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SMP - Cardiopulmonary Exam 1 > Lectures 1 & 2 - Embryology of the Cardiovascular System > Flashcards

Lectures 1 & 2 - Embryology of the Cardiovascular System Flashcards

1
Q

Describe the shape of embryos.

A

C-shaped curved bodies in varying age-dependent degrees (especially in the first 2 months)

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2
Q

Where is the face of an embryo located at first? How does this evolve?

A

It faces the heart and then as the neck develops, the face will erect

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3
Q

Is there a standard reference position for embryos like the anatomical position?

A

NOPE

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4
Q

Cranial side of embryo?

A

Toward back of head

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5
Q

Caudal side of embryo?

A

Toward lower limbs

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6
Q

Dorsal side of embryo?

A

Toward the back

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7
Q

Ventral side of embryo?

A

Toward the front

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8
Q

What are the 2 axes of embryos?

A
  1. Cranial/caudal

2. Ventral/dorsal

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9
Q

What is the anterior portion of the embryo?

A

Same as cranial

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10
Q

What is the anterior portion of the adult?

A

Same as ventral

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11
Q

What is the posterior portion of the embryo?

A

Same as caudal

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12
Q

What is the posterior portion of the adult?

A

Same as dorsal

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13
Q

What is the inferior portion of an embryo?

A

Same as ventral

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14
Q

What is the superior portion of an embryo?

A

Same as dorsal

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15
Q

Describe the axis seen via an adult MRI.

A

Feet coming at you

Head inside the picture

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16
Q

Describe the axis seen via an embryonic microscopy section? What is important to note?

A

Cranial side coming at you
Caudal side inside the picture

Note: the dorsal side is SUPERIOR to the ventral side

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17
Q

Where is the heart located inside the body?

A

In the center of the thorax with its apex to the left side.

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18
Q

Where is the aorta located relative to the heart?

A

Up towards the head, near the vertebral column-encased spinal cord/neural tube

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19
Q

Where are the atria and ventricles of the heart located?

A
  1. Ventricles: most inferior and anterior

2. Atria: most superior and posterior

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20
Q

How does the zygote receive nutrition prior to implantation? What is the rate dependent on?

A

By diffusion
Rate of diffusion dependent on surface area available between the egg and the environment AND the efficiency of the exchange mechanism

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21
Q

Describe the 7 steps from ovulation to implantation.

A
  1. Unfertilized ovum in metaphase II is released from the ovary into the ampulla
  2. Ovum resides in ampulla for 2/3 days
  3. Fertilization by sperm to give zygote
  4. Cleavage divisions without new cytoplasm
  5. Zygote with 64-128 cells enters uterus => morula
  6. Fluid filled cavity develops in morula => blastocyst
  7. Implantation into uterine wall
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22
Q

What is the largest cell in the body?

A

Ovum

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23
Q

What is the smallest cell in the body?

A

Sperm

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24
Q

What is the purpose of the cavity formation in the morula to give the blastocyst?

A

Diffusion of nutrients is too difficult and becomes less efficient due to the high number of cells in the morula

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25
Q

What part of the blastocyst gives rise to the embryo proper?

A

Inner cell mass

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26
Q

What part of the blastocyst gives rise to the placenta and fetal membranes?

A

Trophoblast

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27
Q

What happens to the trophoblast as it enters the uterine wall during implantation? What is this called?

A
  1. Invasive and multinucleated cells lose their plasma membranes and form the syncyotrophoblast as it enters the uterine epithelium
  2. Trophoblastic lacunae develop
  3. The edge of the syncytiotrophoblast erodes into some of the maternal blood vessels and the blood in them fills the lacunae which act like sponges
  4. Differential pressure levels in the lacunae will cause blood to wash through the lacunae and back into maternal veins in the uterine wall = uteroplacental circulation
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28
Q

What is the zygote mostly composed of during implantation?

