

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19
Q

what is the maternal-fetal-placental unit?

A

placenta requires the assistance of the mother and the fetus to produce steroid hormones

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20
Q

what does the placenta lack with respect to steroid hormone synthesis?

A

cannot manufacture enough cholesterol
lacks 2 enzymes needed for estrone and estradiol
lacks enzyme needed for estriol synthesis

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21
Q

how is the placenta supplied with cholesterol?

A

the mother supplies it as LDL particles

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22
Q

how does the fetus contribute to steroid hormone synthesis?

A

the fetal adrenal gland and liver supply the three enzymes lacking in the placenta

23
Q

why does the fetus not have the enzymes that catalyze the final steps in estrogen synthesis?

A

because the fetus would be exposed to too much estrogen that is needed by the mother

24
Q

what is the average duration of pregnancy?

A

38 weeks from the time of ovulation of 40 weeks from the first day of the last menstrual period

25
Q

what occurs to the blood in pregnancy?

A

there is increased plasma volume and erythrocyte number. mean arterial volume decreases in mid pregnancy and rises in the third trimester

26
Q

what happens to cardiac output in pregnancy? where does the extra output go?

A

increases in the first trimester due to increase in stroke volume
extra flow is to the kidney and uterus with some increase to heart, skin and breast

27
Q

what occurs in the lungs with pregnancy? what is the effect on blood gasses?

A

increased tidal volume due to steroid effects on medullary repiratory centers
decreases the maternal arterial pCO2

28
Q

what increase in dietary needs is seen during pregnancy?

A

increased demand for dietary protein, iron and folic acid

29
Q

what happens to the breasts and uterus during pregnancy?

A

the breasts double in size and the uterus increases from 50g-> 1100 g

30
Q

what is the average weight gain in pregnancy? what happens to BMR?

A

weight gain is 25-35lbs

BMR increases by 15%

31
Q

what is parturition? what is the probably cause?

A

the birth of the baby

may be triggered by increase in fetal production of cortisol near term-> increases estrogen/progesterone ratio

32
Q

what causes uterus quiescence through the pregnancy?

A

presence of progestogens and relaxins

33
Q

what happens in the last month of pregnancy until labor?

A

irregular braxton hicks contractions

34
Q

what initiates contractions and what sustains them? what do they cause?

A

prostaglandins
oxytocin and prostaglandins maintain
paracrine stimulation of uterine smooth muscle walls and formation of gap junctions between the cells. dilation of the cervix

35
Q

what happens to oxytocin receptors in the uterus and what causes it?

A

estrogen increases number of receptors during pregnancy

36
Q

what is the ferguson reflex?

A

distension of the cervix that releases maternal oxytocin in bursts with increasing frequency

37
Q

what type of feedback is exhibited during labor?

A

positive feedback

38
Q

where is relaxin produced and what does it do?

A

produced by the corpus luteum, placenta and decidua

softens and dilates the cervix (also involved in breast development)

39
Q

what happens to the uterus ost delivery?

A

involution

40
Q

describe hormonal involvement in lactation and breast feeding

A

oxytocin promotes milk letdown
prolactin promotes milk synthesis
both are released in response to suckling

41
Q

define the terms mammogenic, lactogenic, galactokinetic and galactopoietic.

A

M- promote cell proliferation
L- promote initiation of milk production
GK-promote milk ejection
GP-maintain milk production

42
Q

what type of hormone is progesterone in the breast? what does it do?

A

mammogenic

acts synergistically with estrogen to cause additional growth of breast lobules with alveoli budding

43
Q

what is the functional secretory unit of the breast?

A

the alveolus. organized into lobules that drain into a ductule

44
Q

what promotes milk letdown?

A

myoepithelial cells surround the alveolus and contract to eject milk

45
Q

what comprises the alveolus? what does it respond to?

A

secretory epithelial cells that secrete milk in response to prolactin and cortisol

46
Q

name 5 mammogenic hormones

A

estrogen, growth hormone, cortisol, prolactin, and relaxin

47
Q

name 5 lactogenic hormones and another event that promotes initiation of milk production

A

prolactin, cortisol, insulin, thyroid hormone, growth hormone and removal of estrogens and progesterone

48
Q

name two galactokinetic hormones and two galactopoetic hormones

A

GK- oxytocin and vasopressin

GP- prolactin and cortisol

49
Q

what is secreted upon initiation of lactation? what is the function?

A

colostrum

concentrated, low volume nutrition with little or no fat (more protein) and with protective antibodies

50
Q

describe the composition of breast milk

A

low protein (casein and lactalbumin), high fat emulsion containing lactose and electrolytes

51
Q

what are the main differences between cows milk and human milk?

A

cows milk has higher electrolyte concentration and significantly more casein (protein)

52
Q

what do progesterone and estrogen do for breast development and milk secretion?

A

critical for development but prevent milk secretion

53
Q

what does suckling inhibit the release of?

A

GnRH-> inhibits release of FSH and LH and preventing ovarian cycle

54
Q

what is the effect of suckling on the paraventricular nuclei of the hypothalamus? the arcuate nucleus?

A

PVN- triggers production and release of oxytocin from posterior pituitary
Arcuate- inhibits dopamine release that would inhibit prolactin release (prolactin is released)

Reproductive Physiology (6 decks)

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