integration of the cardiovascular mechanisms Flashcards
how is the systemic vascular resistance (SVR) regulated?
-by vascular smooth muscles
> contraciton of vascular smooth muscles causes vasoconstriction and increases SVR and MAP
> relaxation is opposite
what is vasomotor tone?
- when vessels are partially constricted at rest
what nerve fibers supply vascular smooth muscle?
-sympathetic (noradrenaline)
what is the vasomotor tone caused by?
-tonic discharge of sympathetic nerves, this results in continuous release of noradrenaline
Adrenaline acting on alpha receptors causes what?
vasoconstriction
Adrenaline acting on beta 2 receptors causes what?
vasodilation
what humoral agents cause relaxaton of arteriolar smooth muscles which results in vasodilation
- histamine
- bradykinin
- nitric oxide (NO)
what humoral agents cause relaxaton of arteriolar smooth muscles which results in vasoconstriction
- serotonin
- thromboxane A2
- leukotrienes
- endothelin
what are some endotherlial produced vasodilators?
- anti-thrombotic
- anti-inflammatory
- anti-oxidants
what are some endothelial produced vasoconstrictors?
- pro-thrombotic
- pro-inflammatory
- pro-oxidants
what causes sheer stress?
-dilation of arterioles causes sheer stress in arteries upstream to make them dilate
>increases blood flow to metabolically active tissues
what does change in temperature cause?
cold - vasoconstriction
warm - vasodilatation
what nerve fibers supply venous smooth muscle?
sympathetic nerve fibers
what does increased venomotor tone increase?
- venous return
- SV
- MAP
what does increased vasomotor tone increase?
- SVR
- MAP
