Random USMLE Facts volume 12-9

Rahul's Noteblog Notes on USMLE facts, Exam Tips, and USMLE Lab Values Random USMLE Facts volume 12-9

Random USMLE Facts volume 12-9:

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

How does acetylcholine decrease blood pressure?

Acetylcholine binds to M3R receptors on endothelial cells. then, the M3R protein activates G-q alpha which activates phospholipase C which increases IP3 which produces cGMP causing vasodilatation decreasing blood pressure.

How are macrophages transformed into foam cells?

Macrophages absorb extra cholesterol through lipoproteins binding to scavenger receptors which they are unable to regulate. This is done because macrophages accumulate cholesterol esters faster than they can export them into HDL.

NOTE: glycerol and urea are both permeant molecules.

What are the findings in pseudohypoparathyroidism?

Pseudohypoparathyroidism is caused by resistance to the PTH hormone. Patients present with a short stature, round face, hypocalcemia, and hyperphosphatemia. Genetic testing reveals heterozygosity for Gs alpha allele.

Where is potassium found within the cell? What happens in hypokalemia?

Most potassium is found within the cell. In hypokalemia, the extracellular potassium level drops causing the potassium equilibrium potential to become more negative. This causes membrane potential to become negative or hyperpolarized. In hyperkalemia, there is increased serum potassium calcium, and this decreases the net driving force for potassium from cells.

What stimulates sweat gland secretion?

Sympathetic cholinergic neurons.

Gastric secretions are controlled by?

Parasympathetic nervous system via vagal stimulation (muscarinic receptors).

What kind of receptor is the insulin receptor?

Receptor tyrosine kinase.

What are the causes and findings in hereditary spherocytic hemolytic anemia?

Findings include jaundice and splenomegaly. Laboratory testing reveals anemia that is partially compensated by reticulocytosis. Red blood cells have increased mean corpuscular hemoglobin concentration, and many are spehrocytic in shape. Caused by defective ankyrin-spectrin. Autosomal dominant inheritance and found among northern Europeans. Treatment would be splenectomy.

How does growth hormone work?

• Growth hormone activates a cAMP-mediated receptor that interacts with a G-protein. The G-protein hydrolyses GTP to GDP. The G-protein in this case is G-alpha-s.

• Growth hormone is secreted by the anterior pituitary in response to GHRH. GH then stimulates IGF-1 and IGFBP3 secretion by the liver. Dwarfs have lower IGF-1. GH hormone deficiency comes from measuring IGF-1 and IGFBP3 in blood.

NOTE: resting membrane potential = sum of all (conductance* x equilibrium constants) of involved ions.
Conductance* = individual conductance / [sum of all conductances of involved ions].

What is the difference between permeant and non-permeant molecules?

Permeant molecules diffuse into cells by passing through semipermeable membranes and non-permeant molecules don't. An example of a permeant solution would be glycerol, urea, etc. An example of a non-permeant solution would be sodium chloride.

What molecules trap interstitial fluid?

Proteoglycn filaments.

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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