test 2 lecture 15 heart and vascular Flashcards
Circulatory system includes ___
heart, arteries, veins, & blood
___ develops when embryo grows too large for diffusion to supply its cells.
circulatory system
___ is the 1st function organ system to form
circulatory system
ØIn dog, heart tubes fuse at ~4mm (day 18); septation largely complete by ~12mm (day 25)
___ forms an arc around the anterior end of the neural plate which is full of ___ cell clusters
cardiogenic field
angiogenic
Angiogenic cell clusters form the ___
cardiac crescent
1.Hollow angiogenic cell clusters form in ___
cardiogenic field
cardiogenic field coalesce into a ___ lined by endothelial cells
crescentic endocardial tube
Cardiac tube (crescent) develops ___ and ___ layers
myocardial & epicardial layers
as the embryonic disc folds how does the “heart move”
starts at cranial end
Brings heart caudal to head, below the foregut and in front of the transverse septum (the ventral part of future diaphragm, between the heart & liver)
Flips cardiac crescent back to front and brings it to a position below the dorsal aortae
what happens to cardiac tube during development
‘Head tuck’ folding
reorients the cardiac tube so that the crescent arms point cranially
brings the heart below the foregut
Folding brings cardiac crescent (tube) ventral to dorsal aortae and the foregut
Crescent arms become the ventral aortae, which carry blood away from heart
Ends of ventral & dorsal aortae grow toward each other & eventually join
Folding brings cardiac crescent (tube) ___ to dorsal aortae and the foregut
ventral
Crescent arms become the ___, which carry blood away from heart
ventral aortae
Ends of ventral & dorsal aortae grow toward each other & eventually __
join
First (most cranial) aortic arch is formed when left & right dorsal & ventral ___ fuse
aortae
Aortic arches are paired. Left & right aortic arches connect left (or right) right dorsal aortae to left (or right) ventral aortae
Left & right vitelline veins fuse with the caudal end of the ___
cardiac crescent
fusion of vitelline veins form right & left horns of the ___, the heart’s venous inlet
sinus venosus
sinus venosus
This is where blood from the body returns to the heart
The umbilical and cardinal veins will later drain into the ___
sinus horns
1st aortic arch
fusion of dorsal aortae and ventral aortae
embryo folding laterally will do what for heart formation
brings left & right arms of cardiac crescent into contact
then Apoptosis removes walls between left and right arms of cardiac tube/crescent, forming unpaired midline heart tube
midline heart tube has endocardium, myocardium and epicardium
cardiac midline tube is ___ to the primitive gut
ventral
Primary heart field forms
primordial ventricle
Secondary heart field forms
primordial atria, right ventricle, bases of pulmonary trunk and aorta
cardiac neural crest forms
truncus arteriosus (outflow)
embroyonic veins flow into ___
sinus venosus
5 zones of midline heart tube during development
sinus venosus, atrium, ventricle, bulbus cordis, and truncus arteriosus
Multiple input vessels enter ___ at caudal end of___
sinus venosus
atrium
__ = outflow tract. Delivers blood to ventral aortae via __at cranial end of heart tube
Bulbus cordis
truncus arteriosus
looping of heart tube
Folding wraps atria around outflow tract (bulbus cordis + truncus arteriosus)
Aortic arches carry blood from ___ (outflow tract) to dorsal aortae.
ventral aortae
The ___contributes to the ventral part of the diaphragm
septum transversum
folding of the heart loop happens where
primordial ventricle & bulbus cordis meet
compartmentalization of the heart happens in 3 processes
- Atrio-ventricular separation
- Atrial septation
- Ventricular septation
What does compartmentalization do at a physiologic level
partitioning (separating atrium from ventricle, & dividing primordial atrium & ventricle) creates the heart architecture that keeps oxygenated blood (to body) separate from deoxygenated blood (to lungs)
Atrio-venticular separation
Developing endocardial cushions form the A-V septum that separates primordial atrium from ventricle & bulbus cordis,
will leave space on right and left for the AV valves to form
atrial septation
- Primary septum (blue) divides atrium
- Transient primary osteum is located between primary septum & endocardial cushions. (closes when septum meets cushions)
- Apoptosis fenestrates primary septum dorsally (forming secondary osteum) (at 30-32 days gestation in horse)
- Secondary septum (green) forms in right atrium (does not close ventrally)
- Endocardial cushions fuse to completed primary A-V septum
- 2 openings retained in A-V septum (future A-V valves)
- Secondary septum overlaps secondary osteum, but doesn’t fuse with A-V septum
- 1st & 2nd septae don’t fuse. Blood from fetal right atrium can flow into left atrium
- Passage through wall = foramen ovale. Pushed open (by blood flow) in fetal heart.
