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![ In the Middle Ages Galenic physiology
continued to present the arterial and
venous systems as two distinct circulatory
systems in the human body.
"All the arteries [emanate] from the heart, all
the veins from the liver," declared the
medieval anatomist Master Nicolaus of
Salerno in the late twelfth century.
The great Flemish anatomist Andreas Vesalius
continued to discuss the two systems
separately in the 1530s and 1540s.](https://image.slidesharecdn.com/propertiesofbloodvessels-171103052918/75/Properties-of-blood-vessels-5-2048.jpg)
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Properties of blood vessels
- 1. By: Dr. AnjuJha MBBS MD PGDMCH
- 3. The firstphysiologist of the world, in modern sense, was Wlliam Harvey(1578-1657). He was student of Fbricius, who was successor of Vesalius. Physiology was used in its modern sense half century after Harvey’s death.
- 4. Galen describedthe aorta as "a trunk divided into many branches and twigs" that nourished the body. Arteries and veins did different things for the body. They acted differently when cut -- veins being full of blood and arteries seemingly empty. In the Galenic tradition, the venous and arterial systems were entirely distinct.
- 5. In theMiddle Ages Galenic physiology continued to present the arterial and venous systems as two distinct circulatory systems in the human body. "All the arteries [emanate] from the heart, all the veins from the liver," declared the medieval anatomist Master Nicolaus of Salerno in the late twelfth century. The great Flemish anatomist Andreas Vesalius continued to discuss the two systems separately in the 1530s and 1540s.
- 6. There aremany valves in the veins opposed to the heart: the arteries have none except at the exit from the heart. Hence the first veins are pulsating, the latter are non-pulsating," wrote the English physician William Harvey in 1653. Harvey's well-known image of his experiment to prove that blood flows in only one direction
- 9. There are threemajor types of blood vessels: The arteries, which carry the blood away from the heart. The capillaries, which enable the actual exchange of water and chemicals between the blood and the tissues. The veins, which carry blood from the capillaries back toward the heart.
- 10. Arteries Arteries carryblood away from the heart. The largest is the aorta. The circulation to all the body except the lungs is called the systemic circulation and carries oxygenated blood. The circulation to the lungs is called the pulmonary circulation and carries deoxygenated blood. Arteries divide into smaller arterioles which divide again and again and eventually become capillaries. Pressure within arteries is maintained by elastic stretch and recoil, the recoil keeping up a continuous pressure in the artery, which keeps the blood flowing evenly.
- 11. Veins Veins arelarge blood vessels which carry blood back to the heart. Systemic veins carry deoxygenated blood. The largest veins are the superior and inferior vena cava. Veins have a system of valves to prevent back-flow. The flow of blood is aided by the action of muscles, especially the large muscles of the leg.
- 12. Capillaries Capillaries arethe smallest blood vessels. The average diameter is 8 µm with a very thin wall of 0.2 µm. The body has approximately 100,000 km. of capillaries. They are the site for exchange of gases, nutrients and waste between circulation and body tissues.
- 13. Conducting vessels (elastic) Distributionvessels (muscular) Resistance vessels (arterioles) Exchange vessels (capillaries) Thoroughfare channels (shunts) Capacitance vessels (veins)
- 16. In the pulmonarycirculation: The pulmonary vein distensibilities are similar to those of the systemic circulation. But, The pulmonary arteries normally operate under pressures about one sixth of those in the systemic arterial system, and their distensibilities are about six times the distensibility of systemic arteries. Difference in Distensibility of the Arteries and the Veins. Anatomically, the walls of the arteries are far stronger than those of the veins. Consequently, the arteries, on average, are about eight times less distensible than the veins. That is, a given increase in pressure causes about eight times as much increase in blood in a vein as in an artery of comparable size.
- 19. 1 54% 2 30% 3 11% 4 5% Other 16% Distribution of bloodvolume Veins Heart & pulmonary circulation Arteries capillaries
- 20. The vascular systemmay be considered consisting of the following: Windkessel vessels. Precapillary resistance vessels. Precapillary sphincters. Capillary exchange vessels. Post capillary resistance vessels. Shunt vessels.
- 24. The aortaand its large branches are considered as windkessel vessels. During systole these vessels are distended. On subsequent closure of the aortic valve, the elastic recoil of the vessels push the blood to the periphery. Potential energy stored in elastic tissue of these vessels during systole. During diastole this potential energy converts in to kinetic energy for the blood flow.
