Physiology and Pathophysiology Flashcards

1
Q

What are the major functions of the HPO (Hypothalamic Pituitary Ovarian) Axis?

A
  • Development of sexual characteristics
  • Coordinating regular periodic body changes (ovarian and uterine cycle)
  • Role in cervix, vagina, breast function
  • Maintenance of pregnancy
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2
Q

What is the pathway of hormones from the hypothalamus to the ovaries?

A

Hypothalamus releases GnRH –> anterior pituitary –> LH/FSH –> ovary –> estrogen and progesterone

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3
Q

How is GnRH released from the hypothalamus?

A

In pulses

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4
Q

What type of cells release LH and FSH?

A

Gonadotrope cells in the pituitary (FSH and LH then travel to ovary)

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5
Q

What does FSH and LH bind to in the ovary?

A

Theca and granulosa cells which causes folliculogenesis (maturation of the follicle)

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6
Q

In addition to folliculogenesis, what do FSH and LH stimulate production of in the ovary?

A
  • Steroid hormones: estrogens, progesterone, androgens
  • Gonadal peptides: activins, inhibins, follistatins
  • Growth factors
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7
Q

What are the functions of estrogens?

A
  • Induce surge of LH causing oocyte release
  • Encourage proliferation of endometrium, myometrium
  • Development of secondary sex characteristics
  • Libido
  • Thicken vaginal wall and increase lubrication
  • Reduce acne
  • Reduce cholesterol and atherosclerosis

Secondary sex characteristics: breast enlargement and areolar pigmentation, mature female body shape, increased scalp hair, less body hair

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8
Q

What are the roles of progesterone?

A
  • Maintenance of pregnancy
  • Decrease uterine contractility
  • Breast development and differentiation
  • Falling progesterone triggers menses and signals lactation after pregnancy
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9
Q

What is the role of activins?

A
  • Stimulate FSH secretion
  • WBC production and embryo development
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10
Q

What is the function of inhibins?

A

Inhibit FSH secretion

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11
Q

What is the role of follistatins?

A
  • Regulate gonadotropin secretion
  • Bind to and inhibits activins
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12
Q

What is the role of relaxin?

A
  • Relaxes pubic symphysis, other pelvic joints in pregnancy
  • Inhibits uterine contractions
  • May help mammary gland and follicular development and ovulation
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13
Q

What are positive feedback mechanisms associated with the normal HPO axis?

A
  • High estrogen –> increased GnRH and LH
  • Activin promotes gonadotropin cell function
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14
Q

What are negative feedback mechanisms associated with the normal HPO

A
  • Progesterone inhibits GnRH and LH
  • Inhibin inhibits FSH
  • Follistatin inhibits FSH
  • Lactation –> hyperprolactinemia causes increased dopamine and altered release of GnRH
  • Estrogen decreases LH
  • Estrogen decreases FSH
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15
Q

What are examples of pathologic HPO axis feedback?

A
  • Hypogonadism
  • PCOS
  • hyperprolactinemia
  • Medications: steroids, hormones, opioids
  • Weight status (obesity = higher estrogen)
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16
Q

What is the usual age for puberty?

A
  • 8-13 F, 9-14 M
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17
Q

What factors influence the onset of puberty?

A
  • Weight and nutritional status
  • Genetic factors
  • Abnormal hormone levels
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18
Q

What is adrenarche?

A

Increase in secretion of adrenal androgens, DHEA- prior to or at onset of puberty

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19
Q

What is thelarche?

A
  • Breast development
  • First event of puberty in females
  • Estradiol duct growth
  • Progesterone lobule and alveoli growth
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20
Q

What is pubarche?

A

Development of pubic and axillary hair, which is second event of puberty in females

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21
Q

What is menarche?

A

First menstrual cycle
Typically anovulatory for first 12-18 months

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22
Q

How long does the average menstrual cycle last? How long is the flow? What is the average blood loss?

A
  • 28 days (+/- 7 days)
  • Flow- 3-5 days
  • Average blood loss of 30 mL
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23
Q

How long are menstrual cycles irregular?

A
  • 1-2 years after menarche
  • 2-3 years preceding menopause
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24
Q

What are the 2 cycles that are part of the menstrual cycle?

A

Ovarian and uterine cycle

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25
Q

What are the phases of the ovarian cycle?

A

Follicular phase –> ovulation –> luteal phase

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26
Q

What are the phases of the uterine cycle?

