CP1 & CP2 - Cardio Embryology lecture notes Flashcards
how common are birth defects?
1% of live births have a heart defect
how many cells divisions does the zygote undergo
It can divide to form about 64-128 cells (6-7 divisions)
What is a morula
- from latin word for mulberry
- 32-64 cell stage
- Cells in the middle are at a disadvantage as far as getting nutrients in
what is a blastocyst?
why does it form?
- Group of cells that form a sphere with cavity on the inside.
- the cells need to be near the periphery to be able to access nutrients
inner cell mass becomes
most of the embryo
syncitium is a ____
It begins to invade the endometrium on what day?
-structure that has many nuclei due to the fact that the cells that have lost their cell membrane
5-6 days after fertilization
spotting may happen on what day?
why is this clinically relevant?
14-15 day, Woman may not know she is pregnant until “2nd missed period”
- This is clinically important because important developmental stages occur by this time.
when does uteroplacental circulation form
within the first 2 weeks
what happens on day 23
- heart cells begin to contract (heartbeat)
- there will be a lumen
- if any fluid there, it will be sloshing around
hypoblast cells induce what tissue early in development:
What does the induced part eventually become?
the tissues about it to become epiblast
-This becomes most of the embryo
What is the primitive streak
- it gives us an axis of right/left symmetry
- line where epiblast cells will ingress into to the other side and make the mesodermal cells
what does the mesoderm form?
-bone, muscle, heart, blood
what is the primitive node
- the anterior portion of the primitive streak
- some cells that will ingress through primitive node and will go directly anterior to the AVE
know difference between precordal plate and prochoradal plate
Prechordal plate - area between prochordal plate and notochord ( also helps induce primary migration cells)
Prochordal plate - orophraryngeal membrane.
- AVE is located in the orophraryngeal membrane and induces migrating cells (primary)
“a small area immediately rostral to the cephalic tip of the notochord where ectoderm and endoderm are in contact; when turned under the growing head, it forms the buccopharyngeal membrane.”
what does the region anterior to the primitive node produce?
retinoic acid
The anterior visceral endoderm gets its message to differentiate and then what happens?
-It is able to produce its own signals after this and induce the formation of the head and the heart
retinoic acid
- comes from the region anterior to the primitive node (continually made)
- diffusion leads to a gradient
what does different conc. of retinoic acid lead to
different fates for cells that ingress from different areas of the primitive streak (fate mapping)
How many migrations are there?
what is the first migration gives you___
There are more than one.
the anterior/primary heart field
what is the 2nd cell migration
These contribute to the atria
all models are wrong, but some modles are useful
where does the blood develop?
where?
- Primarily in the extraembryonic region
- It is primarily in the yolk sac
What is vasculogenesis?
What are these aggregation of cells called?
The development of blood vessels from a condensation of mesenchyme.
- mesoderm cells clump together
- angiogenic cells clusters (bad name!, because they occur in vasculogenensis)
What is angiogenesis?
In what pathological disorder does this take place?
The sprouting of new blood vessels from preexisting ones
-happens when you’re developing a tumor
splanchopleure
- involved with guts
- involved with the internal part of the body like the intestines, lungs, stomach and the heart
somatopleure
-involved with skin, connective tissue of the limbs (“…and all that stuff”)
heart develops where?
Why is this specific location important?
in the deep portion of the mesoderm
-This explains why teh e[ricardium is where it is
Do angiogenesis or vasculogenesis happen in the embryo?
Combination of the 2 happens in embryo
cephalocaudal folding
- curved area of heart tube folds forward to inferior ventral position
- The embryo begins to curl around the developing yolk sac
- Heart was anterior and vertebral column was posterior, but after this you wind up with a heart that is ventrally located and inferior to the head
what is the “hinge”
Oralpharyngeal membrane
dorsal aortas are associated with
vertebral column
folding lead to multiple aortas how?
folding and after you cut cross-section you see 4 aortas
lateral folding
brings curve to the midline where they fuse (Fusion of heart tubes)
Since the heart tube grows more rapidly that the rest of the embryo, what happens to it?
why does this happen?
