1. Circulatory system

2. Spleen White pulp – macrophages, monocyte storage
Red pulp - (RBC) storage, and prod’n (in non-mammals)

3. Vertebrate hearts Pericardial cavity – division in coelum
Endocardium continuous w/endothelium of blood vessels

4. Blood vessels

5. Artery Arteriole Capillary Vein Arteries contain connective tissue
with elastin and
collagen
smooth
muscle
Artery
endothelium
elastic tissue
elastic tissue
Arteriole
smooth muscle
endothelium
Capillary
endothelium
endothelium
Vein
Veins include
valves
smooth muscle,
elastic fibers
valve

6. Vessel walls
Artery
Vein
Artery
Vein

7. Large arteries
Systole
Elastic recoil from arteries drives flow of blood during diastole
Arteries temporarily expand and hold pumped blood
Diastole

8. Veins Most of the blood volume is in venous system (60-70%) - resevoir
Blood volume is variable

9. Vertebrate circulation
Vertebrate circulatory systems are either a
single circuit (fish) or double circuit (tetrapods)

10. Heart and vessel development
26 day old human embryo
Early circulation - amphibian
Ventral aorta, aortic arches, dorsal aorta

11. Ancestral vertebrate pattern
Dorsal Aorta
Paired dorsal Aortae
Internal Carotid 6 5 4 3 2 VI V IV
III II 1 I
Ventral Aorta
Heart

12. p.621

13. Venous development
Sinous venosus, hepatic portal system

14. Fish circulation Heart is below pharynx, near gills
4 chambers in sequence
Stiff tissue around heart allow sinus venosus suction during diastole (no collapse)

15. Fish circulation
Conus arteriosus – muscular, maintains pressure during diastole
Teleosts – bulbus arteriosus – enlarged elastic ventral aorta

16. Fish circulation
In fish, the aortic arches (AA) are the afferent and efferent branchial arteries

17. Aortic arches

18. Aortic arches in tetrapods
3rd AA – Carotid 4th AA – Systemic arch (dorsal aorta - many branches!) 6th AA – Pulmonary arch

19. 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

20. Many tetrapods have incomplete separations
Amphibians Dipnoi Ancestral crossopterygii Reptiles

21. Many tetrapods have incomplete separations
Amphibians Dipnoi Ancestral crossopterygii Reptiles Often not using lungs! Most blood in systemic Shunting a must

22. Lungfish aortic arches
facing
A fish with pulmonary circulation
In other fish,
swim bladders
supplied from
dorsal aorta
Aquatic 2 3 4 5 6
On land

23. Lungfish heart
Has incomplete separation of both rt. & lt. atria; and rt. & lt. ventricles
Yet two ‘streams’ are separate
O2 poor to 5th and 6th (back gills and lung).
O2 rich to 3rd and 4th.
Spiral valve in conus
AA 3 and 4
AA 5 and 6
spiral
valve
Ventricle septum

24. Amphibian circulation
Metamorphosis – heart moves towards lungs AA’s are ‘traditional’ tetrapod: 3,4,6 (frog)
Heart moves caudally to lungs

25. Amphibian heart
Atria are completely divided, ventricle division is incomplete
Yet very little mixing occurs

26. Amphibian heart
Ventricle has spongy pockets (trabeculae) Trabeculae separate deoxy. and oxygenated blood in ventricle
trabeculae
trabeculae

27. Frog heart

28. Frog heart

29. Frog heart

30. Frog heart

31. Frog heart
Ventricle
contraction

32. Frog heart

33. Frog spiral valve Spiral valve in conus arteriosus Ventral aorta
shortened
to truncus
arteriosus

34. Reptile circulation
Truncus arteriosus has three trunks RS LS P

35. Reptile heart
When not ventilating lungs, pulmonary resistance increases, blood is shunted from rt ventricle to lt systemic

36. Reptile heart
High CO2, acidity causes Bohr effect and hemoglobin loses affinity for O2
sea snake
Saturation curve
shifts to the right

37. Early ventricle contraction

38. Late ventricle contraction

39. Crocodilia heart
Ventricles divided Crocodiles have foramen of Panizza connecting rt. and lf. systemic Lf systemic can receive rt. ventricle blood

40. Crocodilia heart Using lungs
higher
pressure
valve
Using lungs
Foramen of Panizza allows Ox. blood into left systemic

41. Crocodilia heart Diving-
lower
pressure
Diving-
F. of P. allows mixed blood to flow into right systemic
Cog

42. Bird
Mammal
Systemic arch is one-sided in endotherms
p.618

43. Dinosaur heart – endothermic!
N.C. Museum of Natural Science

44. Human
development

45. Human heart development
One-way flow
in early development

46. Adult mammal circulation

47. Amniote fetus circulation
Oxygenated blood to fetus coming from outside, not lungs developing reptiles, birds, mammals

49. Fetal circulation
Blood flows through umbilical vein, through ductus venosus to vena cava

50. Fetal circulation
Most blood from right atrium goes through foramen ovale to left atrium

51. Fetal circulation
Meanwhile....some blood in right atrium goes instead to right ventricle
Most right ventricle
blood goes through
ductus arteriosus
to aorta

52. Neonatal circulation
At birth pulmonary pressure reduces below systemic Foramen ovale Fossa ovalis After a day or more: Ductus arteriosus Ligamentum arteriosum

54. Neonatal problems Patent foramen ovale Patent ductus arteriosus
(20% of people)
chest pressure causes
flap to open, strokes
Patent ductus arteriosus
Heart can become enlarged

55. Venous systems
Normally: Arteries Capillaries Veins Heart

56. Portal systems With portal system: Veins branch again into capillaries
portal vein

57. Hepatic portal system
Newly absorbed compounds are brought to liver Conservative: found in all vertebrates

58. Renal portal system
From hind limbs to kidney, resorbing portion of kidney circulation All vertebrates except mammals