Cardiac embryology

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Foetal heart adaptations

Oxygenated blood from allantois via umbilical veins in abdomen

Some nutrition from yolk sac via vitelline veins

Pulmonary system is not functional

Blood vessels collapsed and have high resistance to flow??

Oxygenated blood from caudal vena cava moves into right side

Oxygenated blood is dilution

Foramen ovale allows oxygenated blood to get to aorta

Ductus arteriosus allows deoxygenated blood into aorta

Causes further dilution of oxygenated blood

Ductus venosis causes oxygenated blood to bypass liver

Early embryo

Once embryo greater than 1mm size diffusion no longer meets metabolic needs and vasculatory system begins to form

Once embryo reaches 3 layer stage (mesoderm, ectoderm and endoderm) CV system begins to develop

Cells in splanchnic mesoderm start to form blood islands of haemangioblast cells

Mesenchymal cells to form endothelial and smooth muscle cells which form walls around blood island - Forming tubes

These vessels bud together to form larger communicating vessels and eventually the dorsal aortae in the mesenchyme

Cavitation of mesoderm forms right and left coeloms

Coeloms fuse to developing neutral plate to form the coelomic cavity

Mesoderm forms cardiogenic plate

(which will become the heart)

This becomes dorsal to coecelum and forms endocardial tube

Initially endocardial tube has a left and right limb

Mesoderm around tube forms myoepicardial mantle

Becomes contractile

Develops into myocardium

Cardiac tube

Folding results in endocardial tube dorsal to coelom

Two limbs of coelom join endocardial tube forming the primitive heart

Functions as a single pump

Vitelline veins join to cardiac tube and dorsal aortae forming the first aortic arches

Dorsal aortae fuse caudal to developing heart forming one common aorta

Further folding forms 5 portions of embryonic heart

Cranially to caudally

Truncus arteriosus

Divides to form aorta and pulmonary veins

Bulbus cordis

Forms right ventricle

Ventricle

Forms left ventricle

Atrium

Becomes atrial appendages

Sinus venosus

Becomes right atrium

Tubular heart is contractile

Blood flows in via sinus venosus

Blood is pumped into circulation via the truncus arterioles

Blood supplied by umbilical veins (cardinal and vitelline veins)

Pericardium and attachments

Coelomic cavity

Pace maker

- blood into sinus venous

- through chambers

-out truncus arterioles

rubber duck diagrams)

-AV valves form - left and right canals form (where valves will be be)

Atrial septum forms

-inital septum grows down from top

-whole develops halve way up septum-- foramen- maintains communication

-second foramen forms --valve forms over hole

Formation of atria--- look at STREAM

SA node --summary

Bulbus cordus forms right ventricle

foetal ventricle forms left ventricle

between ventricle and bulbs - septum forms?

STREAM

Formation of atria

-sinus veinosis on right side of atrium-- becomes sinus veinosis

-blood vessels form

-appendages form

Formation of valves

--inside ventricles

--wall is thinned out forming capillaries and chordae tendonae

Aorticopulmonary septum

--spiralling occurs

-- pulmonary wraps round

6 pairs of aortic arches

3- carotid arteries

4- RHS subclavian LHS-aorta

6- pulmonary arteries

125-- disappear

STREAM?

6+4 join to form ductus arteriosus

Recurrent laryngeal nerve-- pens larynx when we breathe in

trapped cordially by aorta

causes damage - more prone to being ??

Veins

vitelline veins become vessels that empty gut

- go to liver form sinusoids

--also eft umbillicane and caudal vena cava STREAM

STREAM like 4 slides mate

NB - ALL HAPPENS AT SAME TIME-- LINK