Vasculature Flashcards
What is a pericyte?
A cell superficial to endothelial cells in capillaries that are contractile
What can effect contraction of smooth muscle in arteries?
Blood borne substances such as AT2, adrenaline can stimulate contraction, NO and EDH can inhibit
Local hormones, tissue metabolites can both + and -
Sympathetic nerves can release NA = +
Pressure = +
Does NO cause vasodilation or constriction?
Vasodilation
What causes NO release
Bradykinin - a peptide in the blood ATP Histamine H+ CO2 ACh
What does PGI2 do?
Prostacyclin 2 acts as a vasodilator but mainly is an inhibitor of platelet aggregation
What is oxidative stress?
Stress due to overproduction of reactive oxygen species such as superoxide O2- and hydrogen peroxide
What is produced when superoxide and hydrogen peroxide react?
Peroxynitrile
What can activation of beta2, PGI2, adenosine receptors on vascular smooth muscle cells cause and how?
Vasodilation.
Adenylate cyclase is stimulated, then cAMP is produced which then activates PKA which leads to vasodilation
What do epoxyeicosatrienoic acids (EETS) do?
Activate K+ channels causing hyperpolarisation and relaxation.
How is flow maintained in an artery in which there is a pressure change?
Via vasoconstriction/dilation.
Flow = deltaP/R; constriction raises R therefore compensating for a decrease in pressure and vice versa
How does metabolite production effect autoregulation of vascular function
Metabolites produced cause vasodilation, which increases flow.
Then increased flow washes away metabolites therefore reducing the vasodilatation so that blood flow is proportional to the metabolic rate.
What is metabolic hyperaemia
Metabolites such as K+,H+, CO2, Lactic acid, adenosine cause vasodilation of arterioles causing an increased blood flow proportional to the metabolic rate
What are the types of capillaries
Fenestrated (windows- open/closed)
Continuous (least permeable, tight junctions)
Sinusoidal (big gaps for proteins)
What does the thoracic duct drain into
The subclavian vein
