QUIZ 3# Flashcards
What are the 3 paired veins that drain into the tubular heart of a 4 week old embryo?
1- Vitalline Veins
2-Umbilical veins
3- Common cardinal veins
When do the endocardial develop?
5th week
Endocardial Cushion Defects
ASD’s
Overview
1-inappropriate fusion of endocarial cushions
2- abnormality of arial septum-opstium primum
3-abnormality of ventricular Septum and AV Valves
(AV valves associated with defects of cardial cushions)
4-Lack of AV canal
a) ASD
b) defects in Mitral Valve leaflet
c) defects in leaflet of tricuspid
Conduction system
Atria is the interim pacemaker
-Sinus Venosis opening into atria
by te 5th week, the SA NODE developes
- SA node is originally in the right but becomes encorporated into RA with sinus venosus
- SA node is high in the right atrium near the entrance of the SVC
–Cells from the left wall of the sinus venosus forms cells from the AV region for forming the AV Node and end bundle (located just in from of the endocardial cushions)
- Fibers split into right and left bundle branches
- bundle branches are distributed thru out ventricular myocardium
- SA, AV, Bundle of His are richly supplied with nerves
=Only signaling pathway from atria to ventricle
_very specialed cells
Afterload is
pressure that the heart chamber must pump against to eject blood
If there is an increase in PVR, the heart has to pump harder, so there is an increase in afterload
Calcium’s effect on the heart muscle
Overview
Excess-opposite to K+
- causes spastic contraction of the heart
- diretly excites cardiac conntraction process
- Decreases Ca+-causes cardiac flacidity
- Normal level is 9-11; >11 is hyperCa+
An ionized Ca+ is a better indication; Ionized Ca+ is actually the Ca+ that is being utilized by the body (>5.4)
Clinical presentation: poor feeding, poor weight gain, lethargic? polyuria?
What can be affected by too much peep?
Preload
after 9-10 cm of pressure, it will decrease you will decrease preload
watch setting on CPAP/VENT
Aortic Arch ABnormalities
Most of the aortic arch abnormalities result from the persistence of pharngeal arch artieries that will usually disappear
What does the ductus venosus connect?
The Umbilical Vein with the Inferior Vena Cava?
Bulbr ridges fuse dividing the bulbus cordis from the truncus arteriosis……
the truncus arteriosis divides to orm the aorta and the pulmonary artery
Carinal Veins
Overview of Anterior Cardinal Vein
1-Povide main venous drainage system in the embryo
2-Anterior & Posterior Cardinal Veins
a) drain the cranial and caudal part of the embryo
b) join the common cardinal vein and enter sinus venosus
3-Anterior Cardinal Vein are
a) connected and shunt blood from left to right thru the Anterior Cardinal Vein
b) Anterior Carinal Vein-draining blood into the Common Cardinal Vein into the sinus venosus
4-Cardinal Veins become connected thru anastamosis, which shunt left to right
This shunted area is the brachiocephalic Vein
5-Right anterior and Right Common Cardinal Vein Forms the SVC
After Birth, the blood shunts
Left to Right
Sinus Venosus ASD
OVERVIEW
This is a HIGH ASD near the SVC
Very Rare
- incomplete absorption of sinus venosus into the right atrium
- or- abnormal development of septum secundum
- associated with comon pulmonary venous return connections
- can be detected on fetal Ultrasound
By he endof the 4th week, the heart is turning 180 degrees because…..
things now need to line up
THe heart is changing and totating
THE AV Canals seperate primitive atria from primitive
Ventricles
Remolding of the heart
Day 24
a) blood circulated thru the embryo
b) venous return enters the right and left sinus horns via common cardinal veins
Afterload Overview
pressure that the chambers ofthe heart has to generate to eject blood out of the chamber
- pressure the heart chambers must pump to eject blood
- as afterload increases, cardiac output decreases
Endocardial Cushion defects with an Ostium Premum ASD
OVERVIEW
- defect of endocardial cushion and the AV septum
- the septum does not fuse with the endocardial cushions causing an ostium premum defect
- AV Septal Defect-occurs whe the enocardial cushions fail to close
Which cardinal veins appear first?
