Week of March 23 Flashcards

Question

What are the local cutaenous AEs of chronic topical corticosteroid administration?

Answer 1

Atrophy/thinning of the dermis that is associated with loss of dermal collagen, drying, cracking, and/or tightening of the skin, telangiectasias, and ecchymoses. 1214

Answer 2

Blood flow is directly proportional to the vssel raidus raised to the fourth power. Resistance ot blood flow is inversely proprtional to the vessel radius raised to the fourth power. 1621

Answer 3

Sensitivity: ability to correctly identify those with the disease. Most patietns with the disease will have a positive test result on a test with high sensitivity. Given a test with high **_s_**ensitivity, a **_n_**egative result would help to rule _out_ a diagnosis (**SnNout**) 1300

Answer 4

Alveolar ventilation status. Hypocapnia implies ongoing alveolar **hyper**ventilation; can result from V/Q mismatch that causes ddecreased O2 and CO2 exchange (e.g. PN or PE) --\> resultant hypoxemia stimulates peripheral chemoreceptors and increases respiratory drive above noraml levels. Upper airway obsturction, reduced ventilatory drive, respiratory muscle fatigue, and decreased chest wlal compliance are possible causes of alveolar **hypo**ventilation and hypercapnia. 528

Answer 5

PAH is freely filtered from the blood in the glomerular capillaries to the tubular fluid in Bowman's space. It is also secreted from teh blood into the tubular fluid by the cells of the proximal tubule by a carrier protein-mediated process. The secretion of PAH can be satured at high blood concentrations. 1619

Answer 6

**Seroid and phospholipid biosynthesis**. All steroid-producing cells (e.g. cells in the adrenals, gonads, and liver) contain a well-developed smooth ER. ## Footnote Example: ACTH primarily stimulates the cells of adrenal cortex to produce glucocorticoids, but it also increases adrenal production of mineralocorticoids. These are all cholesterol-derived steroid hormones, and the cells that synthesize them contain promoninent SERs. 2016

Answer 7

Occurs in patients with septic shock becuase of tissue hypoxia, which result in **impaired oxidative phosphorylation** and the shunting of pyruvate to lactate following glycolysis. Hepatic hypoperfusion also contributes to the buildup of lactic acid, as the liver is the primary site of lactate clearence. 2101

Answer 8

Recurring painful genital rash! Viruses known to invade the dorsla root sensory ganglia include HSV-1/2 and VZV. Among these, HSV-2 produces a recurrent, painful genital rash when teh latent virus is reactivated in the sacral sensory ganliga. HSV-1 commonly infects sensory ganglia-innervating dermatomes above waist (e.g. trigeminal ganglia) 1549

Answer 9

Have low bone mass, resulting in increased susceptibility for fragility fractures. In primary osteoporosis, serum calcium, phosphorus, and PTH are typically normal. 982

Answer 10

Selective COX-2 inhibitors (e.g. celecoxib), which do not impair platelet function becuase platelets predominatly express COX-1 715

Answer 11

Glucagon, which increases HR and contracility independent of adrenergic receptors. Activates GPCRs on cardiac myoctes, causing activation of adenylate cyclase and raising intracellular cAMP --\> calclium release from intracellular stores, increased SA node firing, HR and cardiac contracility. 1444

Answer 12

_Alpha 1_: targets peripheral vasculature (increase SBP), bladder (contraction of internal urethral sphincter), and eye (mydriasis). Drugs - Epi, NE, phenylephrine, methoxamine _Beta 1_: targets heart (increase HR, contractility, conductance). Drugs - epi, DA, dobutamine, isoproterenol _Beta 2_: targets peripheral vasculature (vasodilation, decrase DBP), bronchi (bronchodilation), uterus (relaxation/tocolysis). Drugs - isoproterenol, terbutaline, ritodrine. 1368