- Primary septum acts as valve to prevent backflow from left atrium to right atrium
what is the name of the hole in the primary septum that forms after the primary septum fuses with the endocardial cushion
foramen secundum
what is the name of the whole that is formed by the secondary septum
foramen ovale
blood circulation in heart in fetus
right artium → foramen ovale, foramen secundum → left atrium → left ventricle → out to body
___ acts as valve to prevent backflow from left atrium to right atrium
Primary septum
1st & 2nd septae ___ fuse. Blood from fetal right atrium can flow into left atrium
don’t
Secondary septum overlaps secondary osteum, but ___ fuse with A-V septum
doesn’t
Cardiac end of right sinus horn is incorporated into the right atrium as the ___
sinus venarum
Ends of pulmonary veins are incorporated into the left atrium to become the main part of the___
left atrium
The primordial atria become the ___ of the adult heart
auricles
Other sinus horn fates
Cardiac end of right sinus horn → into the right atrium as the sinus venarum
Anterior part of rt. sinus horn → cranial vena cava
Posterior part of right sinus horn → caudal vena cava
Left sinus horn → coronary sinus
Cardiac end of right sinus horn is incorporated into the right atrium as the ____
sinus venarum
Ends of ___ are incorporated into the left atrium to become the main part of the left atrium.
pulmonary veins
the right ventricle is formed from the ___
bulbus cordis
___ grows upward from heart apex toward endocardial cushion
I-V septum
The bottom part of I-V septum is muscular. Top initially incomplete; opening is called the ____
interventricular foramen.
___ is normally closed by growth of membranous upper part of interventricular septum
Interventricular foramen
EC= endocardial cushion
IAS= interatrial septum
right sinus venosus
left= IVF= interventricular foramen
IVS= interventricular septum
AA= ascending aorta
PT= pulmonary trunk
SS= spiral septum
AA = ascending aorta
DucA = ductus arteriosus
LDA = left dorsal aorta
PT = pulmonary trunk
IV septum divides what into what
bulbus cordis and left ventricle
right and left ventricle
spaces next to endocardial cushion is __ and will become __
AV orifices
right and left mitral valves
bulbus cordis turns into
right ventricle and ascending aorta and pulmonary trunk
Bulbar ridges and truncal ridges grow inward from the walls of the ___
bulbus cordis & truncus arteriosus
___ and ___ form the spiral septum
bulbus cordis→bulbar cushion → bulbar septum
truncus arteriosus→ truncal cushion → truncal septum
aortic sac→ aortic cushion?? → aortic-pulmonary septum
The ___ ridges unite to form the spiral septum
bulbar and truncal
the spiral septum divides outflow tract into ___ and ___
aorta & pulmonary trunk
Outflow tract division completes separation of the ___ and ___ loops
oxygenated & deoxygenated
what holds the aorta and pulmonary artery together
ligamentum arteriosum
Truncus arteriosis comes from ___
cardiac neural crest
Bulbus cordis (from ___) develops into the right ventricle and part of the spiral septum
secondary heart field
The primordial ventricle (from ___) becomes the left ventricle
primary heart field
Outflow tract division (into aorta & pulmonary trunk) happens at the same time as ___
ventricular septation
___is involved in outflow tract formation, and its division.
Neural crest
Outflow tract (aorticopulmonary) septum and ___must line up correctly. why?
interventricular septum
if RV and pulmonary trunk, and LV and aorta do not line up correctly then deoxygenated and oxygenated blood can mix or one vessel will be smaller then the other and will not be strong enough to do its job
Right ventricle must open to ___; left ventricle must open to __.
pulmonary trunk
aorta
Failure of septae to line up leads to cardiac malformations (example: __).