A

Extraembryonic tissue

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29
Q

Describe the composition of the blastocyst with relative positions.

A

Inner cell mass located eccentrically close to the uterine wall within a sphere of trophoblast

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30
Q

What are the maternal sinusoids?

A

Maternal vessels in the uterine wall

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31
Q

How many days post-fertilization do the trophoblastic lacunae fill up with maternal blood?

A

13-14

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32
Q

Compare diffusion to uteroplacental circulation.

A

Uteroplacental circulation is more efficient than simple diffusion, but it will not be good enough to support the development of the rapidly growing embryo because very sluggish

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33
Q

Is the uteroplacental circulation made up ENTIRELY of maternal blood?

A

YUP

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34
Q

How many days post-fertilization will you be able to see flow via doppler ultrasound?

A

10th week

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35
Q

When does uteroplacental circulation begin relative to the embryonic CV system development?

A

BEFORE

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36
Q

How many days post-fertilization do germ layers form?

A

13-14

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37
Q

What cavities do the epiblast and hypoblast form?

A
  1. Epiblast: amniotic cavity

2. Hypoblast: yolk sac

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38
Q

What does the inner cell mass develop into?

A
  1. Epiblast

2. Hypoblast

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39
Q

What happens during gastrulation? 5 steps

A
  1. Epiblast cells on the central axis begin proliferating (dividing like cray)
  2. Primitive streak forms.
  3. Cells in neighboring area proliferate rapidly and migrate into the primitive groove and pit
  4. Epiblast cells move inferiorly (ingression) and spread laterally pushing the hypoblast cells to the side (which degenerate) and replacing them to form the endoderm. As they ingress they undergo major structural, physiological, and organizational changes
  5. Once the bottom layer is replaced, another layer of epiblast cells slide in between the top and bottom layers to form the mesoderm. The top layer is the ectoderm
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40
Q

What develops diametrically opposite the primitive streak during gastrulation?

A

Oral pharyngeal membrane

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41
Q

How is the embryo divided if you draw a line from the primitive streak to the oral pharyngeal membrane?

A

Right/left axis

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42
Q

Where is the previously oral pharyngeal membrane found in adults?

A

Back of throat at point of gag reflex

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43
Q

What are the 3 parts of the germ disk?

A
  1. Buccophyaryngeal membrane
  2. Cloacal membrane
  3. Primitive streak
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44
Q

What is fused at both the buccopharyngeal and cloacal membranes?

A

Epiblast and hypoblast

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45
Q

What part of the amniotic cavity becomes the membrane between the primitive mouth and the pharynx?

A

Buccopharyngeal membrane

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46
Q

What part of the amniotic cavity becomes the anus?

A

Cloacal membrane

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47
Q

During what 2 stages of embryonic development does heart induction occur?

A
  1. Pre-streak stage

2. Ingression stage

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48
Q

Describe the formation of the notochord (4 steps)

A
  1. Once all 3 germ layers have formed, cells from the mesoderm migrate through the primitive node to the cranial end of the bilaminar disk and create a tubular structure = notochordal process
  2. The notochordal process advances caudally to the prechordal plate
  3. The floor of the notochord process fuses with the endoderm bringing it in contact with the underlying yolk sac fluids (full of micro-RNA). The notochordal process becomes the notochordal plate in this state (with the neurenteric canal under it)
  4. The proliferating cells create a solid mass of notochordal cells called the definitive notochord
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49
Q

What are the 3 parts of the mesoderm that differentiate during notochord process formation?

A
  1. Paraxial
  2. Intermediate
  3. Lateral plate
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50
Q

What does a portion of the hypoblast develop into? Which part?

A

Anterior visceral endoderm - piece of the oropharyngeal membrane closest to the prechordal plate

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51
Q

What signals the development of the cardiac mesoderm?

A
  1. Fibroblast growth factor 8 (FGF8) released by anterior visceral endoderm onto anterior mesoderm
  2. Retinoic acid gradient produced by the anterior visceral endoderm
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52
Q

Where is the prechordal plate? What germ layer is it made of?