A
  • Proliferative phase
  • Secretory phase
  • Menses
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27
Q

What happens during the preovulatory phase of the follicular phase of the ovarian cycle?

A
  • Rise in FSH > LH early in cycle
  • Several follicles enlarge
  • FSH causes production of inhibin B which decreases FSH release later in follicular phase
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28
Q

What is the midfollicular phase of the ovarian cycle?

A
  • Day 6
  • 1 follicule grows rapidly, becoming dominant follicle
  • Other follicles become atretic
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29
Q

What happens after the midfollicular phase of the follicular phase of the ovarian cycle?

A

Dominant follicle matures, develops LH receptors, and releases estrogens
* Rising estrogen levels –> increased GnRH pulses –> LH surge –> ovulation

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30
Q

What happens during ovulation?

A
  • About day 14
  • Mature follicle ruptures
  • Ovum is extruded into abdominal cavity and transported into oviduct
  • Ruptured follicle fills with blood (corpus hemorrhagicum)
  • Mittelschmerz may occur
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31
Q

What happens during the luteal phase of the ovarian cycle?

A
  • About 14 days post ovulation
  • Corpus luteum forms
  • If pregnancy does not occur, decline in FSH and LH –> atrophy of corpus luteum 3-4 days before menses (eventually becomes corpus albicans)
  • Declining levels of progesterone –> shedding of endometrial lining (menses)
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32
Q

What is the corpus luteum?

A
  • Granulosa and theca cells of follicle lining proliferate post ovulation in luteal phase to form yellowish, lipid-rich luteal cells
  • Reacts to LH by making progesterone and estrogen
  • Rising levels of estrogen and progesterone –> negative feedback –> decline in FSH and LH
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33
Q

What happens during the preovulatory part of the Proliferative phase of the uterine cycle?

A
  • At end of menses, all but stratum basale is sloughed
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34
Q

What happens during days 5-16 of the uterine cycle?

A
  • Estrogen from developing follicles –> endometrium regenerates from stratum basale to form stratum functionale (outer 2/3)
  • Uterine glands lengthen but do not become convoluted or secrete anything
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35
Q

How long is the postovulatory phase of the uterine cycle?

A

14 days

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36
Q

What happens during the secretory phase of the uterine cycle?

A
  • Postovulatory
  • Estrogen and progesterone from corpus luteum cause endometrium to become more vascularized and edematous
  • Glands coil and secrete clear fluid
  • Corpus luteum regresses –> estrogen and progesterone decline –> vascular spasms –> endometrial ischemia
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37
Q

What happens as the endometrium becomes ischemic during the secretory phase of the uterine cycle?

A
  • Breakdown of extracellular matrix of strata functionalis and necrosis of endometrium and supplying arterial walls
  • Causes hemorrhage which coalesces into menstrual flow
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38
Q

What happens to the cervix during the menstrual cycle?

A
  • Cervical mucus has cyclic changes
  • Estrogen and progesterone change mucus
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39
Q

What does cervical mucus do with greater quantities of estrogen?

A
  • Thinner and more alkaline to enhance survival of sperm
  • Dries in fern-like pattern

Around time of ovulation (day 14)

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40
Q

How does cervical mucus change with greater progesterone?

A
  • Mucus is more thick, tenacious, cellular
  • Thickest around day 21 and continuing if pregnancy
  • No fern pattern on slide
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41
Q

How will a slide look if a patient undergoes an anovulatory cycle with estrogen present?

A

Complete ferning (vs partial ferning with ovulation since some progesterone still present)

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42
Q

How does the cervix change during puberty?

A
  • Columnar epithelium extends from endocervix to ectocervix
  • Estrogen rises in puberty, cervical os opens to expose endocervix columnar epithelium causing squamous metaplasia during 20s-30s

Acidic environment of vagina causes metaplasia

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43
Q

What can impact cervical metaplasia?

A
  • OCP can cause persistence or reappearance of ectopy
  • Smoking accelerates metaplasia
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44
Q

Why is it important to know about cervical ectopy?

A
  • Can mimic infectious endocervicitis
  • May increase susceptibility to STIs (columnar is more vulnerable than squamous)
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45
Q

What are the changes in the fallopian tubes that occur due to hormones?

A
  • Progesterone reduces ciliary beat frequency
  • Estrogen increases ciliary beat frequency
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46
Q

What are the impacts of female hormones on muscle?

