Lecture 20: Embryology of the Heart, Lungs, and Diaphragm

Question 1

What forms the right and left endocardial tubes and adjacent myocardial plates of the heart?

Answer 1

lateral plate mesoderm

Question 2

What happens with the two endocardial tubes and myocardial plates

Answer 2

they come together to form one heart tube

Question 3

What are the two layers of the heart tube?

Answer 3

endocardial layer surrounded by a myocardial layer

Question 4

Describe the movement (looping) of the heart tube during the first few weeks of embryogenesis

Answer 4

structures forming the right side of the heart (right atrium and ventricle) swing anteriorly and the left swings to the posterior

Question 5

What is septation

Answer 5

The creation of two atria and ventricles and divides the AV canal and ventricular outflow from aorta and pulmonary trunk

Question 6

What is created first the atrium or ventricles?

Answer 6

They are made simultaneously

Question 7

What forms the AV valves (tricuspid and mitral)

Answer 7

endocardial cushion

Question 8

What forms the aortic and pulmonic semilunar valves?

Answer 8

Endocardial cushion

Question 9

Embryological derivative of the medial wall of left atrium

Answer 9

septum primum

Question 10

Embryological derivative of the medial wall of right atrium

Answer 10

septum secundum

Question 11

Ostium primum

Answer 11

hole in the septum premum that leads into the AV canal

Question 12

What closes the ostium primum

Answer 12

endocardial cushion

Question 13

Ostium secundum

Answer 13

Forms in the septum premium as osmium primum closes

Question 14

What closes ostium secundum

Answer 14

septum secundum

Question 15

What happens to the growth of the septum secundum once the ostium secundum closes

Answer 15

It stops growth

Question 16

When septum secundum stops growing, what forms

Answer 16

foramen ovale

Question 17

Role of foramen ovale

Answer 17

Shunts blood from the right atrium to the left atrium

Question 18

Left heart hypoplasia

Answer 18

premature closing of foramen ovale

Question 19

What forms the membranous portion of the inter ventricular septum

Answer 19

endocardial cushion

Question 20

Ostium primum atrial spetal defect

Answer 20

inadequate development of the cushions can cause failure of final closure of the atrial septum

Question 21

Membranous ventricular septal defect

Answer 21

inadequate development of the cushions can cause failure of final closure of the ventricular septum

Question 22

Persistent AV canal

Answer 22

most severe defect involving the endocardial cushion

Question 23

Ventricular septal disease (VSD)

Answer 23

When the muscular and membranous inerventricular septa do no fuse together

Question 24

Defects in septation are often accompanied by…Why?

Answer 24

Defects in the heart because anything that alters blood flow will affect the path or volume of flow

Question 25

Example of how defects in aorticopulmonary septation results in ventricular septal defects underlying one or both great vessels

Answer 25

Tetralogy Fallot

Question 26

Describe the 4 defects from Tetralogy Fallot

Answer 26

(OVEN). Overriding aorta, Ventricular spetal defect, Pulmonary stenosis (narrow right ventricular outflow tract), Right ventricular hypertrophy (due to higher pressures on the right side of the heart)

Question 27

What do the aortic arches arise from

Answer 27

aortic sac

Question 28

Right and Left aortic arch IV

Answer 28

Right: Right subclavian a. Left: Arch of aorta

Question 29

Connection between the recurrent laryngeal branches and aortic arch IV

Answer 29

The recurrent branches recur around aortic arch IV

Question 30

Aortic Arch VI

Answer 30

Right and left pulmonary arteries and ductus arteriosum on the left side

Question 31

Structures in the respiratory tract that derive from endoderm?

Answer 31

Epithelial linings of - larynx - trachea - bronchi - bronchioles - terminal alveoli

Question 32

what structures in the respiratory tract derive from splanchnic mesoderm?

