Physiology Flashcards
Rightward extension of the ventricular filling portion (bottom line) suggests larger than normal left ventricular end-diastolic volumve (increased preload)- this can occur during any state of fluid overload (renal faolire, CHF), or after IV infusion of fluids
Note that clamping the aorta would increase afterload and dobutamine woud increase contractility
Diabetic ketoacidosis is marked by polydipsia, polyruia, and a fruity odor to the breath and/or urine (excreted acetone). Pts frequently present with abdominal pain, N/V
Labs show elevated anion gap metabolic acidosis secondary to ketone bodies
Bicarbonate is used to buffer the excess ketoacids in the blood, so the bicarbonate level falls
Metabolic acidosis also stimulates ventilation by a chemoreceptor reflex that causes compensatory respiratory alkalosis, which lowers Co2 partial pressure
Outcome of DKA= low pH, low serum bicarbonate and low PaCO2
RBF (renal blood flow)= (renal artery pressure- renal vein pressure)/renal vascular resistance
RPF (renal plasma flow)= PAH clearance= (urine PAH*urine flow rate)/plasma (PAH)
RBF= (PAH clearance)/(1-hematocrit)
Elastase is a neutral protease contained in macrophage lysosomes and in the azurophilic granules of neutrophils. Normally, elastase release from alveolar macrophages and infiltrating neutrophils is balanced by the presence of serum and tissue protease inhibitors
Neutrophil elastase is inhibited by serum a1 antitrypsin and macrophage elastase is inhibited by tissue inhibitors of metalloproteinases
Neutrophil and macrophage elastases can also degrade each other’s (but not their own) inhibitors
The carotid sinus reflex has an affarent limb that arise from the baroreceptors in the sinus and travels to the vagal nucleus and medullary centers via CN IX, whereas the efferent limb carries parasympathetic impulses to the SA and AV nodes via the vagus nerve.
Carotid sinus massage leads to increased affarent firing from the carotid sinus, which in turn increased vagal parasym. tone. This slows conduction through the AV node and prolongs the AV refractory period, helping to tx PSVT.
Cataracts-vision impairing opacifiction of the lens that causes loss of the red reflex with decreased visualization of retinal details (risk factors: age, smoking, diabetes, glucocorticoids)
Due to overwhelming of the polyol pathway (normally glucose to sorbitol via aldose reductase, which is then trapped inside the cell where it forms because it cant cross membranes. Sorbitol dehydrogenase then converts sorbitol to fructose to prevent accumulation but is overwhlemed in cataracts)
Sorbitol accumulation increases osmotic and oxidative stress
