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USMLE World Missed Questions > Deck II > Flashcards

Flashcards in Deck II Deck (30):

What embryological abnormality results in an annular pancreas?

Abnormal migration of the ventral pancreatic bud.


What does an annular pancreas encircle?

The descending part of the duodenum.


The left ureter lies immediately anterolateral to what structure in the true pelvis?

Left internal illiac artery.


Describe the position of the ureters in relation to other vasculature in the area.

Ureters cross over the common/external iliac vessels and under the gonadal vessels (and uterine vessels in females); they lie anterolateral to the internal iliac vessels and medial to the ovarian vessels within the true pelvis.


What is most likely to be punctured due to insertion of a needle along the upper border of the 10th rib at the right midaxillary line?

The liver.


Where should a thoracocentesis be performed?

Above the 7th rib in midclavicular line, the 9th rib along the midaxillary line, and the 11th rib along the posterior scapular line.


What structure may be punctured due to thoracosentesis penetration on the inferior margin of the rib?

The subcostal neurovascular bundles


What artery is most likely to be damaged due to fracture of the humeral shaft?

Deep brachial artery (runs with the radial nerve)


What is the underlying cause of Myasthenia Gravis?

Circulating antibodies against acetylcholine cell surface receptors of the NMJ.


What celluluar processes occur in lymphoid germinal centres?

Germinal centres are the site of B cell proliferation during an immune response. The majority of activated B cells in the germinal centres transform into antibody secreting plasma cells (i.e. undergo isotype switching).


Describe the Type I IgE Hypersensitivity response.

Reaction is triggered by cell surface bound IgE bridging by antigen.


What does a giardia lamblia trophozoite look like on peripheral smear?

Pear shaped, bilaterally symmetric organisms with four pairs of flagella and two nuclei


What deficiency is likely in a patient with recurrent Giardia lamblia infections?

IgA deficiency.


What is the key factor in the elimination of and host defense against mycobacterial infections?



What type of immunodeficiency is implicated by recurrent otitis media infections from strep. Pneumo, H. influenzae, and Moraxella?

Humoral immunodeficiency.


What type of immunodeficiency is implicated by pneumocystic infections and chronic mucocutaneous candidiasis?

T cell deficiency.


What is the candida skin test used to assess?

Cell mediated response (T-cell and NK cell activity)


What type of hypersensitivity reaction can be mediated by sulfonamides?

Type III


What immunologic deficiency is characteristic of a type III hypersensitivity serum sickness reaction?

Low C3 levels 5-10 days after intravascular exposure to an antigen.


What immunologic impairment can be expected in a patient with a defective Fas gene product?

Activation of T lymphocyte death.


What is the function of the Fas receptor?

Initiation of the extrinsic pathway of apoptosis.


How do eosinophils contribute to host defenses in parasitic infection?

By destroying the parasite via antibody dependent cellular cytotoxicity (ADCC) with enzymes from their cytoplasmic granules.


What abnormal immunologic ratio is characteristic of sarcoidosis?

Intraalveolar and interstitial accumulation of CD4+ T cells results in a high CD4:CD8 ratio.


What is likely to appear on biopsy in a patient with chronic organ rejection?

Obliterative vascular fibrosis due to antibody mediated damage to the graft endothelium. This causes obliterative intimal smooth muscle hypertrophy and fibrosis.


What immunologic process mediates Graft vs Host disease?

T lymphocytes of the donor tissue attack MHC antigens of the recipient. Skin, liver, and intestine are commonly involved.


What cytokine is typically involved in mediating the accumulation of pus?



What comprises an MHC Class I molecule?

A single heavy chain and an associated B2 microglobulin.


What cell types possess MHC class II peptides?

Antigen presenting cells only.


How is antigen and APC loaded onto MHC class II peptides?

Antigen is taken into the APC by phagocytosis or endocytosis and is loaded onto MHC Class II within acidified endosomes.


How does the influenza vaccine attenuate flu-symptoms?

By impairing virus entry into cells.