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Physio II Exam 3 > Fetal and Neonatal Physiology > Flashcards

Fetal and Neonatal Physiology Flashcards

1
Q

Prenatal Development

A 
Growth of a fertilized egg between conception and birth.  
Three stages: 
•Germinal Period 
•Embryonic Period 
•Fetal Period 
Full term gestation typically 266 days. 
Neonatal period: •Birth to 28 days
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2
Q

Fetal Development

A

Definition: Time from 9th week of gestation to birth. Birth ends the fetal period.

Prior to this is the Embryonic period.

Fetal period:
•30-week period of development
•Continual cell growth and differentiation
•Fetus length will grow from 10cm to 53 cm in 20 weeks
•Weighs only 1 pound at 23 weeks gestation, but gains significant weight in last 2 months.
•Organs developed by 4 months gestation, but cellular maturity (function) is not complete until after birth

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3
Q

Fetal Circulation

A
  • Placental blood preferentially delivered to heart, upper torso and brain
  • Lower oxygenated blood shunted to lower body
  • Fetal circulation runs in parallel – left ventricle provides 35% of cardiac output; right ventricle 65%.
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4
Q

Heart

A
  • Myocytes start beating before fusion of the tubes.
  • The beats begin in the final region of the pacemaker.
  • Ventricle also acts as pacemaker.
  • Eventually contraction matches mothers.
  • At 5 wks heart beats 3.3/day
  • At 9 weeks beats about 80-85bpm
  • Keeps increasing to 195 bpm
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5
Q

Resistance in lungs is very ___ and it has limited metabolic needs because ___.

A

Resistance in lungs is very high and it has limited metabolic needs because the lungs are not functioning. •Blood just passes through. •Same is true of liver.

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6
Q

what do the umbilical arteries do?

A

carry low-oxygen blood and fecal waste

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7
Q

Fetal Circulation

A

Blood from placenta through umbilical vein bypasses the liver
>Enters the right atrium
>Goes through the foramen ovale to left atrium
>Oxygenated blood pumped to brain and upper extremities
>Blood from superior vena cava go into right atrium to right ventricle and pumped through ductus arteriosus to descending aorta

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8
Q

Blood Formation

A
  • Iron is concentrated in the mother’s endometrium
  • This iron is ingested into the embryo by trophoblastic cells and used to form early red blood cells
  • 3rdweek after fertilization, iron is bound as hemoglobin
  • Later iron accumulates rapidly in the fetus, most of it stored in the liver, to be used after birth to make hemoglobin
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9
Q

Pulmonary Circulation

A
  • Initially high resistance in pulmonary artery pressure
  • Pressure drops with increase in systemic vascular resistance
  • Fetal circulation runs in parallel: left ventricle provides 35% of cardiac output; right ventricle 65%.
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10
Q

Surfactant

A
  • Starts to be produced in last 3 months of gestation
  • Category of compounds that reduce surface tension.
  • Lipoprotein complex with hydrophilic and hydrophobic regions
  • Produced by type II alveolar cells
  • Increases pulmonary compliance, preventing collapse of alveoli at end of expiration
  • Prevents build up of fluid in alveoli
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11
Q

Fetal Metabolism

A
  • primarily uses glucose
  • stores fat and protein
  • most vitamins stored in liver
  • -B12/folic acid= form RBC and nervous sys
  • -C= bone matric and conn tissue
  • -D= bone growth
  • -E= early embryonic dev
  • -K=fetal liver, clotting factors
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12
Q

Nervous system

A

Week 10: brain is present
Activity-independent mechanisms: •Genetically programmed to differentiate from stem cells, migrate and create axons that reach the target
Activity dependent mechanisms: •After reaching target, synapse formation is dependent on activity, modifications of the synapses

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13
Q

Motor

A
  • Fetus moves, but movements are jerky and not controlled.
  • Weeks 16-20: limb movement is more powerful and mother may feel fetal movements
  • Mostly arms crossed and legs bent at knees
  • Most movement is reflexive
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14
Q

Sensory

A
  • Wk16: Able to swallow several ounces of amniotic fluid/day
  • Wk18: nerves become covered with myelin (not complete until year 1)
  • Wk24: Blinking
  • Wk26:Brain develops rapidly •Nervous system develops some control of organs •Cochleae developed •Brain forms smooth surface with grooves and indentations •Cerebellum developing very fast
  • Wk31: Thalamic brain connections develop
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15
Q

Weeks 9-12

A
  • Ossification of bone
  • Fingers and toes begin to develop
  • Eyelashes appear
  • Amniotic fluid is swallowed and urinated
  • In males testes descend
  • Intestines accumulate tarry, greenish black meconium (sterile)
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16
Q

Weeks 13-16

A
  • Sensory organ development
  • Eyes move closer together
  • Mouth makes sucking motions
  • Ears move upward
  • Scalp begins to grow hair
  • Kidneys are formed
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17
Q

Weeks 16-20

A
  • Skin is coated with waxy protective substance, vernix caseosa
  • Silky hair covers all skin as lubricant
18
Q

