Regulation Of Blood Pressure Flashcards
Why is the volume in arteries called stressed volume?
Because it is under high pressure
What does low compliance mean in aretries?
Ability of blood vessels to expand and hold larger volumes of blood without a significant increase in blood pressure
What in arterioles is tonically active?
The vascular smooth muscles
Key ideas about blood pressure in arterioles
Tonically active vascular smooth muscle
Highest resistance to blood flow, changed in response to catecholamines, vasoactive substances and sympathetic nerves:
Sympathetic nerves:
-Alpha 1 adrenergic receptors contract/ constrict (decrease diameter of arteriole OR increase resistance to blood flow)
-Beta 2 adrenergic receptors dilate/ relax
Balance of alpha 1 and beta 2 receptors regulates blood flow to different organs and tissues in changing conditions
What are alpha 1 adrenergic receptors?
A receptors found on skin, mucous membranes and splanchnic arterioles.
When stimulated, They cause contraction of vascular smooth muscle
What are beta 2 adrenergic receptors?
Receptors found in skeletal muscle and heart arterioles
When stimulated, They cause dilation
Key ides about blood pressure in capillaries
Low pressure and slow flow
Controlled by dilation/ constriction of arterioles
Key ideas about blood pressure in veins and venules
Low pressure
Walls contain less elastic tissue than arteries
Large capacitance
Contain largest % of blood in CV system
Activity can be increased via alpha 1 adrenergic receptors
How can the activity of veins or venules be increased?
Activity can be increased via alpha 1 adrenergic receptors- contraction reduces capacitance so decrease in unstressed volume
Does the flow change across blood vessels?
No because its a closed system
How do we work out velocity in IDENTICAL flow?
Velocity= rate
Velocity= Q / A
Q=flow
A=cross sectional area
What is the relationship between blood flow, resistance and pressure?
Equation
Q= Δ P / R
Q=blood volume per unit of time (mL/s)
P= pressure difference (mmHg)
R= resistance (mmHg/mL per min)
What is vasoconstriction?
Contraction of vascular smooth muscle
What is the significance of the relationship between blood flow, pressure and resistance?
BP regulation:
Vasoconstriction = +resistance = +BP
Vasodilation = - resistance = -BP
Blood flow distribution- adjustment due to need increase or decrease of resistance
What is total peripheral resistance (TPR)?
Resistance of the entire vascular system