w7- lung devo

Question 1

if the ventral wall fails to fuse, what connection will be maintained and what condition would this result in

Answer 1

connection between the intra and extra-embryonic coelom

would result in ectopic cordis

Question 2

what does the septum transversum form

where is it derived from

Answer 2

central tendon and the connective tissue of the liver

derived from visceral so the splachnic mesoderm of the lateral plate

Question 4

what divides the:

coleum

the thoracic and the peritoneal cavity

pericardial and the pleural cavity of the thoracic

the pleural and the peritoneal cavity

Answer 4

septum transversum

pericardoperitoneal canal

pleuropericardial membrane

diaphram

Question 5

what forms the fibrous pericardium

Answer 5

pleuropericardial membranes

Question 6

what 4 structures make the diaphragm

what condition can occur if it does not fuse properly

Answer 6

(1) septum transversum, (2) esophageal mesentery, (3) pleuroperitoneal membranes, and (4) muscle

the pleuroperitoneal membranes are overlayed by central musculature of diaphragm from C3-5

body wall mesenchye forms the peripheral musculature innervated by T7-T12

congenital diaphragmatic hernia (CDH).

Question 7

what are the three places that hernias form in CDH

what is CDH often associated with

Answer 7

sternal, esophageal, and posterior regions

posterior are most common

esophageal hiatus–> stomach in pleural cavity

left pleuropericardial membrane –> intestines in pleural cavity

pulmonary hypoplasia

Question 8

where does the respiratory diverticulum derive from

how is it seperated from the foregut

what happens if this fails

Answer 8

Respiratory diverticulum pouches off of foregut endoderm from floor of primordial pharynx

tracheoesophageal ridges –> This septum results in the formation and separation of the esophagus and the laryngotracheal tube

TE fistula

Question 9

what other conditions is TEF often associated with

Answer 9

VATER

vertebral defects

anal atresia

TEF

renal dysplasia

Question 10

what is the psuedoglanular phase characterized by

Answer 10

formation and growth of the respiratory conducting zone , resulting in the formation of terminal bronchioles within the bronchopulmonary segments

Question 11

what is the earliest stage life is viable

Answer 11

the canalicular after 20 weeks when surfactant production begins

Question 12

what occurs in the cannalicular phase

Answer 12

formation of vascular beds. (VEGF), respiratory bronchioles and terminal sacs (primitive alveoli), and surfactant

•Lung epithelium differentiatesinto specialized cells types.

Question 13

when are type I and II pneumocytes fully differentiated

Answer 13

saccular stage

surfactant low until 24 weeks

Question 14

what occurs in alveolar stage

Answer 14

lung size increases due to maturation of alveoli, secondary septationand remodeling and maturation of tissues

: It doesn’t end there—the lungs continue to grow and mature until age 18.

Question 15

what determines fetal lung growth

Answer 15

fetal lung volume –> secrections and movements

• Fetal respiratory movements (FRM) or fetal breathing movements (FBM) are regular muscular contractions occurring as early as the 10thweek.
• Amniotic fluid, produced by maternal plasma as well as fetal kidneys, is breathed into the lungs and is critical for proper lung development.
• Distention of fetal lungs by fetal lung fluid is related to hyperplasia of the lung; drainage or lack of fluid results in pulmonary hypoplasia

Thus, fetuses with kidney anomalies or other conditions that result in oligohydramnios often present with hypoplastic lungs.

Question 16

how is the bulk of fluid cleared from the lungs in newborns

Answer 16

the bulk of the fluid is cleared by osmotic gradient screated by transepithelial sodium reabsorption by alveolar epithelial cells*. This moves fluids from the alveolar lumen to the interstitiumwhere it is absorbed by the lymphatic system and pulmonary capillaries

results in:

• A fall in pulmonary vascular resistance
• An increase in pulmonary blood flow
• Pressure changes in the heart– pressure in the right side of the heart decreases and pressure in the left side of the heart increases as more blood returning from the pulmonary circulation

Insufficient fluid clearance after birth is the most common cause of neonatal RDS -> transient tachypnea of the newborn (TTN). Typically resolves within 3 days. Most common in c-section.