Random USMLE Facts volume 1-7

Rahul's Noteblog Notes on USMLE facts, Exam Tips, and USMLE Lab Values Random USMLE Facts volume 1-7

Random USMLE Facts volume 1-7:

USMLE Facts 1	USMLE Facts 2	USMLE Facts 3	USMLE Facts 4	USMLE Facts 5
USMLE Facts 6	USMLE Facts 7	USMLE Facts 8	USMLE Facts 9	USMLE Facts 10

What are the causes of biliary sludge?

Main cause is gallbladder hypomotility, e.g., due to incomplete gallbladder emptying.

Brown pigment stones are found in?

Biliary tract infection.

Black pigment stones are found in?

Intravascular hemolysis.

Cystine stones are found in?

Persons with high blood levels of circulating amino acid cystine.

When is acute chest syndrome precipitated in sickle cell patients?

During pulmonary infection.

Somatostatin suppresses?

All GI hormones.

What does cholestyramine do to cholesterol synthesis?

Increase.

What mutation causes early adenoma to become late adenoma?

K-RAS mutation.

What mutation causes late adenoma to become adenocarcinoma?

p53 and DCC.

Types of diverticula:

Traction: occur due to inflammation and scarring.
Meckel: true and congenital.
Colonic: inflammation leading to acute diverticulosis.
Pulsion: seen in older individuals - pouches created by weak spots in intestinal mucosal layer. Mostly due to constipation.

What is the difference between free ribosomes and attached ribosomes?

Free ribosomes synthesize cystolic proteins and attached ribosomes synthesize secretory proteins.

What exactly happens in a Meckel diverticulum?

There is an abnormal cyst connected to the ileum and umbilicus. Stools are guaiac positive (blood), black, tarry. There is Tc-99mm pertechnetate (if the diverticulum contains gastric mucosa) accumulation in the right lower abdominal quadrant. Thus, at an advanced stage, a Meckel diverticulum may become impossible to differentiate from an acute appendicitis. There may be "currant jelly" stools if intestinal intussusception is involved. Failure of the obliteration of the omphalomesenteric duct causes Meckel diverticulum.

Which pharyngeal arches give rise to the trigeminal (5), facial (7), and the glossopharyngeal (9) nerves?

First, second, and third respectively. The third pharyngeal arch also gives rise to the common carotid artery - which is used to palpating heart rate in the neck area.

What drug is best for the treatment for a combination of tonic-clonic and absence seizures?

Valproic acid.

Why does calcium level decrease in a hypovolemic patient transfused with packed red blood cells?

Packed red blood cells contain citrate, which chelates calcium in the patient, decreasing calcium levels.

What is the function and origin of IFN-gamma?

IFN-gamma is produced by T-helper cells. IFN-gamma leads to macrophage maturation, enabling them to contain a tuberculosis infection. IFN-gamma also produces iNOS which destroys tuberculosis cells. Thus, IFN-gamma leads to granuloma formation and caseous necrosis.

What is the function of LTC4?

Intense vasoconstriction, increased vascular permeability, and bronchospasm.

What is the function of C3a?

Mast cell histamine release.

USMLE Facts 1	USMLE Facts 2	USMLE Facts 3	USMLE Facts 4	USMLE Facts 5
USMLE Facts 6	USMLE Facts 7	USMLE Facts 8	USMLE Facts 9	USMLE Facts 10

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