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*GIGU I > 41. Fetal and Neonatal Physiology > Flashcards

41. Fetal and Neonatal Physiology Flashcards

1
Q

Gestational age

A

Day 1 is last day of normal menstrual period

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2
Q

Fertilization age (aka embryonic age or fetal age)

A

Day 1 is fertilization

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3
Q

How do you calculate gestational age using fertilization age?

A

Gestational age = fertilization age + 2 weeks

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4
Q

Prenatal hematopoeisis takes place primarily in the _____ from fetal months 1-3

A

Yolk sac

[considered primitive erythropoiesis]

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5
Q

Prenatal hematopoeisis takes place primarily in the _____ from fetal months 3-7

A

Liver

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6
Q

Prenatal hematopoeisis takes place primarily in the _____ from fetal months 7-birth

A

Bone marrow

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7
Q

After ____ weeks gestation, hematopoietic progenitors are no longer detected in the yolk sac

A

7

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8
Q

The _____ serves as the primary source of red cells from the 9th to the 24th week of gestation

A

Liver

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9
Q

Liver is primary site of _____ transcription throughout fetal life

The _______ production of this factor increases throughout fetal life

A

EPO; kidney

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10
Q

________ becomes the major site of hematopoiesis after the 24th week of gestation and remains so throughout the remainder of fetal life

A

Bone marrow

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11
Q

Major hemoglobin of fetal life

A

HbF (alpha2gamma2)

[contrast with adult HbA (alpha2beta2)]

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12
Q

Normal adult levels of ____ are achieved by ~12 weeks of life (full term)

A

HbA2

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13
Q

Hyperbilirubinemia during first 2 weeks of life (full term) = ______ jaundice

A

Physiological

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14
Q

The mean hemoglobin level in cord blood at term is 16.8 g/dL, with 95% of the values falling between 13.7 and 20.1 g/dL

What accounts for this variation?

A

This variation reflects perinatal events, particularly asphyxia and also the amount of blood transferred from the placenta to the infant after delivery

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15
Q

What iatrogenic cause appears to heighten the occurrence of anemia at 2 months and to impair cardiopulmonary adaptation

A

Early cord clamping

[delay of cord clamping may increase the blood volume and red cell mass of the infant by as much as 55%, resulting in fewer transfusions and fewer days requiring oxygen and ventilation in preterm infants]

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16
Q

The serum ____ level in cord blood of the normal infant is elevated compared to normal levels

A

Iron

[the mean serum ferritin levels in iron-sufficient infants are high at birth, 160 mcg/L, rise further during the first month, and then fall toa mean of 30 mcg/L by 1 year of age]

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17
Q

Describe the amount of iron in the marrow at birth and how this changes up to 6 months of age

A

The amount of iron in marrow at birth is small but increases in both term and premature infants during the first weeks after birth

Marrow iron begins to decrease after 2 months and is gone by 4-6 months in term infants and earlier in premature infants

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18
Q

Iron is preferentially allocated to ________ if the availability of iron is limited

A

Erythropoisis

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19
Q

When does nephrogenesis occur and when is it completed

A

Begins at 8 wks getation and completed ~36 weeks

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20
Q

When does fetal urine production begin?

A

Begins as early as 10 weeks through 20 weeks gestation

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21
Q

________ accounts for 70-80% of amniotic fluid

A

Fetal urine

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22
Q

During what trimester of pregnancy does renal function mature rapidly? When does functional development complete?

A

3rd trimester — resulting in body fluid balance, acid-base balance, and electrolyte balance

Functional development completes closer to 1 month of age

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23
Q

Describe the fetal liver handling of bilirubin, plasma proteins and coagulation factors, and gluconeogenesis

A

Poor conjugation of bilirubin

Deficiency in forming plasma proteins and coagulation factors

Deficient gluconeogenesis (blood glucose levels the 1st day could be as low as 30-40 mg/dL of plasma)

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24
Q

Since the fetal liver has lacking gluconeogenesis ability, what does the infant use for metabolism?