A

Cranial to the notochordal process

Mesoderm

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53
Q

How is the prechordal plate formed?

A

By signals sent from the orapharyngeal membrane and the caudal end of the notochord

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54
Q

What is the difference between the prechordal plate and the prochordal plate?

A
  1. Prechordal plate = portion of mesoderm to the cranial side of the notochord
  2. Prochordal plate = oropharyngeal membrane
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55
Q

Describe the relationships between the anterior visceral endoderm, the prechordal plate, the oropharyngeal membrane, and the notochord.

A

Similar to billiard game:

  • Notochord = cue stick
  • Oropharyngeal membrane with fused epiblast and hypoblast = cue ball
  • Anterior visceral endoderm = part of the hypoblast of the oropharyngeal membrane closest to the notochord (most caudal)
  • Prechordal plate = portion of mesoderm to the cranial side of the notochord (tip of the cue stick)
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56
Q

Describe the 3 steps of the establishment of the heart field through geospatial migration.

A
  1. As mesodermal cells ingress at different locations through the primitive streak, they migrate through areas of different retinoic acid concentrations and for different amounts of time, which primes them to receive inductive signals that determine them to become portions of the developing heart and circulatory system: cells that ingress near the cranial end of the primitive streak develop into the outflow tract; those ingressing in mid-streak develop into ventricle; and those that ingress more caudally become atrium
  2. These ingressed cells assemble in a horseshoe shape around the anterior visceral endoderm and cranial end of the primitive streak = cardiogenic plate
  3. A second area of cells migrates from the inferior pharynx to occupy the concave rim of the cardiogenic plate = secondary heart field
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57
Q

What is the source of the retinoic acid inductive signals during the establishment of the heart field? How?

A

Anterior visceral endoderm

By converting retinol (vitamin A) into retinoic acid to form a retinoic acid gradient

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58
Q

Where is the cardiogenic plate located relative to the neural plate and overall embryo? What is it made of?

A

Splachnopleuric mesoderm and is subjacent and anterior to the neural plate, at the cephalic end of the embryo

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59
Q

Where is the highest concentration of retinoic acid found in the mesoderm?

A

Closest to the anterior visceral endoderm

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60
Q

Where do early embryonic blood vessels/blood develop first?

A

Yolk sac wall + some in connecting stalk and allantois

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61
Q

What are the 2 mechanisms of blood vessel network establishment? Which one is most used?

A
  1. Vasculogenesis
  2. Angiogenesis

Most of the time: combination of the 2

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62
Q

Describe vasculogenesis.

A

Blood islands form in the extraembryonic mesenchyme of the yolk sac and clump together and condense to form a vessel:

  • Middle cells slough off to become nucleated blood cells
  • Outside cells become the lining of the blood vessels aka endothelial cells
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63
Q

What is mesenchyme?

A

Loosely organized, mainly mesodermal embryonic tissue that develops into connective and skeletal tissues, including blood and lymph.

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64
Q

Are the first embryonic blood vessels intra or extraembryonic?

A

EXTRAembryonic

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65
Q

What is the difference between vasculogenesis and angiogenesis?

A

Vasculogenesis = differentiation of cells from mesenchyme to endothelial and blood cells to produce blood vessels where non existed

Angiogenesis = sprouting of buds from pre-existing vessels

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66
Q

Describe angiogenesis.

A

Either the sprouting of buds from pre-existing vessels OR splitting of a pre-existing blood vessel into two

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67
Q

Do angiogenesis and vasculogenesis also happen in adults?

A

YUP BUT in vasculogenesis the middle cells will not become blood cells

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68
Q

What type of cells undergo vasculogenesis and angiogenesis?

A

Mesoderm cells

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69
Q

What type of cells make up blood vessels?