Answer 13

D/t toxins that possess strong anticholinergic properties. _Mnemonic_ for clinical manifestations of atropine poisoning: "*blind as a bat, mad as a hatter, red as a beet, hot as a hare, dry as a bone, the bowel and bladder lose their tone, and the heart runs alone."* **Atropine** is a reversible cholinergic antagonist that acts selectively on muscarinic recptors. It can be reversed by cholinesterase inhibitors (**physostigmine**) 1321

Answer 14

Megaloblastic anemia: low hemoglobin, elevated MCV; alcoholics stems from folic acid deficiency **Defect in DNA synthesis**. Folic acid is a single carbon donor required for the synthesis of purine and pyramidine base. RNA and protein synthesis may continue relatively unaltered, leading to a state of unbalanced cytoplasmic growth and impaired cell division. 1580

Answer 15

Alteration of hepatic NAD/NADH ratio in alcoholics induces fatty liver through inhibition of gluconeogenesis and fatty acid oxidation. 370

Answer 16

**Citrate anticoagulant**: chelates calcium and magnesium and may reduce thier plasma levels, causing parasthesias

Answer 17

* zona glomerulosa: cells arranged in rounded/arched clusters * zona fasiculata: foamy-appearing cells in columns * zona reticularis: basophilic cells in anastomosing cords * medulla: sharply demarcated from cortex and composed of chromaffin cells with deeply basophilic cytopaslm. Chromaffin cells are modified postganglionic sympathetic neurons; stimulated by ACh released by symp preganglionic neurons and secrete catecholamines 8424

Answer 18

Presents in 20-50 y/o F with diffuse MS pain, insomonia and emotional distrubances. Presence of multiple symmetrically distributed tender spots over the patients muscles, joints and tendons such as over the spine of teh scapula, the lateral epicondyle and the medial fat pad of knee. 867

Answer 19

Trachea deviates _toward_ opacified lung with **lung volume loss** (atelectasis; an obstructive lesion in a mainstem bronchus can prevent ventilation of an entire lung, leading to lung collapse) and _away_ from opacified lung with large **pleural effusion. **2116

Answer 20

**Common peroneal nerve:** begins in proximal popliteal fossa, where sciatic nerve divides into tibial and common peroneal nerve. Injury results in "fott drop" and characteristic "steppage gait." 1742

Answer 21

Frequency of a given characteristic and a given outcome are studied using **population data**. Useful to generate hypothesis but should not be used to make conclusions regarding indivudals within these populations (**ecological fallacy**). 10570

Answer 22

By undergoing **transformation**, which allows the bacterium to take up exogenous DNA fragments and express the encoded proteins. ## Footnote _Conjugation_ (one-way tx of DNA between bacterial cells through direct physical contact; donor contains F factor that codes for sex pilus) and _transduction_ (bacteriophage) are 2 additional mechanisms by which bacteria can obtain new genetic material. 736

Answer 23

Local defense is performed by T-cells, whereas systemic infection is prevented by neutrophils. For this reason, localized candidiasis is common in HIV-positive patietns, while neutropenic indiviudals are more likely to have systemic disease. 112

Answer 24

**Anterior dislocation of humerus** This injury most commonly results from forceful external rotation and abduction at the shoulder joint. **Axillary nerve injury,** resulting in deltoid paralysis and loss of sensation over lateral arm, is often associated. 1924

Answer 25

**Inhaled glucocorticoids** are the most effective anti-inflamamtory agents for chronic preventative treatment of bronchial asthma. 169

Answer 26

Nephrotoxicity --\> anemia and electolyte abnormalities including hypokalemia and hypomagnesemia due to an increase in membrane permeability of distal tubule. 275

Answer 27

Class III antiarrhythmics such as amiodarone, sotalol, ibutilide and dofetilide. 901

Answer 28

Southern = DNA; Western = Proteins; Northern = mRNA; Southwestern = DNA-bound proteins. Best method for determining whether a gene is being expressed is to analyze teh presence of its mRNA using a Northern blot.

