Cardiovascular System

Question 1

When does the prenatal heart start beating?

Answer 1

Early in the fourth week

Question 2

Why is it so important for the embryo to get a functioning cardiovascular system quickly?

Answer 2

Because as it grows to a certain size it can no longer rely on simple diffusion for distribution of nutrients, oxygen, etc

Question 3

List the four major types of blood vessels in the four week embryo

Answer 3

1) Dorsal aortae (paired), 2) Cardinal veins (A, P, and Common), 3) Umbilical veins and arteries (paired), Vietlline arteries and veins (unpaired)

Question 4

What do the umbilical arteries and veins communicate with in the embryo?

Answer 4

The placenta

Question 5

What do the vitelline arteries and veins communicate with in the embryo, and where do the persist in the adult?

Answer 5

Communicate with yolk sac. Persist in GI tract as unpaired arteries of abdominal aorta

Question 6

Which umbilical vein will persist, and which will degenerate?

Answer 6

The left will persist, the right will degenerate

Question 7

What part of what germ layer holds cardiac progenitor cells?

Answer 7

The anteriomost portion of the splanchnic mesoderm

Question 8

What gives rise to blood vessels in the embryo?

Answer 8

Angioblastic cords

Question 9

Where is the cardiogenic mesoderm relative to the oropharyngeal membrane in the neural plate stage embryo?

Answer 9

Anterior to the OP membrane

Question 10

If the heart tube is anterior to the oropharyngeal membrane in the neural plate stage embryo, how do our hearts end up inferior to our mouths?

Answer 10

Head folding swings the heart tube, pericardial cavity, and septum transversum around the axis of the OP membrane

Question 11

What brings the two endocardial heart tubes together to form one heart tube?

Answer 11

Lateral folding

Question 12

What is the embryonic heart outflow tract called and what does it develop into?

Answer 12

Truncus arteriosus, develops into aorta and pulmonary trunk

Question 13

What is the entrance to the embryonic two-chambered heart called and what are its two parts?

Answer 13

Sinus venosus. It has right and left horns

Question 14

What are the parts of the bulbus cordis and what does each part form?

Answer 14

Proximal third forms trabeculated part of the right ventricle, midportion (conus cordis) forms outflow tracts of both ventricles, distal third (trucus arteriosus) forms roots and proximal portion of aorta and pulmonary artery

Question 15

What do the left and right horns respectively of the sinus venosus become in the heart

Answer 15

Left becomes coronary sinus, Right becomes sinus venarum (smooth walled portion of right atrium)

Question 16

Anastomosis between left and right anterior cardinal veins leads to the creation of what veins?

Answer 16

Left and right brachiocephalic

Question 17

Besides side of the body, how can the left brachiocephalic be told apart from the right?

Answer 17

Right is more vertical, left is more oblique

Question 18

For prenatal and postnatal respectively, is the pressure higher in the left atrium or right atrium?

Answer 18

Prenatally it is higher in right atrium (allowing blood to flow through foramen ovale), postnatally pressure is higher in the LA than in RA

Question 19

What is a probe patent foramen ovale and what is the significance?

Answer 19

A small opening (about the size of a dissecting probe) in the atrial septum. A clot can work its way through here into the LA, then LV, then up ascending aorta to carotids and head and neck.

Question 20

How does the smooth wall of the LA form?

Answer 20

The primordial pulmonary vein gets incorporated into the wall of the LA, becoming the smooth walled portion (pectinate muscles are pushed to the left auricular)

Question 21

What two vessels are created by partitioning of the truncus arteriosus, what shape is the septum between them, and what cells migrate to this area to assist in this process?

Answer 21

Aorta and pulmonary trunk. Spiral shaped. Neural crest cells

Question 22

What four conditions might someone who had unequal partitioning of the truncus arteriosus have?

Answer 22

Stenotic pulmonary trunk, large aorta, right ventricular hypertrophy, patent (persistent) ductus arteriosus

Question 23

What three parts does the membranous part of the IV septum come from?

Answer 23

Left bulbar ridge, right bulbar ridge, and fused endocardial cushions

Question 24

In what part of the IV septum are congenital defects more common and why?

Answer 24

The membranous part, because it requires coordinated fusion of three separate embryonic parts

Question 25

What is the tetralogy of fallot?

Answer 25

1) Pulmonary valve stenosis 2) Ventricular septal defect (VSD), 3) Overriding aorta (aorta overrides ventricular septum, received blood from both LV and RV), 4) Right ventricular hypertrophy (due to pulmonary valve stenosis. Some also have patent ductus arteriosus (PDA)

Question 26

What are the three shunts of fetal circulation and from and to where do they shunt blood?

Answer 26

1) Foramen ovale (from RA to LA), 2) Ductus arteriosus (from pulmonary trunk to aorta), 3) Ductus venosus (shunt around liver)

Question 27

From what vessels do the ligamentum venosum, ligamentum arteriosum, and fossa ovalis respectively form?

Answer 27

Ductus venosus (shunt around liver), Ductus arteriosis (shunt into aorta), and Foramen ovale (RA to LA shunt)