A
  • Progesterone- reduces spasms, relaxes smooth muscle, and antagonizes effects of insulin on glucose metabolism
  • Estrogen- improves skeletal muscle contractility
  • Both estrogen and progesterone may help regulate protein metabolism
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47
Q

What are impacts of ovarian hormones on skin?

A
  • Maintains skin collagen and moisture
  • Increases cutaneous wound healing and hair growth
  • Increases skin pigmentation
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48
Q

What are impacts of ovarian hormones on fat deposition?

A
  • Increase fat deposition for “pear shape”
  • Progesterone- mediator of fat gain in pregnancy
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49
Q

What are impacts of ovarian hormones on sodium/water balance?

A
  • Estrogen- sodium and water retention
  • Progesterone- sodium and water excretion
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50
Q

What are cardiovascular changes during pregnancy?

A
  • PMI shifts laterally
  • Heart size increases 12%
  • Increase in myocardial mass and intracardiac volume
  • Supine hypotensive syndrome can occur
  • Stroke volume increases
  • HR increases
  • CO increases
  • BP decreases slighly with LE venous pressure increasing
  • PVR decreases
  • Blood flow distribution increases to uterus, kidneys, breasts, and skin
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51
Q

What are signs/symptoms of supine hypotensive syndrome?

A
  • Hypotension
  • Bradycardia
  • Syncope
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52
Q

How is supine hypotensive syndrome treated?

A

R or L recumbent position

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53
Q

What could cause a greater increase in stroke volume during pregnancy?

A

Maternal position and multiple gestation

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54
Q

How much does pregnancy impact HR? What other factors can impact maternal HR?

A
  • 15 bpm more at term than nonpregnant rate, progressively increasing throughout pregnancy
  • Exercise, stress, heat, meds
  • Multiple gestation
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55
Q

What causes CO increase during pregnancy?

A
  • Hormonal changes, shunt of uteroplacental circulation
  • Transient increase during L&D
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56
Q

How does blood pressure change during pregnancy?

A
  • Arterial pressure declines slightly and returns to prepregnancy levels at 36 weeks
  • Widened pulse pressure
  • LE venous pressure progressively increases –> edema and varicosities
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57
Q

How does peripheral vascular resistance change during pregnancy?

A
  • Decreases due to enhanced vasodilators
  • At delivery 40% decrease in vascular resistance, offset by rise in CO
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58
Q

What can strenuous exercise do to blood flow distribution during pregnancy?

A

Divert blood

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59
Q

What are changes that occur in heart sounds and murmurs during pregnancy?

A

Heart sounds and murmurs: Systolic murmurs (up to 90%)
* May see split S1 or loud S3
* Murmurs or bruits at left sternal edge d/t increased blood flow through internal thoracic (maternal) artery

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60
Q

What are changes to heart rhythm during pregnancy?

A
  • Decreased threshold for reentrant SVT
  • May see sinus tachy, sinus brady, isolated PAC/PVCs
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61
Q

What are common changes to EKG during pregnancy?

A
  • Left axis shift
  • ST depression
  • T-wave flattening
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62
Q

What are respiratory anatomy changes during pregnancy?

A
  • Capillary dilation: engorged nasopharynx, larynx, trachea, bronchi–> may see prominent pulmonary vascular markings on CXR
  • Rib cage increasingly displaced upward with elevated diaphragm and increased thoracic circumference
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63
Q

What are lung volume and capacity changes in pregnancy?

A
  • Less overall lung space, but less dead space and increased tidal volume
64
Q

What are changes to respiration during pregnancy?

A
  • More diaphragm-dependent
  • Little effect on respiratory rate
  • 50% increase in minute ventilation
  • Increased arterial O2 and O2 consumption
  • Mild respiratory alkalosis
65
Q

What are anatomical renal changes during pregnancy?

A
  • Increased renal size
  • Dilated renal calyces and pelves
  • Dilated and tortuous ureters
  • Bladder- displaced upward, flattened, decreased tone (capacity increased up to 1500 mL)
66
Q

How is plasma flow changed with pregnancy?

A

Increases 50-85% –> decreased vascular resistance

67
Q

How can kidney labs change with pregnancy?

A
  • GFR increases significantly
  • Creatinine clearance increases with GFR, lower serum Cr and BUN
  • Saturation of tubular reabsorption capacity –> glucosuria and urinary protein loss (<300 mL/24 hrs)

Shouldn’t be super dramatic

68
Q

What happens to renin during pregnancy?

