part 3 Flashcards
How will the chemical stimulation of vascular smooth muscle cause a contraction or vasoconstriction?
The chemicals traveling from far or near will use the standard signal transduction pathway to increase intracellular ca2+ and elicit contraction.
Name the chemicals that are given that will cause vascular smooth muscle to contract?
norepineprine angiotensin II Vasopressin, Endothelin-1 Serotonin thromboxane a2
How will chemical stimulation cause vascular smooth muscle to relax or to vasodialate?
They cause a relaxation by inhibiting the contractile machinery.
Name the given chemicals that will chemicaly stimulate vascular blood vessels to vasodialate?
Nitric oxide prostacyclin local metabolites.
What will vascular smooth muscle need to respond to chemical stimulations?
Receptors or nothing will happen.
What are adrenergic receptors used to bind?
norepinephrine and epinephrine.
What specific adrenergic receptor is sensitive to norepinephrine? This receptor is released from what?This reaction will cause what?
alpha1 receptor axons of sympathetic fibers vasoconstriction
What will Beta2 receptors cause?
Vasodilation
What is an alpha blockade?
it uses alpha adrenergic blockers that are specific to alpha1 receptors to manage blood pressure in hypertensive patients this causes widespread vasodilation.
What will endothelin-1 receptors and Angiotensin-2 receptors cause to happen when they get the proper chemical stimulant?
They cause vasoconstriction.
What chemical is cholinergic receptors sensitive to? What will this cause.?
acetylcholine causes vasodilation
Are the same receptors in different areas of the body equally receptive?
no cerebral vascular smooth muscle is not nearly as responsive as GI vascular smooth muscle.
Nitric oxide is secreted due to shear forces of the arterial walls and how else?
It is released by endothelial cells after shear force is excerted on them and when endothelial cells have hormones and paracrine compounds stiumlate them. Both ways nitric oxide is released and causes vasodiliation.
How will nitric oxide cause vasodiliation?
It acts as a paracrine agent and causes intracellular levels of ca2+ to drop.
How will prostacyclin specifically effect vascular smooth muscles?
When signaled to do so by blood borne agents endothelial cells will release prostacyclin(a hormone and paracrine agent) and this causes vasodilation working through the G-protein singal transduction system.
What is a vascular spasm?
A rapid and profound vasoconstriciton with endothelial injury. When the endothlia is damaged it loses it’s ability to secrete nitric oxide and loses its ability to balance diameter and the diameter shifts towards vasoconstriction.
What is the purpose of nitroglycerin & amyl nitrite when talking about vascular vessels?
It is an organic nitrate drug that can cause profound vasodilation. They just serve as an extra source of nitric oxide. Used with chest pain to allow vasodilation and let more blood flow to the heart.
What will the production of H+ and co2 made in tissue cause to happen in vascular vessles?
It inhibits the ability of vascular smooth muscle to contract and this induces a local vasodilation.
What are the 2 broad sources of chemical agents that effect vascular smooth muscle?
Intrinsic- local control Extrinsic- Humoral or nervous control.
Generally intrinsic control causes what? Generally extrinsic control causes what?
Intrinsic- vasodilation Extrinsic- Vasoconstriction
Which control intrinsic or extrinsic is more rapid and more important?
Intrinsic
Intrinsic control usually comes from where?
Local paracrine agents from tissue.
When is the extrinsic control most important?
During critical periods.
What makes extrinsic control more potent?
Receptors Non essential tissues can have lots of receptors and be very vasoconstricted Under these circumstances extrinsic control cna overide intrinsic control.
Increased metabolism will do what to blood flow?
Increase it.
Decreased metabolism will do what to blood flow?
Decrease it.
Why will increased metabolism increase blood flow?
due to the production of tissue metabolites (waste) that needs to be removed. NOT due to oxygen demand.
What is active hyperemia?
Increased blood flow from activity/metablism.
With increased blood flow the tissue produces a reddening color called what?
Rubor.
What is the major metabolic waste from tissues or cells?
H+ This comes from co2 + h2o–> h2co3- + H+ so co2 is part of this process and is also a metablic waste.
Besides H+ and Co2 what are some metabolic waste from tissues or cells?
Adenosine Potassium ion Lactic acid
What is the primary control for setting tissue blood flow in the body and what is it like?
Local control and it is automatic and tissue centered.
Since all tissues are crying out I want blood, but they all cant get what they want and some become deprived of nutrients and this is called?
Ischemia.
When tissues are ischemic they are not getting enough blood and are deprived of oxygen and accumulate deoxygenated blood and get a blue color called?
Cyanosis.
Ischemia will produce what in affected tissues?
Pain.
Since automatic control of blood flow could lead to chaos how will body wide order be controled?
Nervous control.
What is bradykinin?
Damaged blood that causes vasodilation.
What type of chemical stimulant is histamine on vascular vessels? Where will it come from?
vasodilation comes from mast cells.
What is reactive hyperemia?
After a tissue is ischemic it has had no blood for a while and when blood is restored blood will flow there in a massive way that nearly matches the amount of blood that would have been delivered there the whole time it is blocked. Lots of blood will flow here until complete restoration of oxygen levels and all metabolites are gone.
Extrinsic control of the vascular sytem involves what?
The Central nervous system.