SUPRAcardinal veins
VENTRICLES
Overview
- primitive ventricle-most of the left ventricle (1 ventricle)
- Bulbus cordis-most of the Right Ventricle early on
- Intraventricular septum starts to grow towards the endocardial cushions
- Intraventricular septum start to grow from the floor of the primitive ventricle and gorws towards the endocarial cushion
Frank starling found that
the strength of th ventricular contraction was found to change the volume the heart recieved; the effects of preload and afterload
- if effects how much a heart is stretched because it will only strtch to a certain amount and then you HAVE to have a contaction-
- responses re independent; neuronal and hormonal influences the heart; dependent upon the the force of the blood entering the heart
- ability of the heart to change force and change stroke volume in response to changes to venous return is the Frank Starling Mechanism
- Greater the muscle is stretched, the greater the force of the contraction
Septum Secundum?
Contributes to the development of the Foramen Ovale
ROTATION of the Heart
Overview
Day 23
a) heart tube elongates to begin to loop
b) bulbus cordis is displaced to the right
c) vent displaced to the left
d) Primitive atrum will be displaced posteriorlaterally and superiorly
Frank Starling Law States
the greater the volume entring the heart during diastole (end diastolic volume) that the greater the volume ejected durig systolic coontraction (stroke Volume)
In the NEONATE: when there in an increase in Pulmonary Vascular resistence and an increase in Systemic Vacular resistence, this will:
Increase the aterload and decrease contractility
-decrease contractility because more pressure is needed to eject blood from the heart chamber
Nitric Oxide
Discovered by Robert Fertzgaht
Abundant in the epithelial cells and endothelial cells in fetal deelopment
exogenous N.O> plays a cruial role in pulmonary vascular and alveolar development
_when not produced, we see simpflication of alveolri and impaired growth of the pulmonary vasculature and Pulmonary HTN
-After birth NO is responsible for pulmonary vasodilitation, bronchodilitation, improving fx of surfactant, reducing lung inflammation and inhibition of smooth muscle cell proliferation
The septum premim fuses with ?
Enocardial Cushions
PDA
Overview
Ductus is derived from the 6th aortic arch
- tissue from the Pulmonary Artery
- from the 6th week on-ductus is responsible for most of right ventricular outflow
- Contributed to 60% of cardiac output throughour the fetal life
- important fetal structure constrbutes to the flow of blood to the rest of the fetal organs and structures
- if it closes before birth, it causes right sided-heart failure
Normally loses after birth
-5th or th most common cardiac defect
_ofen associated with other infrastrucural defects
- PDA represents 5-10% excluding those in premature infants
- 8/1000 Live preterm births
1/2000 Live term births
THe Foramen Ovale is the opening of what?
Septum Secundum
PDA Functionally Closes by
1st few days
Where is the SA Node Located?
high in the Right atrium near the entrance of th SVC
Where do the endocadial cushions form?
on the ventral and dorsal walls
ENDOCRINE REGULATION
predominant in fetal life
overview
catecholamines are being secreted by adrenal medulla
- establishes the HR before the development of the sympathetic NS
- vasopressin is produced by the fetal pituitary gland causing vasoconstriction of blood vessels in the Musculoskeletal system, skin, gut-which allows the blood to flow to the brain and heart during periods of hypoxia, hypotension and hypernatremia
- PGe increases blood flow to brain during hypoxi episodes
- renin-angiotensin system lead to increase in fetal HR and B/P while increase in blood flow to the heart and lungs during periods of hypoxia and sigificant blood loss
Umbilical Veins
Initially there are 2 UV that run on each side of the liver
The UV:
1-carried well oxygenated blood from the placenta to the sisus venosus
When does the Foramen Ovale structurally close
at 3 months
The valve of the F.O. fuses with the septum secundum forming the oval fossa
Performance of the myocardium is influenced by what 4 things?
