Flashcards in Potpourri UWorld Deck (677)
5 factors that affect molecular rate of diffusion across a semipermeable membrane
Inversely proportional to molecular weight and membrane thickness. Proportional to particle concentration, surface area and solubility of the substance.
A patient presents with fever, lymphadenopathy, a skin rash and facial edema a few weeks after starting a new medication. What medications can cause this condition?
The patient has DRESS syndrome (drug reaction with eosinophilia and systemic symptoms). Common drugs that cause this are allopurinol, anticonvulsants, sulfonamides and antibiotics.
Target organs affected by alpha-1 stimulation?
Peripheral vasculature (vasoconstriction), bladder (contraction of internal urethral sphincter) and eye (mydriasis from pupillary dilator contraction)
Target organs affected by beta-1 stimulation?
Heart (increased contractility, chronotropy and conductance) and juxtaglomerular cells
Target organs affected by beta-2 stimulation?
Peripheral vasculature (vasodilation), bronchodilation and uterine relaxation.
Cytogenic results in a patient with fragile X syndrome.
X-linked mutation of the FMR1 gene results in CGG trinucleotide repeats. This results in cytogenic studies showing a gap at the end of the long arm of chromosome X because the CGG expanded region does not stain when cultured in folate deficient media.
A newborn child of a mother with IV drug use presents with tachypnea, crying, sneezing and diarrhea 2 days after birth. How do you treat this child?
The child has neonatal abstinence syndrome, best treated with opiate replacement and gradual weaning.
How does IgA protease help out bacteria like N. meningitides, N. gonorrhoeae, S. pneumo and H. influenzae?
IgA typically binds to capsular antigens like fimbriae that typically allow for bacterial adherence. IgA protease cleaves IgA and allows for increased adherence to mucosal surfaces.
A 7 year old boy presents with facial hair, paralysis of upward gaze and convergence. MRI shows obstructive hydrocephalus. What is likely causing his condition?
A beta-hCG-secreting pineal germinoma.
Lateral medullary syndrome
Contralateral loss of pain and temperature sensation with ipsilateral loss of CN V, IX, X and XI function.
Medial medullary syndrome
Contralateral spastic paralysis and ipsilateral flaccid paralysis of the tongue (CN XII)
Consequence of common peroneal nerve injury?
Foot drop due to paralysis of peroneus longus, peroneus brevus, tibialis anterior and extrinsic toe extensors. There is also numbness along the anterolateral leg and dorsal foot.
Consequence of superficial peroneal nerve injury?
Poor eversion due to paralysis of peroneus longus and peroneus brevis and loss of sensation along the distal anterolateral leg. However, dorsiflexion is preserved because the deep peroneal nerve innervates the tibialis anterior.
What diseases result in metabolic impairments in glycogenolysis?
Type I (von Gierke disease): deficiency in the conversion of Glc-6-P to Glc by Glc-6-Phosphatase. This results in fasting hypoglycemia, lactic acidosis, hyperuricemia, hyperlipidemia, STEATOSIS and hepatomegaly.
Type II (Pompe disease): deficiency in acid maltase, resulting in inability to degrade glycogen in lysosomes. This results in normal blood glucose, severe cardiomegaly and GLYCOGEN ACCUMULATION IN LYSOSOMES.
Type III (Cori disease): deficiency in debranching enzyme resulting in accumulation of abnormal glycogen with short outer chains (limit dextrins), WEAKNESS AND HYPOTONIA, ketotic hypoglycemia and hepatomegaly.
Type V (McArdle disease): deficiency in muscle phosphorylase resulting in inability to phosphorylate glycogen causing weakness with exercise and LOW POST-EXERCISE BLOOD LACTATE and MYOGLOBINURIA.
Mechanism of opioid-induced hyperalgesia
Chronic mu receptor stimulation causes increased turnover of inhibitory opioid receptors, decoupling of receptors from second messenger system and upregulation of NMDA receptors.
Type of orbital fracture that may impair corneal reflex
Those affecting the superior orbital fissure because CNs III, IV, V and VI pass through here and the corneal reflex involves V1 sensation and VII motor action.
Physical exam findings suggestive of an orbital floor fracture?
Limited superior gaze due to inferior rectors entrapment and numbness of the upper cheek, lip and gingiva due to damage to the infraorbital nerve that normally runs along the floor of the orbit (V2).
1st line treatment of patients with disorders involving the urea cycle?
Protein restrict so the patient gets the AAs they need while minimizing ammonia production.
A 17 year old baseball player presents with upper extremity numbness, tingling and weakness in his right hand. He also complains of pain in exertion only in his right arm and right arm swelling. What is most likely causing his condition?
Thoracic outlet syndrome. The thoracic outlet is the space behind the clavicle and above the first rib and compression of the brachial plexus, subclavian vein and subclavian artery can occur with anterior or middle scalene muscle abnormalities, anomalous cervical rib or repeat overhead injuries.
What test has PYR-positivity replaced
Bacitracin resistance test to determine S. pyogenes (sensitive) from S. agalactiae (resistant)
What is the microbial differential for patients with necrotizing fasciitis?
S. pyogenes, S. aureus and C. perfringens.
What 3 cell types are contained in the juxtaglomerular apparatus?
Macula densa: tall narrow cells in the distal tubule that monitor flow rate and [Na] and send signals to juxtaglomerular cells.
Juxtaglomerular cells: modified smooth muscle cells in the afferent arteriolar wall that secrete zymogen granules in response to macula densa stimulation.
Extra-glomerular mesangial cells
Lymph nodes that receive lymphatic drainage from testes
Lymph nodes that receive lymphatic drainage from glans of penis and superficial inguinal nodes
Deep inguinal nodes
Lymph nodes that receive lymphatic drainage from the scrotum
Superficial inguinal nodes
An immunocompromised patient presents with sinusitis and fungal hyphae that branch at acute angles with septations.
An immunocompromised patient presents with sinusitis and fungal hyphae that branch at wide angles without septations.
Rhizopus species -> mucormycoses
What is the main virulence factor involved in E. coli-related meningitis
K1 capsular polysaccharide. It prevents phagocytosis and complement-mediated lysis.
Mechanisms of LPS-induced shock
Widespread cytokine release of IL-1, IL-6 and TNF-alpha