introduction to CVS

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introduction to CVS

  1. 1. CARDIOVASCULAR SYSTEM
  2. 2. • Cardiovascular system is the first major regulatory system to function in the embryo. • The primordial heart and vascular system appear in the middle of the third week of embryonic life. • The heart starts functioning by the beginning of the fourth week.
  3. 3. • The first regulatory system to function in embryo is • Nervous system • Cardiovascular system A • Endocrine system • Lymphatic system • Macrophage system
  4. 4. • This precocious cardiac development is necessary because the rapidly growing embryo can no longer satisfy its nutritional and oxygen requirements by diffusion alone.
  5. 5. • Consequently, there is a need for an efficient method of acquiring oxygen and nutrients from the maternal blood and disposing of carbon dioxide and waste products.
  6. 6. Cardiovascular system develops from mesoderm. • Mesenchymal cells in the mesoderm
  7. 7. • Mesenchymal cells proliferate and form angioblast cells. • These are arranged in the form of isolated cell clusters called angiogenetic cell clusters. • These clusters develop during third week throughout the mesoderm (intra- embryonic as well as extra-embryonic).
  8. 8. • Three angiogenetic cell clusters.
  9. 9. • Depending on location we can say there are two types of cells in each cluster. 1. The cells present in the central region of a cluster are central cells 2. The cells present in peripheral area of a cluster are peripheral cells
  10. 10. • Each cluster forms a primitive capillary. • The central cells in each cluster form primitive blood cells and the peripheral cells form endothelial cells. • The adjacent primitive capillaries join to form network of capillary vessels.
  11. 11. • Adjacent primitive capillaries join each other and form a network of capillaries in extra-embryonic and intra-embryonic mesoderm. • It is interesting to note that vascular system starts developing first in splanchnic mesoderm around yolk sac and spread everywhere in mesoderm.
  12. 12. • The vascular system starts developing first in • splanchnic mesoderm around yolk sac A • Somatic mesoderm around amniotic cavity • Connecting stalk • Intraembryonic mesoderm • The mesoderm lining the trophoblast
  13. 13. • The larger vessels develop by the union of adjacent networks of capillaries.
  14. 14. • Primordial blood vessels cannot be distinguished structurally as arteries or veins, but they are named according to their future fates and relationship to the heart.
  15. 15. • The earliest sign of the heart is the appearance of paired endothelial cords during the third week. • These cords canalize to form endocardial heart tubes, which fuse to form the tubular heart in the third week. • The heart begins to beat at 22 to 23 days. • Blood flow begins during the fourth week.
  16. 16. • The earliest sign of the heart is • The appearance of paired endothelial cords during fourth week • The appearance of paired endocardial heart tubes during third week • The appearance of paired endothelial cords during third week A • The appearance of paired endocardial heart tubes during fourth week • The appearance of paired endothelial capillaries

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