A

Stored fats and proteins until mother’s milk can be provided

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25
Q

Since the neonate is in a stage of rapid ossification of its bones at birth, a ready supply of _____ throughout infancy is necessary

Normally the adequate amount can be supplied by the usual diet of ________

A

Calcium

Milk

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26
Q

Absorption of calcium by the GI tract is poor in the absence of ______

_____ can develop in infants who have this deficiency

A

Vitamin D

Rickets

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27
Q

The fetus has distinct goals in terms of Ca, Phosphorus, and bone homeostasis regulation. What are they

A

Fetus must actively pump calcium, phosphorus, and magnesium from maternal circulation against concentration gradients, maintain serum mineral concentrations at higher levels than in maternal circulation, rapidly mineralize the skeleton during the final quarter of gestation, and achieve overall positive mineral balance

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28
Q

The infant’s _____ has stored enough iron to keep forming blood for ____ months after birth — provided that the mother has provided adequate iron in her diet during pregnancy

A

Liver; 6

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29
Q

Describe iron content of breast milk vs. infant formula

A

Iron content is low, but bioavailability is high

Studies show that infants exclusively breastfed for first 6 months of life have normal iron status at 6 months, provided mother has adequate iron status

Iron content of infant formula is high because bioavailability is lower than breastmilk

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30
Q

If the mother has iron insufficiency in her diet, _______ is likely to occur in infant after 3 months of life

A

Severe anemia

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31
Q

What vitamin, necessary for appropriate formation of intercellular substances, especially the bone matrix and fibers of CT, is not stored in significant quantities in fetal tissues but can be provided by breastmilk?

A

Vitamin C

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32
Q

T/F: the neonate does not form antibodies of its own to a significant extend, requiring dependence on mother

A

True

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33
Q

By the end of ____ month, there is a decrease in the baby’s gamma globulins (contain the antibodies)

A

1st

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34
Q

The baby’s own immune system begins to form Abs and gamma globulin concentration returns to normal by the age of _____

A

12-20 mos

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35
Q

Antibodies inherited from the mother protect the infant for about ____ months against most major diseases.

However, inherited antibodies against ________ are normally insufficient to protect the neonate - so they require immunization against this illness within the ~1st month of life

A

6

Whooping cough

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36
Q

T/F: other than whooping cough, immunization against most other diseases is usually not necessary before 6 months of age

A

True

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37
Q

Since most maternal-fetal iron transfer occurs in the 3rd trimester, low birth weight pre-term infants are at higher risk of what condition?

A

Iron-deficient anemia

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38
Q

Respiratory consequences of preterm birth

A

Respiration is usually underdeveloped; respiratory distress syndrome is common cause of death

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39
Q

GI consequences of premature birth

A

Poor ingestion and absorption of food

40
Q

Complications of premature birth include mmaturity of liver, kidneys, blood forming mechanism of the bone marrow, as well as depressed formation of _____ by the lymphoid system

They also struggle with instability of different homeostatic control systems.

A

Gamma globulin

41
Q

Why is the neonate particularly susceptible to stress?

A

Underdeveloped HPA axis lacks synaptic maturity in the hypothalamus and related brain centers

Neonatal glucocorticoid response (cortisol level) is blunted because GC’s are toxic to developing nervous system

42
Q

Neonatal glucocorticoid response (cortisol level) is blunted because GC’s are toxic to developing nervous system

Buffering to this response is maintained by what?

A

A consistent caregiver relationship with an adult (e.g., the mother)

43
Q

Consequences of “toxic stress” experienced by the neonate in critical period of development

A

Increased risk of psychological disorders, physiological dysregulation, and chronic pain in adulthood

44
Q

The fetal lungs develop slowly and there is no true respiration during fetal life. However, some respiratory movements will occur over the last ___-____ months of gestation

What is the purpose of inhibited respirations?

A

3-4

Inhibited respiratory development prevents lungs from filling with fluid and debris

45
Q

Small amounts of fluid are secreted into the lungs by the _____ ____ up until birth

A

Alveolar epithelium

46
Q

What occurs in weeks 4-5 of respiratory development?

