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42 Cards in this Set
- Front
- Back
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are there any parasympathetics to peripheral vasculature?
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no, only SNS
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what is active vasoconstriction?
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dilation of vasculature due to a stimulus
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what is active vasodilation?
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dilation of vasculature due to a stimulus
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what is passive vasoconstriction?
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return to normal tone after a dialatory stimulus has been removed
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what is passive vasodilation?
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the return to a normal tone after constrictive stimuli have been removed
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what causes vasoconstriction?
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increase in:
myogenic activity O2 concentration endothelin vasopressin angiotensin II cold Decrease in: CO2 metabolites |
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what causes Vasodilation?
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increase in:
NO CO2 Metabolites heat histamine Decrease in: SNS O2 myogenic activity |
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what are intrinsic factors?
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active and reactive hyperemia
autoregulation |
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what are extrinsic factors?
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hormones
neural influences |
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what causes active hyperemia?
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increased metabolic activity decreases O2 concentration and increases local metabolite concentration. this dilates the vessels and increases blood flow
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what are the local metabolites and electrolytes that effect vasodilation?
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K+
PO4 prostaglandins lactic acid H+ adenosine NO |
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what is the only difference between reactive and active hyperimia?
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reactive hyperimia is induced by an occlusion
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what are the organs that autoregulate?
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Kidney
heart Brain Skeletal Muscle |
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what is the primary goal of autoregulation?
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to maintain a constant blood flow despite changes in pressure
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what is the myogenic hypothesis?
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if Pressure increases, smooth muscle in arterial walls will constrict to compensate
if pressure decreases, the smooth muscle will relax to compensate |
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where is vasopressin released from and what does it do?
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it is released from the pituitary and it is a vasoconstricter and increases water retention
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where does angiotensin II come from and what is its function?
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it comes from a stepwise process that converts angiotensinogen into angeotensin I and then angiotensin II via the use of renin and ACE
it is a vasoconstrictor |
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where does atrial natriuretic peptide come from and what is its function?
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atria
vasodilator |
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what does the SNS use for vasodilation? vasoconstriction?
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dilation- B2
constriction- a1 |
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are there sympathetic cholinergic fibers?
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yes, M3 SNS fibers
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what does angiotensin II bind to on vascular bed smooth muscle cells?
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AT1 receptors
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what is another name for vasopressin?
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ADH
vasoconstrictor and causes water retention |
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what does ADH bind to?
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V1 receptors on the distal convoluted tubule of nephron
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what do ANPs and BNPs do?
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they are vasodilators
stimulate guanylyl cyclase activity |
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what are the effects of ANP in the kidney
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increased water and Na+ secretion
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what is the effect of epinephrine release on the system>?
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vacoconstriction of most arterioles via a1 and a2
Vasodilation of skeletal muscle arterioles via B2 |
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how is NO release stimulated?
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neurotransmitters
shear stress causes an increase in cGMP |
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what is EDHF?
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causes endothelial cell dilation by hyperpolarizing the cell
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what is prostacyclin?
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released by the same stimulus for NO.
causes dilation and inhibits platelet formation |
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what is endothelin?
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most powerful vasoconstrictor yet discovered
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what are the effects of prostaglandins?
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induces vasoconstriction in arease with platelet aggregation
i.e. blood loss |
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what is the role of kinins?
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vasodilators
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what effect does histamine have on vasculature?
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vasodilator
but also stimulates the release of prostoglandins |
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where is the velocity of blood flow the slowest?
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in the capillaries
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what type of vessel contains precapillary sphincters?
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metarterioles
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what are the factors that influence bulk flow?
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capillary blood pressure (Pc)
Plasma osmotic pressure (pieP) interstitial fluid hydrostatic pressure (Pif) interstitial fluid osmotic pressure (pie if) |
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what is capillary blood pressure (Pc)?
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the pressure exerted on the inside of a capillary wall
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what is plasma osmotic pressures (pie P)
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the force caused by plasma proteins (fluid movement into the capillary)
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what is interstitial fluid hydrostatic pressure(Pif)?
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the fluid pressure exerted on the outside of the capillary by interstial fluid
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what is the interstitial fluid osmotic force (pie if)?
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the small force exerted by proteins that have leaked into the interstitial fluid. (fluid flow outward)
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what is the equation for net exchange pressure?
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NEP= (outward forces) - (inward forces) = (Pc + pie if) - (Pif + pieP)
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what happens to bulk flow during a hemorrhage?
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the net flow of fluid will be from interstitial fluid to plasma
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