Embryology and Development 4 Flashcards
Cardiovascular Respiratory system development
What day does the development of the circulatory system begin?
day 15-16
right after gastrulation
describe the process of how blood vessels form
happens in yolk sac and embryo, but happens faster in yolk sac
- ANGIOBLASTS: mesoderm cells in wall of yolk sac differentiate into angioblasts
- BLOOD ISLANDS: angioblasts proliferate
- ENDOTHELIAL CELLS + BLOOD CELLS: under blood islands, little pockets lined with endothelium appear. Pluripotent cells that create blood proliferate. Inside space is lumen.
- ENDOTHELIAL TUBES: pockets fuse to create tubing networks
role of angioblast cells
build walls of the blood vessels
Does the embryo get its blood supply from its mother?
No! It creates its own.
describe development of the heart
- Day 20: 2 endothelial tubes located in CARDIOGENIC REGION (“heart-genesis”) specialize into ENDOCARDIAL TUBES
- Day 21: these 2 endocardial tubes fuse together to make the PRIMITIVE HEART TUBE with 4 main dilations at day 22
- Day 23: complete fusion and bending (via pericardial cavity)
- contractions (non-neural) begin at end of 3rd week
Name the 4 main dilations of the primitive heart tube and when they form
Day 22
1. Sinus venosus
2. Ventricle
3. Atrium
4. Bulbus cordis
Describe structure and function of endocardial tubes
development starts day 20
- ARTERIAL END: exit point for blood
- VENOUS END: entry point for blood
Describe the process of heart folding, what causes it?
Cause: pericardial cavity
- ventricles move forward and down
- atria move backwards and up
(gotta flip ‘em)
- sinus venosus -> part of R atrium and SA node (pacemaker)
-primitive atria -> L and R atrium - ventricles -> L and R ventricles
- bulbous cordis -> R ventricle, arteries that leave heart
tissue between L and R ventricles in pre-natal heart
interventricular septum
Name the tissues that separate the 2 sides of the pre-natal heart
top: Interarterial septum
R: septum secondum
L: septum primum
bottom: interventricular septum
Name the hole in the interarterial septum, what it does and how it works
FORAMEN OVALE
- diverts blood flow
- high pressure in R atrium pushes blood directly to L atrium and into the body
Why does blood bypass fetal lungs and liver? What are the mechanisms that allow this to happen?
- lungs deflated (passes through foramen ovale and ductus arteriosus)
- placenta is doing the liver’s job filtering blood (passes through ductus venosus)
what is the closed foramen ovale called?
FOSSA OVALIS
degraded ductus arteriosis
LIGAMENTUM ARTERIOSUS
degraded ductus venosus
LIGAMENTUM VENOSUM
What happens the the fetal circulatory system when a newborn takes its first breath?
lungs inflate
foramen ovale closes
- pressure in L atrium increases, pushing together the septum secundum and septum primum
- now called FOSSA OVALIS
ductus arteriosus - LIGAMENTUM ARTERIOSUM
ductus venosus - LIGAMENTUM VENOSUM
umbilical vein - LIGAMENTUM TERES (round ligament of liver)
umbilical arteries - MEDIAL UMBILICAL LIGAMENTS (cords of the umbilical arteries)
Describe fetal blood flow through circulatory system, starting at the right artium
- right atrium
- right ventricle
can also bypass to L atrium via foramen ovale - pulmonary arteries
can bypass to aorta via DUCTUS ARTERIOSUS - lungs (only to supply O2 to tissues, lungs are deflated)
- pulmonary veins
- left atrium
- left ventricle
- aorta
- umbilical arteries
picks up O2 from maternal blood - umbilical cord -> umbilical vein via DUCTUS VENOSUS
- inferior vena cava (this is where O2 rich and O2 low blood coming back from fetal veins will mix)
what region of the gut produces the lung evaginations?
foregut
Describe development of the lungs
Day 28
- begins as single mid-line evagination from foregut: TRACHEAL BUD
- lung buds branch off of developing trachea. first two buds are BRONCHIAL BUDS.
- Week 5: trachea as base, PRIMARY BRONCHI and then SECONDARY BRONCHI branch
Week 6: TERTIARY BRONCHI
Week 7: 3 lobes on R, 2 on left. SUPERIOR, MIDDLE and INFERIOR lobes
- branching continues up to 17 times
