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Lecture 12

Lecture 12 - Circulation in Animals

2 Pages
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Department
Biology
Course Code
Biology 2601A/B
Professor
Graeme Taylor

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LECTURE 12 – CIRCULATION IN ANIMALS Circulation: Basic Principles  Circulatory system is made up of o Fluid o Vessels o Pump(s)  Galen – first looked at circulatory systems and described it  Al-Nafis – countered the argument by Galen, saying that the flow through the circulatory system was unidirectional – clear separation between left and right ventricles  Harvey – extensive work about quantifying blood flow and volumes  Circulatory system is a closed system – the blood does not leave the confines of the vascular system  Heart independently contracts and pushes the blood around – hydraulic system = puts tremendous pressure on the fluid and sends it around  When the blood leaves the hear, its under high blood pressure  Pressure o 12 kPa (90 mmHg) – Arteries o 4.4 kPa (33 mmHg) – Arterioles  Drop in pressure reflects energy loss in the system when entering capillaries o 2 kPa (15 mmHg) – Capillaries  Velocity  Total cross sectional area 2 o 48 cm/s – Arteries o 500 cm – 2rteries o 10 cm/s – Arterioles o 2000 cm – Arterioles o 1 cm/s – Capillaries o 5000 cm – Capillaries  Gunther von Hagens – German anatomist who invented the technique for preserving biological tissues specimens called plastination  Injected polymers into the vascular system – allowed him to mummify bone muscle and the circulatory system  200 human specimens revealing skeletal, muscular, nervous, respiratory, digestive, urinary, reproductive, endocrine and circulatory systems Closed Circulatory System  Closed circulatory – blood does not leave the confines of the vascular system and as such, there is a clear distinction between blood and lymph  Characteristic of mammals and birds – homoeothermic endotherms – require this circulatory system, it matches their metabolic system  Closed system makes it efficient, yet costly at the same time Circulation: Basic Principles  Insects have open circulatory system  Open circulatory system – blood leaves the confines of the vascular system, then tisse are directly bathed in blood that circulates sinuses and lacunae (small pores of the organism)  Low pressure system  Crustaceans and mollusks have similar systems – open circulatory systems  Open systems have all the characteristics of a circulatory system but they don’t join up  Heart – laid out along the body of the organism  Low pressure system  Relatively inefficient – mixing oxygenated blood with deoxygenated blood  Can’t keep interstitial fluids and blood separate  Don’t allow impressive athletic feats Open vs. Closed Circulatory Systems  The vessels in open systems can be quite elaborate  Vessel circulatory system of th
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