Teratology of Fallot*
Teratology of Fallot: large defect in IV septum; aorta overrides both ventricles; pulmonary stenosis; enlarged right ventricle
(high pressure in right ventricle pushes deoxygenated blood through septal defect into left ventricle to mix with oxygenated blood to aorta)
Teratology of Fallot:
large defect in IV septum; aorta overrides both ventricles; pulmonary stenosis; enlarged right ventricle
(high pressure in right ventricle pushes deoxygenated blood through septal defect into left ventricle to mix with oxygenated blood to aorta)
___= most common congenital malformation in domestic animals.
Cardiac malformations
heart has 4 valves:
2 AV valves (bicuspid)
2 semilunar (aortic and pulmonary) (tricuspid)
Valves prevent___as it passes through heart and exits heart
backflow of blood
___ are essential to normal heart function
Valves
how do AV valves form
formed by apoptosis, which sculpts the ventricular walls. Apoptosis leaves behind the valve flap, cordae tendinae, and papillary muscles
Normal A-V valves are closed by ___ to prevent backflow from ventricles to atria
ventricular pressure
what do chordae tendineae do?
prevent AV valves from flapping up into the atrium
The AV valves are made from
remnants of myocardial cushion
and apoptosis of ventricular walls
__: have 3 ~triangular cusps, each with a nodule in the center of its free edge that helps seal the valve shut
Semilunar valves
Semilunar valve cusps start as ___ that grow inward from the walls of the aorta or pulmonary trunk
mesenchymal swellings
Three swellings form at each valve location. Each swelling will become a valve cusp.
what type of valve?
Tricuspid/semilunar
___ sculpts the swellings into thin, flexible flaps that form the 3 cusps of each semilunar valve
Apoptosis
what stops back flow in semilunar valves?
valve cusp lining up correctly create one way valve
the SA node is formed where
the sinus venosus and primordial atrium met
how does heart pump
SA node (sinoatrial) starts contraction
travels to AV node (atrioventricular) which delays signal
waits for atrium to contract then sends signal down bundle of his through purkinje fibers to make ventricle contract
•The __(pacemaker) initiates contraction
SA Node
Impulse travels from the SA node through atrial walls to the ___
AV Node
AV Node __ impulse (so that ventricles contract __ atria)
delays
after
AV Bundle transmits impulse to ___ network in ventricle walls. (Coordinates ventricular contraction)
Purkinje fiber
purkinje fibers make the ventricle contract ___
apex to base (bottom to top) push blood up
___ develops very early in development and acts as pacemaker
SA node
blood cell formation begins ___
in the yolk sac
__clusters in yolk-sac mesoderm coalesce to form vessels
Haemangioblast
Outer cells differentiate into angioblasts that form vessel walls (___)
vasculogenesis
vasculogenesis
Outer cells differentiate into angioblasts that form vessel walls
Outer cells differentiate into ___that form vessel walls
angioblasts
Haemangioblast clusters : Inner cells differentiate into ___
primitive blood cells
Earliest erythrocytes are ___; later erythrocytes lack nuclei
nucleated
Later endothelial cells are derived from ___, which give rise to ___ that make adult blood cells
embryonic mesoderm
Haematopoietic Stem Cells (HSCs)
Site of blood cell formation changes during development
Mesoblastic stage – blood cells form in the yolk sac
Hepato-lienal period – blood formation in liver, then spleen. Begins in approx. 8mm embryo (in the ox), & fully active at 18mm
Medullary – blood formation in bone marrow. Begins at ~18cm in the ox.
By birth hematopoiesis is confined to the bone marrow
___ is when blood cells form in the yolk sac
Mesoblastic stage
__ is when blood formation in liver, then spleen. Begins in approx. 8mm embryo (in the ox), & fully active at 18mm
Hepato-lienal period
__ is when blood formation in bone marrow. Begins at ~18cm in the ox.
medullary
By birth hematopoiesis is confined to the ___
bone marrow
blood cell formation mesoblastic stage
the embryo has 3 circulatory loops
body
vitelline
allantoic(umbilical)
of the 3 embryo circulations: vitelline, allantoic and body which remain in adult?
body
Vascular endothelium has 2 sources: ___ & ___ from yolk sac.
embryonic mesoderm
erythro-myeloid progenitors (EMPs)
Proportion of (erythro-myeloid progenitors) EMP-derived cells in vessel walls varies between organs, ranging from __ in brain to ___in liver
30%
60%
Early development: no ___ yet. Blood flow = artery to intercellular space to vein.
capillaries
Embryonic ‘body’ loop is divided into 2 pathways in the fetus & adult: one to lungs (to oxygenate blood) and one to body (to distribute O2 & nutrients; and to ___)
collect wastes)
Primitively, __ aortic arches connect the dorsal & ventral aortae.
