B4.064 - Microcirculation and Organ Blood Flow Flashcards
ischemia/reperfusion leads to the creation of what
generation of ROS
what does the generation of ROS from ischemia/reperfusion lead to
damage to endothelial cells
inactivation of NO
increased formation of ET-1
what is the difference between contractile force with and without endothelium
ACh increases contractile force without endothelium
decreases contractile force with endothelium
what happens with leukocytes after ischemia/reperfusion
increased leukocytes adherence
antioxidants
superoxide dismutase
catalase
lipoic acid
what is a danger of giving IV NO
its a potent vasodilator so if you give it IV it will dilate throughout systemic arterioles decreasing TPR and causing arterial BP to fall aka shock
what would a local intra arterial infusion of NO do to a transplanted organ
dilate arterioles within that organ, increasing blood flow to that organ and increasing capillary pressure which would promote edema
in the case of head trauma leading to cerebral edema what happens
there is a loss of plasma across damaged vessels within the brain promoting edema, reducing oncotic pressure gradient and reducing the force for reabsorption of fluid from the cerebral interstitial space.
as edema in the brain becomes more severe what happens
intracranial pressure will progressively increase and compress the veins, which increases vascular resistance and decreases cerebral blood flow
what are some remedies to cerebral edema
hyperventilation
give mannitol
why does hyperventilation work for cerebral edema
reducing arterial PCO2 levels will cause cerebral arteriolar vasoconstriction. This will reduce capillary pressure and thus the rate of filtration
will cerebral arterioles remain constricted as long as the person hyperventilates?
No. Eventually vasodilator metabolites will accumulated in the brain and cause cerebral arteriolar dilation
what is mannitol
mannitol is rapidly excreted by the kidney causing increased fluid excretion
how does mannitol work for cerebral edema
IV mannitol would increase solute concentration in plasma which would increase the rate of reabsorption of fluid from the interstitial space of the brain
what happens in lymphatic obstruction
decreased removal of fluid and protein from interstitium, increased interstitial protein, decreased oncotic reabsorption of fluid all leading to edema
swelling in the leg due to lymphatic obstruction is particularly difficult to manage because
when the person stands venous pressure will increase in the legs and this will increase capillary pressure causing increased filtration of fluid into the interstitial space in the legs
how does edema affect oxygen consumption
edema increases the diffusion distance between blood vessels and cells, thus making O2 distribution more difficutl
in the context of cirrhosis how does edema in GI organs affect this
edema in GI organs causes hypoxia, and metabolic vasodilators will accumulate in the interstitial fluid, causing dilation of arterioles. This dilation will increase blood flow into the portal vein and increase the severity of portal hypertension
what is ascites
accumulation of fluid in abdominal cavity
what is active hyperemia
exercise
when the metabolic rate of skeletal muscle increases tissue O2 level decreases resulting in increased formation of vasodilator metabolites.
decreased vascular resistance of skeletal muscle in active hyperemia causes what
increased skeletal muscle blood flow. This causes TPR to be reduced, stimulating the baroreflex to increase CO
how does exercise affect systemic arterial pressures
low TPR means increased runoff, lowers arterial diastolic BP (despite increase in HR), increased pulse pressure due to increased SV
cause of swelling in burnt legs?
activation of circulating leukocytes
impaired lymph flow
increased capillary pressure due to art. dilation
increased vascular permeabllity
