Development of Cardiovascular System

Question 1

“The cardiovascular system is derived from the ________, which arises from the mesenchyme, an aggregation of cells derived from the mesoderm. The process of blood vessel development is called _______”.

Answer 1

“The cardiovascular system is derived from the angioblastic tissue, which arises from the mesenchyme, an aggregation of cells derived from the mesoderm. The process of blood vessel development is called angiogenesis”.

Question 2

Cardiogenic field

Answer 2

Cardiogenic field: horseshoe-shaped structure located around the anterior and lateral portions of the neural plate. Here, stuff happens that eventually gives rise to the primative heart, blood vessels and blood cells.

• hemangioblasts: are in visceral mesoderm and eventually coalesce to form the stuffs

Question 3

development of cardiovascualr system

Answer 3

development of cardiovascualr system

1. endocardial heart tube: caudal portion gives rise to heart, dorsal/ventral aorta. makes contact with developing venous system

2. cardiac tube: forms when fusion of endocardial heart tube is surronded by myoblasts.

• bulbus cordis- right ventricle
• ventricle- left ventricle
• atrium- joins venous system

3. loop formation: portions of cardiac tube expand at different rates and differences in expansion force “U” shape of cardiac tube

4. internal division: formation of four chambered heart

Question 4

Derivatives of primative heart structures

Answer 4

Derivatives of primative heart structures

Primative atrium—left and right atria

Primative ventricle—-left and right ventricle

Truncus arteriosus—outflow tracts of aorta and pulmonary trunk

Question 5

Atrial Partitioning

Answer 5

Atrial Partitioning:right/left

Septum Primum- grows down partitioning right and left atria. eventually becomes valve for foramen ovale

Foramen primum- gap that allows flow of blood from right to left atrium

Foramen secundum- (first foramen closes) replaced by second foramen which forms higher up

Septum Secundum- forms to right of septum primum

Foramen ovale- is basically the second foramen later in development. the formaen ovale becomes fossa ovalis. valved foramen ovale prevents return of blood into the right atrium, while allowing flow into left atrium.

** blood from lungs enters left side of heart. blood from body enters right side. after birth pressure in left side is greater than other side (due to lung expansion), so valvue is closed/blood flow from right atria does not enter left atria.

Question 6

Define: truncus arteriosus, aorto-pulminary septum, transposition of the great vessels

Answer 6

Truncus arteriosus: (most cranial) divided into ascending aorta and pulmonary trunk by spiral septum. septum made up of two ridges

Aorto-pulmonary septum: two ridges of truncus arteriosus fuse developing the spiral aorto-pulmonary septum. spiral form ensures that blood from right ventricle flows into the pulmonary trunk and blood from left ventricle flows into the ascending aorta.

** if septum is strait= transposition of the great vessels which is a condition that is “incompatible with life”.

Question 7

Examples of congenital cardiovascular anomalies

Answer 7

Congenital Cardiovascular Anomalies

persistent foramen ovale: foramen ovale does not close (fusion of septum and foramen is normal). communication b/t left and right atrium result in clinical problems

patent ductus arteriosus: common! communication between pulminary artery and ductus arteriosus (normal in fetus) should close after birth. when it does not close, blood will go from arteriosus to pulminary artery, which results in pulmonary hypertension

Persistent Right Aortic Arch (PRRA): aorta should come from 4th left aortic arch. right aorta should dissappear. (normally aorta is to right of essophagus). when aorta develops abnormally, esophogeal constriction occurs. animal has trouble swallowing and usually dies. (when kitties cant drink milk. R.I.P yoda)

Question 8

Trace fetal circulation from placenta to all bypasses and back

Answer 8

Fetal Circulation

Deoxygenated blood (blue)

• from superior and infereior vena cava, it flows into right atrium and right ventricle
• it is ejected into pulmonary artery, and most of it goes through the ductus arteriosus to the descenting aorta
  
  • normally it would flow to lungs through pulmonary arteries and back to right atria through pulmonary veins. in fetus collapsed lungs cause resistance to flow and only a little blood does this

Oxygenated blood (red)

• from placenta, it enters through the inferior vena cava, crosses the right atria, through the foramen ovale, to the left atria.
• mixes with deoxygenated blood

Muggle blood (purple)

• mixed blood is pumped from left ventricle into the aorta, and then distributed to brain/ rest of body