6/22 UWorld Flashcards
Nerves involved in pupillary light reflex
CN II = afferent signal
CN III = eferent signal
- Sequence of events:
- Light in either retina = signal via CN II (optic) to pretectal nuclei in midbrain = activation of bilateral Edinger-Westphal nuclei = signal from EW nuclei to ciliary ganglion via CN III (oculomotor) = bilateral pupillary constrictor muscle activation
Afferent and efferent nerves of corneal reflex
- Afferent = CN V1
- Efferent = CN VII
What does “power” of a test tell you
- Probability that the test will correctly reject the null hypothesis, when it is indeed false
- Aka the likelihood that you will correctly identify a difference when one does exist
In what disease do you see Orphan Annie nuclei
Papillary carcinoma of the thyroid
Which hernia is medial/lateral to inferior epigastric vessels - direct vs. indirect
THINK: MD’s don’t LIe
Direct = medial
Indirect = lateral
MOA of Carbidopa vs. COMT inhibitors
- Carbidopa = inhibits peripheral conversion of DOPA to DA, so DOPA can head to brain
- Does not cross BBB
- COMT inhibitors = inhibits conversion of DOPA to inactive metabolite
- Tolcapone works both peripherally and centrally
MOA of Ropinirole
D2 receptor agonist
MOA of Pramipexole
D3 receptor agonist
Location of bile acid reabsorptino
Ileum
Maybe have decreased reabsorption in Crohns (affects terminal ileum), leading to increased ratio of cholesterol to bile within bile acid, thus predisposing to gallstones
What is the mutation caused by aflatoxin that leads to hepatocellular carcinoma
p53 mutation
What type of reactions are vitamin B6 used in
Transamination (ALT and AST)
What type of reactions is biotin (B7) used in
Carboxylation
Where is the cell does Vitamin C play a role in collagen synthesis?
Rough ER
Collagen synthesis:
- o Signal sequence directs growing polypeptide chain into endoplasmic reticulum
- o Signal sequence is cleaved
- o Hydroxylation of selected proline and lysine residues (vitamin C dependent)
- o Glycosylation of selected hydroxylysine residues
- o Assembly of pro-alpha-chains into procallagen triple helix
- o Procollagen transferred to Golgi apparatus and secreted into extra cellular matrix
- o Terminal propeptides cleaved by N- and C- procollagen peptidases
- § Ehlers Danlos can be caused by a deficiency in procollagen peptidase, leading to soluble collagen that does not properly crosslink
- o Collagen molecules spontaneously assemble
- o Covalent cross links formed by lysyl oxidase
Where in the cell/what enzyme in collagen synthesis is the problem of Ehlers Danlos
Extracellular matrix
- Terminal propeptides cleaved by N- and C- procollagen peptidase
- Ehlers Danlos can be caused by a deficiency in procollagen peptidase, leading to soluble collagen that does not properly crosslink
What muscle is often associated with compression of the sciatic nerve
Piriformis
What part of the penis does Sildenafil work on?
Vasodilation leads to increased bloodflow into corpus cavernosum
MOA of Ras as an oncogene
Oncogene = is a signal transducer (GTP-binding protein)
- o Ras is associated with growth factor receptors in an inactive GDP-bound state
- o Receptor binding causes GDP to be replaced with GTP, activating Ras
- o Activated Ras sends growth signals to the nucleus
- o Ras inactivates itself by cleaving GTP to GDP via GTPase protein
- o Mutated Ras inhibits the activity of GTPase, thus producing a prolonged activated state of Ras
Crohn’s vs. Ulcerative colitis
Histology
Crohn - noncaseating granulomas with lymphoid aggregates
UC - crypt abscesses with neutrophils
What is Trousseau syndrome
Caused by pancreatic adenocarcinoma
- Hypercoagulability
- Venous thrombosis
- Migratory thrombophlebitis
Describe primary sclerosing cholangitis
- Concentric fibrosis of the intra- and extra-hepatic bile ducts
- Contrast imaging will show “beaded” appearance due to alternating fibrotic and dilated regions
- Mostly occurs in men around age 40
- Associated with (+) pANCA and Ulcerative colitis
- Increased risk for cholangiocarcinoma
Vs. Primary biliary cholangitis which is autoimmune (anti-mitochondrial) with lymphocytes/granulomas
Describe fluid compartment/composition of body
- 60-40-20 rule
- 60% of body mass is water, of that 60%:
- 40% is ICF
- 20% is ECF
- Only 25% of ECF is plasma
When does glucose begin to appear in the urine
- Glucose is completely reabsorbed up until plasma glucose level ~200 mg/dL
- This is when glucosuria begins (threshold)
- At ~375 mg/min, all transporters are fully saturated
Describe the defect in type 1 renal tubular acidosis, hyper/hypokalemia, urine pH
- Distal renal tubular acidosis à defect in collecting tubule
- Alpha-intercalated cells are unable to secrete H+ à acidosis
- Hypokalemia
- Urine pH will be > 5.5 (because no H+ in urine)
- Causes:
- Amphotericin B toxicity, analgesic nephropathy, congenital anomalies (obstruction) of urinary tract
Describe the defect in type 2 renal tubular acidosis, hyper/hypokalemia, urine pH
- Proximal renal tubular acidosis à defect in proximal tubule
- Impaired HCO3- reabsorption à Increased HCO3- excretion à acidosis
- Hypokalemia and hypophosphatemia
- Urine pH < 5.5 (urine is acidified by a-intercalated cells in collecting tubule)
- Causes:
- Fanconi syndrome, carbonic anhydrase inhibitors