6
ventral aortae will turn into
common (caudal part) & external (cranial part) carotid
The dorsal aortae will turn into
internal carotid aa. (cranial part) & aorta (caudal part)
3rd aortic arch will ___
connects common carotid to internal carotid (not in ruminant, cat)
4th aortic arch will turn into
aorta (on left side), or subclavian artery (on right side)
6th aortic arch turns into
on the left side: pulmonary trunk (& ductus arteriosus)
on right side: 6th arch regresse
which aortic arches remain and which degenerate
3, 4 and left side of 6
1, 2, 5 and right side of 6
during development of aortic arches what is formed to divide them
pharyngeal pouches
In the embryo, the body is drained by __
cardinal, subcardinal, & supracardinal veins
Adult veins are derived mainly from the ___ veins
subcardinal
with small contributions from the other veins (cardinal and supracardinal)
Vitelline veins become
Sinusoids of liver
Part of caudal vena cava
(e.g. hepatic & hepatocardiac parts)
Hepatic portal vein
Umbilical veins regress:
- Right – regresses in fetus
- Left – closes at birth (failure to close (patent ductus venosus) can produce pathologies (examples: hepatic encephalopathy, disuria, polyuria
patent ductus venosus
failure to close left umbilical vein
produce pathologies (examples: hepatic encephalopathy, disuria, polyuria)
Development of the heart begins in the ___, a horseshoe-shaped region of visceral mesoderm which forms an arc around the anterior end of the neural plate.
cardiogenic field
“Head tuck” folding of the embryo repositions the cardiac tube ventral to the embryonic disc and ___ to the embryo’s head
caudal
head tuck folding also reverses the orientation of the cardiac crescent so that the arms of the crescent – which will become the ventral aortae – point ___ instead of __
forward (toward the embryo’s head)
caudally
Lateral folding of the embryo brings the edges of the embryonic disc together ___ of the embryonic disc.
ventral to the midline
The caudal portions of the left and right ventral aortae (the caudal part of the cardiac crescent) are brought into contact; these tubes are fused into a single midline heart tube as ___removes the walls that separate the left and right sides of the cardiac crescent from each other.
apoptosis
___ fuse with the caudal arch of the cardiac crescent to form the inlet of the heart; slightly later other veins (umbilical and cardinal veins) also connect to the caudal (input) end of the heart tube.
Vitelline veins
The unpaired midline heart tube that was formed by fusion of the left and right limbs of the cardiac crescent plus fusion with the vitelline veins now begins pumping blood out into the ventral aortae at its ___end.
cranial (output)
The simple heart tube is suspended in the pericardial cavity by a dorsal mesocardium; and is initially anchored by a ___. what happens to the this structure?
ventral mesocardium
transient structure, goes away
the heart tube chambers from posterior to anterior
the sinus venosus; the atrium; the ventricle; the bulbus cordis; and the truncus arteriosus
The truncus arteriosus is formed by ___
cardiac neural crest cells.
looping of the heart happens at where ___
where the primordial ventricle meets the bulbus cordis.
Walls of the primordial ventricle (future left ventricle) and the part of the ___ that will become the right ventricle become thicker and ___as the heart grows.
bulbus cordis
trabeculated
The opening between the bottom of this septum and the endocardial cushions, the ___, is eventually closed when the primary septum meets the endocardial cushions.
primary osteum
As the primary osteum closes apoptosis creates a ___ near the top of the primary septum
secondary osteum
After the septum primum has formed secondary osteum, a second, thicker fold of tissue (___) grows downward just to the __ of the septum primum. The secondary septum extends downward far enough to cover the right side of the secondary osteum, but a gap (__) between the two septae remains patent in the __ atrium.
the septum secundum
right
the foramen ovale
right
___ allow blood to flow from the right atrium to the left atrium.
foramen ovale in the septum secundum
secondary osteum in the septum primum
The ventral part of the thinner ___ acts as a valve to keep blood from flowing back into the right atrium and ensure unidirectional blood flow through the foramen ovale and into the left atrium.
primary septum
As the fetus grows and the fetal heart handles more blood, the right atrium grows by incorporating the ___ into the right atrium
right horn of the sinus venosus
Initially all of the blood returning to the heart from the developing lungs enters the left atrium through a single common ___. This common venous trunk later is incorporated into the ___, and forms the smooth-walled main portion of the left atrium.
pulmonary vein
developing left atrium
single common pulmonary vein develops into __
4 individual veins
At first there is an opening (___) between the top of the muscular interventricular septum and the endocardial cushions.