A

Endothelial cells

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70
Q

When do blood islands start to form in the embryo?

A

Couple days after formation in extraembryonic mesoderm

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71
Q

From what mesoderm does the heart develop from?

A

Splanchnic mesoderm of the lateral plate mesoderm

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72
Q

What is another name for splanchnic mesoderm?

A

Visceral mesoderm

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73
Q

What is splanchnopleuric mesoderm?

A

Mesoderm related to the wall of the gut

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74
Q

Where is the splanchnic mesoderm located relative to the presumptive brain before folding?

A

Anterior

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75
Q

Describe the 2 axes of folding of the lateral plate mesoderm. When does each take place relative to the other? Overall result?

A
  1. Cephalocaudal folding: brings the cardiovascular tube inferior to the head, more ventrally
  2. Lateral folding: brings the endocardial tubes together to fuse

Take place simultaneously

RESULT = X-shaped structure with a single midline that diverges into 2 laterally extending vessels on the caudal side (the presumptive venous return) and 2 on the cranial side (the presumptive outflow tract)

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76
Q

What are the nerves that stream downwards from the brain stem to the heart a result of?

A

Cephalocaudal folding

77
Q

Which 2 structures curve during cephalocaudal folding?

A

Paired primitive aortae which stay dorsal near the vertebral column

78
Q

Which 2 structures do not bend during cephalocaudal folding?

A

Paired endocardial tubes

79
Q

Where do the paired endocardial tubes remain during cephalocaudal folding?

A

Remain parallel to the neural tube

80
Q

What causes cephalocaudal folding?

A

Amniotic cavity grows faster than the yolk sac

81
Q

What do the paired endorcardial tubes form from?

A

Middle of the C shaped cardiogenic plate

82
Q

What happens to the paired endocardial tubes during lateral folding of the embryo?

A

They FUSE to become the cardiac tube at the midline aka the future HEART

83
Q

What do the aortic arches develop from?

A

From the bends from the dorsal aortae being pulled ventrally during cephalocaudal folding

84
Q

What is the truncus arteriosus?

A

Segment that connects the embryonic heart to the aortic arches

85
Q

What is the bulbus cordis?

A

Swelling of the embryonic heart inferior to the truncus arteriosus

86
Q

Describe the structure of the embryonic heart around day 22-23 post-fertilization (aka after the 2 foldings have occurred). Indicate the fate of each structure.

A

From cranial to caudal:

  1. Aortic arches: vessels
  2. Truncus arteriosus: ascending aorta and the pulmonary trunk
  3. Bulbus cordis: proximal region: right ventricle and smooth parts of left ventricle/distal region: outflow tract
  4. Primitive ventricle: left ventricle and trabeculated portion of the right ventricle
  5. Atrium: rough right and left atria (seen as auricles in adults)
  6. Sinus venosus: smooth RA wall (right one) and coronary sinus (left one)
87
Q

Purpose of sinus venosus in embryonic heart?

A

Brings blood to the heart from a number of veins:

  1. Umbilical veins from placenta
  2. Vitelline veins from yolk sac (eventually the gut tube)
  3. Cardinal veins from the body wall and head
88
Q

If the embryonic blood was going in only one direction in the heart tube prior to looping, describe its path.

A

Body => sinus venosus => atrium => primitive ventricle => bulbus cordis => truncus arteriosus => aortic arches => dorsal aortae => around the body

89
Q

Is the cardiovascular tube (after 2 embryonic foldings) anchored to the thorax?

A

Anchored at 2 points (where cranial and caudal tubes diverge) but mostly free-floating in the coelom

90
Q

Describe the looping of the embryonic heart tube. When does this happen?

A

The heart tube is growing a little faster than the coelom expands so as the tube gets longer it is forced to bend with:

  1. Sinus venosus shifts cephalically posterior to the ventricle and to the right, bringing the atrium with it
  2. Primitive ventricle moves anterior, to the left, and caudal
91
Q

What is another name for the embryonic heart tube?