Answer 29

Associated with **abnormal collagen formation**. Manifests clincally as over-flexible (hypermobile) joints, over-elastic (hyperelastic) skin, and fragile tissue susceptible to bruising, wounding, and hemarthrosis. 1244

Answer 30

When the mucosa of the terminal ileum is inflamed (as in Crohn's disease), bile acids are not reabosrbed, becoming lost with feces. As a result, a lesser amount of bile acid is present in bile, and the ratio of cholesterol/bile acids increases. Cholesterol precipitates in bile of the gallbladder and forms gallstones. 412

Answer 31

Incidence: breast \> lung \> colon Mortality: lung \> breast \> colon

Answer 32

Result in niacin deficeincy d/t excess loss of dietary tryptophan, resulting from defective intestinal and renal tubular absorption of that amino acid. Treatment: nicotinic acid or nicotinamide (niacin/vitain B3) and a high protein diet Main lab finding in Hartnup is aminoaciduria, RESTRICTED to the neutral amino acids. The urinary excretion of proline, hydroxyproline, and arginine remains unchanged (differentiates from other causes of generalized aminoaciduria such as Fanconi). 1334

Answer 33

**Ecthyma gangrenosum**. Occurs after P. aeruginosa invades perivascularly and releases tissue destructive exotoxins that cause vascular destruction and resultant insufficiency of blood flow to patches of skin which become edematous and subsequently necrose. Pseudomonas infections are common in neutropenic patients, hospitalized patients, pts with burns and chronic indewlling caths. 973

Answer 34

Results from an allergic, or Type I HSR. The allergens present in the insect venom result in antibody class switching to IgE on inital exposure, and subsequent exposure results in degranulation of mast cells and basophils with release of **histamine** and heparin --\> increase local vascular permeability (wheal), but can also cause systemic vasodilation, bronchoconstriction and inflammation leading to anaphylactic shock. 556

Answer 35

Parietal cells are oxyntic (pale pink), round, plate-like cells found in the **upper glandular layer** that secrete gastric acid and IF. Because IF is required for absorption of B12 in the ileum, its abscence leads to B12 deficiency. _Pernicious anemia_ is d/t antibody-mediated destruction of parietal cells in gastric body and fundus --\> chronic atrophic gastritis, which is characterized by loss of parietal cells with marked lymphocytic and plasma cell infiltration. 124

Answer 36

D/t elasticity of lungs, the **alveolar transmural pressure is always positive**, resulting in a collapsing force on lungs. Inversely, the chest wall tends to transmit an expanding force on the lungs, resulting in a **negative transmural prssure** across the chest wall most of the time, except during maximal inspiration. At the **FRC**, the airway pressure is zero and there is no tendency for air to flow either into or out of the lungs (i.e. the tendencies of the chest wall to expand and the lung to collapse oppose one another, creating a **negative intrapleural pressure of -5 cm H₂0**) 1519

Answer 37

Nitrites cause posioning by oxidizing the heme iron to the ferric state --\> **methemoglobin** which is unable to bind oxygen and there is also a leftward shift of oxygen dissociation curve. Methemoglobin cannot bind to oxygen and therefore the **oxygen content and oxygen carrying capacity of arterial blood will decrease**. The **bound fraction of oxygen and oxygen delivery to peripheral tissues will also decrease** because of the inability of methemoglobin to carry and deliver O2. Methemoglobinemia causes a dusky discoloration to the skin (simmilar to cyanosis), and because methemoglobin is unable to carry O2, a state of **functional anemia** is induced. The **blood partial pressure of O2, however, will be unchanged** because oxygen's partial pressure is a measure of O2 dissolved in plasma and not related to hemoglobin function. 1416

Answer 38

Hormone binds to GPCR that activates PLC, causing degradation of membrane lipids into DAG and IP3. Protein kinase C is activated by DAG as well as calcium released from the sarcoplasmic reticulum under the influence of IP3.

