Lecture 18: Respiratory System

Question 1

what comprises lower resp tract

Answer 1

larynx, trachea, bronchi, and lungs

Question 2

when do lower resp organs begin to form

Answer 2

4th week

Question 3

respiratory primordium

Answer 3

median outgrowth of ventral wall of pharynx called the laryngotracheal groove

Question 4

laryngotracheal groove eventually becomes the

Answer 4

laryngotracheal tube

Question 5

laryngotracheal tube composed of

Answer 5

endoderm and splanchnic mesoderm

Question 6

endoderm of LT tube

Answer 6

gives rise to epithelium and glands of larynx, trachea, bronchi, and pulmonary epithelium

Question 7

splanchnic mesoderm of LT tube

Answer 7

connective tissue, cartilage, and smooth muscle

Question 8

functions of larynx

Answer 8

swallow, respiration, voice production

Question 9

borders of larynx

Answer 9

upper = epiglottis, lower = cricoid cartilage

Question 10

larynx communicates with

Answer 10

above: mouth and nasal cavities
below: trachea

Question 11

what does the epithelial lining develop from(in larynx)

Answer 11

endoderm of LT tube

Question 12

where does cartilage develop from (in larynx)

Answer 12

4th and 6th pharyngeal arches (come from neural crest)

Question 13

where to arytenoid swellings come from

Answer 13

mesenchyme at cranial end proliferating rapidly. causes paired swellings.

Question 14

what do the arytenoid swellings do

Answer 14

grow towards tongue converting primordial glottis into T shaped laryngeal inlet (lumen becomes narrow slit)

Question 15

when does the laryngeal lumen recanalize

Answer 15

10th week

Question 16

what is the t shaped glottis bound by

Answer 16

lateral arytenoid swellings and cranial epiglottis

Question 17

what are the vocal cords formed from

Answer 17

during recanalization, laryngeal ventricles (recesses) form. bound by mucous membranes which form vocal cords.

Question 18

what does the epiglottis do

Answer 18

covers the larynx

Question 19

what does the epiglottis develop from

Answer 19

hypobrachial eminence (muscles form from myoblast in 4th-6th arches)

Question 20

laryngeal web

Answer 20

from incomplete recanalization of larynx in week ten – partial obstruction of airway in a newborn

Question 21

what controls branching in respiratory tract

Answer 21

mesoderm

Question 22

what happens at the end of week four

Answer 22

laryngotracheal groove invaginates to form laryngotracheal diverticulum

Question 23

what do the tracheo-esophageal folds become

Answer 23

the TE septum

Question 24

what does the TE septum do

Answer 24

divides LT tube from oro-pharync and esophagus

Question 25

TE fistula

Answer 25

abnormal communication between trachea and esophagus

Question 26

what is a TE fistula caused by

Answer 26

incomplete division of foregut into resp tracht (trachea) and esophageal parts -- incomplete fusion of TE folds

Question 27

where do lung buds develop

Answer 27

caudal end of LT tube during 4th week

Question 28

lung buds become

Answer 28

bronchial bud

Question 29

how many bronchi

Answer 29

2 on L, 3 on R

Question 30

difference between R and L bronchi

Answer 30

R are larger, shorter, and more vertical | L only have two lobes

Question 31

bronchopulmonary segment

Answer 31

bronchus and mesenchyme

Question 32

how many orders of branches at week 24

Answer 32

17

Question 33

periods in lungs

Answer 33

1) pseudoglandular (5-17 weeks) 2) canalicular (16-25 weeks) 3) terminal sac (24 weeks to birth) 4) alveolar (birth to 8 years)

Question 34

pseudoglandular period

Answer 34

formation and growth of duct system, branchopulmonary segments not well developed, fetuses cannot survive

Question 35

canalicular period

Answer 35

bronchi and terminal bronchioles enlarge, highly vascular, alveolar sacs not really differentiated, respiration possible

Question 36

terminal sac period

Answer 36

epithelium very thing, contact between epi and endothelial cells permit gas exchange, type I alveolar cells line terminal saccules, proliferation of capillary netowrk, type II alveolar cells secrete surfactant

Question 37

issues with lungs prior to 26-28 weeks

Answer 37

inadequate surfactant, insufficient alveolar surface area, inadequate pulmonary vasculature

Question 38

alveolar sac

Answer 38

terminal sacs have very thin epithelial lining, alveolocapillary membrane allows gas exchange, terminal saccules = future alveolar ducts

Question 39

autonomous gas exchange requires

Answer 39

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

Question 40

when do most alveoli develop

Answer 40

95 percent post natally

Question 41

what does in utero normal lung development depend on

Answer 41

1) adequate thoracic space for lung growth 2) fetal breathing movements 3) amniotic fluid volume

Question 42

what is the preparation for respiration

Answer 42

1) fetal breathing movements (condition resp muscles, stimulate lung development) 2) at birth, lungs filled with fluid 3) birth - replacement of intra alveolar fluid with air

Question 43

pharynx connects

Answer 43

``` to larynx (which goes to trachea) the esophagus ```