A

Renin activity increases but doesn’t cause pressor effects

Increases renal blood flow (1st step in RAAS), aldosterone helps retain water and sodium to increase blood flow

69
Q

What are changes to the GI system during pregnancy?

A
  • Stomach pushes upward
  • Bowels pushed up and laterally
  • Gum hypertrophy and hyperemia
  • Increased salivation
  • Intestinal transit time decreases in 2nd and 3rd trimesters
  • Gallbladder emptying slows and is often incomplete
  • Reflux/heartburn more common
  • Decreased gastric emptying
  • Mild decrease in protein, esp. albumin
  • Increased serum alkaline phosphatase
70
Q

Why does reflux/heartburn occur more commonly in pregnancy?

A

Greater production of gastrin, decreased esophageal peristalsis, hormone-mediated relaxation of LES

71
Q

What happens to blood volume during pregnancy? Why?

A
  • 50% elevation in plasma volume
  • Increased estrogen –> stimulates RAAS –> increased aldosterone –> Na+ reabsorption –> water retention
72
Q

What are functions of maternal hypervolemia?

A
  • Meets increased metabolic demands
  • Protects from effects of impaired venous return with postural changes
  • Compensates for maternal blood loss at delivery
73
Q

What are hem/onc changes during pregnancy?

A
  • RBC increase by 33%
  • Physiologic anemia (iron deficiency d/t enhanced erythropoeiesis)
  • WBC increase
  • Platelet increase in production and consumption –> overall decrease as pregnancy progresses
  • Increase in clotting factors, decrease in protein S and fibrinolytic activity –> procoagulant
74
Q

What happens to immunologic function during pregnancy?

A

Overall slightly decreased –> predisposed to infections

autoimmune disease generally gets better

75
Q

What are endocrine changes during pregnancy?

A
  • Enlarged pituitary gland
  • Increased growth hormone
  • Increased prolactin (10x)
  • Increase in thyroid hormone production
  • TSH naturally drops
  • Decreased PTH 1st trimester, increased 2nd and 3rd
  • Decreased calcium
  • Increased vitamin D
  • Increased ACTH and free cortisol
  • Increased aldosterone
76
Q

Why is there such a significant increase in thyroid hormone production during pregnancy?

A

Fetus is dependent on maternal thyroid in 1st trimester

77
Q

Why would TSH naturally drop during pregnancy? Why can this be confusing?

A
  • hCG structurally similar to TSH
  • May be mistaken for subclinical hyperthyroidism
  • Low TSH can mask hypothyroidism during pregnancy

Cretinism can occur in untreated hypothyroidism

78
Q
A
79
Q

Why is calcium decreased during pregnancy?

A

Increased plasma volume, increased GFR, fetal transfer, lower albumin

80
Q

What is the function of increased ACTH and free cortisol in pregnancy?

A

May help maintain homeostasis with elevated plasma volume

81
Q

What is the function of increased aldosterone in pregnancy?

A

RAAS activity can protect against natriuresis

82
Q

What are ophthalmologic changes during pregnancy?

A
  • Decreased intraocular pressure
  • Decreased sensitivity and increased thickness of cornea
  • Krukenberg spindles: brownish-red opacity on posterior cornea
  • May see transient loss of accommodation (blurry vision)
  • Visual function essentially normal
83
Q

What are skin changes that occur during pregnancy?

A
  • Hyperpigmentation of linea nigra and malasma
  • Striae gravidarum (stretch marks)
  • Spider angiomas
  • Palmar erythema
  • Cutis marmorata
  • Varicosities
  • Brittle nails with horizontal grooves (Beau’s lines)
  • Thickened and increased hair
84
Q

What is melasma?

A
  • Uneven darkening in centrofacial-malar area that is exacerbated by sun exposure
  • “mask of pregnancy”
  • Also seen in women on OCPs
85
Q

What is striae gravidarum?

A
  • Stretch marks
  • Decreased collagen adhesiveness and increased ground substance formation
  • Usually on abdomen, breasts, thighs, buttocks
  • Begin in 2nd trimester
  • Increased risk with genetic predisposition, weight gain, young maternal age
86
Q

Who more commonly gets spider angiomas? Palmar erythema?