Answer 39

**Dizygotic twins** results from fertilization of 2 oocytes by 2 different sperm and always have 2 amnions and 2 chorions. In contrast, **monozygotic twins** arise from fertilization fo a single oocyte. Monozygotic twinning may occur at different stages of embryogenesis, which affect the organization fo fetal membranes: dichorionic/diamnionic (days 0-4), monochorionic diamniotic (day 4-8), monochorionic monoamniotic (days 8-12), and monochorionic monoamniotic conjoined twins (\>13 days). 8406

Answer 40

Offisprings genes are expressed in a parent-specific manner. Genomic imprinting is produced by DNA methylation (carried out by DNA methyltransferases), which is an epigenetic process in which genes can be silenced by the attachment of methyl groups (such as S-adenosyl-methionine) to cytosine residues in the DNA molecule. 7791

Answer 41

In cases in which a child is at signficant risk of harm. Physicians are justified in obtaining a court injunction to proceed with life-saving medical treatment of the child. 10533

Answer 42

***Camylobacter infection*** (curved Gram negative rod with a filametn that allos it to move in a characteristic "corkscrew") is a common cause of inflammatory gastroenteritis (fecal-oral route) and can be acquired from **domestic animals** (cattle, chicken, dogs) or from **contaminated food**. The diarrhea is inflammatory (initally watery, later bloody) and is acompanied by fever, abdominal pain (possibily mimicing appendicitis), tenesmus and leukocytes in stool. Infection is associated with **Guillain-Barre syndrome**. 1422

Answer 43

Morphologic findings in branches of pulmonary artery, including increased arteriolar smooth musle thickness (**medial hypertrophy**), **intimal fibrosis**, and signficant **luminal narrowing**. In setting of severe HTN, lesions can progress to form interlacing tufts of small vascular chanells (**plexiform lesions**). Presents as a 20-40 y/o F with dyspnea and excercise intolerance. **Bosentan** is an **endothelin-receptor antagonist** that blocks the effects of endothelin (potent vasoconstrictor that also stimulates endothelial proliferation). Therapy decreases pulmonary arterial pressure and lessens the progression of vascular and RVH. 903

Answer 44

Short-acting barbiturate. After equilibration with the brain it rapidly **redistributes into skeletal muscle and adipose tissue**, which results in rapid recovery from anesthesia. 852

Answer 45

Slowly growing, well circumscribed and benign tumors. **Psammoma bodies** are characteristic; composed of core of dense calcification with surrounding collagen-fiber bundles. 1151

Answer 46

T-lymphocyte immunodeficeincy that results form maldevelopment of the 3rd and 4th branchial (pharyngeal) pouches due to deletion on chromosome 22. 543

Answer 47

_Presentation_: tumor arising from **alpha-cells** of pancreatic islets. * **Necrolytic migratory eryhtema**: elevated painful and pruritc rash typically affecting face, groin, and extremities. Lesions enlarge and coalesce, leaving a bronze-colored central indurated area with peripheral blistering and scaling. * **Diabetes mellitus** (hyperglycemia) * GI Sx (diarhea, anorexia, abdominal pain) * Normocytic normochromic anemia _Diagnosis_: markedly **elevated glucagon levels.** 585

Answer 48

By binding to **nuclear receptors**, which control gene expression by binding to DNA at hormone-responsive elements in the promoter region of target genes. Other molecules that act through nuclear receptors include retinoids, peroxisomal proliferating activated receptors, and fatty acids. Receptors for several steroid hormones such as glucocorticoids, mineralocorticoids, androgens, and estrogens are usually initially present in cytoplasm, although they do migrate to nucleus once activated.

