Quiz 8 Flashcards
Name 3 endogenously found vaso-constricting substances. (5)
Catecholamines: (Epinephrine, Norepinephrine, Dopamine)
- Endothelin
- Serotonin
- Angiotensin II
- Vasopressin
Name 3 endogenously found vaso-dilating substances. (9)
Carbon Dioxide Histamine Adenosine Nitric Oxide (NO) Prostaglandins Potassium Hydrogen Ion Acetylcholine Bradykinin
What is the Metabolic Mechanism? What substance is responsible for this mechanism?
inadequate oxygen (nutrient) supply for the metabolic requirements of the tissues results in the formation of vasodilator substances which increase blood flow to the tissues
Adenosine Potassium ions Carbon dioxide Hydrogen ion Inorganic phosphate Lactic acid
What is the Myogenic Mechanism?
When the lumen of a blood vessel is suddenly expanded, the smooth muscles respond by contracting in order to restore the vessel diameter and resistance. The converse is also true.
Proposed mechanism is stretch of vascular smooth muscle causes activation of membrane calcium channels.
What is Reactive Hyperemia? Give a common clinical example of Reactive Hyperemia
transient increase in organ blood flow that occurs following a brief period of ischemia
the removal of a tourniquet, unclamping an artery during surgery, or restoring flow to a coronary artery after recanalization
What is Autoregulation? What mechanism of blood flow regulation is thought to be involved?
Theintrinsic ability of an organ to maintain a constant blood flow despite changes in perfusion pressure.
Myogenic and metabolic mechanism
Name 3 endothelial factors that help regulate blood flow?
- Nitric Oxide (NO)-most important endothelial derived relaxing factor
- Prostacyclin
- Endothelin
- Endothelial-derived hyperpolarizing factor (EDHFZ)
What is nitric oxide?
-a lipophilic gas that is released fromendothelialcells in response to a variety of chemical and physical stimuli
-Generated from amino acid L-arginine
-Generated from NO synthase
-Increases GMP concentration which produces relaxation by decreasing cytosolic free calcium
-Very short half-life (6 seconds)
(Due to rapid oxidation to nitrite and nitrate
Also due to binding by substances such as hemoglobin)
Is Endothelin a vaso-dilator or -constrictor?
constrictor
Why are blood vessels prone to vaso-constriction, vaso-spasm and thrombosis when the endothelium is damaged?
- Decreased Nitric Oxide and Prostacyclin production
- Increased Endothelin production
what is active hyperemia? Example?
theincrease in organ blood flow (hyperemia) that is associated with increased metabolic activity of an organ or tissue
increase in blood flow that accompanies muscle contraction
How might it be helpful during one-lung ventilation?
Increased arterial oxygen tension
This improves V/Q relations by vasodilating capillaries and improving blood flow to areas participating in gas exchange.
