quiz 3/15 Flashcards
do capillaries contain smooth muscle or constrict?
no and no
why can capillaries withstand high intravascular pressure?
la places law. small radius = low pressure. wall tension = transmural pressure x radius of vessel. wall stress = transmural pressure / wall thickness
Is the permeability of the capillary endothelium the same in all the tissues of the body?
no
what percentage makes up ECF
20
what percentage makes up ICF
40
what happens if you give someone 1L of NS
increase ECF, no change in osmolality
what does dextrose do
reduces ECF osmo and therefore helps correct the increase in ECF osmo associated w dehydration
hypotonic increases ___ volume
intracellular
hypertonic increases
extracellular
what is capillary filtration
the sum of the hydrostatic and osmotic forces favors the movement of water from the capillary to the interstitial space (+ filtration, arteriolar)
what is capillary reabsorption
movement of fluids or h20 back into the capillary (venular end)
starling forces - increased capillary pressure and interstitial fluid osmotic pressure moves fluid ____
out of the capillary.
increased plasma colloid osmotic pressure causes
inward movement of fluids
what is osmosis
h20 moves from areas of high h20 concentration to areas off low h20 concentration through a semi-permeable membrane
if net driving forces are positive, does it favor capillary filtration or reabsorption?
filtration
if net driving forces are negative what does it favor
reabsorption at venular end
are pressures higher at the arteriolar end or the venous end
arteriole side (30 vs 10mmhg)
under normal circumstances, what net driving force favors fluid movement into the capillary?
negative pressure - absorption
what would the net driving forces be in a patient with CHF? cirrhosis? venous thrombosis?
filtration (positive). d/t increased capillary hydrostatic pressure. and decreased plasma oncotic pressure
whats the function of the lymphatic system?
movement of excess fats, fluids, proteins, and albumin back into the circulation.
lymphatic system causes ___
negative pressure in the interstitial fluid space
4 ways plasma filtrate is returned to the circulation by the lymphatic system
tissue pressure, intermittent skeletal activity, lymphatic vessel contractions and one way valves
what 3 things empty into the thoracic duct
left head, left arm, lower body
where is the thoracic duct
posterior chest and is connected to the left IJ and left subclavian
what things cause edema
*hydrostatic pressure. lymphatic obstruction, changes in permeability, reduced plasma protein
name 3 endogenously found vaso-constricting substances
catecholamines (epi, norepi, dopamine), endothelial, serotonin, angiotensin 2, vasopressin
name 3 endogenously found vaso-dilating substances
histamine, adenosine, nitric oxide, CO2, K, hydrogen ion, prostaglandins, acetylcholine, bradykin
what is the metabolic mechanism
inadequate o2 for metabolic requirements of tissues result in formation of vasodilator substances which increase blood flow to tissues
what substances are responsible for metabolic mechanism
adenosine, K, CO2, H+, lactic acid, inorganic phosphate
what is the myogenic mechanism
lumen of blood vessel suddenly expanded, the smooth muscles response by contracting in order to restore the vessel diameter and resistance
what is reactive hyperemia
transient increase in organ blood flow that occurs following a brief period of ischemia, usually produced by temporary arterial occlusion
give an example of reactive hyperemia
tourniquet to a limb, arterial vessel clamped and released later in surgery, transient coronary occlusion
what is autoregulation
intrinsic ability of an organ to maintain constant blood flow despite changes in perfusion pressure
what 2 mechanisms of blood flow regulation is thought to be involved in autoregulation
myogenic and metabolic
name 3 endothelial factors that help regulate blood flow
nitric oxide, prostacyclin, endothelial-derived, hyperpolarizing factor, endothelin
prostacyclin dilator or constrict?
dilator
EDHF dilator or constrict
dilator
endothelin dilate or constrict
potent constrict
what is nitric oxide
regulates blood flow under normal physiologic conditions; generated from amino acid L-arginine to synthesize NO synthase; relaxes smooth muscle via activation of intracellular guannyly cycllase to form cgmp
how might nitric oxide be useful during one lung ventilation
inhaled Nirtric oxide delivered only to ventilated alveoli thus improving v/q relations by vasodilation capillaries and improving blood flow to areas participating in gas exchange
why are blood vessels prone to vasoconstriction, vasospasm, and thrombosis when the endothelium is damaged
when a decrease of nitric oxide and prostacyclin production occurs, an increase of endothelin production causes vasoconstriction, vasospasm, and thombosis
what causes dehydration
decreased capillary hydrostatic pressure. increased oncotic pressure (push into cap so - )
what causes edema
increased capillary hydrostatic pressure. decreased plasma oncotic pressure (push into interstitum so + overall)
plasma colloid osmotic pressure goes ___, interstitial fluid colloid osmotic pressure goes ___
in, out