A

Cardiovascular tube

92
Q

Where are the inflow and outflow tracts of the embryonic heart located after looping?

A

Cranially and posteriorly

93
Q

How is kinking of the cardiac tube avoided during looping?

A

The thick walls of the tube contain cardiac jelly which contains hyaluronic acid which absorbs water

94
Q

What is hyaluronic acid? 2 names

A

Mucopolysaccharide = glycosaminoglycan

95
Q

What is hyaluronic acid used for nowadays?

A

To plump up lips

96
Q

What will eventually replace the cardiac jelly?

A

Cardiac muscles

97
Q

Do all of the embryonic valves and septums develop simultaneously?

A

YUP

98
Q

Describe the process of atrial separation.

A
  1. Bulbus cordis/truncus arteriosus lean on the atrium forming the left and right atria
  2. This leaning causes a bend in the roof of the atria
  3. Septum primum grows from the posterior/superior wall to the inferior/anterior border and an orifice remains open between the two presumptive atria
  4. The hole, the ostium primum gets smaller and smaller
  5. Most of the blood returning from the body does so from the placenta via the IVC, which points toward the septum primum and this causes cell death in this area = new opening forms, the ostium secundum, and gets larger and larger
  6. Septum secundum grows down from anterior wall but does not anchor to the posterior/inferior wall, so an aperture remains
99
Q

What are the the septum primum and secundum?

A

Endocardium in sickle-shaped structures

100
Q

Which embryo heart cavity receives very little blood? Why?

A

Left atrium since the lungs are not functioning

101
Q

What is a “blue baby” caused by? Explain.

A

Incomplete development of the interatrial septum = too much unoxygenated blood from the right atrium passes to the left atrium and then to the rest of the body making the baby look blue

102
Q

Where are both the ostium primum and secundum located?

A

The septum primum

103
Q

Which is thicker: septum primum or secundum? What are the implications of this?

A

Septum secundum

When pressure in the left atrium becomes larger than in the right, blood in the left atrium pushes the flimsy septum primum against the firm septum secundum, and blood cannot flow from the left to the right (foramen ovale is now closed) = this happens with breathing at birth

104
Q

What is the embryonic foramen ovale? What do we call this?

A

Right to left shunt between atria in embryonic heart through which blood passes: right atrium => aperture in septum secundum => ostium secundum => left atrium

=> Flutter valve

105
Q

What happens to the sinus venosus? What is this called?

A
  1. Right sinus venosus: gets absorbed by the right atrium wall = intussusception
  2. Left sinus venosus: forms adult coronary sinus
106
Q

What is the adult coronary sinus?

A

Dumping spot for the coronary veins to drain into the right atrium

107
Q

Describe the intussusception happening in the left atrium.

A

Left atrium incorporates the pulmonary vein which has 4 branches forming 4 openings => form the smooth wall of the LA

108
Q

Where is intussusception also seen in the body other than in embryonic heart development?

A

Gut tube: oral portion is “swallowed” by aboral portion

109
Q

What takes up most of the posterior thorax space?

A

Lungs

110
Q

What is the coelom?

A

Presumptive pericardial cavity

111
Q

What do we call the vestige of the foramen ovale?

A

Fossa ovalis

112
Q

What do we call the vestige of the embryonic atria?

A

Auricles

113
Q

Describe the atrioventricular separation.

A

Atrial floor narrows by shifting endocardial cushions to form an H like structure: rung of the H is obliterated, resulting in 2 atrioventricular orifices leading to each ventricle

114
Q

Describe the proliferation and differentiation of the endocardial cushions.

A

Tissue furthest from the lumen, the epimyocardium, secretes adherons in the cardiac jelly, which stimulate cells of the endocardium lining the lumen to migrate into the cardiac jelly and become the mesenchymal cells of the endocardial cushions

115
Q

What are adherons?

