Spleen. Vertebrate hearts Pericardial cavity division in coelum. Vessel walls. Endocardium = endothelium of blood vessels. Artery elastic tissue

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1 Spleen White pulp macrophages, monocyte storage Red pulp - (RBC) storage, and prod n (in nonmammals) Vertebrate hearts Pericardial cavity division in coelum Endocardium = endothelium of blood vessels Fig Spleen. Artery elastic tissue smooth muscle elastic tissue endothelium Arteries contain connective tissue with elastin and collagen Artery Vessel walls Vein Arteriole smooth muscle endothelium Capillary endothelium Vein smooth muscle, elastic fibers endothelium valve Veins include valves Artery Vein 1

2 Elastic recoil from arteries drives flow of blood during diastole Arteries temporarily expand and hold pumped blood Large arteries Systole Veins Most of the blood volume is in venous system (60-70%) - resevoir Blood volume is variable Diastole Vertebrate circulation Vertebrate circulatory systems are either a single circuit (fish) or double circuit (tetrapods) Heart and vessel development p day old human embryo Early circulation - amphibian Ventral aorta, aortic arches, dorsal aorta 2

3 Ancestral vertebrate pattern Venous development Dorsal Aorta Paired dorsal Aortae Internal Carotid 6 VI 5 V 4 IV 3 III 2 II 1 I Sinous venosus, hepatic portal system Heart Ventral Aorta Fish circulation Heart is below pharynx, near gills 4 chambers in sequence Stiff tissue around heart allow sinus venosus suction during diastole (no collapse) Fish circulation Conus arteriosus muscular, maintains pressure during diastole Teleosts bulbus arteriosus enlarged elastic ventral aorta 3

4 Fish circulation Aortic arches In fish, the aortic arches (AA) are the afferent and efferent branchial arteries Aortic arches in tetrapods 3 rd AA Carotid 4 th AA Systemic arch (dorsal aorta - many branches!) 6 th AA Pulmonary arch Tetrapod hearts Sinus venosus and conus arteriosis are lost/reduced sinus venosus reduced to junction of vena cava and rt. atrium Blood returns from two sources 4

5 Many tetrapods have incomplete separations Amphibians Dipnoi Ancestral crossopterygii Reptiles Often not using lungs! Most blood in systemic Shunting a must A fish with pulmonary circulation In other fish, swim bladders supplied from dorsal aorta Lungfish aortic arches facing Aquatic On land Has incomplete separation of both rt. & lt. atria; and rt. & lt. ventricles Yet two streams are separate O 2 poor to 5th and 6th (back gills and lung). O 2 rich to 3rd and 4th. Lungfish heart AA 3 and 4 AA 5 and 6 Amphibian circulation Metamorphosis heart moves towards lungs AA s are traditional tetrapod: 3,4,6 (frog) Spiral valve in conus spiral valve Ventricle septum 5

6 Amphibian heart Atria are completely divided, ventricle division is incomplete Yet very little mixing occurs Amphibian heart Ventricle has spongy pockets (trabeculae) Trabeculae separate deoxy. and oxygenated blood in ventricle trabeculae trabeculae Frog heart Frog heart 6

7 Frog heart Frog heart Ventricle contraction Frog spiral valve Spiral valve in conus arteriosus Reptile circulation Truncus arteriosus has three trunks Ventral aorta shortened to truncus arteriosus P LS RS 7

8 Reptile heart When not ventilating lungs, pulmonary resistance increases, blood is shunted from rt ventricle to lt systemic Reptile heart High CO 2, acidity causes Bohr effect and hemoglobin loses affinity for O 2 sea snake Saturation curve shifts to the right Crocodilia heart Crocodilia heart Ventricles divided Crocodiles have foramen of Panizza connecting rt. and lf. systemic Lf systemic can receive rt. ventricle blood valve Left to right shunt higher pressure Using lungs Foramen of Panizza allows Ox. blood into left systemic 8

9 Crocodilia heart Bird Mammal Systemic arch is one-sided in endotherms Cog lower pressure Diving- F. of P. allows mixed blood to flow into right systemic Right to left shunt p.618 Human heart development Adult mammal circulation One-way flow in early development 9

10 Amniote fetus circulation Oxygenated blood to fetus coming from outside, not lungs developing reptiles, birds, mammals Fetal circulation Blood flows through umbilical vein, through ductus venosus to vena cava Fetal circulation Most blood from lt atrium goes through foramen ovale to rt atrium 10

11 Fetal circulation Meanwhile...some blood in right atrium goes instead to right ventricle Neonatal circulation At birth pulmonary pressure reduces below systemic Most right ventricle blood goes through ductus arteriosus to aorta Foramen ovale After a day or more: Ductus arteriosus Fossa ovalis Ligamentum arteriosum Neonatal problems Patent foramen ovale (20% of people) chest pressure causes flap to open, strokes Patent ductus arteriosus Heart can become enlarged 11

12 Portal systems With portal system: Hepatic portal system Newly absorbed compounds are brought to liver Veins branch again into capillaries portal vein Conservative: found in all vertebrates Renal portal system From hind limbs to kidney, resorbing portion of kidney circulation All vertebrates except mammals 12