A

Week 4: respiratory diverticulum forms

Week 4-5: respiratory diverticulum branches into left and right bronchial buds; stem of diverticulum will differentiate into trachea and larynx

47
Q

What happens in weeks 5-7 of respiratory development

A

Branching yields secondary bronchial buds, which represent future lung lobes

Closer to week 7, branching yields tertiary bronchial buds, which represent future bronchopulmonary segmens

48
Q

When in respiratory development do terminal bronchioles form? Is the next step after this?

A

Week 16

Week 16-36 respiratory bronchioles form, surrounding mesenchyme becomes highly vascular; first terminal sacs (primitive alveoli) form

49
Q

From week 36 to birth, ________ ____ begin to differentiate into mature alveoli. Alveoli continue to form through the ___ year

A

Terminal sacs; 8th

50
Q

Function of surfactant

A

Decreases surface tension

51
Q

Surfactant is secreted by what cell type

A

Type II alveolar epithelial cells

52
Q

When does surfactant production begin

A

Synthesis begins in last trimester

53
Q

T/F: once alveoli open, it is harder to close them when exhaling without surfactant

A

True

54
Q

Breathing initiates within seconds of birth. What are the stimuli for this?

A

Asphyxiation during birth

Sudden drop in temperature/cooling of skin

55
Q

What might cause delayed breathing upon birth?

A

Use of general anesthesia during delivery

Prolonged labor

Head trauma

56
Q

Describe the alveoli at birth

A

Alveoli are collapsed, amniotic fluid fills them

57
Q

More than _____ mm Hg negative inspiratory pressure is needed to overcome surface tension and open alveoli at birth

The 1st inspiration — infant capable of ______ mm Hg

The 1st inspiratory movements — brings in nearly ____ mL air

A

25

-60

40

58
Q

Deflation of lungs after birth requires strong _____ pressure to overcome viscous resistance of fluid in bronchioles

A

Positive

59
Q

How long after birth does breathing normalize? What is the respiratory rate at that point?

A

~40 mins

Settles into 40 breaths per minute with a tidal volume of 6-10 mL/kg

60
Q

Causes of hypoxia during delivery

A

Compression of umbilical cord

Premature separation of placenta

Excessive uterine contractions

Excessive anesthesia of the mother (depressed maternal breathing)

61
Q

T/F: Neonates have a lower tolerance for hypoxia than adults

A

False: they have higher tolerance

Adults tolerate for 4 mins while neonates tolerate for 8-10 mins

62
Q

Failure to secrete adequate amounts of surfactant resulting in collapsed alveoli and development of pulmonary edema

A

Respiratory distress syndrome

63
Q

RDS is common in premature infants and infants born to mothers with _____

A

Diabetes

64
Q

Common sign of RDS

A

Pulmonary edema

65
Q

The heart begins to beat during the ____ week after fertilization with an intial HR of ___ bpm

This increases steadily to _____ bpm pre-birth

A

4th

65

66
Q

The fetal heart does not pump much blood through the lungs or liver, but does through the ________

A

Placenta

67
Q

Four unique shunts for fetal blood flow

A
  1. Placenta
  2. Ductus venosus
  3. Foramen ovale
  4. Ductus arteriosus
68
Q

Massive blood flow to the placenta shunts blood away from what body region?

A

Lower trunk

69
Q

Describe umbilical arteries

A

Branch repeatedly

Return deoxygenated blood

Dense capillary network at terminal villi

“Legs” connect to inferior vena cava

70
Q

Describe umbilical vein

A

Returns oxygenated blood to fetus from placenta

PO2 = 30-35 mm Hg

71
Q

Blood from the umbilical vein enters the ___ ____

A

Ductus venosus

72
Q

The ductus venosus serves as the ____ bypass, since this organ is largely non-functional

Thus the ductus venosus is a direct route from umbilical vein to _____

A

Liver

IVC

73
Q

Hole in septum dividing the atria, posterior aspect of right atrium

A

Foramen ovale

74
Q

The foramen ovale is a ___ to ___ shunt

A

Right to left

75
Q

The foramen ovale bypasses what heart region

A

Right ventricle

76
Q

The foramen ovale allows blood at PO2 ~27 mm Hg (high) to pass right through to the _________ to supply the carotid arteries and brain

A

Left ventricle

77
Q

T/F: of the blood entering the right atrium, almost all is shunted through the foramen ovale

A

False - about 27% is shunted through foramen ovale, the remainder enters the right ventricle

78
Q

T/F: blood from the superior vena cava is not shunted through the foramen ovale

A

True

79
Q

Is PO2 greater in left ventricle or right ventricle in fetus?