Answer 49

Effect modification is present when the effect of the main exposure on the outcome is modified by the presence of another variable. _Example_: smoking status modified the effect of a new estrogen receptor agonist (exposure) on DVT incidence (outcome). It is NOT a bias. Stratified analysis (analyzing the cohort as different subgroups) can help distinguish from confounding. With effect modification, the different strata will have different measures of association vs. confouding where teh stratifiation usually reveals no significant difference between strata. 1279

Answer 50

Accumulates within the **tunica vaginalis**, which is embryologically derived from the peritoneum. When it remains in communication with the peritoneum, a communicating hydrocele results. 1827

Answer 51

Accumulation of activated macrophages and formation of **noncaseating granulomas**. CXR will show **bilateral hilar adenopathy**. Sarcoid granulomas produce ACE and vitamin D, so patients often have **elevated ACE levels and hypercalcemia**. **CD4+ T helper cells** are the predominant type of lymphocyte found in sarcoid granulomas. 796

Answer 52

Requires 2 of the following 5 symptoms: delusions, hallucinations, disorganized speech, grossly disorganized behavior, and negative Sx. One of these must be delusions, hallucinations, or disorganized speech. The total illness duration must be at least 6m with at least 1m of active Sx. 2045

Answer 53

Thiazide diuretics and dihydropyridine calcium channel antagonists (e.g. amlodipine; can lead to flushing and peripheral edema)are first-line drugs to treat in nondiabetic patients (where an ACE-I or ARB would be utilized first). 154

Answer 54

**Saturation**: there is a finite number of carrier proteins in the cell membrane, and these carrier proteins require a discrete amount of time to pass a single molecule or ion through the membrane. Once all the carrier molecules are bound by substrate, no further diffusion can occur until a carrier protein is vacated (transport maximum or Tm). 1378

Answer 55

The tertiary amine **physostigmine**! NOTE that the anticholinesterase agents neostigmine and edrophonium have a quaternary ammonium structure that limits CNS penetration.

Answer 56

**Bronchoconstriction** and increased bronchial mucus secretion (via ACh cting on M3 receptors). These effects increase airway resistance and the work of breathing. Anticholinergic agents such as tiotropium and ipratropium work to counteract these effects and are useful in treating obstructive lung diseases such as asthma and COPD.

Answer 57

The zinc-containing aminolevulinate dehydratase and ferrochelatase are enzymes in the heme biosynthetic pathway that are inactivated by lead. 1454

Answer 58

Significant renal artery stenosis causes renal hypoperfusion and activation of the RAAS. **Modified smooth muscle (JG) cells of the affernt glomerular arterioles** synthesize renin. Chronic renal hypoperfusion will cause **hypertrophy and hyperplasia of the JG cells**. 7569

Answer 59

**_Toxic megacolon_**: abd pain and distention, fever, diarrhea, adn signs of shock (decreasing BP, increasing HR). Complete cessation of neuromuscular activity in the intestinal wall is the first step in the pathogenesis of toxic megacolon. **Plain abdominal X-ray** should be used for diagnosis. Barium contrast studies and colonoscopy are CI d/t risk of perforation. 410

Answer 60

Pancreas forms from the dorsal (tail, body, and most of head) and ventral (portion of head, uncinate process, and main pancreatic duct) buds, which are foregut invaginations that fuse. **Abnormal migration of the ventral pancreatic bud** leads to formation of an annular pancreas, which encircles the descending part of duodenum and may lead to Sx of duodenal obstruction (recurrent bilious vomiting) soon after birth. 438

Answer 61

Caused by age-related decrease in the compliance of the aorta and its proximal major braches.

