Lecture 18: Embryonic Respiratory System Flashcards Preview

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Flashcards in Lecture 18: Embryonic Respiratory System Deck (51):
1

lower respiratory tract consists of

epiglottis, larynx, trachea, left and right lung, pulmonary blood vessels, heart, upper lobes, middle lobe (r), lower lobes

2

when/where laryngothracheal groove forms

week 4
lower/back part of throat, connects w/ surface ectoderm of mouth

3

respiratory primordium is

laryngotracheal groove; median outgrowth of ventral wall of pharynx

4

respiratory diverticulum

bud outpouching of tissue of ventral wall of foregut, will form 2 lungs

5

laryngotracheal tube tissue layers

endoderm, sphlancnic mesoderm

6

endoderm of laryngotracheal tube becomes

epithelium and glands of larynx, trachea, bronchi, and pulmonary epithelium

7

sphlancnic mesoderm of laryngotracheal tube becomes

connective tissue, cartilage, and smooth muscle

8

larynx functions

communicates with mouth/nasal cavities for swallowing, respiration, voice production

9

larynx borders

upper: epiglottis
lower: cricoid cartilage

10

artenoid swellings

cranial end of L-T tube; are 4th and 6th pharyngeal arches mesenchyme that proliferate

11

laryngeal inlet

T-shaped region of mesenchymal tissue formed by meeting of artenoid swellings; temporarily occludes respiratory tract before recanalizing

12

vocal cord formation

after recanalization of larynx, laryngeal ventricles/cartilages become vocal cords

13

epiglottis function

covers the larynx so food doesn't get into the lungs

14

epiglottis derivation

caudal hypobranchial eminence 4th-6th arch myloblasts

15

laryngeal web

non-lethal anomaly, occurs when recanalization of larynx isn't complete (week 10) and get partial obstruction of newborn's airway

16

trachea derivation

lung buds that separate from foregut become trachea and 2 bronchial buds

17

laryngothracheal (L-T) diverticlum timing

end of week 4

18

tissue layers of L-T tube

mesoderm, endoderm

19

where long bud forms

distal end of L-T diverticulum

20

T-E folds become

T-E septum

21

number of lobes of each lung

Left: 2; Right:: 3

22

what T-E septum separates

laryngotrachel tube from oro-pharynx, esophagus

23

T-E fistula is

when T-E folds don't completely separate the trachea and esophagus, get abnormal communication between trachea and esophagus

24

most common anomaly of lower respiratory tract

T-E fistula; 85% associated with esophegeal atresia

25

incidence of T-E fistula

1/3000-1/4500 live births; male>females; 85% associated w/ esophageal atresia

26

what surrounds alveoli/why

capillaries; take in oxygen

27

where lungs form

within pericardioperotneal canals (2)

28

1st branch off trachea on each side

primary bronchus

29

branches of primary bronchus

secondary bronchi; 2 on L, 3 on R

30

characteristics of right secondary bronchi

larger, shorter, more vertically oriented

3 secondary bronchi

more likely to get something stuck in bronchi because of verticality

31

characteristics of left secondary bronchi

2 secondary bronchi with 2 lobes

more horizontal orientation

32

number of orders of branching of bronchi by 24 weeks

17 orders

33

bronchopulmonary segment made of

bronchus + mesenchyme

34

lung maturation stages

1. pseudoglandular pd

2. canalicular pd

3. terminal sac pd

4. alveolar pd

35

pseoduglandular period

1st period of lung development, 6-16 weeks

formation and growth of duct systems

bronchopulmonary segments not well developed

fetuses can's surive

inefficient/impossible oxygen exchange

36

canalicular period

16-25 weeks (2nd pd of lung development)

bronchi and terminal bronchioles enlarge, encompass capillaries

highly vascular

alveolar sacs not truly differentiated

respiration possible

37

terminal sac period

26 weeks to birth

capillaries bulge into alveoli

epithelium very thin so no intervening mesoderm for oxygen to get across

contact between epithelial and endothelial cells permit gas exchange

type II alveolar cells secrete surfactant

38

function of surfactant

from type II alveolar cells

form monomolecular fil over internal walls of terminal saccules

lower surface tension

reaches adequate levels in late fetal period

39

respiratory distress syndrome

babies born prior to 26-8 weeks; due to lack of surfactant, insufficient alveolar surface area, inadequate pulmonary vasculature

40

alveolar period

gestation/birth to 8 years old

capillaries are immediately adjacent to alveoli- gas exchange easy

terminal saccules will be future alveolar ducts

41

percentage of alveoli formed after birth

95%

42

what autonomous gas exchange requires (in alveolar pd)

surfactant
transformation of lungs to a gas exchanging organ
est of parallel pulmonary and systemic circulations

43

what increases after birth re: lungs

surface area of air-blood barrier, via growth of alveoli and capillaries

44

number of capillaries from birth to age 8

50 million to 300 million

45

chest xray of newborn infant vs adult

will be dense

46

how does fetus prepare for breathing

fetal breathing movements that condition respiratory muscles, stimulate lung development

47

at birth, what exchanges re: lungs?

intra-alveolar fluid exchanges with air

48

what in-utero normal lung development depends on

adequate thoracic space for lung growth, fetal breathing movements, amniotic fluid volume

49

why amniotic fluid matters for lung development

keeps muscles of uterus from collapsing on baby's lungs/chest

50

respiratory distress syndrome

caused by lack of surfactant production, so alveoli don't inflate properly

occurs in 2% live newborns

treat with berthamethasone, a steroid mother takes that causes fetal lung cells to make surfactant

51

what causes esophageal atresia with a TE fistula

incomplete fusion of T-E folds