1-ventricular preload
2-contractility
3-heart rate
4-ventricular afterload
Vitalline Veins
RIght and Let Vitalline Veins enters the heart at the Sinus Venosa
the Vitalline Veins
1- Follow the yolk stalk into the the embryo
2- Reeturn poorly oxenated blood from the yolk sac
3-Poorly oxygenated blood enters the venous end of the heart (Sinus Venosus)
4-there is no 4
5-Portal Vein-
The LEFT Vitalline vein regresses
The RIGHT Vitalline Vein forms
a) the hepatic portal system
b) Inferior Vena Cava
6- The Ductus Venosus Develops-this large venous shunt develops within the liver and connects the ubilical vein with the Inferior Vena Cava
- “DV formed from the left vitalline vein within the portal system”
20-30% of blood from the Umbilical vein will perfuse the liver and the rest of the blood goes thru the DV and enters the Inferior Vena Cava
Increase in preload increases stroke volume
Decreasse prelod decreases stroke volume by altering the force of the contraction by the cardiac muscle
-concept of preload can be applied to the ventricles as well as the atria; regardless of chamber-preload is related to chambr volume just prior to contraction
Ostium Secundum Defects
Review
PFO
- small opening in secundum
- PFO
- there is a shortseptum premim
or
Large F.O> with a normal septum premim
Right and Left AV canals gives ise to what?
Mitral and tricuspid valve
what divides to form the aorta and the pulmonary artery?
Truncus arteriosis
Where is the AV node located?
In the center of the heart, in the floor of the Right Atrium between the atria and ventricles
Contractility
Overiew
- depends on pumping abilty of the heart
- depends on Preload
- depends on changes i the cardiac muscle
- depends on afterload
- dependson the maturation of the cardiac muscles
= pumping ability of the heart is dependent on the influx of CALCIUM in the myocardium
- acidosis, hypercarbia, hypoxia will alter the cellular permeability of both Na+ and K+ and this can lead to a decrease in contractility
- changes in th muslce length can alter the force of the contraction
- the development of force is related to the maturation of the cardiac muscle
Other Cardiac Anomalies are:
HLHS
TOF
PDA
Development of the AORTIC Arches
1-1st pair of arches
a- provide arteries to maxillary area (ears, teeth, muscles of eyes & face)
b) external carotid artery
2- 2nd pair provide blood flow to the inner ear
3- 3rd pair of arhes
a) common carotid arteries
b) Internal Carotid Arteries
4- 4th Pair of arches
a) arch of the aorta
b) Right Subclavian Artery
5-6th pair of arches
a) Right Pulmonary Artery
b) Left Pulmonary Artery (which forms the Ductus Arterosis)
What does the left sinus horn become?
(Sinus Venosus)
The coronary Sinus
THe common carotid arteries and the internal arters receive blood flow from which arches?
3rd pair of of arches
Foramen Ovale
Overview
pressure changees within the het cause the FO to close
- septum secundum and septum premum are involved in the formation of the F.O.
- With iniation of breathing, we have closure of the little flap because Increase in systemic blood flow and pressure
- Flap that is part of the septum premum closes the FO
- Fo may remain patent for 9 months, but usual structural closure is within 1 year of age
Hypoplastic Left Heart Syndrome
HLHS
Overview
- Under-developed Aorta and Aortic Valve, Left Ventricle & Mitral Valve
- Blood returning from the lungs muust return thru and opening in the wall between atria (ASD)
- Right Ventricle pumps blood into the aorta and blood reaches the body thru the PDA
- seem normal at birth, but het into trouble when the ductus closes
- become ashen, rapid/difficult breathing and difficult eating
- Usually fatal withing days or 1st months of life unless treated
- Stages ffor surgical repair-1st palliative
What are the earliest veins to develop? When to they develop?