Answer 62

DNA polymerase I has 5' to 3' exonuclease activity in addition to its 5' to 3' polymerase and 3' to 5' exonuclease activities. This 5' to 3' exonuclease activity is used to remove the RNA primer (which initiates DNA polymerization) and to remove damaged DNA. 1434

Answer 63

Cystic degeneration of the putamen as well as damage to other basal ganglia structures. The putamen is located medial to the insula and lateral to the globus pallidus on coronal sections. 1689

Answer 64

**5-HT 1B/1D agonists** that directly counter the pathophysiologic mechanism of migraine HA by inhibiting the rlease of vasoactive peptides, promoting vasoconstrction and blocking pain pathways in the brainstem. BBs, antidepressants (e.g. amitriptyline and venlafaxine), and anticonvulsants (e.g. valproate and topiramate) are used for prophylaxis. 8476

Answer 65

Nitroprusside is initially metabolized to cyanide, with subsequent conversion to thiocyanate by liver rhodanase. Thus, one major disadvantage of its use involves the risk for developing **cyanide toxicity.** **Sodium thiosulfate** is used to treat cyanide toxicity and works by **donating sulfur** to liver rhodanase to enhance conversion of cyanide to thiocyanate. 1254

Answer 66

**2/3 chance** ## Footnote See 1790

Answer 67

Supresses bacterial protein synthesis by binding to the 50S RSU and inhibiting the peptidyl transferase enzyme. SE: **dose-related anemia, leukopenia, and/or thrombocytopenia** that are reversible. Also causes **dose-independent aplastic anemia**, which is usually severe and fatal without treatment. 359

Answer 68

Inability of B-lymphocytes to undergo isotype switching from IgM to other immunoglobulin isotypes --\> lymphoid hyperplasia and recurrent sinopulm infections. MC d/t genetic **abscence of CD40 ligand** on T-lymphocytes. NOTE: the genes coding for constant region of heavy immunoglobulin chains lie next to one another in following order: **IgM, IgD, IgG, IgE, IgA**. IgM is the initial immunoglobulin synthesized by all B-lymphocytes prior to class switching. 541

Answer 69

Salmonella Typhi or Paratyphi and presents with escalating fever (with inital diarrhea or constipation), followed by abd pain, formation of rose spots on the chest/abd, and hemorrhagic enteritis with possible bowel perforation. Usually occurs after traveling to an edemic region; fecal-oral following ingestion of contaminated food/water. 1138

Answer 70

Opportunistic infection with CMV, which is an enveloped virus that contains a dsDNA genome. 1576

Answer 71

Organophosphates stimulate both muscarinic and nicotinic cholinergic receptors. Atropine reverses muscarinic effects but does not prevent the development of nicotinic effects such as **muscle paralysis.** Pralidoxime is the only medication tht reverses both muscarinic and nicotinic effects by "restoring" cholinesterase from its bond with these substances. 1323

Answer 72

Posterior cerebral and superior cerebellar arteries. An aneurysm arising from either artery can lead to a non-pupil-sparing third nerve palsy, which clinically presents with unilateral HA, eye pain, diplopia, dilated nonreactive pupil, and ptosis with the ipsilateral eye in a down and out position. 2126

Answer 73

Calcium-laden gallbladder than can develop in some patients wiht chronic cholecystitis. Cholecycstectomy is recommended b/c of increased risk of gallbladder carcinoma

Answer 74

Superomedial: risk injury to superior gluteal nerve Superomedial, Inferomedial, Inferolateral: risk injury to sciatic nerve Superolateral quadrant is a relatively safe site for intragluteal injections, although the anterolateral gluteal region is preferred. 1640

Answer 75

Folinic acid (leucovorin) can reverse the toxicity of methotrexate in non-cancerous cells in the GI mucosa and bone marrow if administered at the appropriate time. Leucovorin, a 5-formyl-derivative of THF acid, does not require the action of DHFR for its conversion to THF. 1818

Answer 76

**Atrioventricular node refractory period** AFib occurs d/t irregular electrical activity within the atria and presents with absent P waves, irregularly irregular R-R intervals and narrow QRS complexes. 1977

