Heart tube, great vessels & atrial septation.

Question 1

myoblasts form in what part of the early embryo?

Answer 1

in the yolk sac

Question 2

the myoblasts of the early embryo grow together to form what?

Answer 2

little vessels/tubes

Question 3

which endocardial tubes fuse to become the heart tube?

Answer 3

the lateral endocardial tubes

Question 4

describe the two structures pictured

Answer 4

the upper bulge = early ventricle

lower bulge = early atrium

Question 5

does the heart grow at the same rate as the cavity it sits in?

Answer 5

no - it grows much faster - so it has to twist and turn on itself to continue development

Question 6

describe the different regions of the primitive heart

Answer 6

Question 7

what is it called when the apex is on the right side of the body?

Answer 7

Dextrocardia

Question 8

what are the three major parts of the bulbus cordis?

Answer 8

trabeculated part of right ventricle

conus cordia

truncus arteriosus

Question 9

what vein enters the primitive heart?

Answer 9

the Sinus venosus- right and left - enters the right primitive atrium and narrows

has ‘horn’s which recieve the vitelline vein, umbilical vein, and the common cardinal vein (anterior and posterior)

Question 10

which veins vanish in heart embryology?

Answer 10

the right umbilical

left vitelline

Question 11

which vein remains in the adult body behind the falciform ligament?

Answer 11

the left umbilical vein

Question 12

what vein forms the connection between the two anterior cardinal veins?

Answer 12

blood flows from left to right = left brachiocephalic vein

Question 13

where does the coronary sinus originate from from?

Answer 13

the left sinus horn

Question 14

the anterior cardinal vein becomes…?

Answer 14

the right superior vena cava

Question 15

what makes up the smooth/rough walls of the right atrium?

Question 16

during atrial septation- where does the blood flow through?

Answer 16

throughout the development of atrial septation, the blood continues to flow from right to left

the septum primum (goes from roof of right atrium and divides the two parts of the chamber from eachother)

Question 17

where does the septum secundum develop?

Answer 17

grows down in a sickle shape from the roof of the atrium - but it wont close all the way down to the endocardial cussion - the lower free edge= the foramen ovale

Question 18

in the embryo, which side of the heart has higher pressure?

Answer 18

the right side - Note that in the adult, the left side has greater pressure

Question 19

when does the atrial pressure switch from the right to the left?

Answer 19

when the baby takes its first breath - increases the pressure on the left side

Question 20

what is it called when the septum primum doesnt properly anatomically fuse?

Answer 20

the patetn foramen ovale - usually asymptomatic -

Question 21

if you have an atrial septal defect, where is the blood shunted?

Answer 21

from left to right b/c of difference in pressure - however, this ‘leaking’ of blood doesn’t change the oxygenation levels of blood

Question 22

If partial pressure in oxygen isn’t changed from an atrial septal defect… what do we call it?

Answer 22

if it doesn’t change the oxygen level = acyanotic

Question 24

what type of murmer would you have with an atrial septal defect?

Answer 24

Ejection systolic murmer -

Question 25

why may you hear a different heart sound with an atrial septal defect?

Answer 25

the endocardial cushions (which make up the eventual valves) are potentially effected by the defect in the septum = leads to different valve sounds

Question 26

ostium secundum defect leads to a defect in which region of the heart?

Answer 26

in the fossa ovalis

• where the septum primum and secondum fail to fuse - or if there excessive cell death in the septum primum - allows TOO big of an ostium secundum

Question 27

how do the atrioventricuar canals develope?

Answer 27

they develop from a common atrioventricular canal- which then pinches together to make two

Question 28

where does the interventricular septum develop from?

Answer 28

the inferior aspect just stays put - and things grow around it, but the ‘membranous part’ develops from the inferior endocardial cushion

Question 29

how does an atrial septal defect and ventrical septal defect differenciate in the murmer?

Answer 29

atrial septal = ejection murmer

ventricular= pansystolic murmer left lower sternal border