Answer 32

The cartilage, muscle, and CT components of: - trachea - lungs - pulmonary blood vessels

Question 33

Where is there open communication between the respiratory divritiulum and forget in the embryo

Answer 33

Trachea (respiratory divriticulum) and the esophagus (forgut)

Question 34

Which is located more anterior the esophagus or trachea

Answer 34

trachea

Question 35

Tracheoesophageal fistula

Answer 35

esophagus ends in a blind pouch (baby throws up food)

Question 36

What does the main stem of the lung bud (respiratory divriticulum) form

Answer 36

trachea

Question 37

Where do the bronchial buds come from?

Answer 37

lateral outpocketings of the lung buds

Question 38

What do the bronchial buds form

Answer 38

mainstem (or primary) bronchi

Question 39

How many secondary bronchus are formed by the right mainstream bronchi? left?

Answer 39

Right: 3 (one per lobe) Left: 2 (one per lobe)

Question 40

Type II pneumocyte

Answer 40

type of cells derived from endoderm in the alveolar ducts and alveoli. Produces surfactant

Question 41

What is the role of surfactant

Answer 41

prevents lungs from collapsing during expiration

Question 42

Respirtory Distress Syndrome (RDS)

Answer 42

happens in some premature infants due to inadequate levels of surfactant in lung airways

Question 43

What structures of the diaphragm derived from somatic lateral plate mesoderm

Answer 43

- Septum transverum | - Pleuroperitoneal membranes

Question 44

What structures of the diaphragm derived from myoblasts

Answer 44

skeletal muscle cells

Question 45

What structures of the diaphragm derived from mesenchyme surrounding the forgut

Answer 45

dorsal mesentery of esophagus

Question 46

What did the crura of the diaphragm arise from

Answer 46

dorsal mesentery of esophagus

Question 47

Which portions of the respirator system derived from the forgut?

Answer 47

Trachea, bronchi, alveoli, alveolar ducts

Question 48

How does splanchnic mesoderm contribute to the formation of the lungs

Answer 48

All cartilage, muscle, and CT in the trachea and lungs developed from splanchnic mesoderm

Question 49

How can the esophageotrachea fistula form

Answer 49

An abnormal separation between the trachea and the esophagus uses the esophagus to end in a "blind pouch"

Question 50

What are the cellular derivatives of endoderm in the bronchial tree/lung

Answer 50

Epithelial singing of larynx, trachea, bronchi, brochioles, terminal alveoli

Question 51

How is the diaphragm formed?

Answer 51

Septum transversum, pleuroperitoneal folds, mesoesophagus, myoblasts (skeletal muscle)

Question 52

Where are defects in the diaphragm normally found and why?

Answer 52

In the pleuroperitoneal folds because the pleura and peritoneum fail to fuse

Question 53

Basic formation of the heart

Answer 53

Lateral plate mesoderm forms two endocardial tubes and two adjacent myocardial plates. These come together to form one heart tube with and endocardial and myocardial layer.

Question 54

What is the endocardial cushion? What is its clinical significance?

Answer 54

Forms the tricuspid, mitral, pulmonic, and aortic valve. When there is a deficiency in the endocardial cushion many clinical issues arise (i.e osmium premum atrial septal defect or membranous ventricular septal defect).

Question 55

How is the intertribal septum formed

Answer 55

endocardial cushion

Question 56

What is a common defect of the interatrial septum

Answer 56

Persistent AV canal

Question 57

What is the Tetrology of Fallot

Answer 57

Septum dividing the aorta and pulmonary artery is displaces resulting in the 4 defects: Over-riding aorta, ventricular septal defect, pulmonary stenosis, and right ventricular hypertrophy

Question 58

What are the aortic arches

Answer 58

IV and VI left and right

Question 59

What is derived from the 4th aortic arch on the right and left side

Answer 59

Right: Subclavian a. Left: Arch of aorta

Question 60

What is derived from the 6th aortic arch

Answer 60

Pulmonary arteries (ductus venosum on the left)