Lecture 19: Embryonic Cardiovascular System

Question 1

cardiogenic mesoderm of heart primordium

Answer 1

epiblast cells ahead of precordal plate that migrate through primitive groove as mesoderm forms, and will become heart

Question 2

angioblastic cords

Answer 2

pairs of vessels that will make pair of aorta and then fuse to become single aorta

Question 3

where does heart begin in fetus?

Answer 3

above chest

Question 4

what comes down to chest during folding

Answer 4

cardiogenic mesoderm, pericardial sac, septum transversum

Question 5

why no circulation through lungs in fetus

Answer 5

because lungs haven’t formed and no air/oxygen in the lungs, so don’t need blood circulation

therefore blood pumps out of aortic arches, oxygenated blood is used by fetus’s tissues, and then carried back to heart by vein

Question 6

cranial to caudal, parts of embryonic single heart tube

Answer 6

aortic sac, truncus arteriosis, bulbus cordis, primitive ventricle, primitive atrium, sinus venosus

Question 7

where veins entering into heart tube go through

Answer 7

from ylk sac, through sinus venosus, to embryonic heart

Question 8

why single heart tube folding occurs

Answer 8

genes tell heart to fold, and cells proliferate more rapidly on 1 side causing cranial fold

Question 9

fetal heart circulation

Answer 9

blood goes into sinus spinosis - ventricle - bulbus cordis - aortic sac - 1st pharyngeal arch artery

Question 10

endocardial cushions

Answer 10

2 mounds of tissue that separate primordial atria from ventricle and divide heart into R and L atrio-ventricular canals

also play role in AV valve formation (mitral, tricuspid)

Question 11

papillary muscles

Answer 11

hold tissue strands growing from walls of ventricles to endocardial cushion in places

will become the AV valves

Question 12

interventricular septum

Answer 12

separates R and L ventricles

muscular, membranous parts

Question 13

muscular part of interventricular septum

Answer 13

ingrowth of cardiac mesoderm that grows toward cardiac cushions

Question 14

membranous interventricular septum

Answer 14

tissue that grows from endocardial cushions and meets up with muscular part of septum

Question 15

ventriculo septal defect

Answer 15

in membranous portion of interventricular septum most likely

when thin tissue there doesn’t grow closed properly and so child needs surgery to close it

Question 16

leaflets that partition right and left primitive atrium

Answer 16

septum primum, septum secundum

Question 17

septum primum

Answer 17

starts from posterior wall of primitive atrium, grows toward endocardial cushion; as grows, little fenestrations within so blood can get from R to L atria

includes foramen primum and foramen secundum

Question 18

foramen primum

Answer 18

little space that remains in septum primum so blood can pass from R to L atria; eventually is fused/obligerated

Question 19

foramen secundum

Answer 19

growth of fenestrations in septum primum causes this opening

it remains into development of heart, doesn’t get obliterated - becomes the foramen ovale

Question 20

foramen ovale

Answer 20

remnant of the septum secundum

passage between 2 atrial cavities through which blood flows from right to left atrium

Question 21

septum secundum

Answer 21

second septum in atria

is anterior to septum primum

leaves opening in development of heart so blood can flow from R to L atria through foramen ovale

Question 22

structures associated with primitive atria

Answer 22

septum primum, foramen primum, septum secundum, foramen ovale

Question 23

where a stroke in a young person could go across

Answer 23

foramen ovale

Question 24

foramen ovale function

Answer 24

right to left shunt
allows blood to bypass fetal lungs
closes after birth when pulmonary vascular resistance decreases and left atrial pressure increases

Question 25

conotruncal ridges (bulbar, truncal)

Answer 25

form in truncus arteirosis and part of bulbus cordis

Question 26

aorticopulmonary septum

Answer 26

formed by ridges of right superior truncus and left inferior truncus growing toward the aortic sac, swelling and twisting around each other meets interventricular septum divides truncus into aorta and pulmonary artery

Question 27

aorta v pulmonary artery re: outflow

Answer 27

aorta- L ventricular outflow tract pulmonary artery- R ventricular outflow tract

Question 28

order of aorta/pulmonary trunk and why

Answer 28

pulmonary trunk- more ventral, aorta- more dorsal, because of spiraling

Question 29

2 types of valves

Answer 29

semilunar, atrioventricular

Question 30

semilunar valves

Answer 30

aortic and pulmonic aortic: separates aorta from left ventricle pulmonic: separates arteries from right ventricle

Question 31

derivation of semilunar valves

Answer 31

swellings in subendocardial region usually 3 cusps/seminlunar portions, although have a bicuspid aortic valve

Question 32

types of AV valves

Answer 32

tricuspid: right atria to right ventricle mitral: left atria to left ventricle

Question 33

derivation of atrioventricular valves

Answer 33

proliferation of tissue around endocardial cushions/A-V canals

Question 34

dorsal aorta

Answer 34

initially, pair of tubes; fuses to form single dorsal aorta; connects w/ aortic arches; aortic arches connect to aortic sac in primitive heart tube

Question 35

paired dorsal aortae

Answer 35

each paired arch is assocaited with a pharyngeal arch; they connect to aortic sac

Question 36

how many aortic arches develop

Answer 36

6; do not all develop at the same time

Question 37

what is descending aorta result of

Answer 37

fused dorsal aorta

Question 38

pharyngeal arches

Answer 38

pair to form aortic arch

Question 39

left 4th pharyngeal arch

Answer 39

becomes much of aortic arch

Question 40

left 6th pharyngeal arch

Answer 40

becomes left pulmonary artery and ductus ateriosis

Question 41

ductus arteriosis

Answer 41

derivative of left 6th pharyngeal arch shunt in fetal pulmonary artery that shunts blood through to aorta instead of going to lungs

Question 42

3 pairs of primitive veins

Answer 42

all empty into sinus vinosus; will contribute to vena cava and primitive blood return to heart vitelline veins- drain yolk sac (low O2) umbilical veins- form placenta (high O2) common cardinal veins- from body of embryo (low O2)

Question 43

what happens to R umbilical vein?

Answer 43

it disappears

Question 44

what carries blood from mom to fetus?

Answer 44

L umbilical vein only vein in umbilical cord has ductus venosus shunt to shunt blood back to heart, doesn't go through liver like normally does

Question 45

derivatives of superior vena cava

Answer 45

right anterior cardinal vein, right common cardinal vein

Question 46

tetrology of fallot components

Answer 46

frequent abnormality due to unequal partitioning of truncus arteriosis from spinous arteriosis 4 cardiovascular alterations: 1. pulmonary stenosis (narrow right ventricular outflow region) 2. ventricular septal defect 3. overriding aorta 4. right ventricular hypertrophy

Question 47

do embryonic umbilical arteries have high or low O2 content?

Answer 47

they have the highest O2 content of the embryonic veins