Heart Development

Question 1

Truncus arteriosus

Answer 1

blood out top of developing heart
one artery - develops into aorta and pulmonary trunk
continuous with aortic sac

Question 2

Bulbus cordis

Answer 2

outflow part of ventricles, before semilunar valves
becomes conus arteriosus and aortic vestibule leading to valves
proximal to truncus arteriosus

Question 3

Sinus venosus

Answer 3

blood in, bottom
recieves blood from vitelline, umbilical, and cardinal vv.
Develops into right and left horns

Question 4

vitelline v.

Answer 4

drains yolk sac

Question 5

umbilical v.

Answer 5

from mom

Question 6

cardinal v.

Answer 6

early v. of embryonic body

Question 7

Bulboventricular loop

Answer 7

bend between inflow and outflow parts

causes atrium and sinus venosus to come to lie dorsal

Question 8

Semilunar valves develop from

Answer 8

3 swellings of subendocardial tissue

restructred into cusps

Question 9

AV valves develop from

Answer 9

proliferation of endocardial cushions - cardiac jelly - around AV canals

Question 10

Septum Primum

Answer 10

first septum between atriums

closes Foramen primum - opening

Question 11

Foramen Secondum

Answer 11

opens in septum primum to allow flow between atriums

Question 12

Septum secundum

Answer 12

2nd wall, crescent shaped

Overlaps foramen secondum

Question 13

Foramen Ovale

Answer 13

opening in septum secundum

Forms a flap valve with septum primum between atrium

Question 14

Fossa Ovalis

Answer 14

after birth two septums fuse, causing fossa ovalis
membrane of fossa ovalis (over old foramen ovale) is from septum primum
border of fossa ovalis is from septum secundum
only seen in RA

Question 15

Right horn of sinus venosus

Answer 15

becomes posterior wall of right atrium - sinus venarum

Question 16

Atrial septal defects

Answer 16

No overlap in septum between atriums
Secundum - occurs in area of oval fossa (defects in either or both septums)
Endocardial cushion - defect in septum primum (doesn’t fuse with endocardial cushions)
Sinus venosus - incomplete absorption of sinus venosus into RA, abnormal development of septum secundum or both
Common atrium - all three types of defects

Question 17

Ventricular septal defects

Answer 17

Membranous - membranous IV septum doesn’t close

Muscular - muscular septum doesn’t close at some point

Question 18

Abnormal division of truncus arteriosus

Answer 18

Persistent truncus arteriosus - aorta and pulmonary trunk don’t separate (failure of truncal ridges and aorticopulmonary septum to develop) - single arterial trunk

Question 19

Pulmonary stenosis

Answer 19

cusps of pulmonary valve fused together with a narrow opening
obstruct blood flow

Question 20

Tetralgy of Fallot

Answer 20

Pulmonary stenosis - obstructed right ventricular outflow
VSD
Overriding aorta
Right ventricular hypertrophy

Question 21

1st pharyngeal arch a.

Answer 21

largely disappears

forms parts of maxillary arteries

Question 22

2nd pharyngeal arch a.

Answer 22

stapedial arteries

Question 23

3rd pharyngeal arch a.

Answer 23

form common carotid arteries

Question 24

4th pharyngeal arch a.

Answer 24

part of aortic arch

right subclavian a.

Question 25

5th pharyngeal arch a.

Answer 25

disappears

Question 26

6th pharyngeal arch a.

Answer 26

pulmonary arteries

ductus arteriosus - becomes ligamentum arteriosum (between pulmonary artery and aorta)