A
  • spider angiomas: white women (2/3) (10% black women)
  • Palmar erythema: white women (2/3) (1/3 of black women)
87
Q

What is cutis marmorata?

A

Mottled appearance to skin secondary to vasomotor instability

88
Q

Where are varicosities commonly seen in pregnancy?

A
  • Legs, anus, vulva (waist down due to compression)
89
Q

What are maternal changes to appetite/thirst and desire to rest?

A

Increased desire to rest, appetite, and thirst (also with breastfeeding)

90
Q

What are changes to weight and fat metabolism during pregnancy?

A
  • Increased weight (average 27.5 lbs)
  • Loss of 12 lb at delivery, 9 lb in next 2 weeks, remainder lost gradually or not at all with greater loss in breastfeeding women
  • Total body fat increase during pregnancy
  • Plasma lipids increase
91
Q

What are changes to water metabolism and carbohydrate metabolism during pregnancy?

A
  • Increased water retention –> often demonstrable pitting edema in LE
  • Mild fasting hypoglycemia
  • Postprandial hyperglycemia
  • Hyperinsulinemia and insulin resistance
  • Glucose metabolism changes disappear after delivery
92
Q

What are changes to protein metabolism during pregnancy?

A
  • Protein –> 1 kg of weight gain with 500 g fetus and placenta and 500 g uterine contractile protein, breast glandular tissue, plasma protein, and hemoglobin
93
Q

What are changes to electrolyte and mineral metabolism during pregnancy?

A
  • Sodium and potassium is slightly decreased
  • Increased retention of sodium and potassium but diluted due to increased plasma volume
  • Calcium and magnesium: decreased
  • Phosphate: little change
  • Iron: decreased, need supplemental iron for normal pregnancy; fetal RBC production not impaired
94
Q

What is the recommended weight gain for a patient with a normal BMI during pregnancy?

A
  • 25-35 lb
95
Q

What are dietary recommendations during pregnancy?

A
  • Balanced diet
  • Special need for iron, folic acid, calcium and zinc
  • 2300 kcal/day for avg 127 lb (58 kg) woman
  • additional 300 kcal/d during pregnancy
  • additional 500 kcal/d during lactation
96
Q

What are recommendations for protein intake during pregnancy?

A
  • 1 g/kg/day, plus 20 g/d in 2nd half of pregnancy
  • 60-80 g/d in the average woman
  • Lean animal, low-fat dairy, vegetable protein

Crucial for embryonic development

97
Q

What are recommendations for calcium during pregnancy?

A
  • 1200 mg/d during pregnancy and lactation
  • If <600 mg/d maternal skeletal demineralization can occur
98
Q

What are recommendations for iron during pregnancy?

A
  • Adequate intake of iron-rich foods
  • Supplement 30-60 mg/day during 2nd/3rd trimester
  • Iron deficiency anemia 60-120 mg/day
99
Q

What are recommendations for folic acid during pregnancy?

A
  • At least .4 mg/day for 1 month prior to conception and through 1st 3 months of pregnancy
  • 1 mg/d insulin dependent DM or taking valproic acid or carbamazepine - increase risk for NTD
  • 4 mg/d if + hx of NTD

Reduces risk of neural tube defects

100
Q

What supplements can be given to specific pregnant patients?

A
  • B12: vegetarians, hx megaloblastic anemia
  • B6: risk for inadequate nutrition
101
Q

How much vitamin C should a pregnant patient get per day?

A

80-85 mg/day
* typically can get through diet

102
Q

How much zinc is suggested during pregnancy?

A
  • No set recommended level, suggestion for 12 mg/d
103
Q

How much iodine is recommended during pregnancy?

A
  • Can get through diet via iodized salt
  • Pregnancy: 220 mcg/day
  • Lactation 290 mcg/day
104
Q

What could be a problem with oversupplementation of iodine in pregnancy?

A

Thyroid disease

105
Q

What are functions of the placenta?

A
  • Release hormone and enzymes to maternal bloodstream
  • Transport of fetal nutrients and metabolic products
  • Exchange of O2 and CO2 for fetal circulation
  • Fetal in origin but relies on maternal blood
106
Q

What are circulatory functions of the placenta?

A
  • Transport blood to uterus (500-700 mL/min) with 85% to divisions of the placenta
107
Q

How is arterial bleeding controlled?

A

Uterine contraction

108
Q

What is the function of placental secretions?