Answer 77

Sign of **diastolic dysfunction** and occurs when there is a sudden rise in end-diastolic ventricular pressure caused by **atrial contraction** against a ventricle that has reachd its elastic limit. Present in any condition that cuases reduced ventricular compliance (e.g. hypertensive heart disease, aortic stensois, hypertrophic cardiomyopathy). It is heard as a low-frequency late diastolic sound that occurs **just prior to S1.** 246

Answer 78

Causes hemolytic anemia d/t failure of glycolysis and resultant failure to generate sufficent ATP to maintain erythrocyte structure. In this case, splenic hypertrophy results from **increased work** of the splenic parenchyma, which must remove these deformed RBCs from circulation. 1020

Answer 79

Secondary to decreased synthesis and net loss of dermal collagen and elastin

Answer 80

Genetic differences 627

Answer 81

HIV+ pts often experience reactivation of latent EBV infections with a resulting incresed incidence of EBV-induced lymphoproliferative disorders, including the aggressive non-Hodgkin's diffuse B-cell lymphomas. 1724

Answer 82

**Paramesonephric ducts** fuse to form the uterine tubes, uterus, cervix, and superior 1/3 of the vagina. Uterus didelphys: occurs when there is total nonfusion of the paramesonephric ducts; seperate vagins, cervices and uterine horns. 1831

Answer 83

Considered a hallmark of cell injury and death, occuring in all types of **necrosis** in the setting of **normal calcium levels**. Grossly, dystrophic calcium deposits are fine, gritty, white granules or clumps. In aged (or damaged) cardiac valves, thought to be d/t endothelial and fibroblast death secondary to **chronic hemodynamic stress** or atherosclerotic inflammation. Subsequent release of cellular degradation products into valvular interstitum then promotes calcification and thickenign of valve leaflets. These changes are benign in elderly (**aortic sclerosis**); however, over time, progressive valvular stiffening can lead to outflow obstruction (**calcific aortic stenosis**). 296

Answer 84

**Hyperacute rejection** is an **antibody-mediated reaction** (**Type II HSR**) caused by **preformed IgG antibodies** within the recipient that are directed against donor antigens. Examples include anti-ABO and anti-HLA antibodies. Morphology: **gross mottling and cyanosis**; arterial fibrinoid necrosis & capillary thrombotic occlusion. 569

Answer 85

* _Capitation_: **paid a fixed amount per enrollee**, not per service. Have incentives to contain costs d/t fixed budged; MDs **motivated to provide more preventative care** (e.g. pap smears/mammo) **and better health counseling**. * _Fee-for-serve (FFS)_: **paid fixed amount for every service and diagnostic test; no incentive to avoid costly tests and procedures. ** * _Discounted FFS_: reimbursed a discounted amount; may be more conservative when ordering tets and providing services compared to FFS. * _Salary_: fixed amount and pay is not tied to number of enrollees or services; no finanical incentive to change their treatment patterns, either in services provided or number of follow-up visits. 8456

Answer 86

Increased incidence of **pulmonary HTN**, which manifests with dysnpea on exertion, and can progress to cor pulmonale with **right ventricular hypertrophy**, potentially leading to sudden cardiac death. 199

Answer 87

**Nifedipine**: causes peripheral vasodilation (vasculature specific) which may result in reflex tachycardia; therefore this antihypertensive is useful for patients with bradycardia. 145 ## Footnote NOTE: * Amlodipine, nimodipine, nifedipine (**dihydropyridines**; more specific for **vascular smooth muscle**). All (except nimodipine) are used for HTN, angina (including Prinzmetal), and Raynauds * Diltiazem and Verapamil (**non-dihydropyridine**; more specific for **heart**; **_v_**erapamil = **_v_**entricle): HTN, angina, afib/flutter; slow conduction through AV node. * Nimodipine: subarachnoid hemorrhage (prevents cerebral vasospasm)