A

BIG (seen with naked eye) particles that contain vasoactive compounds: TGF-beta, fibronectins, proteoglycans, and other inductive signals

116
Q

Describe the composition of the heart tube of embryos.

A
  1. Inner layer: endocardium
  2. Middle layer: myocardium
  3. Outer layer: epimyocardium
  4. Gelatinous material in between myocardium and endocardium: cardiac jelly
117
Q

Which organ is the first to function in embryologic development? When?

A

Cardiovascular system at 23 days post-fertilization with irregular heart beat

118
Q

What are the 3 types of cardiac tissue? List from outer to inner.

A
  1. Epicardium
  2. Myocardium
  3. Endocardium
119
Q

What is endocardium tissue continuous with?

A

Endothelium lining blood vessels

120
Q

What is a probe-patent foramen ovale? In what % of people is this seen?

A

The foramen ovale will re-open after birth if pressure is applied to it (can allegedly save the life of people with congestive heart failure)

25%

121
Q

Describe interventricular separation.

A
  1. The muscular interventricular septum arises at the juncture of the bulbus cordis and the primitive ventricle at a ripple that is slightly medial to where blood is traveling to get out of the heart (a little to the left to the base of the bulbus cordis)
  2. As the ventricles expand with increased amount of blood, their walls elaborate polyglycans that are very sticky and so as they enlarge the apposition of the walls of the ventricles grows the MUSCULAR interventricular septum
122
Q

What are the dorsal aortae and the heart separated by in the embryo?

A

Pharynx

123
Q

What are the 2 needed events to finalize the outflow tract of the embryo’s heart?

A
  1. Complete the muscular interventricular septum

2. Separate the aortic and pulmonary vessels

124
Q

What 2 cell populations contribute to the formation of the outflow tract?

A
  1. Cells from secondary heart field

2. Neural crest cells

125
Q

Describe how the cells from the secondary heart field contribute to the outflow tract of the embryonic heart.

A
  1. Cells are kept in undifferentiated state by canonical Wnt’s
  2. As the cardiac looping completes, the non-canonical Wnt’s from the pharynx stimulate their differentiation to signal them to migrate, accumulate, and divide within the walls of the outflow tract (right ventricle, bulbus cordis, and truncus arteriosus)
126
Q

When do malformations of the primary heart field occur relative to those of secondary heart field?

A

Early in development vs late in development

127
Q

Describe how the neural crest cells contribute to the outflow tract of the embryonic heart.

A

Cells migrate through the aortic arches and stimulate the formation of the membranous interventricular septum and the clockwise-oriented spiral aorticopulmonary septum

128
Q

Where do the neural crest cells originate?

A

The hindbrain

129
Q

What are the 2 parts of the interventricular septum? How is each formed?

A
  1. Muscular from apposition of adjacent ventricle walls

2. Membranous from migrating neural crest cells

130
Q

Describe the formation of the atrioventricular valves.

A
  • The epithelium connecting the ventricles to the atria is thickened = dense mesenchyme and there are holes in the walls of the ventricles that get larger and free this dense mesenchyme to form the chordae tendineae which cover the eroded muscle walls
  • Leaflet of valves is formed by the dense mesenchyme at the atrium-ventricle border
  • Papillary muscles anchor the chordae tendineae to the ventricular wall
131
Q

How do the atrioventricular valves prevent blood backflow into the atria?

A

The papillary muscles contract with each heart beat to keep the valves close

132
Q

What are the embryonic aortic arches?

A

Connections between ventral and dorsal aortas in the head region

133
Q

How many aortic arches do humans have?

A

5 (1, 2, 3, 4, 6)

134
Q

Do all aortic arches exist at the same time in the developing embryo? Provide an example

A

NOPE

As aortic arch III appears, aortic arch I starts to disappear

135
Q

Do the aortic arches form symmetric vessels on the right and left sides of the body?

A

NOPE

136
Q

Aortic arch I: right and left side derivatives?

