Shared Flashcard Set

Details

Phys. Exam 2 Microcirculation
Phys. Exam 2 Microcirculation
22
Physiology
Graduate
10/17/2010

Additional Physiology Flashcards

 


 

Cards

Term
AV shunt important for ___ regulation, also provides ___ ___ pathway from __ to ___.
Definition
- temperature
- arteriole
- venules
Term
Even though a capillary is only one endothelial cell thick, the pressure is about 20-25 mm Hg. It can get this high b/c the __ is a function of the __ and __, and since the radius is so small, a higher pressure can be achieved.
Definition
- tension
- pressure
- radius
Term
Wall tension acts to prevent a rupture along the theortecal long slit of the vessel.
Definition
Term
__ ___ is a potent vasodilator produced in response to shear stress.
Definition
Nitric oxide
Term
FASTER BLOOD FLOW, MORE SHEAR STRESS, MORE NITRIC OXIDE PRODUCED, THIS A FEED FORWARD MECHANISM: SO IF BLOOD FLOW INCREASES IN RESPONSE TO ANOTHER VARIABLE> INCRASE SHEAR STRESS> INCREASED NO
Definition
Term
shear stress also causes dilation by making :
Definition
prostaglandins or prostocyclins PGI2
Term
Prostacyclin:
Definition
Released in response to shear stress and ?
Inhibits platelet adherence to endothelium
Relaxes vascular smooth muscle
Term
Nitric oxide:
Definition
Released in response to shear stress, acetylcholine, ATP, bradykinin, histamine, hypoxia
Relaxes vascular smooth muscle
Term
Endothelin
Definition
- potent vasoconstrictor
- made by endothelium
Term
transcapillary exchange:
Definition
Lipid-soluble molecules (such as O2 & CO2) readily pass through the lipid component of endothelial cell membranes.

Water readily crosses the capillary wall, through the cell membranes and fenestrations.

Water-soluble molecules and ions must diffuse through the pores (water-filled pathways) in the capillary wall at the junctions between cells.

Large molecules cross the capillary wall by pinocytosis.
Term
capillary permeabiiity of a substance varies from tissue to tissue, but is not physiologically regulated.
Definition
Term
Capillary surface area is physiologically regulated by ___ and ___ ___ constriction or dilation.
Definition
- arterioloar
- precapillary sphincter
Term
List the four pressures that determine filtration or absorption:
Definition
1) Pc = capillary hydrostatic pressure
2) Pi = interstitial fluid hydrostatic pressure
3) Πp = plasma oncotic pressure
4) Πi = interstitial fluid oncotic pressure
Term
The capillary reflection coefficient in the Starling equation relates how much of the ___ ___ ___ ___ will be expressed across the ___ wall.
Definition
- potential net oncotic pressure
- capillary
Term
If the capillary wall is impermeable to sources of oncotic pressure (plasma proteins), then the coefficient is:
Definition
1.0
Term
As the capillary wall becomes more permeable the coefficient ___.
Definition
decreases
Term
coefficient varies from 0-1.
Definition
Term
LOOK AT SLIDE 18 AND KNOW HOW TO DO THIS
Definition
Term
POSITIVE NUMBER= NET FILTRATION

NEGATIVE NUMBER= ABSORPTION

WITH POSTIVE NUMBER, EDEMA WILL OCCUR DEPENDING ON LYMPHATICS
Definition
Term
As flltration increases, the lymph flow will increase to match filtration, but to do this it needs an increased tissue pressure.
Definition
Term
So excessive filtration, edema is occuring, to save itself> increased arteriole constriction and sphincter close> less pressure downstream> less filtration, then in interstitial space you have increased pressure b/c of edema so lymphatics compensate
Definition
Term
6 Factors of the margin of safety that help prevent edema:
Definition
1. Myogenic compensation:
- increased precapillary resistance
- decreased capillary surface area
2. Interstitial compensation:
- rise in interstitial fluid pressure
- dilution of interstitial proteins
3. Lymphatic compensation
- acceleration of fluid removal
- washout of interstitial proteins
Supporting users have an ad free experience!