Anterior and posterior Cardinal Veins
Develop during the 8th week
Effects of K+ 0n the heart muscle
Overview
K= effects contractility of the heart
Normal is 4-6 meq/l
HyperK+ causes the heart to dilaate and become flacid; slows the HR; interferes with the conduction of the impulses thru the heart
- Results in Tall T waves, loss of P wave and progresses
- widens the QRS leading to bradycardia, 1st degree block and AV block (because there is no condunction through the SA and AV nodes)
- must be careful with K+ supplementation-usually starting at around day 3 of life on 1-2 Meq/kg/day
_important to make sure the urine output is good before starting K+
- can become hyperK+ from metaboli and resp acidosis (causes K+ to come out of the cell)
- immature kidney fx can rsult in hyperK+ due to decrease in glomelular filtration rate
- HyperK+ from NEC due to tissue necrosis
- Must be astute in monitoring K+ level(if hyperkalemia, take it out of IV fluids, can give ca+ gluconate or Ca+ chloride
- HYPERGLYCEMIA can cause HYPERK+ due to insulin resistence
- Hypercalcemia can penetrate the effects of HyperK+
Endocardial Cushions will…..
move towards each other and fuse ABSOLUtELY dividing the AV canal into the R&Lcanals
Where does the 2nd pair of arches spply blod flow to?
Inner ear
The TOP parrt of the septum Premum closes the FOramen ovale when?
aftr birth
what divides the bulbus cordis from the truncus arteriosis?
when bulbar ridges fuse
Preload
Overview
If the heart fills with more blood than usual:
when the heart fills with more blood than uaual, the force of the contraction with increase
-The increase is resulting from an icrease in load placed on the muscle fibers die to the extraneous blood entering the heart
Transition
epinephrine and norepinephrine increase rpidly at birth and increase 4 hrs after birth
- increase mild asphyxia associated with birth process
- decrease in ambient temp, cord clamping, Increased ICP
What are the 4 main segments that comprise the IVC?
1- Hepatic Segment-Proximal part off the right vitalline vein
2-Pre-renal Segment: Right Subcardinal Vein
3- Renal Renal Segment: Sub and supracardinal vein
4-Post-Renal-Right supracardinal vein
Cardinal Veins
Review of POSTERIOR Cardinal Vein
Posterior Veins
a) vessels of the primitive kidney disappear when the kidney actually develop
b) The only remnant of the posterior cardinal veins are the “Common Iliac Veins”
which arch supplies the arch of the aorta and the right subclavian artery?
4th
Right and Left Atria
Overview
Right and Left sinus horns take on a new shape and become
a) Right Atrium
b) Left atrium
c) 2 right and left pulmonary veins
Closure of the Ductus Arteriosis
Overview
What facilitates the closure of the Ductus?
with increae in SVR and decrease in PVR the ductal shunt becomes left to right (in utero the shunt is from right to left)
PVR may remain higher han the SVR for a short time after delivery, and in this case, the R?L shunt will persist
- if PVR continues to be higher than SVR, then you get into PPHN
- PVR decreases and SVR increases and shunt becomes L>R after birth
- It’s functionally closed within 12-14 hrs of age; can close in 6-9 hours of age in full-term infants
- Remains open for alonger peiod of time in preemies
- Before anatomic closure, the ductus can reopen if the baby becomes hypoxic ad increase in PVR
Anatomic closure in 2-3 months of age
1st pair of arches provide?