A
  1. Right: maxillary artery

2. Left: maxillary artery

137
Q

Aortic arch II: right and left side derivatives?

A

Right AND left: hyoid and stapedial arteries

138
Q

What happens to stapedial arteries eventually?

A

They disappear

139
Q

Aortic arch III: right and left side derivatives?

A

Right AND left: common carotid artery (proximal arch) and internal carotid artery (distal arch)

140
Q

Aortic arch IV: right and left side derivatives?

A
  1. Right: proximal right subclavian artery

2. Left: medial portion of the aortic arch

141
Q

Aortic arch VI: right and left side derivatives?

A
  1. Right: right pulmonary artery

2. Left: left pulmonary artery + ductus arteriosus

142
Q

Ventral aorta cranial to aortic arch III: right and left side derivatives?

A

Right AND left: external carotid artery

143
Q

Ventral aorta between arches III and IV: right and left side derivatives?

A

Right AND left: common carotid artery

144
Q

Ventral aorta between arches IV and VI: right and left side derivatives?

A
  1. Right: brachiocephalic artery

2. Left: ascending aorta

145
Q

Dorsal aorta cranial to aortic arch III: right and left side derivatives?

A

Right AND left: internal carotid artery

146
Q

Dorsal aorta between arches III and IV: right and left side derivatives?

A

Both disappear with growth of neck

147
Q

Dorsal aorta between arches IV and VI: right and left side derivatives?

A
  1. Right: central right subclavian artery

2. Left: descending aorta

148
Q

Dorsal aorta caudal to arch VI: right and left side derivatives?

A
  1. Right: disappears

2. Left: descending aorta

149
Q

What does the space between the dorsal and ventral aortas give rise to?

A

Vessels

150
Q

Which is more variable: arterial or venous distribution of vessels? Why?

A

Venous because lower pressure

151
Q

At what aortic arch boundary does the branch point between head and trunk occur?

A

Arches III and IV

152
Q

What is the main venous drainage of the body?

A

Anterior and posterior cardinal veins

153
Q

What happens to the umbilical veins in adults?

A

They become ligaments

154
Q

What veins give rise to the superior and inferior mesenteric veins?

A

The vitelline veins

155
Q

Describe the pathway of fetal circulation.

A

Placenta => umbilical vein => ductus venosus (bypassing the liver) => mixing of blood in inferior vena cava => right atrium => foramen ovale => left atrium => left ventricle => fetus body => dorsal aorta => umbilical arteries => placenta

156
Q

Does any blood enter the right ventricle in fetal circulation? If so, what happens to it?

A

Yes, a small amount:

  • 90% of it is pushed back into systemic circulation through the ductus arteriosus connecting the pulmonary trunk to the aortic arch
  • 10% of it goes to pulmonary vasculature to support fetal lung development
157
Q

What happens to the ductus arteriosus at birth?

A

Oxygen and endothelin (vasoconstrictors) functionally close it up after 48-96 hours (full anatomical closing occurs over next 1-3 months)

158
Q

What keep the ductus arteriosus open (aka patent) during embryologic development?

A

High levels of prostaglandins E2 and I2 (vasodilators) from the DA smooth muscle and placenta

159
Q

Describe the cardiovascular pathway post-birth.

A

Right atrium => tricuspid valve => right ventricle => pulmonary valve => pulmonary trunk => right and left pulmonary arteries => right and left lungs alveolar capillaries => 4 pulmonary veins => left atrium => mitral valve => left ventricle => aortic valve => aorta => capillary beds of all body tissues where gas exchange occurs => superior and inferior vena cavae and coronary sinus => right atrium

160
Q

What % of babies are born with malformations? What % of babies are born with heart malformations?

A

5-7% born with major and minor malformation

1% born with heart malformations

161
Q

What % of stillbirths born with heart malformations?

A

10%

162
Q

What is the most common cardiac malformation?

