2-1-5
Terms
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- True or False: The Early Cardiovascular System is well developed at the FOURTH week.
- True
- What deliever nutrient and O2 rich blood from the placenta to the embryo?
- A pair of umbilical veins
- ________ drain the yolk sac.
- Vitelline Veins
- ________ return venous blood from anterior and posterior parts of the embryo
- Cardinal Veins (anterior and posterior)
- Where is venous blood discharged in early cardiovasc. system?
- into the posterior chamber of the heart known as the Sinus Venosus
- Cardinal veins deliver O2 from _____ and ______ parts of the embryo.
- Ant and Post
- First organ system to become functional and why.
-
Cardiovasc. System (CVS)
- The embyro is growing so fast that diffusion from placenta to embryo is not sufficient to supply O2 and nutrients...circulation must be established to help carry O2. - In the Early CVS, blood is pumped through a series of __________ into the _________ which distributes blood to the ____ and _____ end of the embryo.
-
- Aortic arches
- paired dorsal aorti
- cranial and caudal - ________ arteries supply posterior segments of the body
- Segmental
- In the caudal region, a pair of ________ distribute blood back to placenta for reoxygenation.
- umbilical arteries
- The heart appears at day ____ and begins to beat at day _______.
-
18
21 - The embryo at day 18 is what shape? What comprises this shape?
-
Flat Disc
- 3 germ layers (ecto, endo, mesoderm) - Germ layer of partic. importance in heart development
- Mesoderm
- The ________ mesoderm, which lies adjeacent to the _______, gives rise to the heart.
-
Splanchnic
Endoderm - In 3rd-4th wk, _______ and _______ are paired, and are found adjacent to the splanch. mesoderm
- body cavities and future pericardial cavity
- Within the _________, some cells become arranged into longitudinal cords called __________.
-
Splanchnic Mesoderm
Angioblastic cords - Appearance of _______ is the earliest appearance of the heart.
- Angioblastic cords
- At day _____, the embryonic disc begins to ________ producing a cylindrical embryo.
-
20
fold inward - At day 20, angioblastic cords __________ and form ________.
-
begin to hollow out
endocardial heart tubes - At day 20, _______ begin to approach each other at the ventral midline. Also, the ______begin to approach each other. Further folding produces fusion of the heart tubes to a ________.
-
endocardial heart tubes
the halves of the pericardial cavity
single longitudunal vessell - Day 20, _______ bring the endocard. heart tubes and halves of pericardial coelom
- lateral folds
- At day 22, the _______ are now confluent and surround the ______.
-
2 halves of pericardial pericardial cavites
primordial heart - At day 22, the single heart tube is suspended by _______.
- dorsal mesocardium
- At 28 days, the ________ begin to differentiate and the _________ is formed.
-
- 3 germ layers
- transverse pericardial sinus - At 28 days, the original endocard. heart tubes form the ______, the splanch. mesoderm forms the _______, and the _________ differentiates into the myocardium.
-
- endocardium
- myocardium
- outermost part of splanch. mesoderm - At 28 days, the _________ breaks down and the ________ becomes continuous above and below the heart - so now the heart is only suspended at its _____ and _____ ends.
-
- dorsal mesocardium
- paricardial cavity
- cranial and caudal - In adults, the transverse pericardial sinus separates the _________ of the heart from the __________.
-
- arterial end (pulm. trunk and aorta)
- SVC - The fusion of the endocardial heart tubes occurs in a _____-to-______ sequence.
-
cranial
caudal - 5 primitive chambers of the heart from cranial to caudal:
-
1. sinus venosum
2. primitive atrium
3. prim. ventricle
4. bulbis cordis - just in front of prim. ventricle
5. truncus arteriosus - The _______ and _______ grow faster than the other chambers of the prim. heart causing bending and is referred to as the ______. Such bending brings the ________into a more posterior position
-
bulbus cordis
prim. vent.
bulboventrtricular loop
two caudal chambers (sinus venosus and atrium) - The bulbis cordis will later form what two major structures?
-
aorta
pulm. trunk - Two simultaneous processes in the 4th and 5th weeks
- Atrial and Ventral Septation
- What is the atrioventricular valve?