arteries to maxillary area
&
External Carotid
Common Atrium
1 atrium
Rare
caused by the failure of the secundum and primum to develop
Functional closure of the Ductus Arteriosis
Pge2 keeps ductus open during fetal life
- decrease in fetal PGE due to increased pulmonary blood flow that enhances elivery of PGE2 ro the lungs for metabolism
- this enhances ductal closure as the infant takes his first breaths
- removal of the plcenta enhances ductal closure because placenta is the main source of PGE2 produed in the fetus
- With an increase in pulmonary blood flow, we see a decrease in Pge2, with removal of the placenta, we see a decrease in PGE1 so there is a decrease in the amount of circulating PGE2
Coarc of the Aorta Overview
Most common
the aortic lumen is narrowed
usually occurs inferior to origin of left subclavian artery:
JUXTADUCTAL COARC
Transition:
With the iniatiation of breathing
Lungs expand
O2 getting into the alveoli
vasodilitation occurs: drop in PVR
PVR drops by 80% causing dramatic increase in pulmonary blood flow and ductal shunting
Development of the heart tubes
OVERVIEW
Myocardium- is the external layer that is formed as the tubes fuse
- at this stage, the heart is comprised of a thind endothelieal tube seperated by a primitive thick myocardium gelatenous connective tissue called “cardiac jelly”
- Endothelial tubes internal lining of the heart
- Endocardium & Primitive myocardium becomes the muscular wall of the heart (Myocardium)
- as folding of the head region of the embryo occurs, the heart and pericardial cavity come to lineup in front of the foregut
- we see the tubular heart elongating - develops deviations and constrictions
Development of Valves
continued overview
- development of cusps are firmly rooted in canal
- attatched by the chordae tendonae (papillary muscle)
- valve cusps fold back allowing blood to enter at diastole and they are then shut to prevent backflow when the ventricles contract
Left AV Valve-Bicuspid
Right AV Valve-Tricuspid
The Right AV Valve is the?
Tricuspid
Septum Secundum forms which opening?
Foramen Ovale
What does the Right Sinus horn become?
(Sinus Venosis)
The adult Right arrium
Av Canals and Ventricles
Overview
1-AV canals provide an opening between the future atrium and left ventricle
2- Left AV Canal must be aligned with Left atrium and ventricle
3-right AV must be aligned with the right venticle and atrium
At Day 23- see rotation occuring to correctly align
-Left Ventricle must have an outflow path to bulbus cordis to truncus arterosis
In what week(s) will the capillaries connect forming the coronary veins and coronary arteries that grow off of the aorta?
5th & 6th Week
right and left ventricles communicate thru and opening in the septum called the
Intraventricular foramen
Transformation of the Umbilical Veins
What happens with the UV’s?
Right and Left UV will degenerate and Caudal of the left UV is between the liver and sinus venosus
- Remaining caudal part of the left UV develops actual umbilical vein
- Develops large venous shunt, the Ductus Venosus” which develop in the liver
- The Ductus Venosus connects the Umbilical vein with the Inferior Vena Cava
TAPVR
Overview
- Pulmonary vein draws into the right atrium instead of the left atrium
- threre is NO direct communication between pulmonary venus and left atrium
- TAPVR rare congenital defect in which all 4 of the pulmonary veins do not normally connect to the Left Atrium
- Common to all types of TAPVR is an ASD because none of the pulmonary veins connect normally to the left side of the heart and thus-out to the body; so blood is shunted from the RA across the ASD
- Absence of an ASD in TAPVR is not comaptible with survival
Primitive Heart
What does it look like?
How is it Developed?
- Develops from cardiac area of the Mesoderm
- The appearance of paired endothelial strands called “Angioblastic Cords”
- During the 3rd week, the angioblastic cords canalize/”open up” to form the HEART TUBES
- The heart tubes will approach each other and fuse and then the heart tubes will join your blood vessels, the stalk and they yolk sac in the embryo
Contractility
There are a lot of things co-related tht have an effect on the heart
- maturation; an increase in the contractility and development of force is part of the maturation process of the heart muscle itself
- Myocardial contractility is altered in the NN due to the infants derease ventricular compliance and reduced contractile mass
Persistent Truncus Arteriosis
- ONE AORTA
- Because failure of the truncal ridges in the arteriorpulmonary septum to develop normlly and divide the truncus arteriosis into the pulmonary and aortic trunk
There is a VSD always Present
Truncus straddles the ASD
Truncus arteriosis supplies the cardiac, pulmonary and systemic circulation
Regulation of Cardiac Function
Cardiac functions:
central mechanisms from: Medulla
Hypothalmus
Cebreal Cortex
Central Mechanisms are affeted by:
Blood pressure
Heart rate
distribution of blood to the vital organs
Blood flows during the 4th week of circulation and can be vsisualized by doppler
Cardinal Veins
Supra Cardinal Vein
SupraCardinal Veins appear 1st and they form the:
a) Left renal vein
b) veins of the gonads
1-They become part of the Interior vena cava where they continue to form
a) Right internal and external Jugular Veins
b) Left Subclavian
c) Interior and exterior Iliac Veins
Endocardial Cushions will form when?