A

Ventricular septal defects (40%): most of them membranous defects that close spontaneously in the first year of life

163
Q

What are the 4 categories of cardiac malformations? Include %

A
  1. Septal defects: 50%
  2. Outflow tract defects: 8%
  3. Valvular defects: 5%
  4. Late gestation defects: 12%
164
Q

What are the 2 septal defects?

A
  1. Ventricular septum defect (membranous)

2. Atrial septum defect (foramen ovale open)

165
Q

What are the 3 outflow tract defects?

A
  1. Persistent truncus arteriosus
  2. Transposition of great vessels
  3. Tetralogy of Fallot
166
Q

What is the defect transposition of great vessels? Is this fatal?

A

Spiral septum spiraled the wrong way and the only mixing occurs at the ductus arteriosus

FATAL, unless there is an IV septal defect

167
Q

What is tetralogy of Fallot?

A
  1. Overriding aorta: spiral septum did not separate the outflow tract evenly
  2. Pulmonary stenosis
  3. Right ventricular hypertrophy (due to stenosed pulmonary trunk)
  4. Membranous interventricular septal defect
168
Q

What is the heart called in an X-ray of a patient with tetralogy of Fallot patients?

A

Coeur en sabot

169
Q

What position do children with tetralogy of Fallot often do? Why?

A

Crouch because it compresses the femoral vessels in the thigh to increase pressure in the left ventricle and reduces the right to left shunt + ameliorates dyspnea

170
Q

What is a potential cause of tetralogy of Fallot?

A

Low VEGF = vascular endothelial growth factor

171
Q

What is a potential amelioration treatment for tetralogy of Fallot?

A

Periconceptual vitamins

172
Q

What are the 2 valvular defects?

A
  1. Tricuspid atresia

2. Pulmonary valvular stenosis

173
Q

What is tricuspid atresia? Fatal?

A

Absence of formation of the tricuspid valve, preventing the right ventricle from pumping blood to pulmonary circulation so blood from the right atrium goes through foramen ovale and from the left ventricle to the right via a defective IV septum

174
Q

What is pulmonary valvular stenosis?

A

Pulmonary valve is too small leading to right ventricle hypertrophy

More details TBD

175
Q

What are the 2 late gestational cardiac defects?

A
  1. Persistent ductus arteriosus

2. Coarctation of the aorta

176
Q

What is coarctation of the aorta?

A

When the ductus arteriosus closes down it stimulates part of the aorta to narrow

177
Q

Where does the endothelin to close the ductus arteriosus come from?

A

O2 rise causes release from DA endothelium

178
Q

What do we call the vestige of the ductus arteriosus?

A

Ligamentum arteriosum

179
Q

When does the heart tube appear?

A

20 days post-fertilization

180
Q

When have both the foldings and looping of the heart happened?

A

23 days post-fertilization

181
Q

What does TGF-beta stand for?

A

Transforming growth factor beta

182
Q

Do the zygote, morula, and blastocyst all obtain their nutrition from diffusion?

A

Yup

183
Q

Describe the development of the aortic arches.

A

Connection between the dorsal aorta (from fused dorsal aortae) and the ventral aorta (connected to the truncus arteriosus) on either side of the pharynx starting with 1 and ending with 6

184
Q

What 2 aortic arches are the only 2 to undergo asymmetric development?

A

Aortic arches IV and VI

185
Q

What are 3 other names for the cardiogenic plate?

A

= primary heart field = cardiac crescent = angiogenetic cell clusters

186
Q

What do we call the ductus venosus at birth?

A

Ligamentum venosum

187
Q

What do we call the umbilical vein at birth?

A

Ligamentum teres

188
Q

Describe persistent truncus arteriosus.

A

No membranous IV septum and no spiral septum resulting in mixing of blood in both pulmonary trunk and aorta and ventricles

SMP - Cardiopulmonary Exam 1 (28 decks)

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