A
  • Control intrauterine growth, maturation of vital organs, and childbirth -7 weeks - term
  • Includes hCG, placental proteins, steroids (DHEAs and estriol)
109
Q

What is the function of placental transport?

A
  • High metabolism - consumes oxygen and glucose faster than fetus
  • Oxygen and nutrient transport to fetus
  • CO2, urea, and catabolites to mother
  • Very few drugs cross placental, especially large size or chage (heparin, insulin)
  • Albumin-bound drugs are more likely to cross due to higher unbound concentrations and higher placental gradient (ie warfarin, salicylates)
110
Q

What happens during weeks 1-4 of gestation?

A
  • Conception via sperm entering egg
  • Formation of zygote
  • Zygote divids to form ball of cells called morula
  • Enters uterus 3-5 days post fertilization
  • Accumulation of fluid in cells of morula –> blastocyst
  • Days 6-7 blastocyst implants and invades endometrium and myometrium
  • Day 10 blastocyst encased in endometrium
  • Outer cell group- chorionic villi become placenta
  • Inner cell group- becomes major cell lines that eventually create tissues
111
Q

What does the inner cell group of the blastocyst become? Outer cell group?

A

Inner –> embryo
Outer–> supportive tissues

112
Q

What is the endoderm and what does it become?

A
  • Innermost layer
  • Epithelial lining of multiple systems
  • GI, respiratory, endocrine, auditory, urinary
113
Q

What is the mesoderm and what does it become?

A
  • Middle layer
  • Connective tissue-pericardium, peritoneum, pleura
  • Muscle tissue, bone, most of circulatory and GU systems
114
Q

What is the ectoderm and what does it become?

A
  • Outermost layer
  • Skin-epidermis, sweat glands, hair, nails
  • Tooth enamel
  • “outer” epithelium- lining of mouth, nostrils, anus
  • Nervous system
115
Q

What happens during week 5 of gestation?

A
  • Development of brain, spinal cord, heart, and GI tract begins
116
Q

What happens during weeks 6-7 of gestation?

A
  • Development of eyes, ears, some bones begins
  • Limb buds and some cranial nerves visible
  • Brain divides into 5 areas
  • Heart begins to beat at regular rhythm: rudimentary blood in main vessels
117
Q

What happens during week 8 of gestation?

A
  • Lung development begins
  • Limbs lengthen, with foot/hand areas and early digits
  • Brain continues to develop
118
Q

What happens during week 9 of gestation?

A
  • All essential organs have begun to form
  • Nipples, hair follicles, elbows, toes develop
119
Q

What happens during week 10 of gestation?

A
  • Eyelids, external ear, facial features continue developing
  • Intestines rotate and swallowing begins
  • FHT (fetal heart tones) audible by doppler US
  • End of embryonic period
120
Q

What happens during weeks 11-14 of gestation?

A
  • Further refinement of face, limbs and genitals
  • Ability to distinguish genitalia on US
  • Fetus can make a fist with its fingers
  • RBC produced in liver
  • Urine produced and put into amniotic fluid
  • Centers of ossification in most fetal bones
121
Q

What happens during weeks 15-18 of gestation?

A
  • Fine hair called lanugo develops
  • More bone and muscle tissue develop
  • Active movements, including sucking
  • Meconium produced in intestinal tract
  • Fat begins to accumulate
122
Q

What happens during weeks 19-21 of gestation?

A
  • Fetus capable of hearing
  • Vernix caseosa covers body
  • Fetus moves every minute and begins to swallow
  • Mother may begin feeling fluttering fetal movement
  • Week 20 is midpoint of pregnancy
123
Q

What happens during week 22 of gestation?

A
  • Lanugo hair covers body
  • Fetal heartbeat can be perceived with fetoscope
124
Q

What happens during weeks 23-25 of gestation?

A
  • Bone marrow begins to make blood cells
  • Fingerprints and footprints form
  • Fetus is regularly sleeping and waking
  • Fetus may respond to sounds
125
Q

What does fetal survivability look like in week 23, 25, and 26+?

A

23: 20-35%
25: 50-75%
26+: up to 90%

126
Q

What happens during week 26 of gestation?

A
  • Fetus has hand and startle reflex
  • Alveoli form in lungs
127
Q

What happens during weeks 27-30 of gestation?

A
  • Rapid brain development, enough to control some body functions
  • Eyelids open and close
  • Surfactant begins to be produced
128
Q

What happens during weeks 31-34 of gestation?

