Special circulations B6 Flashcards
2 ways you can control flow to an organ
Blood flow can be controlled extrinsically= someone else decides, Neural and hormonal (receptors)
Blood flow can be controlled intrinsically- local control- the organ tissue decides
Blood flow is maintained constant despite changing arterial pressure
Autoregulation
Blood flow changes as metabolic demand changes
Active hyperemia
Period of reduced blood flow are followed by supernormal flow.
Reactive hyperemia
What are the 3 levels of local control?
Autoregulation
Active hyperemia
Reactive hyperemia
Smooth muscle adjusts diameter of vessels to maintain blood flow
Myogenic mechanism
Metabolic by-products act as local signals to alter flow
Metabolic mechanism
Blood flow in the coronary vessels to feed heart
Coronary flow
-Metabolic control most important
-active hyperemia through hypoxia and adnosine
Reactive hyperemia during diastole
(little neural control)Blood flow to skeletal muscle
Skeletal flow- important during exercise
-neural most important during rest
Blood flow to skin
Skin- primarily neural for body heat regulation
- little metabolic control
- hormonal regulation- histamine
Increasing skeletal muscle CO2 production would ________ blood flow?
Increase
Increasing skeletal muscle CO2 production would increase blood flow, an example of _______________ regulation.
Increasing metabolic demand
-Active hyperemia
(Reactive requires a loss of blood flow…)
Know what kind of blood flow changes organs we talked about and give examples…
slide 5 6 7
Process of forming clots on vessel walls in response to injury is what? what does it do?
Hemostasis
Prevents further blood loss
3 stages of hemostasis
Vascular constriction
Formation of a platelet plug
Clot formation- coagulation
Collagen binds to _______________ which binds to circulating platelets.
von Willebrand factor
Immediately after damage, vessel ____________.
Constricts, slowing flow to damaged area
Damaged endothelium release vasoactive compounds to cause ___________
Vasoconstriction
adenosine and Calcium
Pain response from ________ also cause vasoconstriction
CNS
What protein is responsible for platelet flug formation? (IMPORTANT)
Von willebrand factor
Enzymatic cascade that converts fibrinogen into fibrin.
Coagulation
If thrombus breaks off it is called a __________
embolus
____________ usually originate in legs (deep vein thrombosis). They can get stuck in lung, causes ___________________
Venous emboli
pulmonary embolism (pulmonary hypertension and right sided heart failure
These usually originate in atria or carotids. Get stuck in cerebral or ocular vessels, cause stroke and reitnal ischemia
Arterial emboli
2 pathways of activation of clot cascade
Intrinsic: initiated by exposed collagen
Extrinsic: initiated by release of tissue factor
What is an important component of an embolus?
The first capillary bed that an embolus goes into next is where it usually gets stuck.
Vitamin K-dependent Factors __________ is by far the most sensitive. (IMPORTANT)
Factor VII
____________ is where intrinsic and extrinsic factors converge/meet. (IMPORTANT)
Factor 10
What are the steps of Clotting.
Clot retraction- after an hour (pulls vessel walls together)
Clot dissolution- fibrinolysis (healing the wound)
Tissue plasminogen activator (tPA)-clot buster
-used during strokes to try and break clot up
What is the clot buster?
Tissue plasminogen activator (tPA)
What does aspirin do?
Blocks Thromboxane A2 production
-stops platelets from sticking together.
Aspirin a day keeps the clots away
What is a fast acting anti-platelet drug that inhibits factor IIa and Xa?
Heaprin
What is a slow acting anti-platelet drug that inhibits vitamin K production, through Factor VII?
Warfarin (Coumadin)
