Anatomy- Development/Conditions of the Cardiovascular System

Mesoderm

(the middle layer of the three primary germ cell layers) gives rise to the vascular system: heart, arteries, veins, lymph vessels, and all blood and lymph cells

when does the primordial heart and vascular system appear

3rd week of embryonic development

What are the earliest blood vessles?

blood islands- surrounding wall of the yolk sac (give rise to the heart and its vessels)

Endothelium

Part of the tunica intima, a single layer of simple squamous epithelial cells that directly contacts the flowing blood

Mesenchyme

a type of loose, unspecialized embryonic connective tissue

Placental (Umbillical) system

2 arteries and 1 single vein, two arteries deliver DEOXYGENATED blood and waste to the placenta.

Singular vein transports oxygenated and nutrient-rich blood from the placenta back into the baby.

When the early heart reaches the thorax it is a_________

pair of endothelial tubes in body midline

When do the pair of endothelial tubes fuse together?

Day 20

Heart begins pumping on________

Day 22

Sinus Venosus

a primitive cardiac structure that gives rise to coronary sinus and SA node

Bulbus Cordis

a primitive cardiac structure that gives rise to the pulmonary trunk and aorta

Cardiac looping (week 4)

heart folds on itself and assumes its normal position in left part of thorax

How does the heart fold?

ventricle moves caudally and atrium cranially

Heart continues to elongate and begins to bend

Day 24

Bending continues as ventricle moves caudally and atrium moves cranially

Day 28

Bending complete

Day 35

Heart divides into 4 definitive chambers

Month 2

During fetal development, 3 early vascular systems are established, list them?

intraembryonic ,vitelline, placental

intraembryonic system

aorta and cardial veins in the embryo

Vitelline system

vessels supply blood to and drain blood from the yolk sac; this system contributes to the blood supply on the GI tract

Placental system

transports blood and wastes between the baby and the placenta through the umbilical arteries and vein

How is the fetal circulation path different than a adult human

it bypasses lungs and most of liver

Foramen ovale

small hole in the wall between the atria of a baby's heart before birth

Ductus arteriosus

blood vessel in an unborn baby that connects the aorta to the pulmonary artery (later becomes ligamentum arteriosum)

what does the foramen ovale become after birth?

fossa ovalis- a small oval depression in the heart wall of the RA

what does the ductus arteriosus become after birth?

ligamentum arteriosum- tough, fibrous band of connective tissue that connects aorta to the pulmonary trunk

What does the Umbilical vein become after birth?

ligamentum teres (“round ligament”) that anchors liver to body wall.

What do the Umbilical arteries become after birth?

medial umbilical ligaments- folds in anterior abdominal wall inferior to navel

Ventricle moves ______ and ______ during cardiac looping

Ventrally and Caudally (forward + down)

Atrium moves ______ and ______ during cardiac looping

Dorsally and Cranially (backward + up))

Heart and vascular abnormalities are present in _____________

1% of live born infants

congenital

A condition present from birth

Atrial Septal Defect (ASD)

occurs when heart does not develop correctly and there is a hole in the wall (septum) between the Atriums

causes oxygen rich and poor blood to mix creating more workload for the heart

Not Fatal

Ventricular Septal Defect (VSD)

Most common, occurs when heart does not develop correctly and there is a hole in the wall (septum) between the ventricles

causes oxygen rich and poor blood to mix creating more workload for the heart
Not Fatal

Transposition of the Great Vessels

Occurs when bulbus cordis does not divide properly, as a result the location of the Aorta and Pulmonary Artery are swapped

Requires corrective surgery

Tetralogy of Fallot

Rare heart defect that is a combination of 4 different problems

1. VSD- hole between ventricles

2. Pulmonary Stenosis- narrowing of the pulmonary valve and trunk

3. Overriding Aorta- Aorta is shifted to the right and sits over the VSD

4. Right Ventricular Hypertrophy- muscular wall of the RV becomes thickened because it has to work extra hard to pump blood thru the narrowed pulmonary valve

Requires corrective surgery

Ductus Venous

temporary blood vessel in a fetus that connects the umbilical vein directly to the IVC, bypassing the liver

Ligamentium Venosus

remenant of Ductus Venous