an interventricular foramen
Growth of the ___ is accompanied by thickening and trabeculation of the walls of the primordial ventricle (the adult left ventricle) and proximal bulbus cordis, which will become the adult right ventricle.
interventricular septum
Division of the heart into four chambers has great physiologic significance. It allows the separation of ___ and ___ blood into two separate circulatory loops – the pulmonary and body systems of the adult animal.
oxygenated and de-oxygenated
At first both the left and right ventricles empty into the bulbus cordis, and blood from both ventricles flows into the undivided ___
truncus arteriosus
Complete separation of oxygenated and deoxygenated blood requires that the bulbus cordis and truncus arteriosus also be divided. Division of these structures is accomplished by the bulbar ridges, which grow inward from the bulbar walls and meet to form the ___
spiral septum
___ separates outflow from the right ventricle (to the pulmonary trunk) and outflow from the left ventricle (to the aorta)
the spiral septum
___ cells contribute significantly to formation of the bulbar ridges, semilunar valves, and to the walls of the proximal parts of the coronary arteries.
Cardiac neural crest
Myocardial cells are replaced by connective tissue in the ___; the papillary muscles remain muscular.
cordae tendinae
The semilunar valves begin their development as swellings at the outlet of the ___ into the ventral aortae
truncus arteriosus
Clusters of haemangioblasts (blood islands) form in the yolk sac mesoderm. The outer cells in these clusters will become ___, which form endothelial cells. The inner cells will become ___.
angioblasts
primordial blood cells
The blood islands coalesce into larger elongate structures, and their outer endothelial cells form the first ___ (which are located in the yolk sac).
blood vessels
Spontaneous formation of blood vessels is called ___. These first-formed vessels later grow side branches, a process which is called___.
vasculogenesis
angiogenesis
The embryo has three circulatory loops
1) the vitelline loop, which supplies the yolk sac
2) the umbilical loop, which connects to the placenta for gas and nutrient exchange
3) the body loop.
The body loop of the embryo gives rise to the two definitive circulatory loops of the fetus and adult: __
the pulmonary and systemic loops.
The aortic arches develop in a ___ direction as the embryo grows, meaning that the 1st aortic arch is the most cranial, and the 6th aortic arch is the most caudal.
cranial-to-caudal
Not all of them are present in a mammalian embryo at any one time – arches that will be lost (like the 1st or 2nd arch) will degenerate before later arches like the 6th aortic arch begin to form.
The ventral aortae of the embryo become __
the common carotid and external carotid arteries of the adult animal.
The cranial portions of the dorsal aortae (i.e. the parts that lie cranial to the 3rd aortic arch) will become the __
internal carotid arteries of the adult
The 3rd aortic arch will be retained (in some species) as the extracranial part of the ___. In other species (e.g. the ox or cat) this extracranial segment of the future internal carotid artery degenerates in utero, and is not present in the adult animal.
internal carotid artery that connects to the common carotid artery
The left 4th aortic arch becomes the ___ of the adult mammal; on the right side the 4th aortic arch becomes the ___
ascending aorta
right subclavian artery
The 6th aortic arch connects to the right ventricle and the left side becomes the ___. The right side ___
pulmonary circuit
pulmonary artery – and its distal end, which is still connected to the aorta (= the dorsal aorta of the embryo) becomes the ductus arteriosus of the fetus (which allows blood to bypass the developing lungs). This distal part of the left 6th aortic arch closes at birth to become the ligamentum arteriosum of the adult.
regresses
left side of the 6 th aortic arch becomes pulmonary artery – and its distal end, which is still connected to the aorta (= the dorsal aorta of the embryo) becomes the ___ of the fetus (which allows blood to bypass the developing lungs). This distal part of the left 6th aortic arch closes at birth to become the ___ of the adult.
ductus arteriosus
ligamentum arteriosum
Segmental arteries of the embryo branch from the __. Dorsal segmental arteries will supply the __ and __
dorsal aortae
body wall and neural tube
Lateral segmental arteries supply the ___
organs developed from intermediate mesoderm (like the kidneys and reproductive tract organs).
Ventral segmental arteries will become the ___
celiac; cranial, and caudal mesenteric; and umbilical arteries.
