Organogenesis

Question 1

5 stages lung development (and time)

Answer 1

• Embryonic: 22 days- 6/8 weeks
• Pseudoglandular stage: 6-16weeks
• Canalicular stage: 16-26 weeks
• Terminal sac (saccular) stage: 26 weeks-birth
• Alveolar stage: 32 weeks-birth/post natal

Question 2

lung development: what happens during embryonic stage

Answer 2

• respiratory diverticulum forms from ventral foregut endoderm
• splanchic mesoderm gives rise to cartilage, muscle and CT, vascular network
• tracheoesophageal septum develops

Question 3

lung development: what happens during pseudoglandular stage

Answer 3

• branching to form terminal bronchioles
• vessels develop (vasculogenesis)

Question 4

lung development: what happens during canalicular stage

Answer 4

• respiratory bronchioles form
• lung size increases
• greatest expansion of capillary network
• primordial capillary-airspace interface develops

Question 5

lung development: what happens during termincal sac stage

Answer 5

• mature capillary-epithelium interface
• secondary crests and saccules develop
• increase elastic network
• increasing amounts of surfactant

Question 6

lung development: what happens during alveolar stage

Answer 6

• increase in respiratory bronchioles and alveoli
• alveoli form adult shape

Question 7

when does surfacant production start

Answer 7

20 weeks (very little), measurable by 24-28 weeks

accelerates by week 35

Question 8

Hyaline Membrane Disease

Answer 8

aka neotnatal respiratory distress syndrome

• preterm, male, maternal diabetes, C section
• immaturity of lungs/lack of surfactant
• causes hyaline membranes to develop
• TREATMENT: delay labour, induce lung maturation w/ corticosteroids, surfactant replacement therapy and ventilation

Question 9

pulmonary hypoplasia

Answer 9

• most common congenital lung lesion
• usually secondary
  
  • congenital diaphragmatic hernia, oligohydroamnios, decreased respiration during fetal period

Question 10

congenital diaphragmatic hernia

Answer 10

• most common malformation of diaphragm
• compression of lung
• on posterior body wall, pleural cavity is continuous with peritoneal cavity

Question 11

when does CVS start to develop

Answer 11

week 3

Question 12

parts of fetal heart before looping occurs

Answer 12

left and right horns of venosus

atrium

ventricle

bulbus cordis

truncus arteriosus

Question 13

summary of looping

Answer 13

Cephalic portion (ventral, caudal, R)

Caudal portion (dorsal, cranial, L)

Question 14

4 septa that form in heart

Answer 14

1. atrioventricular canal
2. primitive atrium
3. outflow tract
4. primitive ventricle

Question 15

ostium secundum defect

Answer 15

septum primum is too small to cover all of oval fossa

near center or middle of atrial septum

Question 16

ostium primum defect

Answer 16

• involves region adjacent to endocardial cushions
• less common, more severe

Question 17

where are conotruncal ridges found

Answer 17

when separating single outflow tract of heart into two

Question 18

tetralogy of fallot

Answer 18

• congenital heart defect present at birth

1. pulmonary stenosis
2. ventricular septal defect
3. overriding aorta
4. right ventricular hypertrophy

• surgery usually within first 2 years of life

Question 19

branchial vestige

Answer 19

remnant of pharyngeal cartilages that do not dissapear

cartilage or bone, usually below SCM just under skin