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25 Cards in this Set
- Front
- Back
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within 1 minute after an increase in arterial blood pressure resulted in an immediate increase in blood flow, the blood flow returns to almost baseline and arterial pressure remains elevated
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autoregulation of blood flow
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when arterial pressure within tissues becomes too great, increased blood flow provides excess O2
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metabolic autoregulation
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blood flow decreases while upstream arterial pressure remains elevated
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metabolic autoregulation
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sudden stretching of small blood vessels in response to increased blood pressure contracts vascular smooth muscle for a few seconds
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myogenic autoregulation
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aka: reactive vasocontriction
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myogenic autoregulation
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within 1 minute after an increase in arterial blood pressure resulted in an immediate increase in blood flow, the blood flow returns to almost baseline and arterial pressure remains elevated
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metabolic autoregulation
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when arterial pressure within tissues becomes too great, increased blood flow provides excess O2
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metabolic autoregulation
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blood flow decreases while upstream arterial pressure remains elevated
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metabolic autoregulation
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sudden stretching of small blood vessels in response to increased blood pressure contracts vascular smooth muscle for a few seconds
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myogenic autoregulation
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what does reactive vasoconstriction do
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reduces local blood flow to near baseline
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sudden stretching of small blood vessels in response to increased blood pressure contracts vascular smooth muscle for a few seconds
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myogenic autoregulation
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this response is not stimulated directly by tissue metabolism
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reactive vasoconstriction in myogenic autoregulation
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increase blood flow to the microvasculature does what
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increases shear stress on the endothelial cells of upstream arteries supplying the microvasculature
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what is nitric oxide also known as?
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endothelium derived/dependent relaxing factor (EDRF)
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what does nitric oxide do
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vasodiates upstream arteries
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full activation of mechanisms for acute control of local blood flow provide approximately how much blood flow required by tissues, this effect is temp
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75%
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vascular endothelial growth factor (VEGF), fibroblast growth factor and angiogenin
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angiogenic factors
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how and why are angiogenic factors secreted
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from tissue cells in response to chronically decreased tissue o2 and nutrient delivery
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Name the long term mechanisms for blood flow control
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changes is tissue vascularity, role of oxygen, and angiogenic factors
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these substances stimulate new vessel growth from existing small vessels
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vascular endothelial growth factor (VEGF), fibroblast growth factor, and angiogenin
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vasoconstrictor substances
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norepinephrine, epinephrine, angiotensin II, vasopressin (ADH) and endotherlin which works locally
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a powerful vasoconstrictor of small arterioles through the body; systemic vascular resistance increases and arterial blood pressure increases
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angiotensin II
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what is the primary mechanism for long term blood flow regulation around a vascular obstruction
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growth of collateral vessels
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physiologists believe only trace amounts of this are normally released from the posterior pituitary gland at any given time; therefor its effects on blood circulation is minimal
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vasopressin (ADH)
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what is the limitation of collateral vessels
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are not equip to supply O2 and nutrients during periods of significantly increased tissue metabolism
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