During the end of the 4th week
Umbilical Veins
Important to remembers
As the LIVER develops, the Ductus Venosus LOSE connection with the heart and empty into the liver
RIGHT UV disappears during the 7th week leaving only the left UV (we pul lines in the LEFT UV)
In the transition after birth
Overveiw
after birth, cardiac output is increased due to :
Increased pulmonary blood flow
Pulmonary b/p decrease
systmic b/p increase
Pulmonary truck and ascending Aorta
Overview
In the 5th week- proliferation of cells in the walls of the bulbus cordis
- results in the formation of bulba and trunchal ridges
- bulba nd truncal riges fuse forming the articopulomnary septum
- setum divides bulbus cordis and truncus arteriosis forming the ascending aorta and pulmonary trunk
PDA Structurally closes by the
12 postnatal week
Coarc occurs twice as often in males or females?
Males
Sinus Venosus
Overview
_Receives Blood from the umbilical Veins and common cardinal veins from the chorion
-As the primitive heart gets bigger, we see 2 simus horns develop (LEFT and RIGHT Sinus Horn)
–SV begins to seperate chambers of the primitive heart
- SV opens into the right atrium
- Left and Right Sinus horns
- Bulbus Cordis gives rise to the ventricle and partially to the truncus arterosis
- Bulbus Cordis becimes truncus arteriosis
Right horn becomes the adult right atrium
Left horn becomes the coronary sinus
Coronary sinus is associated with coronary arteries, so the heart muscle will receive blood supply
-
the venous system is remodles weeks later as;
blood enters the inferior and superior vena cava
LEFT sinus horn becomes small venus sac on the back wall of the heart
-Sac becomes the coronary sinus and vein of the Left atrium
The coronary sinus
associated with coronary arteries
so that blood can be supplied to the heart
Abnormalities of the Arteriopulmonary Septum
Overview
1-transposition of the great vessels
2-truncus arteriosis
3-VSD
4-TAPVR
Where does the Ductus Arteriosis Come from?
From the 6th pair of Aortic Arches
ASD’s are Common
The are more common is males of females?
Females
The 5th pair of Arches
Is rudamentary and disappears
In utero, the blood shunts
Right to Left
Branches of the Right and Left Pulmonary Veins will…
Branch towards the lungs and attatch to develop bronchial buds
ASD Defects
4 types of ASD’s
1-Ostium Secundum Defects (PFO)
2- Endocardial Cushions
3- Sinus Venosus
4- Common atriu with no seperation of atria
Bradycardia
Causes:
response to hypoxia
heart block
changes in afterload
Tachycardia
HR>160
causes:
sympathetic control excitation
fetal anemia
acute fetal blood loss
abnormal fetal conduction
Heart Rates
20 weeks=155
30 weeks=144
term=140
Nervous System response
Baroreceptors and chemo receptors
-Baroreceptors (sensitive to the changes in blood pressure)
1- aortic arch
2- carotid sinus
Chemoreceptors: PNS and CNS
Sensitive to pH and CO2
alters heart rate in rsponse to hypoxemia and acidosis
Circulation
Heart beats at day 22 or 23
Blood flows during the 4th week of circulation and can be vsisualized by doppler
Septum secundum grown NEXT to the septum premum but it————
Overlaps
Partition of the Atria
Review of facts
1-primitive atria is divided into right and left atria by the Fusion of 2 septa
1-septum primum
2-septum secundum
Heart rate is sensitive to vagal stimulation and is regulated initially by the sympathetic nervous system
HOWEVER: as the neonate gts older: you will see a change from the sympathetic NS to the PARAsympathetic NS
As the neonate gets older and as there is an Icrease in age, there is a decrease in HeartRate
The decrease in heart rate is seen because they are switching from sympathetic NS to parasympathetic NS control of the Heart rate