How does this happen?
- bound by pericardial sac which joins everything posterior to the heart.
- it folds on itself
- Venous portion grows faster and appears that it is moving cephalically and to the right.
- tube folds toward the left
what is the cavity that holds the developing heart called?
pericardial cavity
blood in heart tube travels
- comes from inferior up (through 5 pieces)
- blood comes from sinus venosus on 2 sides, then it goes through the embryonic atrium, tehn through the embryonic ventricle, then through the bulbus cordis, and teh out through the truncus arteriosus
what happens to venous return position
venous return and atria moves posteriorly and superiorly.
walls of the tube have what thickness and what substance
They are thick and have cardiac jelly (prevent kinks)
What does connective tissue have that prevents kinks?
- stuff in between the cells called brown substance or ECM material, etc
- This is usually composed of fibers like collagen and liquid
- liquid is in this molecule called hyaluronic acid
- HA is like a sponge and has the shape of a feather. and it holds things in shape.
what is the atrioventricular canal
connects atria to ventricles (before atrial and ventricular septums develop)
From where does the septum primum develop?
from the place where the outflow tract is
- 1st septa grows from what to what?
- what is it called?
- From posterior wall of the atrium down tot he anterior wall
- It looks like a half moon shape and will grow towards the floor
- Septum primum
what is the osteum primum
The opening in the septum primum located anteroinferiorly
- closes eventually as septum primum forms completely
bloodflow from what will be the inferior vena cava causes what
causes flimsy septuum (swiss cheese) to regular septum
Septum secundum
- more substancial, much thicker, forms on right side of septum primum
- grows from anterior to posterior
- has an opening on the growing part and never completes its closes on the posterior wall.
Ostium secondum
- Begins to form as swiss cheese like holes which are opened by blood flow from what will the the inferior vena cava.
osteum secundum of the 2 septa are offset.
what does that cause?
it causes the structure to act as flutter valve, pushing the flimsy septum out of the way.
which is the flimsy septum?
septum primum
at birth the septum primum :
is pushed against the septum secundum, closing the foramen ovale
What is the flutter valve called?
what is it called when is does not seal after birth?
What medical conditions ia probe-patent foramen ovale associated with?
- Foramen ovale
- probe-patent foramen ovale (funtionally closed, but tissues do not fuse)
- higher incidence of migraines, strokes and are more suceptable to altitude sickness
Heart is located where in an adult?
in the center
mostly behind the sternum
looks like a pyramid (4 sided):
- Base is just to the side of the sternum;
- Apex is to the left of it near the nipple and goes to the 4th intercostal space.
- It is asymmetric
what is the convention of how you section an embryo? how about and MRI/cadaver
- looking from head, down
- looking from feet up
what are the most common groups of malformations
cardivascular; many of which are heart malformations
Fertilization occurs where?
the ampullary region of the fallopian/uteran tube
what happens after fertilization?
cleavage divisions
what is released from the ovary
haploid egg
what are blastomeres
- a blastomere is a type of cell produced by cleavage (cell division) of the zygote after fertilization and is an essential part of blastula formation. -Wiki
what is particular about the size of the zygote
it is potentially visible to the naked eye
what does the extraembryonic tissue become?
the placenta, chorion, etc.
In the beginning how much of the embryonic tissue is the embryo proper?
very little of it.
most of it is extraembryonic.
When do lacunae begin to form?
During days 8-10
When do sinusoids begin to become eroded and leak into the lacunae
days 11-13
what does the evidence suggest about when does the strong uteroplacental circulation show up?
that it is not present until the 10th week of gestation
what is the first system to appear?
first to function?
Nervous system appears first
cardivascular system functions first.