Deck XII Flashcards Preview

USMLE World Missed Questions > Deck XII > Flashcards

Flashcards in Deck XII Deck (30):

What happens to the pressure-volume relationship of the lung in the event of reduced compliance?

For any given volume, the pressure is significantly increased.


Reduced pulmonary parenchymal compliance is the hallmark of what condition?

Pulmonary fibrosis.


What conditions are caused by an alpha-1 antitrypsin deficiency?

Panacinar emphysema and liver cirrhosis. The lung parenchyma has increased compliance.


How does idiopathic pulmonary arterial hypertension affect lung compliance?

It doesnt significantly affect lung compliance.


Where is ACE produced?

In vascular endothelial cells, especially those in the pulmonary vasculature.


What is the difference in presentation of an acute salicylate overdose vs. that of approximately 4-5 hours after ingestion?

Immediate respiratory alkalosis which progresses to an anion gap metabolic acidosis due to accumulation of organic acids in the blood (this causes a mixed respiratory alkalosis- metabolic acidosis condition at about 4-5 hrs after ingestion). Metabolic acidosis effects progress with time.


What are the three phases of acid secretion in the stomach?

Cephalic (vagal/ cholinergically induced- triggered by thought, sight smell, taste), gastric (mediated by presence of gastrin which stimulates histamine secretion and thus acid secretion and is triggered by chemical stimulus of food and distension of the stomach), intestinal (when protein containing food enteres the duodenum (minor role))


What helps down regulate gastric secretion after a meal?

Intestinal influences (inhibit gastrin release); somatostatin; prostaglandins


What is the function of secretin?

Stimulation of release of bicarbonate from exocrine pancreas


Where is secretin produced?

S enteroendocrine cells in the duodenum


What is the most potent stimulator of secretin release?



What is human placental lactogen (hPL)?

A hormone secreted from the syncytiotrophoblast with structural and biologic properties similar to prolactin and growth hormone-- it increases maternal insulin resistance which increases blood glucose levels allowing glucose to be shunted towards the fetus. It also increases maternal lipolysis and proteolysis.


How do hPL levels change throughout pregnancy?

They increase with increasing gestational age to meet energy requirements of the fetus.


What causes gestational diabetes mellitus?

When a woman's pancreatic function cant over come the pregnancy related increase in insulin resistance due to placental secretion of hPL, GH, estrogens, progesterone, and glucocorticoids.


An EKG with bradycardia, narrow QRS complexes and desynchronization of P and QRS waves indicates that cells from what region are leading the pacing?

The AV node.


What are the EKG findings in a patient with a heart that is paced by the purkinje system?

Bradycardia (as low as 20 beats/ minute) with prolonged, abnormally shaped QRS complexes due to aberrant impulse conduction through the ventricles.


How does exercise increase glucose uptake by muscle cells?

Through sensitization of the muscle cells to the action of insulin and to increased insulin-independent glucose uptake into the exercising muscles.


Infections and stressors cause what condition in a diabetic?



Upon muscle relaxation, calcium efflux from the cytoplasm occurs through what mechanism?

The Ca2+-ATPase and Na/Ca exchange mechanisms


What is the function of calmodulin?

An indirect contributor to calcium efflux from the cell upon muscle relaxation. It binds and activates plasma membrane Ca2+-ATPase which removes Ca2+ by hydrolyzing ATP.


What is the function of the thyroid peroxidase enzyme?

Responsible for thyroglobulin iodination, oxidation of iodide to iodine, and the iodotyrosine coupling reaction that forms T3 and T4.


What is the pathophysiology associated with Hashimoto's Thyroiditis?

Autoantibodies to the thyroid peroxidase enzyme.


Vagal stimulation of bronchi would most increase what pulmonary parameter?

Work of breathing due to increased bronchial smooth muscle constriction.


Stimulation of vagus nerve branches that supply the lung will cause what physiologic changes?

Bronchoconstriction an increased bronchial mucus secretion. This will increase airway resistance and work of breathing.


What drugs act to counteract work of breathing due to increased vagal stimulation?

Anticholinergic agents (tiotropium, ipratropium)


What is a risk of using tPA in arterial re-opening?

Reperfusion arrhythmia on arterial re-opening (these are usually benign)


PAH clearance is dependent on what factor?

Renal plasma flow (at low concentrations, PAH is filtered and completely secreted by the proximal tubules)


What is beta endorphin?

An endogenous opioid peptide that is derived from POMC


POMC is a polypeptide precursor that undergoes enzymatic cleavage and modification to produce what products?

Beta endorphins, ACTH, MSH.


What is somatomedin C?

A peptide that is structurally similar to insulin- is also called Insulin Like Growth Factor and it stimulates growth in target cells