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
