12: Heart Development

Question 1

Causes of heart defects

Answer 1

Single gene mutations, chromosomal anomalies, teratogens, 85% multifactorial

Question 2

The heart is the first what in the embryo?

Answer 2

First functioning organ

Question 3

AGM stands for?

Answer 3

Aortic-gonadal-mesonephric

Question 4

EPC stands for?

Answer 4

Endothelial precursor cells

Question 5

Angiogenesis

Answer 5

Budding and sprouting of new vessels from existing ones

Question 6

Intussusception

Answer 6

Splitting

Question 7

How does the first aortic arch form?

Answer 7

Cranial ends of developing dorsal aorta are dragged centrally along with the heart -> forms a loop

Question 8

Inflow of blood into the primitive heart is from what three vessels?

Answer 8

Common cardinal veins, vitelline veins, umbilical veins

Question 9

Cardiac jelly

Answer 9

ECM between endocardium and myocardium

Question 10

What forms the LV and RV?

Answer 10

Primitive ventricle -> LV

Outflow tract -> RV

Question 11

When does rhythmic contraction and blood flow begin in fetal heart?

Answer 11

Contraction: day 22

Blood flow: day 24

Question 12

Three veins that drain into the sinus horns and their sources of blood

Answer 12

1. Umbilical V: placenta blood, O2 rich
2. Vitelline V: blood from gut
3. Common cardinal V: blood from head and trunk

Question 13

First major step required for cardiac sept action

Answer 13

Cardiac looping

Question 14

Three tissues that have to interact for maintenance of cardiogenic mesoderm proliferation for the second heart field

Answer 14

NCCs + pharyngeal arch mesoderm + pharyngeal arch endoderm

Question 15

Crista terminalis

Answer 15

Junction between pectinate of RA and smooth walled part of RA (sinus venarum)

Question 16

What two structures form the SA node? AV node?

Answer 16

Right sinus horn + right common cardinal vein; AV node comes from similar tissue in left sinus horn

Question 17

ECT stands for?

Answer 17

Endocardial cushion tissue

Question 18

What tissue type forms the tricuspid and bicuspid valves?

Answer 18

Endocardial cushion tissue

Question 19

How does septum primum act as a one way flutter valve?

Answer 19

Allows RA blood to enter LA, but not the opposite direction

Question 20

Steps in heart blood flow after first breath at birth

Answer 20

1. Pulm circulation opens -> increased blood flow thru lungs -> into LA
2. Pressure increase in LA -> R sided pressure decreases -> L sided pressure will now be higher
3. septum primum driven against septum secundum -> foramen oval shuts

Question 21

Partitioning of outflow tract

Answer 21

Common lumen divided into two tubes -> aorta connected to LV + pulmonary A connected to RV

Question 22

Myocardialization

Answer 22

Outer myocardial wall is thinned as some myocardial cells begin to be replaced by cushion cells in specific areas -> helps form muscular interventricular septum

Question 23

What provides primorida for semilunar valves of aorta and pulmonary trunk?

Answer 23

Spiraling ridges at truncus/conus junction

Question 24

Sinus inversus

Answer 24

Complete reverse symmetry of heart and GI organs, not fatal and can be asymptomatic

Question 25

Situs ambiguous

Answer 25

Reversal of some organs, can be problematic

Question 26

Visceroatrial heterotaxia is a form of what?

Answer 26

Situs ambiguous

Question 27

Visceroatrial heterotaxia

Answer 27

Heart and GI tract asymmetrically arranged from one another -> problems w/ inflow and outflow tract development

Question 28

Probe latency

Answer 28

If foramen ovale does not completely close

Question 29

Two causes of ostium II or high atrial septal defect

Answer 29

1. Excess absorption of septum I

2. Inadequate development of septum II