BLOOD CIRCULATION © 2016 Paul Billiet ODWS

Galen 2nd Century AD Blood is formed all the time from food and drink that a human consumes Blood flows to the heart where it passes from the left to the right side Blood is consumed by the body or it passes out as wastes. © 2016 Paul Billiet ODWS

William Harvey (1578-1657) The scientific approach to medicine Took the bodies of sheep and pigs and drained out all their blood, which he measured Calculated the volume of the ventricles of the animal’s heart Measured the pulse Conclusion: impossible for food and drink to replace all the blood leaving the heart. © 2016 Paul Billiet ODWS

Blood circulates Systole is the active phase of the heart's movement Exercitatio Anatomica de Motu Cordis et Sanguinis in Animalibus 1628 Systole is the active phase of the heart's movement Heart valves allow blood flow in only one direction The ventricles contract together The heart septum contains no gaps or perforations The valves in the veins permit the blood to flow only in the direction of the heart. © 2016 Paul Billiet ODWS

Marcello Malpighi 1661 Harvey suggested the existence of small capillaries between arteries and veins 1660s Anthony Leeuwenhoek & Robert Hook started to use microscopes on biological tissues Malpighi observed blood capillaries vindicating Harvey. © 2016 Paul Billiet ODWS Frog lungs observed by Malpighi C Hwa, & W C. Aird American Journal of Physiology - Heart and Circulatory Physiology (2007) Vol. 293 no. 5,

Double circulatory system LUNG TISSUE Pulmonary circulation Left Heart Right Heart Systemic circulation BODY TISSUES © 2016 Paul Billiet ODWS

CHARACTERISTICS VESSEL LUMEN DIAMETER /mm WALL THICKNESS NUMBERS VOLUME OF BLOOD / % AORTA 25.0 2.0 1 2 ARTERIES 4.0 1.0 160 8 ARTERIOLES 0.03 0.02 57 million CAPILLARIES 0.006 0.001 13 000 million 5 VENULES 0.002 1 300 million 54 VEINS 5.0 0.5 204 VENA CAVA 30.0 1.5 HEART - 12 PULMONARY CIRCULATION 18 © 2016 Paul Billiet ODWS

Pressure changes © 2016 Paul Billiet ODWS http://cnx.org/contents/14fb4ad7-39a1-4eee-ab6e-3ef2482e3e22@7.1:133/Anatomy_&_Physiology © 2016 Paul Billiet ODWS

© 2016 Paul Billiet ODWS http://classes.midlandstech.edu/carterp/Courses/bio211/chap19/chap19.html

Arteries © 2016 Paul Billiet ODWS www.vetmed.wsu.edu/Van308/images/105.jpg © 2016 Paul Billiet ODWS

Veins © 2016 Paul Billiet ODWS

Capillaries © 2016 Paul Billiet ODWS http://darwin.iz.uj.edu.pl/iz/anatomy/jakub/grafika/s3e.html © 2016 Paul Billiet ODWS

Blood vessels compared Arteries Capillaries Veins Take blood away from the heart Exchange materials between the blood and the tissues Return the blood to the heart High pressure blood Fast flowing blood Pulses HighLow pressure Slow flowing Low pressure blood Slow flowing blood Against gravity Thick, muscular, elastic walls Walls one cell thick (0.5 µm) Diameter 6 µm Very numerous so total xsectional area v. large Muscular not very thick Valves Large internal diameter © 2016 Paul Billiet ODWS