- 26. Pre capillary resistancevessels: Arterioles are the examples. These vessels offer great resistance to blood flow. Changes in radius of the arterioles determine the blood flow to that region. Radius of the arteriole is controlled by local myogenic tone and also by extrinsic neural control.
- 27. Precapillary sphincters: Theseare part of precapillary resistance vessels. The sphincters are important in determining the size of the capillary exchange area. Radius of sphincters is regulated by local metabolites concentration and neural factors.
- 28. Capillary exchange vessels: Tube like structures having single layer of epithelium. These are important part of CVS because solutes pass to the tissues through capillary walls. In the resting condition of the tissues, about 25% of capillaries are open. During activity change in tone of precapillary sphincters decreases thus more capillaries are open.
- 29. Capacitance vessels: Theseare comprised of venular and venous compartments. Their resistance has very little effect. They are important for change in capacities. The capacity adjustment in postural changes is greatly influenced by alteration in luminal configuration. Myogenic tone of the veins activated by the sympathetic constrictor nerves.
- 30. 54% ofcirculating blood is in veins. 12% is in heart cavity. 18% is in low pressure pulmonary circulation. 16% in arterial system. In arterial system 2% in aorta, 8% in the arteries, 1% in the arterioles and 5% in the capillaries.
- 31. 1 54% 2 30% 3 11% 4 5% Other 16% Distribution of bloodvolume Veins Heart & pulmonary circulation Arteries capillaries
- 32. High pressure system:- Comprising left heart , windkessel vessels, precapillary resistance vessels. Having blood pressure between 100- 20mmHg. Blood pressure in this system is according to the region.
- 33. Low pressure system: Right side of heart, systemic veins and pulmonary circulation. Having pressure between 25-0mmHg. Its function is to control blood volume and venous return.
- 34. Shunt vessels: Fewtissues are having shunt vessels. These vessels bypass the capillaries. When these are patent, allow the rapid blood flow to the tissue without nutritive function. During thermal stress, inhibition of sympathetic vasoconstrictor action via CNS causes high increase of skin blood flow resulting in dissipation of heat.
- 37. characteristics Arteries VeinsCapillaries Direction of blood flow Away from heart. Towards heart From arterioles to venules (towards heart) Valves Absent Present Absent Thickness of wall Thick Thin Thinest Layers of elastic and muscle tissues Thick Thin Absent O2 content Oxygenated except in pulmonary arteries. Deoxygenated except in pulmonary veins. Oxygenated at arteriolar end and deoxygenated at venular end. Color Red Bluish red Bluish red Location Deep Nearer to body surface. Inside all tissue
- 39. Arterial venous Skin Cool/cold, hairless, dry and shiny skin, pallor on elevation and rubor on depending position. Warm, thickened,motteled and pigmented areas. Pain Sharp stabbing. Worsen with activity. Aching and cramping type. Activity some time helps. Ulcers Extremely painful, pale and grey based. Specially found at heel, toes and dorsum of foot. Moderately painful, pink based. Found on medial aspect of the ankle. Pulse Usually absent. Present Edema Infrequent Present specially at the end of the day.
- 40. Lymphatics: These aresometime known as second circulatory system. These are network of blind ended thin endothelial tubes. Endothelial lining is not fenestrated. Endothelial junctions are permeable to large molecules. Large lymphatics are also furnished with smooth muscles and elastic tissues.
- 41. Lymphatics alsohave valves to ensure unidirectional flow. All lymphatics eventually open into the venous system. Due to final drainage it is directly connected to circulatory system. Lymph kept in motion by squeezing of smooth muscle lining the larger lymphatics. Flow is assisted by pumping action of skeletal muscles. Suction exerted by the thorax is accentuated during inspiration is also one factor for lymphatic flow.
- 42.
- 43. By returning mentionedsubstances to the circulation lymphatics: a) Help to conserve these substances. b) Restore blood volume and composition. c) Prevent osmotic pressure of interstitial space and thereby prevent accumulation of fluid in this area. d) Special significance of lymphatics in the small intestine where digested lipids are absorbed in to lymphatics. e) Large undesirable particulate matters as well as bacteria carried to nearest lymphnodes.