Arterial - Venous Shunt
Blood from artery shunts blood to venous side without passing thru the capillaries
Capillary Anatomy
7-10micron diamater
Single layer endothelium and basement membrane
Low Continuous Exchange
Muscle, nerve adipose
High Continuous Exchange
Lymph and thymus
Open Fenestrated
Renal Glomeruli
Closed Fenestrated
Endocrines adn intestinal villi
Discontinuous
liver, bone marrow, spleen
Neural Control of peripheral circulation
Sympathetic Alpha-adernergic vasoconstriction
Sympathetic Alpha adernergic vasoconstriction work on
metarterioles
arteriols
some Beta 2-adernergic vasodilation
Local control of periphery
local metabolic control of precapillary sphincter opening and closing; AUTOREGULATION
Regulation of microvascular resistance
Myogenic regulation
activer hyperemia
Mygenic regulation
increased pressure causes active relaxation
relaxation causes active contraction
prevents edema with sudden BP increase
assists with organ AUTOREGULATION
Active hyeremia
increased blood flow with increased metabolism
Products that relax sphincter smooth muscle
H+
O2
CO2
Adenosine
potent dilator and especially important for the heart and brain
Increased pressure causes _____________
active relaxation
Relaxation causes ___________
active contraction
Encothelial cell shear causes synthesis of __
NO
NO inhibits _____________
smooth muscle contraction
NO activates
Guanylate cyclase
guanylate cyclase makes
cGMP
cyclic Guanosine Monophosphate
cGMP inhibits
smooth muscle contraction
NO released from endothelial cells by ____________ and _____________
endothelial NO synthase and arginine
Fick's Law of Perfusion
J=PS(dc/dx)
PS
permeability and surface area
dc/dx
concentration difference between blood and interstitium
Permeability and surface area depend on
-temp, molecular radius and viscocity
-% of capillaries open
-type of endothelium
Types of Limited Transport
Flow Limited
Rate Limited
Flow Limited transport
diffusion is fast and transport is only changed by the rate of blood perfusing a tissue
Rate Limited Transport
Larger molecules have difficulty moving thru pores and thus diffusion is rate limiting
Pneumonia
Oxygen and CO2 are normally flow limited
Fluid adds diffusion distance and viscocity
diffusion of gases shifts from flow-limited to diffusion-limited
Water movement depends on (2)
pressure differences across teh capillary membrane
Hydrolic conductivity and area of diffusion
Starling-Landis Equation
equation for movement of water
Capillary filtration Coefficient
Water vol/ml/min per 1 mmHg P change / 100 g tissue
Compares how leaky different tissues are for water
Capillary filtration coefficent changes with _____________-
permeability of each capillary and which cross section is perfused
Burns
destroys capillary integrity so permeability increases, plus increase albumen leaks out
CHP
Capillary Hydrostatic Pressure
BP of capillary
THP
Tissue hydrostatic Pressure
Fluid pressure associated between fluid between the cells
TOP
Tissue Oncotic Pressure
Force of water trying to dilute the protein concentration of the interstital fluid
COP
Capillary Oncotic Pressure
Force of water trying to dilute the protein concentration of interstitial side
Ch.18 LTI-MA 509