A
  • Rapid increase in body far
  • Bones fully developed but still soft and pliable
  • Fetus begins storing iron, calcium and phosphorus
129
Q

What happens during weeks 35-38 of gestation?

A
  • Lanugo begins to disappear
  • Body fat continues to increase
130
Q

What happens during weeks 39-42 of gestation

A
  • Lanugo gone except for upper arms and shoulders
  • Small breast buds present on both sexes
131
Q

What is one of the systems with the highest rate of malformation?

A

GU tract

132
Q

What is needed for the male GU tract?

A

Functional Y chromosome

133
Q

What germ layer does most of the GU tract develop out of?

A

Intermediate mesoderm

134
Q

When do the major GU structures develop?

A

Weeks 4-8

Including urogenital ridge and urogenital sinus, most likely to develop major anomalies at this time

135
Q

What is the path of reproductive development?

A

Genetic –> gonadal –> ductal –> genital

136
Q

How is genetic development of reproductive system determined?

A

at fertilization by sex hormones

137
Q

How does gonadal tissue develop in males?

A
  • Genetic sex expressed
  • Begins week 8
  • Sex-determining region of Y chromosome encodes for testis-determining factor
  • TDF–> gonad differentiates into a testis with production of antimullerian hormone and testosterone
138
Q

What happens during ductal development of male?

A
  • Initially both male wolffian (mesonephric) ducts and female mullerian (paramesonephric) ducts exist in embryo
  • Antimullerian hormone suppresses female mullerian ducts
  • Testosterone encourages persistence and differentiation of male wolffian ducts
139
Q

What happens during genital development of the reproductive system?

A

Wolffian or mullerian ducts develop into distinct sex-specific genitalia

140
Q

What is agenesis?

A

Gonad did not form at all

141
Q

What is agonadism?

A

Gonads formed initially and later degenerated

142
Q

What happens with streak gonads?

A

Primordial gonadal formation
* No differentiation –> lacks germ cells
* May have release of antimullerian hormone without testosterone –> suppresses both ducts
* May see ectopic gonadal tissue

143
Q

What is a cloaca?

A

Precursor of urogenital structures

144
Q

What happens during weeks 5-7 to the cloaca?

A
  • Urorectal septum divides cloaca into urogenital sinus and anorectal canal
  • Male: becomes urinary bladder, urethra, and penis
  • Female: becomes urinary bladder, urethra, and vagina
145
Q

What is vaginal agenesis?

A

vagina does not form

146
Q

What is vaginal atresia?

A

lower portion is only fibrous tissue

147
Q

What is vaginal septa?

A

Vagina has a transverse or longitudinal septum
May have imperforate hymen

148
Q

What are conditions that can arise from abnormal vaginal development?

A
  • Vaginal agenesis
  • Vaginal atresia
  • Vaginal septa
  • Rectovaginal fistula
149
Q

What do the wolffian/mesonephric ducts become in males?

A
  • Epididymis, ductus deferens, ejaculatory ducts
  • Vestigial remnant- appendix epididymis
  • Requires presence of gonads to develop
150
Q

What happens to the mullerian/paramesonephric ducts in males?

A
  • Regress under hormonal influence
  • May persist as appendix testis
151
Q

What is the process of relocation in male sex development?

A
  • 28th week: testes descend through inguinal canal
  • 32nd week: testes in scrotum
152
Q

What happens to the wolffian/mesonephric ducts in female sex development?

A
  • Mostly regress
  • Small portion becomes trigone of bladder
153
Q

What happens to the mullerian/paramesonephric ducts during female sex development?

A
  • Midline fusion –> uterus
  • Distal ducts –> oviducts
  • Does not descend in abdomen
  • Can have complete or partial absence of uterine tube or problems with fusion
154
Q

What abnormalities can occur during development impacting the labia majoria/minora?

A
  • Fusion –> tissue separation failure or inflammatory reaction
  • May be hypertrophic or hypoplastic
155
Q

What abnormalities can occur to the clitoris during development?

A
  • Agenesis: atresia or lack of genital tubercule formation
  • Bifid/double: failure of fusion
  • Hypertrophy: in intersex disorders
156
Q

What abnormalities of the perineum can occur in male/female?

A
  • Imperforate anus
  • Anal stenosis
  • Anal agenesis with fistular ectopic anus