perfusion david taylor [email protected] dcmt
TRANSCRIPT
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
Learning Outcomes
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….
Physiological components of the cardiovascular system
Chapter 17, p 189 in Preston and Wilson (2013)Chapter 11, p 500 in Naish and Court (2014)
Velocity and cross sectional area
Cross sectional area cm2
0
5,000
0
50
Velocity cm/s
arte
ries
arte
riole
s
capi
llarie
sve
nule
s
vein
s
Chapter 19, p 215 in Preston and Wilson (2013)
Systemic Pressures
00
120
arte
ries
arte
riole
s
capi
llarie
sve
nule
s
vein
s
Chapter 19, p 215 in Preston and Wilson (2013)
80
40
Systolic pressure
Diastolic pressure
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
Fluids
Chapter 3, p 30 in Preston and Wilson (2013)Chapter 2, p 20 in Naish and Court (2014)
Perfusion pressure
arteriole
venule
capillary
Chapter 19, p 227 in Preston and Wilson (2013)
35mmHg 15mmHg
Osmotic pressure inside capillary 25mmHg
For O2 and nutrients
arteriole
venule
capillary
Chapter 19, p 227 in Preston and Wilson (2013)
high low
low
For CO2 and waste products
arteriole
venule
capillary
Chapter 19, p 227 in Preston and Wilson (2013)
high lower
low higher
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.
General Homeostasis
There are others, but the most important system is
Buffers
HCO3- + H+
H2CO3
CO2 + H2OChapter 3, p 35 in Preston and Wilson (2013)Chapter 1, p 11 in Naish and Court (2014)