Control of Tissue Blood Flow Flashcards
What organs have alpha-1 receptors?
GI, skin
What organs have beta-2 receptors?
skeletal & coronary arteries
What kind of receptors do cerebral arteries have?
THEY DO NOT RESPOND TO NEURAL/ENDOCRINE CONTROL. only local.
What contribution does the PNS make to neural control of tissue blood flow?
Vasodilation & secretion of the salivary gland through VIP & ACh
What compounds have effects as hormones to control tissue blood flow?
1) epinephrine
2) AngII
3) ADH/Vasopressin
4) Bradykinin
5) Histamine
How does AngII affect tissue blood flow?
directly causes smooth muscle vasoconstriction
–> increase TPR
How does ADH affect tissue blood flow?
causes vasoconstriction & water/salt retention
How does bradykinin affect tissue blood flow?
causes vasodilation & increased capillary permeability
How does histamine affect tissue blood flow?
vasodilation & increased capillary permeability
What cells release histamine?
mast cells & basophils
where are mast cell located?
tissue
where are basophils located?
blood
How bradykinin activated?
1) lysis/inflammation –> kallikrein activation
2) kallikrein: a2-globulin –>kallidin
3) kallidin –> bradykinin
How is bradykinin inactivated?
carboxypeptidase or ACE
What are the two theories for local control of tissue blood flow?
1) vasodilator
2) nutrient/o2-lacking theory
Describe the vasodilator theory of local control?
increased metabolism –> vasodilator production
vasodilators: adenosine, histamine, H+, CO2
Describe the nutrient/O2 lacking theory.
1) Decreased flow –> O2/nutrient depletion
2) inability of vessels to contract, so they relax
Define autoregulation.
acute increase in P will increase Q, but Q returns to normal within a range of P’s
What are the 2 theories for autoregulation?
Metabolic & Myogenic
Describe the myogenic theory for autoregulation.
Vascular smooth muscle contracts due to stress-activated channels
Describe the metabolic theory for autoregulation.
Increased o2 + nutrients –> contraction
When is endothelin released?
endothelium releases endothelIN due to damage to prevent blood loss
What are the consequences of endothelin in HTN?
may cause additional vasoconstriction
How are endothelin receptors used in drug therapy?
endothelin receptor antagonists for pulmonary HTN