Myocardial Performance
During adaptation process to extrauterine life, there in an increase in the HR
- even at rest, the NN is at full capacity with little or no reserve in preload, afterload or contractility
- NN Heart has limited ability to adapt to changes in pressure or afterload or volume (preload)
*in the cases of cardiac conditions which require an increase in cardiac output and the only way the baby can do this is my increasing the HR and ONLY the HR to a certain amount and the the heart is Unable to meet additional demands placed on it
4 segments that form the Interior Vena Cava
1-Hepatic
2-Pre-renal
3-Renal
4-Post-Renal
PDA
More Overview
Female to male ratio is 2:1
It is common in preemies, but less likely to occur as G.A. increases
Incidence:
205 older than 32 weeks
60% if less than 28 weeks
30%V of LBW < 2500 grams develop a PDA
Results of loopiing of the primitive heart
Brings 4 future chambers in spacial relation to each other
- Further Ddevelopment
a) remodeling of the chambers
b) development of the septa and valves
The most commom ASD is?
a PFO
Blood is shunted from the Foramen Ovale into the Left atrium causing CYANOSIS
What forms from he foramen ovale structurally closing?
Oval Fossa
ARTERIES
3 VATELLINE Arteries
a) pass to yolk sac and primitive gut
b) Remain as:
1-celiac artery to the foregut
2-superior mesenteric artery to the Midgut
3- Inferior Mesenteric artery to the hindgut
WHen does the Formen Ovale functionally close?
after birth
What valve is the Left AV Valve?
Bicuspid
Septum Primum
Divides the atria into the right and left side
Ability of the heart to change force and change stroke volume in response to changes to venous retrun is
Frank Starling Mechanism
Cushions conribute to the formation of which valves?
Mitral and tricuspid
Why does heart rate decrease with maturity?
PARAsympathetic nervous system is taking over
WHich arch forms/supplies blood for the right and left PA’s?
6th
Development of Aortic Arches
1- 4th week-pharngeal arches develop arches 1-4 an 6 (there is no 5)
These arches give rise to
1-Mandible
2-Pharnyx
3-middle ear bones
4-hyoid bone
5-muscles of the head and neck
2- Each pharngeal arch contain an artery that is called the “Aortic Artery” (comes of the dorsal part of the aorta)
because the myocardial contractility is altered in the NN
will rely more on increasing the heart RATE than the stroke volume to increase cardiac output
Review of Coronary Vessels
1-Begin at the 5th week
2-the coronary vessels are a structure-like islands
3-Arise from epicardium
4-during 5th & 6th Week, the capillaries connect forming coronary veins and coronary arteries that grow off the aorta
Sinus Venosus ASD occurs where?
Very HIGH, near the Superior Vena Cava
when do coronary vessles form?
Beginning of 5th week
Endocardial cushions also contribute to the….
septa of the hears
What is the opening in the Deptum Primum?
Foramen Ostium
Which Umbilical Vein actually forms to make the UV?
The LEFT UV
What determines the heart rate?
Depolarization of the SA node
Coarc review
Coarc is locatedDistal to the origin of the left Subclavian Artery at entrance of the ductus arterosis
Is classified as “preductal or postdutal”
However, 90% of the time the coarc is directly opposite of the ductus arteriosis, so most of the time we have a juxtaductal coarc
Occurs twice as often in MALES
Associated with bicuspid aortic valve in 70% of cases
Fetal Circulation before birth
Foramen Ovale allows most oxygenated blood entering Right Atrium from the Inferior Vena Cava to pass into the Left Atrium and prevent passage of blood in the opposite direction
Inferior Vena Cava
SUPRAcardinal vein continue to develop part of the IVC