The embryo has three major veins: ___ (which drain the yolk sac), ___ (returning blood from the placenta), and ___ (which drain the body).
vitelline veins
umbilical veins
cardinal veins
The vitelline veins will ultimately become the ___ of the liver (the cranial parts of the vitelline veins); the ___ segment of the caudal vena cava (the cranialmost part of the right vitelline vein); and the ___(the caudal part of the vitelline veins).
sinusoids
hepatocardinal
portal vein
The right umbilical vein largely ___, but its cranial end contributes to the sinusoids of the liver.
involutes
The left umbilical vein contributes to the ___, which allows most of the blood from the placenta to bypass the liver on its way to the heart.
ductus venosus,
- The more caudal part of the left umbilical vein will involute after birth and become the ___of the liver.
round ligament
The body of the embryo is drained by a complex network of different types of “cardinal” (body-draining) veins. These are the ___, ___ and __.
lateral cardinal
medial subcardinal
dorsal supracardinal veins
The cardinal and ___ veins anastomose with each other extensively.
subcardinal
The caudal vena cava is ultimately derived from ___ types of embryonic cardinal vein
all three
The pelvic part of the caudal vena cava develops from the ___ vein.
right supracardinal
the lumbar part of the caudal vena cave is formed by anastomosis of the __ and __
subcardinal and cardinal veins
The abdominal part of the caudal vena cava is derived from the anastomosis of the ___ and ___
right subcardinal and vitelline veins.
The ___ vein is derived from cranial parts of the cardinal and supracardinal veins
azygous
Cardinal veins that are located cranial to the heart give rise to the ___ and ___
internal jugular and brachiocephalic veins.
The segment of the cranial vena cava that enters the heart is derived from the cranial part of the ___
right sinus venosus horn
The caudal vena cava is derived from the caudal part of the ___
right sinus venosus horn.
The ___ becomes the coronary sinus of the adult heart, and returns blood from the heart walls to the general circulation
left horn of the sinus venosus
In the fetus blood is oxygenated and CO2 is removed by the __
placenta.
Oxygen-rich blood returns to the conceptus via the ___
umbilical veins.
In the early embryo, umbilical veins were paired. The part of the__ umbilical vein between the umbilicus and the liver involutes early on in development; only the ___ umbilical vein remains functional in the fetus.
right
left
Most of the blood in the left umbilical vein bypasses the liver through the ___ but a small amount supplies the developing liver with oxygenated blood and nutrients.
ductus venosus,
___ blood traveling through the ductus venosus mixes with ___ blood draining from the caudal body and digestive tract in the caudal vena cava. This mixed blood enters the right atrium, where it is mixed with more ___ blood from the cranial vena cava.
Oxygenated
deoxygenated
deoxygenated
Most of the blood that enters the right atrium gets shunted toward the left atrium through the ___
foramen ovale
Only a small amount of the somewhat oxygen-rich blood in the right atrium passes through the ___ into the right ventricle, and is then pumped out into the pulmonary trunk.
A-V valve
Most of the blood in the pulmonary trunk bypasses the lungs by flowing through the ___, which carries it directly to the aorta.
ductus arteriosus
The blood that entered the left atrium through the foramen ovale is joined by the small amount of ___ blood returning from the fetal lungs.
deoxygenated
Some of the blood in the aorta is returned to the placenta via the ___; the rest supplies body tissues and organs and is returned to the heart via the venous system.
umbilical arteries
At birth, the loss of __ supplied by the umbilical cord results in an increase in __ tension in the neonate
O2
CO2
The __ increase stimulates respiratory centers in the medulla, and triggers respiration.
CO2
The first breath expands the lungs, which in turn stimulates ___.
pulmonary circulation
The increase in blood flow to the lungs results in an increase in the volume of blood entering the left atrium through the pulmonary veins. This increased input increases pressure in the left atrium. The increased pressure pushes the thin primary septum against the thicker secondary septum, closing the ___
foramen ovale.
The closed foramen ovale remains visible as the ___ in the right atrium
fossa ovale
Reflexive constriction of the walls of the ___ stops oxygen-poor blood in the pulmonary trunk from flowing through the ___ and mixing with the oxygen-rich blood in the aorta
ductus arteriosus
ductus arteriosus
The lumen of the ductus arteriosus is obliterated, but the vessel walls of the ductus persist after birth as the ___.
ligamentum arteriosum
During birth, blood flow to the placenta is shut down by contraction of the umbilical arteries (which become the ___ ), and blood flow from the placenta is closed off by constriction of the ductus venosus and umbilical vein. The (left) umbilical vein persists after birth as the ___
round ligaments of the bladder
round ligament of the liver.
