Blood Pressure Ch 21 Flashcards
BP
Force exerted on the internal wall of a vessel by blood flowing in the vessel
Blood pressure in the body is usually measured within
Arterial system, not venous
BP
What creates initial force? The heart- through cardiac output
Cardiac output is chief generator of BP
The pump creates the pressure in the tubes attached to it
BP is determined by cardiac output , blood volume and
Peripheral resistance
Resistance hinges on blood viscosity, vessel length and vessel radius
All must be controlled
Blood pressure
BP= COxPR
PR= peripheral resistance
2 variables effect BP
CO- HRxSV
And
Flow of blood thru vessels
Modified
BP= (HRxSV)xPR
HR increase, BP increase vice versa- proportional relationship
Peripheral resistance
Friction that is created by the moving blood against the wall of the vessel
Friction
Always tried to stop the flow of blood-to prevent this, pressure must always be stronger than the friction to push blood forward
Shock
Pathological Drop in BP
Peripheral vascular resistance- afterload
Total resistance against which blood must be pumped
Measure of friction between vessel walls and fluid and between molecules within fluid itself ( viscosity)
Both oppose flow
When resistance to flow increase, blood pressure must increase for flow to remain constant
Resistance hinges on 4 variables- 4 v of vascular resistance
Blood volume- blood contribution
Blood viscosity - thickness- blood contribute
Vessel length- vessel contribute
Vessel radius- vessel contribute
Create friction
Blood volume
Amount of blood that is circulating inside the curcukstory system and stored in certain organs (spleen)
Represents total blood in the body
80ml
5-6L/ 70 kg body weight
Increase volume
Increase mass /pressure you’re moving
High BP can be treated with a water pill. Remove water, remove weight
Viscosity- thickness
Measure of resistance of blood to flow
Viscosity of blood is 3-5 times that of water, which is 1
(Viscosity)Depends on red blood cell and plasma protein
Hematocrit
Increase in RBC, increases viscosity, increases volume too
Increase viscosity, increase BP
Disorders- increasing viscosity
Increase immunoglobulins
Increased blood cells
Reduced deform ability of rbc
Vessel length
Increase length will increase the resistance to flow so, you increase the pressure to re establish flow
Longer vessel, more contact
Creates more friction
It’s harder to push blood through a
Long vessel
Capillaries can be
Made as we need them, we can make micro circulation
To feed added tissue
Extra capillaries are needed
Extra lbs= extra circulatory routes- diet to reduce adipose tissue- reduce capillaries-,decreasing vessel length, decreasing BP
Increase blood vessel length
Resistance to flow increase, BP increase
Vessel diameter
Greatest impact on resistance/friction
Primary way we control friction in vessels
Vasomotion
Change in vessel radius
Vasoconstriction/ dilation- adjust radius, resistance and flow
Muscular effort to contract/dilate smooth muscle
Poiseuille law
Vascular resistance
Narrow vessel (constricted) more friction
Wide vessel same as low friction
Smooth muscle in wall of vessel
Gives nervous and endocrine system ability to regulate blood flow and pressure thru vessel to organs
Peripheral dilators
Decrease BP
4 vs volume, viscosity, vessel length vessel diameter
Control friction and adjust BP as we need to
BP regulatory mechanism
Neural- cardiovascular reflexes- short term- rapid
Hormonal- endocrine- short term immediate (longer)
Renal body fluid- long term
Control blood fluid
BP will be kept normal
