Random USMLE Facts volume 7-5

Rahul's Noteblog Notes on USMLE facts, Exam Tips, and USMLE Lab Values Random USMLE Facts volume 7-5

Random USMLE Facts volume 7-5:

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

Where are type I slow twitch red muscle fibers found?

Long back muscles, soleus, and breast muscles of migrating birds. Used for stamina. Remember "one slow red ox."

Where are type II fast twitch white muscle fibers found?

Extraocular muscles, gastrocnemius, etc. Used for speed.

What is a chi-square test?

A chi-square test is used to compare the proportions of categorized outcomes in a 2 x 2 table.

What is the lac operon?

The lac operon is a genetic sequence in the E. coli that is used to make proteins required for lactose metabolism. The lac operon consists of the regulatory gene, the promoter region, operator region, and three structural genes. If E. coli is cultured in a lactose-containing media, lactose binds to the repressor protein, and the lac operon becomes activated. However, if E. coli is cultured in a glucose-containing media, cAMP is reduced, and this causes inhibition of lac genes.

What happens in calcium pyrophosphate accumulation?

Accumulation of calcium pyrophosphate is the cause of pseudogout. In pseudogout, synovial fluid analysis reveals increased white blood cells with a neutrophilic predominance. Furthermore, there is presence of rhomboid-shaped calcium pyrophosphate crystals with weak positive birefringence under polarized light.

What are the various types of seizures?

• Simple partial: one part of body is involved; no loss of consciousness and no postictal confusion.
• Complex partial: temporal love involved (mood changes, hallucinations, etc.); impaired consciousness and postictal state present.
• Tonic-clonic: extension of extremities followed by clonic rhythmic movements; loss of consciousness and prolonged postictal confusion.
• Myoclonic: brief arrhythmic jerking movements less than one second; no loss of consciousness.
• Absence: brief episode of staring; no postictal confusion.

What cells play a major role in toxic shock syndrome?

T-cells (release IL-2) and macrophages (release IL-1 and TNF).

What is a complication of S. pyogenes infection?

Rheumatic fever and post streptococcal glomerulonephritis. Note that post streptococcal glomerulonephritis may either follow a skin infection (impetigo) or an episode of streptococcal pharyngitis. However, rheumatic fever is only associated with streptococcal throat infection.

What are the stages of lobar pneumonia?

• Congestion: first 24 hours; affected lobe is red, heavy and boggy; vascular dilation; alveolar exudate contains bacteria.
• Red hepatization: days 2-3; red, firm lobe; alveolar exudate contains erythrocytes, neutrophils, and fibrin.
• Gray hepatization: days 4-6; gray-brown firm lobe; alveolar exudate contains neutrophils and fibrin; disintegrated RBCs.
• Resolution: restoration of normal architecture; enzymatic digestion of exudate.

Why should TCAs be used with caution in individuals with benign prostatic hyperplasia?

TCAs have strong anticholinergic properties, and they may cause urinary retention. Note that TCAs are also used for the treatment of peripheral neuropathy.

What is the innervation of the tongue?

General sensory:

• Anterior 2/3 - mandibular branch of the trigeminal nerve (CN V₃).
• Posterior 1/3 - CN IX.
• Posterior area of the tongue root: CN X.

Innervation of taste buds:

• Anterior 2/3 - chorda tympani branch of CN VII.
• Posterior 1/3 - CN IX.
• Posterior area of the tongue root and taste buds of the larynx and upper esophagus: CN X.

What exactly happens when hepatocytes are exposed to insulin?

Insulin acts on hepatocytes via a cytosolic tyrosine kinase receptor. The tyrosine kinase causes activation of protein phosphatase. Protein phosphatase dephosphorylates glycogen synthase thereby promoting glycogen synthesis.

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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