- opening b.w prim. atrium and prim. ventricle
- Thickenings of tissue on either side of AV canal
- ventral and dorsal endocardial cushions
- The endocard. cushions grow together and fuse which futher divides the _______.
- AVC into rt. and left AVC's
- Give the steps of Atrial Septation:
-
1. Septum primum growns down from roof of primordial atrium creating the border of the ostium primum
2. Ostium primum gets smaller until disappears
3. Complete fusion of sept. primum w/ endocard. cushions
3. Ostium secondundum arises from perforations in ostium primum
4. Forms inside of cranial end of sept. primum.
5. Stops short and doesn't form a complete partition - The septum primum and secondum develop at same/different time?
- same
- The septum secondum basically forms the ______
- interatrial septum
- What does the septum primum do in fetal life?
- Moves back and forth allowing blood to cross b/w the atria
-
HIGH pressure in rt. atrium causes the Sept. Primum to _____.
EQUAL pressure b/w atria causes Sept. Prim. to _____ -
Open
Close - The _________ is the most caudal chamber
- sinus venosus
- Left and Rt. horns of sinus venosus are initially _____, then the _______ recieves more blood and enlarges
-
equal in size
Right Horn - Opening of sinus venosus into atrium shifts from ______ to ______ and will become the ________.
-
central position
the right
rt.atrium - Left horn of sinus venosus will eventually become _____
- coronary sinus
- Right horn of sinus venosus eventually gets incorporated into the wall of the rt atrium as the ______
- sinus venarum (smooth part of wall)
- Rough wall part of rt. atrium (pectinate) derives from the _________ before the __________ was incorporated.
-
Primordial Atrium
Sinus Venosus - What two valves existed where the sinus venosum orginally attached to rt. atrium?
- Rt. and left sinuatrial valves.
- The rt. sinuatrial valves will become the _______ and the left will become _________.
-
- crista terminalis
- incorporated into the interatrial septum - The smooth walled part of the left atrium develops from __________, and the rough part arises from ______.
-
pulmonary vein tissue
primitive atrium itself - The muscular part of the IV septum begins at the _____ and grows _______ towards the ________.
-
apex of heart
caudally
endocard. cushions - Opening b/w the endocard. cushions and muscular septum
- IV foramen
- Three tissues that grow to fuse IV foramen shut:
-
1. Left bulbar ridge
2. Rt. bulbar ridge
3. Upgrowth of endocard. cush. - The ________ will form the membranous part of the IV septum
- endocard. cushion
- Partitioning of the bulbus cordis and truncus arteriosus take place in the ____ and _____ week of development.
- 5th and 6th
- The ridges of the bulbus cordis have a ______ orientation and will slowly grow towards one another turning ________
-
spiral
one chamber into two vessels - Fusion of bulvar ridges creates a septum known as the _______ creating ____ and _____ vessels.
-
aorticopulmonary
anterior and posterior - Rt. ventricle contribution of the ______ is the conus arteriosus and the left ventricle contribution is the ________.
-
promximal bulbus cordis
aortic vestibule - Unequal division of bulbus cordis can result in _____ of pulm. trunk or aorta
- stenosis
- Misalignment of bulbar ridges in bulbus cordis can result in a ______ defect.
- Ventric. septal defect
- ________ produce chordae tendonae.
- cavitation of the walls of ventricles
- T/F: conducting system is fully developed at birth
- false
-
____% of birth defects are cardiac in nature
while of these
2% are _____
8% are _____
and 90% are _______ -
25%
environmental (viruses, etc.)
Genetic (trisomy 18)
Miltifactorial - Types of atrial septal defects:
-
1. Patency of foramen ovale
2. Short septum primum
3. Sept. Secondum can stop short in in its growth
4. Combo of 2 and 3
5. High atrial septal defect (rare)(rt. horn of sinus venosus not properly incorporated into rt. atrium) - Most common ventric. sept. defect is when ____
- memb. part of IV septum does not form properly and allows vent.'s to communicate
-
Embryonic period:
Fetus: -
wks 0-8
Wk 9 to term