ch 1

Question 1

define conception

Answer 1

first 2 wks of pregnancy

Question 2

define gestation

Answer 2

period from conception-birth

Question 3

define embryo

Answer 3

conception-8wks gestation

Question 4

define fetus

Answer 4

8 wks gestation-delivery

Question 5

define neonate

Answer 5

first 28 days or 1 month of life

Question 6

define infant

Answer 6

1-12 months`

Question 7

define pedatrics

Answer 7

0-18 years of age

Question 8

define newborn

Answer 8

recently born baby

Question 9

define preterm

Answer 9

born before 37 weeks of gestation

Question 10

define full term

Answer 10

37wk-42 wks gestation

Question 11

define post term

Answer 11

born after 42 wks

Question 12

what are the 3 requirements needed for lungs to function properly

Answer 12

1. alveoli have to possess an adequate surface area for gas exchange

2.pulmonary vascular system must have sufficient capacity to transport an adequate amount of blood through the lungs for CO2 and O2 exchange

3. the alveoli must be structurally and functionally stable and sufficient elastic and resilient to endure stretching for breathing and crying ( surfactant vital role in reducing surface tension and preventing alveoli collapse)

Question 13

how much alveoli are at birth to adulthood

Answer 13

50 mil at birth
300 mil by adult hood

Question 14

in premature babies insufficient surfactant production leads to what?

Answer 14

-neonatal respiratory distress syndrom (rds)
- requires interventions such as surfactant replacement therapy or mechanical ventilation

Question 15

what are the 5 stages of fetal lung development

Answer 15

1. embryonic (conception-6wks)
   2.pseudoglandula (wk7-16)
   3.canalicular (wk17-26)
   4.saccular (wk27-35/36)
2. alveolar (wk36-term)

Question 16

define phase: embryonic (first 2 months of gestation)

Answer 16

1.R&L lung buds arise from esophagus,trachea forms and major bronchi form
-day 21-26:endoderm–pharynx–lung bed–2 bronchial buds& trachea
-tracheosophageal septum separates the trachea

2. day 28-31
   -lobar bronchi–2 on left/3 on right
   -mesoderm–mesenchyme–pulmonary interstitium,smooth muscle, blood vessels & cartilage
3. diaphragm completes development
   -31days-7 wks: mesoderm–diaphragm forms

Question 17

what can happen if the tracheoesophageal septum doesn’t separate the trachea

Answer 17

TE fistula

Question 18

define phase: pseudoglandular (7wks-16wk)

Answer 18

1.airways continue to branch-forming framework for conducting airways
2.hard and soft palates grow
3.pulmonary vasculature develops: airways, arteries, veins
4.cilia (10 wks) and cartilage appear in lrg conducting aiways ( at end of phase)
5. lungs still incapable of gas exchange
6. 7wks: thin tissue membrane that separates nasal cavity from the oropharynx disintegrates

Question 19

what happens if the thin tissue membrane that separates the nasal cavity from the oropharynx remains at birth (fails to break down)

Answer 19

-choanal atresia (nasal airway remains blocked)–>early respiratory distress

Question 20

define the phase: canalicular (17wks-26wks)

Answer 20

-marks significant development toward lung function
1. capillary network forms (bring blood flow closer to alveolar structures)
-capillaries develop @20wks

2.airways complete branching

3.acinar(function gas units) first seen

4.immature surfactant noted (not yet sufficient to prevent alveolar collapse)
-formed by alveolar type 2 (22-24wks)

5.survival of the fetus becomes possible at 22wks-24wks gestation

6. wk 24-26 lungs are fully developed but not efficient for gas exchange

Question 21

define pneumocyte epithelial cells : type 1 & type2

Answer 21

identified @ 20-22wks gestion

-type 1: (creates necessary surface area for gas exchange) cells that line alveoli and allow O2 and CO2 to pass bw the lungs and blood. [ become alveolar capillary membrane]

type 2: (ensure alveoli remain open and function) contain layers of lipid and protein for the production of surfactant called lamellar bodies

Question 22

why is surfactant important

Answer 22

without surfactant alveoli will struggle to remain open during exhalation breathing becomes more difficult

-essential for fetal lung viability

Question 23

define the survival rates for babys based on completed weeks of gestation

Answer 23

-survival increased 3-4% per day bw 23-24wks, 2-3% perday bw 24-26wks, after 26wks rates slow down because its already higher

21 wks or less: 0%
22 wks: 0-10%
23wks:10-35%
24 wks: 40-70%
25 wks: 50-80%
26wks: 80-90%
27 wks: >90%
30wks: >95%
34 wks: >98%

Question 24

define phases : saccular and alveolar

Answer 24

saccular: wk 27-35/36
1.development of alveolar saccules ( become alveoli)
-true alveoli

2.end of structural lung formation

3. 32-34 wks: surfactant is produced in large amounts

alveolar: wk36-term
1.alveolar proliferation (increasing # of alveoli)
-50 mil alveoli developed
-alveoli continues to develop till 8years

Question 25

what are the factors affecting prenatal and postnatal growth in embryonal phase?

Answer 25

1. laryngeal, tracheal or esophageal atresia or stenosis -incomplete separation or abnormal dev of the respiratory & digestive tracts -trachea or esophagus forms improperly-->airway obstruction or swallowing

Question 26

what are the factors affecting prenatal and postnatal growth in pseudoglandular phase

Answer 26

1. pulmonary hypoplasia- incomplete development of the lungs -caused by congenital diaphragmatic hernia, low amniotic fluid level or space occupying conditions like hydrosfatalis (conditions restrict lung growth)

Question 27

what are the factors affecting prenatal and postnatal growth in the cannicular phase

Answer 27

IRDS- infant respiratory distress syndrome -immature surfactant production -most common in preterm infants before 32 wks

Question 28

what are the factors causing diminished lung growth

Answer 28

1. chest wall compression -diaphragmatic hernia -chest wall abnormalities -hydrops fetalis 2.diminished respiration -fetal does not engage in normal fetal breathing movements 3.oligohydramnios -pulmonary hypoplasia -low amniotic fluid levels -placental insufficiency -premature rupture of memebrane from fetal kidney abnormalities 4.hormonal and metabolic disorders -thyroid dysfunction -growth hormone deficiencies -metabolic syndrome

Question 29

define the conditions affecting structural development of the lungs in Utero or postnatal events

Answer 29

-growth retardation of the fetal lung: affect size and weight but not maturation of the airways and alveoli -malnutrition may slow functional rather than structural maturation : lack of nutrients, proteins, fatty acids vitamins--delay pulmonary function and increase ARDS in preterm infants

Question 30

define pulmonary hypoplasia and what it is related to

Answer 30

failure of the lungs to develop in utero -presents when decreased cells,alveoli or airways -leading to limited lung volume and poor oxygenation after birth related to: -CDH (congenital diaphragmatic hernia) -olihohyramnios -glucocorticoids -maternal diabetes

Question 31

are fetal lungs filled with air or liquid

Answer 31

fetal lungs are filled with fluid ( the canalicular phase until delivery)

Question 32

how can fetal lung development be measured?

Answer 32

sample of the amniotic fluid - L/S ratio: prediction of lung maturity -lecithin: major component of surfactant -maturity 2:1- surfactant production has reached level of sufficient enough or proper alveolar expansion after birth

Question 33

if lung development is insufficient what can we. administer

Answer 33

antenatal corticosteroid to accelerate surfactant