Embryology Tutor

Cardiovascular System Lesson

© 1996
by
Thomas F. Fletcher, DVM, PhD
Department of Veterinary Biology
University of Minnesota
St.Paul MN 55108

Contents:
         Lesson Objectives
         Lesson Content Outline
         Student Evaluations
         Platform requirements
         Download instructions

Lesson Objectives:

• Understand that the heart is re-located from a position anterior & external to the embryo to a position that is ventral to the foregut & within the embryo.
• Identify regions of the endocardial tube and identify the definitive heart structure(s) that each region gives rise to.
• Understand the process by which a single tube is transformed into a four-chambered heart, while it continues to pump blood. In particular, describe how right and left atria and ventricles and atrioventricular openings are formed.
• Identify the major vessels conveying blood to the embryo and to the yolk sac and allantois.
• Describe how aortic arches become vessels cranial to the heart and how the cranial vena cava, caudal vena cava, azygos, and portal veins develop.
• Understand how congenital anomalies of the heart and major vessels arise.
• Describe cardiovascular adaptations associated with the transition from in utero to birth.

Detailed Outline of Lesson Content:

I. Angiogenesis
A. Early angiogenesis and hematopoiesis
• transitions from fetal to definitive vessels
(new vessel development, vessel merger, & vessel degeneration)

II. Heart development
• cardiogenic plate
A. Formation of a tubular heart: (endocardial tube)
• primitive heart regions (five):
truncus arteriosus, bulbus cordis, ventricle, atrium, & sinus venosus
B. Formation of a four-chambered heart:
• elongation & looping of the endocardial tube
• venous return shifted to the right side
• growth of endocardial cushions to partition A-V openings
• formation of right & left ventricles
• partitioning of right & left atria
• partitioning of truncus arteriosus into aorta & pulmonary trunk
C. Cardiac anomalies:
• Tetralogy of Fallot

III. Arteries
A. Paired dorsal and ventral aortae
• dorsal intersegmental aa.
a) lumbar, intercostal, subclavian & vertebral aa.
• ventral branches of dorsal aortae
a) vitelline aa. ( right persists as cranial mesenteric a.)
b) umbilical aa. (external & internal iliac artery outgrowths)
B. Aotic arches
• disposition of aortic arches 3, 4, & 6
a) third aortic arch (common & internal carotid aa.)
b) fourth aortic arches (left — arch of aorta; right — subclavian a.)
c) sixth aortic arches (pulmonary aa.; distally on left — ductus arteriosus)
• further modifications of aortic arch derivatives
C. Aotic arch anomalies

IV. Veins
A. Sinus venosus
• vitelline vv.
• umbilical vv.
• cardinal vv.
B. Cranial vena cava formation
C. Caudal vena cava formation
D. Azygos v. formation
E. Portal vein formation (& ductus venosus)
• porta-systemic shunt anomalies

V. Lymphatics
A. Early lymph angiogenesis
• lymph sacs (jugular, cranial abdominal, & iliac)
B. Lymph node formation

VI. Cardiovascular adjustments at birth

Student Evaluations:

Platform Requirements:

      Embryology Tutor 0.9.8 is a HyperCard stand-alone application. Minimal requirements are a Macintosh computer with a 9-in. black & white screen and 2 MB of RAM available to run the application. Disc size is 4.5 MB (including all lessons).

Download Instructions:

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