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Perfusion David Taylor [email protected] http://www.liv.ac.uk/~dcmt Learning Outcomes By the end of this lecture you should be able to describe The physiological components of the circulatory system The physiology of tissue perfusion Oxygen and nutrient delivery Removal of waste products General homeostasis of pH and ions Physiological components of the cardiovascular system The heart, of course, is the pump Three things are essential to remember. Pressure from the right of the heart to the lungs is low Pressure from the left side of the heart is high, but reduces as the blood is distributed through the body. The same amount of blood leaves the right side of the heart as leaves the left…. Chapter 17, p 189 in Preston and Wilson (2013) Chapter 11, p 500 in Naish and Court (2014) Velocity and cross sectional area 50 5,000 Cross sectional area cm2 Velocity cm/s 0 0 Chapter 19, p 215 in Preston and Wilson (2013) Systemic Pressures 120 Systolic pressure 80 40 Diastolic pressure 0 0 Chapter 19, p 215 in Preston and Wilson (2013) Fluids In a male 60% of body weight is due to fluid, in a female 55% 2/3 of the fluid is inside cells – intracellular fluid (ICF) 1/3 is extracellular (ECF) Of the ECF 80% is interstitial fluid And 20% is plasma Osmotic pressure and hydrostatic pressure determine the flow between interstitial fluid and plasma Chapter 3, p 30 in Preston and Wilson (2013) Chapter 2, p 20 in Naish and Court (2014) Perfusion pressure arteriole capillary Osmotic pressure inside capillary 25mmHg 35mmHg 15mmHg venule Chapter 19, p 227 in Preston and Wilson (2013) For O2 and nutrients arteriole capillary high low low venule Chapter 19, p 227 in Preston and Wilson (2013) For CO2 and waste products arteriole capillary low higher high lower venule Chapter 19, p 227 in Preston and Wilson (2013) General Homeostasis This topic will unroll as you cover more of the body systems. Concentration gradients (as mentioned above are of crucial importance), and blood flow and tissue perfusion are needed to ensure them. But remember that the circulatory system is also a crucial buffer system and if it, or part of it stops working there are local as well as central effects. Buffers There are others, but the most important system is HCO3- + H+ H2CO3 CO2 + H2O Chapter 3, p 35 in Preston and Wilson (2013) Chapter 1, p 11 in Naish and Court (2014)