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USMLE World Missed Questions > Deck II > Flashcards

Flashcards in Deck II Deck (30)
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1
Q

What embryological abnormality results in an annular pancreas?

A

Abnormal migration of the ventral pancreatic bud.

2
Q

What does an annular pancreas encircle?

A

The descending part of the duodenum.

3
Q

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

A

Left internal illiac artery.

4
Q

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

A

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.

5
Q

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?

A

The liver.

6
Q

Where should a thoracocentesis be performed?

A

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

7
Q

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

A

The subcostal neurovascular bundles

8
Q

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

A

Deep brachial artery (runs with the radial nerve)

9
Q

What is the underlying cause of Myasthenia Gravis?

A

Circulating antibodies against acetylcholine cell surface receptors of the NMJ.

10
Q

What celluluar processes occur in lymphoid germinal centres?

A

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).

11
Q

Describe the Type I IgE Hypersensitivity response.

A

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

12
Q

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

A

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

13
Q

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

A

IgA deficiency.

14
Q

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

A

IFN-y.

15
Q

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

A

Humoral immunodeficiency.

16
Q

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

A

T cell deficiency.

17
Q

What is the candida skin test used to assess?

A

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

18
Q

What type of hypersensitivity reaction can be mediated by sulfonamides?

A

Type III

19
Q

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

A

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

20
Q

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

A

Activation of T lymphocyte death.

21
Q

What is the function of the Fas receptor?

A

Initiation of the extrinsic pathway of apoptosis.

22
Q

How do eosinophils contribute to host defenses in parasitic infection?

A

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

23
Q

What abnormal immunologic ratio is characteristic of sarcoidosis?

A

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

24
Q

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

A

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

25
Q

What immunologic process mediates Graft vs Host disease?

A

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

26
Q

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

A

IL-8.

27
Q

What comprises an MHC Class I molecule?

A

A single heavy chain and an associated B2 microglobulin.

28
Q

What cell types possess MHC class II peptides?

A

Antigen presenting cells only.

29
Q

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

A

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

30
Q

How does the influenza vaccine attenuate flu-symptoms?

A

By impairing virus entry into cells.