Vasculature Flashcards
What happens to veins at low pressures?
They collapse
What affects venous tone and venous volume?
Small changes in pressure
What happens to venules near the sites of infections?
They become permeable to leucocytes so that they can enter for an immune response
What releases nitrous Oxide?
Blood flow, bradykinin, ATP, histamine, H+, CO2, Acetylcholine
What does NO do?
Vasodilator
What releases Prostacyclin (PGI2)?
The endothelium of sm cells
What does Prostacyclin do?
Inhibits platelet aggregation and endothelin ( vasoconstrictor)
How does hyperpolarisation of a cell cause relaxation?
Closes ion channels
What is oxidative stress?
The overproduction of reactive oxidation species- associated with cardiovascular disease
What does oxidative stress do?
Tends to prevent blood vessels from dilating as NO reacts with superoxide form peroxynitrite which is not a vasodilator
What is autoregulation?
Blood flow is certain vascular beds remain fairly constant over a wide range of pressures
What happens when there is an ongoing production of metabolites in tissues?
Vasodilating effect- increase blood flow, which then increases vascular tone therefore increase in local resistance
What is metabolic hyperaemia
Increase organ blood flow that is associated with the metabolic activity of the organ
What happens if local blood flow is cut off?
Metabolites accumulate and cause vasodilation
What is reactive hyperaemia?
Transient increase in organ blood flow that occurs following a brief period of ischemia, occurs in isometric exercise
