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The Evolution of the Aortic Arches Embryonic Human Circulation

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The Evolution of the Aortic Arches Embryonic Human Circulation 1/10/2013 Topic 21: Aortic Arch & Embryonic Circulation Aortic Arch Evolution What view are we getting here? The evolution of the aortic arches ________________ 6-8 gill & aortic arches How do the aortic arches differ among taxa? Heart Ventral aorta What vessels do they become? Afferent branchial aa. Gill capillaries Efferent branchial aa. Lamprey Dorsal aorta Body & Head Embryonic human circulation Why does it differ from adult circulation? _____________ What is the pattern of embryonic circulation Efferent branchial aa. develop collector loops and what structures are involved? Aortic arch I efferent spriacular a. How does it change with adulthood? Aortic arch II modified Aortic arches III-VI Shark unmodified Liem et al. Focus 19-1 Aortic Arches of Aortic Arches of the Shark Actinopterygii Dorsal view representation Loss of aortic arch __________ Very generalized Loss of aortic arch __________ _______________ I Aortic arches III-VI serve the ____ I II II _______________ How many gill arches do bony III III _______________ fishes have? IV IV Aortic arches V V I: Efferent spiracular a. Loss of collector loops sensory function More efficient gas exchange at gills VI VI II: Modified gas exchange function Anterior dorsal aortae connect – III-VI: Unmodified gas head circulation exchange function Anterior ventral aorta contributes to ______________________ Liem et al. Focus 19-1 Liem et al. Focus 9-1 • Oxygenated • Deoxygenated Aortic Arches of Dipnoi Aortic Arches of Dipnoi I II III IV V VI Valves are used to bypass Evolution of _______ respiratory structures I Supplied by _____________, II To bypass lungs: pulmonary a. III Shut aortic arches Drained by new pulmonary v. __________________ Gills used to ‘breathe water’ IV V To bypass gills: Aortic arches III & IV bypass I II III VI Shut aortic arches IV V gills VI __________________ Aortic arches serving gills What are shunts? Modified _____________ ______________ Lungs used to breath air Liem et al. Focus 19-1 Liem et al. Fig. 19-9; tamuk.edu 1 1/10/2013 Aortic Arches of Larval & Adult Adult Amphibians Amphibians Loss of circular cranial artery Tadpole Evolution of “tetrapod” carotid Retains aortic arches III, IV, V VI artery system Tadpole Loss of aortic arches I & II ____________: Gills Loss of dorsal aorta between _____: Bypass lungs aortic arches III & IV Ductus arteriosus _________________ (arch III) supplies internal & external Adult carotid aa. Typical tetrapod circulation Loss of aortic arch V Aortic arch III: carotid Adult Aortic arch IV becomes Aortic arch IV: systemic __________________ Aortic arch VI: Aortic arch VI is pulmocutaneous __________________ Skin Liem et al. Focus 19-1; Fig. 19-10 Liem et al. Fig. 19-10 Aortic Arches of “Reptiles” Aortic Arches in Birds How does this differ from How does this differ the adult amphibian? from a turtle? Basics the same Carotid circulation is similar _____________ division of ventral aorta Subclavian aa. come off common carotid a Slight asymmetry in systemic circulation Left aortic arch IV _______________! Carotid duct increases connectivity between Right aortic arch IV is head and body ______________ No pulmonary circulation to ______________ Liem et al. Focus 19-1; Fig. 19-12 Liem et al. Fig. 19-14 Aortic Arches in Mammals Aortic Arches in Mammals Aortic arch developmental homology with adult circulation Similar to birds, but left aortic arch IV is systemic What does this tell us? Even more asymmetry Left subclavian a. comes off L aortic arch IV Right sublavian a. is right aortic arch IV Liem et al. Fig. 19-14 Liem et al. Fig. 19-15 2 1/10/2013 Aortic Arch Lampreys Evolution Sharks 1. 8 aortic arches Ray-finned 2. 6 aortic arches fishes 3. Collector loops 4. Aortic arch I efferent spiracular a. 5. Aortic arches I & II lost Lungfish 6. Circular cranial circulation 7. Aortic arch II modified 8. Aortic arches III & IV shunt past gills 9. Aortic arch VI Pulmonary Amphibians 10. Carotid circulation established 11. Aortic arch IV Systemic 12. Loss of cutaneous a. “Reptiles” 13. Retention of carotid duct 14. Right aortic arch IV Systemic 15. Left aortic arch IV Systemic Birds Mammals Liem et al. Focus 19-1 Mammalian Embryonic Circulation Why would embryonic circulatory needs differ from those of the adult? Human Embryo © MA Hill 1 1/10/2013 Human Embryonic Circulation Human Embryonic Circulation _________________ Blood to placenta __________________ _________________ Become medial umbilical ligament Oxygenated blood from placenta to body __________________ Mixes with deoxygenated blood from Become round ligament of liver tissues __________________ _________________ Closes and dissapears Shunt to bypass liver Fetal alcohol syndrome All blood from the guts now goes to the liver via hepatic portal v. _________________ Shunt from R atrium to L atrium __________________ Blood bypasses lungs Closes and becomes fossa ovale _________________ __________________ Shunt from pulmonary a. to aorta Closes and becomes the Blood bypasses lungs ligamentum arteriosum Liem et al. Fig. 19-16 Liem et al. Fig. 19-16 Human Embryonic Circulation FO – fossa ovale © ipeg.org 1.
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