Cards Flashcards
Explain the differences in hemodynamics of an acute AV fistula compared to a chronic AV fistula.
Acutely, an AV fistula causes a decrease in TPR, which results in an increased cardiac output and an increased venous return.
Over time, the sympathetic nervous system and kidneys will compensate for a chronic fistula by increasing cardiac contractility, vascular tone, and circulating blood volume. These changes further increase cardiac function as well as increase mean systemic pressure.
Initially venous return increases secondary to increased cardiac output, later venous return is further increased secondary to sympathetic constriction of veins and return of pooling blood.
What is Guillain-Barre syndrome?
Antibodies formed against a ganglioside-like substance in the lipopolysaccharide layer of an infection agent and activated T-cells cross-react through molecular mimicry with the ganglioside components of myelin and Schwann cells, resulting in immune-mediated segmental demyelination and ascending, symmetric muscle weakness.
What is Lambert-Eaton syndrome?
Paraneoplastic syndrome seen in patients with SCC of the lung that presents with weakness that improves with muscular repetition. Caused by autoantibodies that react with voltage-gated calcium channels on the presynaptic membrane, hampering release of acetylcholine.
What is subacute combined degeneration?
Due to vitamin B12 deficiency, leads to degeneration of dorsal columns and lateral cerebrospinal tracts. Slow progression, central demylenation, distal progressive weakness and ataxia associated with spasticity, paresthesia, and macrocytic anemia.
What is Beriberi?
Thiamine deficiency, characterized by weakness, areflexia, pain, and paresthesias worse in the distal lower limbs.
What is Werdnig-Hoffman syndrome?
Spinal muscle atrophy type 1, due to degeneration of anterior horn cells caused by SMN1 gene mutation, causes symmetric progressive weakness, more prominent proximal than distal.
What is the primary mechanism underlying giant cell arteritis?
Cell-mediated immunity. The production of cytokines, in particular IL-6, is an important driver.
Differences between unfractionated heparin and low molecular weight heparin targets?
Both bind to antithrombin and cause a conformational change that increases its ability to inactivate Factor Xa. Only unfractionated heparin has a pentasaccharide chain long enough to bind both antithrombin and thrombin in order to inactivate thrombin.
How does ethanol inhibit the citric acid cycle?
Chronic alcoholics are frequently thiamine deficient, which is a necessary cofactor for pyruvate dehydrogenase and alpha-ketoglutarate dehydrogenase.
Ethanol metabolism can also inhibit the entire pathway through consumption of NAD+ in alcohol dehydrogenase and aldehyde dehydrogenase reactions.
Explain the reasoning behind the heterophile antibody test.
EBV commonly infects B cells, stimulating them to proliferate continuously while maintaining the ability to secrete immunoglobulins and B-cell activation products (eg, CD23).
Heterophile IgM antibodies then react with antigens on horse/sheep erythrocytes, causing agglutination.
What is Fragile X syndrome?
X-linked disorder involving a unstable expansion of trinucleotide repeats (CGG) in the FMR1 gene of the long arm of the X chromosome that appears “broken” due to poor staining.
Most common cause of inherited intellectual disability with key findings including dysmorphic facial features (eg, large jaw, protruding ears, long face) and macroorchidism.
Differences in aspiration when supine versus standing.
Right main bronchus has a larger diameter, is shorter, and more vertically oriented then the left, making it more prone to aspiration.
When upright, patients tend to aspirate into the basilar segments of the lower lobes. When supine they tend to aspirate into the posterior segments of the upper lobes and the superior segments of the lower lobes.
What structures run through the cavernous sinus?
CNs III (oculomotor), IV (trochlear), V1 (opthalmic), V2 (maxillary), VI (abducens), internal carotid, internal carotid plexus (postganglionic sympathetic fibers ascending from the superior cervical ganglion).
Differences between Schizoid and Schizotypal personality disorders.
Schizoid - Socially detached “loners”, unemotional.
Schizotypal - Eccentric behavior, odd thoughts, perceptual distortions, social anxiety.
Symptoms of digoxin toxicity
Cardiac - Life-threatening arrhythmias.
GI - Anorexia, N/V, Abd pain.
Neuro - Fatigue, confusion, weakness, color vision alterations.
