Flashcards in Chap 10-12 Arterial and Venous Physiology Deck (32):
Name the superficial veins of the LE.
confluence of superficial inguinal veins
post accessory GSV
Name the superficial veins of the UE.
What is dynamic pressure?
Dominates in supine position
pressure generated by cardiac pumping
majority dissipated before capillary bed
blood flow along gradient
What is hydrostatic pressure?
dominates in upright position
weight of column of blood below right atrium
return of blood to heart must overcome this pressure
Which muscle pump is the most important for blood return? and how does the muscle pump work?
generates high pressure during muscle contraction propels blood forward
during relaxation, valves close preventing reflux
negative pressure generated by valve closure creates negative pressure which draws blood from superficial system
What is venous compliance?
change in blood volume that occurs for each unit change in transmural pressure in a segment of vein
compliance is the slope of the capacitance curve
What is venous capacitance?
relationship b/w pressure and volume at a given level of smooth muscle tone
How does transmural pressure relate to venous volume?
transmural P is the difference b/w pressure acting to expand vein and pressure acting to collapse vein
high transmural pressure = high venous volume
15mmhg increase can = 25-% increase in volume
What law dictates passive flow of blood in/out of organs?
ohm's law Pdiff = F x R
What factors contribute to venous return?
movement of diaphragm
changes in intrathroacic/intraabdominal pressure (less for UE)
What are the types of valvular anomalies that lead to valvular incompetence?
Type I elongated and atrophic cusps
Type II expanded and depressed commissures with cusps changes
Type III cusps with other deformities
Type IV absent cusps
type II most common
What are ranges for venous filling index?
7 associated with venous ulcers
How does venous HTN occur?
presence of incompetent valves/obstruction, blood refluxes distally during muscle relaxation
re-establishes the hydrostatic column
periph venous P rises b/w contraction and HTN occurs
How do ambulatory venous pressure relate to incidence of venous ulceration?
What are symptoms of post-thrombotic syndrome?
What is the cause of PTS?
DVT causes obstruction and valve incompetence leads to vHTN
What % of patients get PTS after DVT?
up to 50%
10% severe with ulcers
What are the symptoms of venous claudication?
bursting thigh pain and tightness during exercise with iliofem thrombosis
What is the mechanism of venous claudication?
venous volume increase but unable to increase venous outflow because of fixed resistance
What is the venous thrombosis pathway?
damage to endothelium
release of TF which activate extrinsic pathway of coat cascade
plt activation forms plt plug (primary thrombotic event)
plt activation leads to release of prothrombotic contents, AA metabolites (thromboxane) leads to more pot aggregation
What is the central fibrinolytic enzyme?
What are 3 mechanisms of plasminogen activation?
fibrin bound tPA
urinary plasminogen activator
activated XII, kallikrein, XI
under normal conditions, how do endothelial cells maintain non-thrombogenic state?
endo production of thrombomodulin and subsequent activation of protein C
endothelial expression of heparin sulphate and derma tin sulcate (accel AT and heparin cofactor II)
expression of TFPI
local production of tPA and uPA
How does inflammation lead to thrombosis?
reactivity of pot
How does reflux lead to injury?
vein inujry/valve damage leads to reflux
increased hydrostatic pressure
vHTN activates leuks
leads to fibrosis (worsens hydro P)
What are RF for VV?
congenital absence of valves
What are vein wall changes in VV?
intense disorganized deposition of collagen
TGGB and fibroblast growth factor increased
less type III and V collagen
What leads to C4-6 development?
extrav of macromolecules and RBC into interstitium
creates inflame response
leads to skin hypoxia
What are findings for thrombophlebitis?
tenderness to palpation with a cord presence
What is migratory thrombophlebitis?
TBP that recurs in different locations years before diagnosis of timor (usually pancreatic cancer)
What is Mondor disease?
superifical TBP in breast tissue