Introduction to Cardiovascular System

Question 1

Cardiovascular system

Answer 1

1st major organ system to function in embryo

Question 2

All blood vessels begin as what?

Answer 2

Condensations of mesodermal mesenchyme (blood islands) during week 3

Question 3

Blood islands will rise to what?

Answer 3

Blood cells
Vessels
Heart

Question 4

Blood islands that would become the heart form where?

Answer 4

In splanchnic mesoderm around future head and neck of embryonic disc (cariogenic region)

Question 5

When embryonic heart reaches the thorax, it is what?

Answer 5

A pair of endothelial tubes in the body’s midline that fuse into a single tube on Day 20

Question 6

On what day does the heart start pumping?

Answer 6

Day 22

Question 7

Are the earliest heart chambers paired or unpaired?

Answer 7

Unpaired

Question 8

What are the chambers from tail to head?

Answer 8

sinus venosus, atrium, ventricle, and bulbs cordis

Question 9

Sinus Venous– will become…

Answer 9

• Smooth-walled part of R atrium, coronary sinus, and SA node
• Also contributes to posterior wall of L atrium

Question 10

Atrium gives rise to?

Answer 10

Ridged parts (pectinate muscles of R and L atria

Question 11

Ventricle

Answer 11

Strongest pumping chamber
- gives rise to L ventricle

Question 12

Bulbus cordis

Answer 12

The truncus arteriosus (4a), gives rise to R ventricle, pulmonary trunk, and 1st part of aorta

Question 13

What shape does the heart take on when the 4 chambers appear?

Answer 13

S- shape
- ventricle moves caudally and atrium cranially. Bending occurs due to rapid growth of ventricle and bulbus cordis

Question 14

What happens as a result of cardiac looping during week 4?

Answer 14

The heart folds on itself and assumes its normal position in left part of the Thorax with atria posterior and ventricles located in a more anterior direction

Question 15

What happens by month 2?

Answer 15

The heart is divided into the 4 definitive chambers by formation of midline atrial and ventricular septa and valves
- Develop from regional thickenings of endocardium: endocardial cushions

Question 16

During fetal development, what are the 3 early vascular systems?

Answer 16

Intraembryonic
Vitelline
Placental

Question 17

Intraembryonic system

Answer 17

Dorsal aorta supplies blood to embryonic tissues
Cardinal veins return poorly oxygenated blood from body of embryo into heart tube

Question 18

Vitelline System

Answer 18

Vitelline vessels supply blood to and drain blood from yolk sac

Question 19

What system contributes to blood supply of gastrointestinal tract?

Answer 19

Vitelline system

Question 20

Umbilical/Placental system

Answer 20

Paired umbilical arteries deliver deoxygenated blood and fetal waste products to placenta
Well-oxygenated blood and nutrients from placenta are carried to fetal heart tube via an unpaired umbilical vein

Question 21

By when are all the major vessels formed?

Answer 21

Month 3 of development

Question 22

What are the differences between fetal and postnatal circulation (O2 and nutrients access)

Answer 22

During pregnancy, the placenta provides both O2 and nutrients to fetus
Therefore, fetal circulation is different in that it bypasses lungs and most of the liver

Question 23

Umbilical Vein

Answer 23

Provides oxygen
- rich blood from placenta

Question 24

Some highly oxygenated blood is shunted through…

Answer 24

Through the liver to IVC via ductus venosus

Question 25

Ductus venosus

Answer 25

Drains into IVC where oxygen-rich placental blood mixes with oxygen-poor blood returning to heart from caudal region of fetal body

Question 26

Where do the IVC and SVC drain moderately oxygenated blood into?

Answer 26

Right atrium

Question 27

Blood passage to nonfunctioning lungs is limited by what?

Answer 27

Foramen ovale and ductus arteriosus

Question 28

Blood from the right atrium passes into the left atrium via what opening?

Answer 28

The foramen ovale in the inter-atrial wall

Question 29

From the left atrium, where does the blood continue?

Answer 29

To the left ventricle and aorta to supply the body

Question 30

Does blood from the right atrium reach the right ventricle and pulmonary trunk?

Answer 30

Some blood only

Question 31

What is the name for the shunt that diverts blood from the pulmonary trunk to the aorta?

Answer 31

Ductus arteriosus (since the lungs are nonfunctioning)

Question 32

What happens to the ductus arteriosus?

Answer 32

Constricts and closes which persists as ligaments arteriosum

Question 33

Clamping of umbilical cord causes what?

Answer 33

Umbilical vein to constrict- persists as ligamentum teres ("round ligament") that anchors liver to body wall Ductus venosus to close- persists as ligaments venous on inferior surface of liver Umbilical arteries to close- persist as medial umbilical ligaments (folds in anterior abdominal wall inferior to navel)

Question 34

What causes the 2 valve flaps of the oval foramen to close? What comes of it?

Answer 34

Oxygenated pulmonary blood pours into the left atrium which raises pressure, the structure known as fossa ovalis in the right atrium persists

Question 35

What constitutes to the largest category of birth defects?

Answer 35

Heart and vascular abnormalities; present in 1% of live born infants- 30% of heart defects occur in infants with other major malformations

Question 36

Approximately 2% of heart defects are due to what?

Answer 36

Environmental agents, which most have multifactorial causes

Question 37

What is the most common congenital heart malformation?

Answer 37

Ventricular Septal Defects (VSDs) - Occur in isolation in 12/10,000 births (80% concern muscular portion of septum and resolve as child grows)

Question 38

What occurs when bulbs cordis does not divide properly?

Answer 38

Transposition of the great vessels - As a result, aorta originates in the right ventricle and the pulmonary trunk from the left ventricle

Question 39

What has 4 cardiovascular alterations?

Answer 39

1. Pulmonary infundibulum stenosis 2. Large IV septal defect 3. An overriding aorta arising directly above the septal defect 4. Right ventricular wall hypertrophy due to right side pressure