Weeks 21-31

A
  • Eye lids are no longer fused
  • Bone Marrow synthesizes erythrocytes
  • Eyelashes appear
  • Lungs produce surfactant (reduces tension in lungs)
  • Finger and toe nails begin to develop
19
Q

Invasive Prenatal Screening

A

Amniocentesis, etc

  • Used for genetic assessment
  • Amniocentesis -only between 14 -20 weeks gestation
  • Chorionic villus sampling (Placenta sample) between 9.5 and 12.5 weeks gestation
  • Chorionic villus associated with more risk to the fetus
20
Q

Non-Invasive Prenatal Screening

A

Ultrasound- anatomy

Blood tests
•Some trisomies can be picked up by detecting fetal DNA in maternal blood
•If abnormalities picked up, then invasive procedures used to confirm

21
Q

Teratogens

A

Compounds that can permanently deform the function or structure of a developing embryo or fetus.
•Thalidomide, anti-nausea sedative
•Severe limb defects in babies born in 1960s.
•Most common is due to smoking -growth retardation, abruption of placenta
•Fetal alcohol syndrome (FAS) (1% of all births)

22
Q

Fetal Alcohol Syndrome

A
  • Flattened and thin upper lip, epicanthal folds, flattened nasal bridge, short nose.
  • Can have microcephaly, mental retardation and learning disabilities.
23
Q

Effects of Cocaine on Fetus

A

produces growth restriction, preterm delivery, microcephaly, limb anomalies, CNS abnormalities

24
Q

Effects of ACE Inhibitors on Fetus

A

cause fetal renal failure and pulmonary hypoplasia

25
Q

Full Gestation

A

37-42 weeks

26
Q

Premature

A

born before 37 weeks

27
Q

Neonate

A

first 28 days of life

28
Q

Low Birth Weight

A

less that 1000 gm at birth

at risk of: Hypothermia, respiratory distress, hyperbilirubinemia, electrolyte imbalance, infections and feeding problems

29
Q

What is the single most important event immediately after birth

A

the first breath, development of respiratory system

Stimulus in normal delivery
•Hypoxia
•Cold air

With delayed breath greater hypoxia and hypercapnia

30
Q

At birth the alveoli are ___. Firsts breaths must be very strong in order to open them for the first time. Surfactant is produced in the lungs at __ weeks. Drugs can be given the mother to improve neonate lung function. Alveolar development continues through age __.

A

collapsed

24

5

31
Q

Delayed or abnormal breathing at birth

A

28

32
Q

Failure to breath

A
  • If 4 min or greater –death of neonate
  • If they survive, will have serious and permanent brain damage
  • Cerebral Palsy
  • The portion of brain that appears to be most affected is thalamus
  • Loss of motor control
33
Q

Respiratory Distress

A
  • Most common in prematurity and mothers with diabetes
  • Develops in first hours to days after birth
  • Failure to produce enough surfactant
  • Alveoli fill with high protein fluid
34
Q

Compare liver blood flow before and after birth

A
  • Prior to birth, liver had little blood flow, but immediately after birth blood flow increases.
  • Loss of placental blood flow
  • Pulmonary vascular resistance decreases associated with taking the first breath.
  • Subsequently decreases pulmonary arterial pressure, right ventricular pressure and right atrial pressure
35
Q

Describe the closure of foramen ovale

A

Changes in pressure between left and right atria causes blood to flow backward through foramen ovale (left to right).
Valve associated with the foramen ovale now closes.
2/3 of all people will have permanent closure within months to years.
Rest have patent foramen ovale, but valve should function to stop back flow.

36
Q

Jaundice

A
  • Bilirubin formed by the fetus passes the placenta into the mother to be excreted through the mother’s liver.
  • After birth, the neonates own liver must work.
  • Plasma bilirubin rises 5 times the first 3 days of life and slowly return to normal as liver functions.
  • Typically treated with sunlight
37
Q

Hyperbilirubinemia

A

There can be intrinsic causes of excessive bilirubin
•Enzyme conditions
•Sickle cell

Extrinsic
•Sepsis
•Rh incompatibility

38
Q

Most severe cases –Kernicterus

A

Severe CNS injury

39
Q

Apgar Scores

A

Appearance, Pulse, Grimace, Activity, Respiratory (0-2 in each category for total 10)

  • Given at 1 and 5 min after birth.
  • Score 4-5 –low
  • 3 and below are critical
  • Below 3 at 10-30 minutes associated with long-term neurological damage
  • Score of 10 almost never seen, due to normal early cyanosis
40
Q

Neonatal Metabolism

A
  • Before birth glucose comes from mother
  • Stored glucose lasts only a few hours
  • Liver still too immature for gluconeogenesis
  • Mother’s milk not fully developed
  • Blood glucose falls to 30-40 mg/dL
  • Begins using stored protein and fat for next few days –> Body weight will drop by up to 20%

Physio II Exam 3 (9 decks)

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