Extrinsic Regulation Flashcards
Neural control facts
Innervation
SNS/PNS transmitters
Receptor for NE
Majority of BV receive SNS but not PNS (do= Salivary glands/ GI glands/ erectile tissues
S- NE
P- Ach
Alpha adrenergic in SM
Characteristics of SNS control of BV
Terminal arterioles
Symp activity serves systemic needs
Terminal arterioles- local/individual tissue control
Symp vasoconstrictor tone
Vasomotor tone
VC area transmits signals continuously to SNS fibers
Slow firing of these fibers (symp vasoconstrictor tone)
Maintains a partial state of contraction
Rapidity of nervous control of arterial pressure
within seconds- extremely rapid
SNS regulates contractile state of resistance/capacitance vessels
Supply?
Constrict resistance
Capacitance
More responsive
arteries/arterioles/veins
Constricts and inc periph resistnace
Inc venous pressure/return
Capacitance- lower stimulation necessary
Hormones
directly/indirectly effect BF by facilitating VC/VD
Epi/Norepi
What?
Where?
What do they do?
AA vs B2A
Humoral factors that affect vasc resistance
AM in response to inc symp neural activity
Acts on AA receptors for VC
Acts on B2A for VD
AA outnumbers- VC/resistnace
RAAS
AT2 action sites
Release hormones
Act on kidney to retain Na
Vasoconstrictor
RAAS most powerful vasoconstrictor
Mechanisms
1-4
Direct
Potentiate constriction of symp activity by inhibiting NE euptake
Eliciting secretion of endothelin
Release renin, making AT2
ADH
Where?
Functions- low/high conc
Stimuli
Posterior pituitary
low conc, dec excretion of H2O high conc, vasoconstriction
Osmotic conc of ECF
Decreased blood volume
Hierarchy of vascular control
Bottom tier
Middle tier
Top tier
B- autoregulation via myogenic
M- autoregulated flow inc/dec via intrinsic mechanisms
VD- functional hyperemia, endothelial secretions, autocoids
T- vasomotor nerves/hormones
