introduction to c&b Flashcards
what is pressure and its units
pressure= force/area
units= either pascal, atmosphere or mmHg
what is 1 atmosphere equivalent to
1atm= 101.325kPa
what is absolute pressure
- includes atmospheric pressure
- atmospheric pressure at sea level is 1
- partial pressures of oxygen at sea level 21% of 101.325kPa= 21.23kPa
what is guage pressure
- does not include atmospheric pressure
- usually is above atmospheric pressure- looks at difference of pressure
- measurment of pressures in the body is guage pressure e.g. blood pressure
- so if systollic pressure is 120 that is 120 above atmospheric pressure
what is volume measured in
- cm^3
-ml
-L
what is boyles law
- decrease in volume causes an increase in pressure of gases
- graph is a negative reciprocal graph
in liquids can pressure be exerted without a change in volume
yes
what are the two types of flow
- turbulent flow- creates heart mummers
- laminar flow
what are the factors that affect flow
- resistance is inversely proportional to flow
- increase in resistance decrease in flow
flow equation
flow= change in pressure/resistance
what affects resistance
- radius- increased radius decreased resistance
- viscosity- increased viscosity increased resistance
- vessel length- increased length increased resistance
hagen-poiseullie equation
q= (change in pressure.r^4.π)/ (µ.L.8)
in clinical situations what can we alter to change resistance
- radius of vessels
- dont really change viscosity or length as its harder to change
what is the relationship between flow and radius
- flow is proportional to radius^4
- postive reciprocal graph
what is cardiac output
- flow
- the volume of blood the heart pumps out in one minute
what are the two equations for cardiac out put
co= stroke volume x heart rate
co= (map- rap)/ tpr(resistance)
what is the equation for mean arterial pressure
MAP= DP + 1/3( sp-dp)
across the peripheral cardiovascular system what changes and what stays the same
- pressure drops
- flow stays the same
- resistance changes
why is decreased flow important and what are its clinical consequences
- decreased flow= less blood reaching tissues and therefore less oxygen
- cells need oxygen to undergo respiration
- decreased oxygen delivery= artherosclerosis
- no oxygen delivery= pulmanory embolus
in terms of pressure how does inhalation happen
- during inhalation
- pressure outside is greater than pressure in lungs
- creates a pressure gradient and therefore air flows in
in terms of pressure how does exhalation happen
- pressure in lungs is greater than pressure outside
- pressure gradient created this causes air to flow out from high pressure to low pressure
what pressure does the lungs create
- negative pressure which allows air to flow into lungs from atmospheric pressure
is inhalation, exhalation active or passive
inhalation- active
exhalation- passive
how deos resistance in lungs affect air flow
- decreased diameter of airways increases reisistaance and therefore decreases flow in both inspiratory and expiratory
what is compliance
refers to the vessel’s ability to respond to pressure changes by increasing or decreasing its volume
- something which is more compliant would stretch/change its volume more easily when theres small changes in pressure
- something which is less compliant would need large pressure changes to change its volume/ expand its vessel
out of arteries, veins and hardened arteries what are the most compliant and what are the least
- veins most compliant
- arteries low
- hardened arteries- really low
what is compliance affected by
- resistance to flow
- stiffness of system
