Blood pressure, Vascualar resistance, factors affecting blood flow Flashcards
Blood flow is the volume
of blood that flows through any tissue in a given time period (in mL/min)
Total blood flow is cardiac output (CO),
the volume of blood that circulates through systemic (or pulmonary) blood vessels each minute
Cardiac output=
heart rate (HR) x stroke volume (SV)
What generates blood pressure?
contraction of the ventricles
Blood pressure is determined by
CO and vascualr resistance
Define blood pressure
the amount of force exerted on the walls of the
blood vessel when blood is flowing through
The higher the blood pressure,
the greater the blood flow
Define vascular resistance(R)
the opposition to blood flow due to friction
between blood and the walls of blood vessels
The higher the vascular resistance (R),
the smaller the blood flow
Vascular resistance(R) depends on:
- Size of the blood vessel (diameter)
- Blood viscosity
- Total blood vessel length
changing cardiac output (CO) and
blood vessel diameter result in
Rapid adjustments in blood pressure, such as those that occur during changes
in posture and exercise
increasing CO, either by increasing stroke volume or
heart rate,
increases blood pressure while decreasing CO decreases blood pressure.
Blood vessel diameter, especially the diameter of arterioles, results in
changes in systemic vascular resistance (SVR).
. A decrease in blood vessel diameter
(vasoconstriction) increases
SVR and therefore blood pressure
increase in blood vessel diameter (vasodilation)
decreases SVR and blood pressure.