A

Greater in left ventricle. Blood from right ventricle enters the trunk of pulmonary artery

80
Q

What serves as shunt from pulmonary artery to aorta?

A

Ductus arteriosus

81
Q

The ductus arteriosus is a ____ to ____ shunt

A

Right to left

82
Q

The ductus arteriosus is associated with a substantial amount of smooth muscle that is being dilated by _______

A

Prostaglandins (PGE2)

83
Q

Blood flow changes upon birth include ______ pulmonary vascular resistance and ______ systemic vascular resistance

A

Decreased; increased

84
Q

Describe reasoning for decreased pulmonary vascular resistance at birth

A

Lung expansion

Vasodilation due to aeration of lungs eliminating hypoxia (local prostaglandins)

Reduced pulmonary arterial pressure, right ventricular pressure, and right atrial pressure

85
Q

Describe reasoning for increased systemic vascular resistance

A

Loss of blood flow from placenta doubles systemic vascular resistance

Increases aortic pressure, left ventricular pressure, and left atrial pressure

86
Q

What causes closure of foramen ovale

A

Reversal of pressure gradient across atria which pushes foramen ovale’s “valve” shut

This is due to increased venous return to left atrium and elevated left atrial pressure, as well as reduced right atrial pressure

Eventually the flap seals

87
Q

What causes closure of ductus arteriosus?

A

Aortic pressure rises above pulmonary artery pressure — blood flows the wrong way

Now well-oxygenated aortic blood flows through the ductus arteriosus; high PO2 —> vasoconstriction within a few hours, which when coupled with falling prostaglandin levels leads to sufficient constriction within 1-8 days, and full anatomical occlusion in 1-4 months

88
Q

Closure of what 2 shunts establishes separate right and left circulatory systems?

A

Foramen ovale

Ductus arteriosus

89
Q

What causes patent foramen ovale

A

Increased right atrial pressure can push flap open

Sustained pulmonary HTN or transient increases with BM, coughing, or sneezing

[occurs in 20% of individuals by 2 years of age]

90
Q

Describe patent ductus arteriosus

A

Heart problem that occurs soon after birth

Can be heard as heart murmur with stethoscope

Oxygenated blood mixes with deoxygenated blood in pulmonary artery — puts strain on heart and increases pulmonary blood pressure

91
Q

Immediately after birth, most portal blood flows through the __________

Describe closure of this structure

A

Ductus venosus

[within 1-3 hours, the muscle wall of ductus venosus contracts and closes; portal venous pressure rises, forcing venous blood through liver sinuses]

92
Q

Neonatal HR

A

100-150 bpm (higher in premature neonate)

93
Q

Neonatal BP

A

During 1st day after birth: 70/50

After few months increases to 90/60

Adult pressure is attained during adolescence 115/70

94
Q

Neonatal respiratory rate

A

~40 breaths/min

95
Q

Neonatal metabolism

A

2x adult

96
Q

Neonatal kidneys

A

Immature — functional development is not complete until end of 1st month of life

High fluid turnover rate (rate of fluid intake and fluid excretion relative to weight is 7x greater than in adult)

Rapid acid formation — can only concentrate urine to only 1.5x osmolality of plasma (adult can concentrate urine to 3-4x plasma osmolality); problems with acidosis and dehydration

97
Q

Erythropoiesis pathway

A

Multipotent hematopoietic stem cell

Common myeloid progenitor

Proerythroblast

Basophilic erythroblast

Polychromatic erythroblast

Orthochromatic erythroblast

Polychromatic erythrocyte

Erythrocyte (RBC)

*GIGU I (67 decks)

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