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42 Cards in this Set

  • Front
  • Back
are there any parasympathetics to peripheral vasculature?
no, only SNS
what is active vasoconstriction?
dilation of vasculature due to a stimulus
what is active vasodilation?
dilation of vasculature due to a stimulus
what is passive vasoconstriction?
return to normal tone after a dialatory stimulus has been removed
what is passive vasodilation?
the return to a normal tone after constrictive stimuli have been removed
what causes vasoconstriction?
increase in:
myogenic activity
O2 concentration
endothelin
vasopressin
angiotensin II
cold

Decrease in:
CO2
metabolites
what causes Vasodilation?
increase in:
NO
CO2
Metabolites
heat
histamine

Decrease in:
SNS
O2
myogenic activity
what are intrinsic factors?
active and reactive hyperemia
autoregulation
what are extrinsic factors?
hormones
neural influences
what causes active hyperemia?
increased metabolic activity decreases O2 concentration and increases local metabolite concentration. this dilates the vessels and increases blood flow
what are the local metabolites and electrolytes that effect vasodilation?
K+
PO4
prostaglandins
lactic acid
H+
adenosine
NO
what is the only difference between reactive and active hyperimia?
reactive hyperimia is induced by an occlusion
what are the organs that autoregulate?
Kidney
heart
Brain
Skeletal Muscle
what is the primary goal of autoregulation?
to maintain a constant blood flow despite changes in pressure
what is the myogenic hypothesis?
if Pressure increases, smooth muscle in arterial walls will constrict to compensate
if pressure decreases, the smooth muscle will relax to compensate
where is vasopressin released from and what does it do?
it is released from the pituitary and it is a vasoconstricter and increases water retention
where does angiotensin II come from and what is its function?
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
where does atrial natriuretic peptide come from and what is its function?
atria
vasodilator
what does the SNS use for vasodilation? vasoconstriction?
dilation- B2
constriction- a1
are there sympathetic cholinergic fibers?
yes, M3 SNS fibers
what does angiotensin II bind to on vascular bed smooth muscle cells?
AT1 receptors
what is another name for vasopressin?
ADH

vasoconstrictor and causes water retention
what does ADH bind to?
V1 receptors on the distal convoluted tubule of nephron
what do ANPs and BNPs do?
they are vasodilators

stimulate guanylyl cyclase activity
what are the effects of ANP in the kidney
increased water and Na+ secretion
what is the effect of epinephrine release on the system>?
vacoconstriction of most arterioles via a1 and a2

Vasodilation of skeletal muscle arterioles via B2
how is NO release stimulated?
neurotransmitters
shear stress

causes an increase in cGMP
what is EDHF?
causes endothelial cell dilation by hyperpolarizing the cell
what is prostacyclin?
released by the same stimulus for NO.
causes dilation and inhibits platelet formation
what is endothelin?
most powerful vasoconstrictor yet discovered
what are the effects of prostaglandins?
induces vasoconstriction in arease with platelet aggregation
i.e. blood loss
what is the role of kinins?
vasodilators
what effect does histamine have on vasculature?
vasodilator
but
also stimulates the release of prostoglandins
where is the velocity of blood flow the slowest?
in the capillaries
what type of vessel contains precapillary sphincters?
metarterioles
what are the factors that influence bulk flow?
capillary blood pressure (Pc)
Plasma osmotic pressure (pieP)
interstitial fluid hydrostatic pressure (Pif)
interstitial fluid osmotic pressure (pie if)
what is capillary blood pressure (Pc)?
the pressure exerted on the inside of a capillary wall
what is plasma osmotic pressures (pie P)
the force caused by plasma proteins (fluid movement into the capillary)
what is interstitial fluid hydrostatic pressure(Pif)?
the fluid pressure exerted on the outside of the capillary by interstial fluid
what is the interstitial fluid osmotic force (pie if)?
the small force exerted by proteins that have leaked into the interstitial fluid. (fluid flow outward)
what is the equation for net exchange pressure?
NEP= (outward forces) - (inward forces) = (Pc + pie if) - (Pif + pieP)
what happens to bulk flow during a hemorrhage?
the net flow of fluid will be from interstitial fluid to plasma