Answer 88

1. **Hemoglobin concentration**: 1g of hemoglobin can carry 1.34 mL of oxygen when fully oxygenated 2. **Oxygen saturation of hemoglobin (SaO2)** 3. **Partial pressure of oxygen dissolved in blood (PaO2)**: dissolved oxygen is not bound to hemoglobin, and accounts for a very small proportion of the total oxygen content of blood. ## Footnote _Anemia_: blood hemoglobin concentration is decreased. Thus, PaO2 (dissolved oxygen - independent of hemoglobin concentration) and SaO2 (% hemoglobin saturation with oxygen) can be normal, but **total oxygen content of blood is decreased**. 1527

Answer 89

**CSF**: elevated opening pressure, increased neutrophils, decreased glucose, elevated protein **Strep pneumoniae**: lancet-shaped, gram-positive cocci in pairs. Meningitis often follows a pulm infection or mild URI. Alcohols, sickle cell anemia patients, and asplenics are at greater risk. 735

Answer 90

Deficiency of any enzymes responsible for porphyrin synthesis can result in porphyria, which can be classified as either hepatic or erythropoietic, dpending on site of enzymatic deficiency. Heme is synthesized in liver for use in CYP450 system, while in bone marrow is generated for Hb use. Acute attacks of intermittent hepatic porphyria can be precipitated by **drugs** such as phenobarbital, griseofulvin, phenytoin. Additionally, **alcohol, hypoxia,** and a **low caloric diet** can induce an attack. All of these factors decrease hepatic concentration of heme, which causes an **increase in hepatic ALA synthase activity** and increased **formation of aminolevulinic acid and porphobilinogen** (heme normally serves to inhibit synthesis of ALA synthase) --\> abd pain + neuro manifestation,s no photosenstivity, urine darkens upon standing. 1338

Answer 91

**_Polycistronic_**: **one mRNA codes for several proteins.** For example, all 3 proteins of the lac operon (beta-galactosidase, permease, and transacetylase) are synthesized from a single mRNA molecule containing z, y, and a gene sequences, respectively. _Bacterial lac operon_ codes for proteins necessary for lactose metabolism by E. coli. The transcription and translation of these bacterial proteins is regulated by a **single promoter, operator, and set of regulatory elements**. 1485

Answer 92

In stable angina, atherosclerosis leads to reduced O2 delivery to cardiac mitochondria resulting in mismatch between myocardial oxygen demand and supply. Since glucose oxidation requires less oxygen, it is believed that shifting energy production from FA oxidation to glucose oxidation may be more oxygen efficient and beneficial in treating angina (i.e. **less oxygen use per one ATP synthesized**). This not only decreases the amount of oxygen needed to support cardiac fxn, but also decreases potentially toxic FA metabolite production. 950

Answer 93

_Morphology_: **calcified cystic tumor**s that are lined by stratified squamous epithlelium. Keratin parls may also be seen. Filled with a **yellow, viscous fluid that is rich in cholesterol**. Arise from **remnants of Rathke's pouch** (an embryonic precursor of the anterior pituitary/adenohypophysis), which is an evagination fo ectoderm that lines the fetal oral cavity. NOTE: posterior pituitary (neurohypophysis) develops from neruoectoderm. _Sx_: HA, growth failure, bitemporal hemianopia. 1152

Answer 94

Beta-adrenergic pathway is mediated through sympathetic stimulation of **beta-1 receptors on JGA cells**; NE binds to beta-1 receptors and stimulates renin release. Thus BBs inhibit renin release, reduce angiotensin I and II, and aldosterone levels. No affect on ACE activity, and thsu do not affect bradykinin levels. 692

Answer 95

_Leydig cells_ (analogues to female _theca cells_): produce **testosterone** in response to stimulation by **LH**. Through a negative feedback mechansim, testosterone inhibits both LH and GnRH. _Sertoli cells_ (analogues to female _granulosa cells_): produce hormone **inhibin** in respone to **FSH**, maintain **spermatogenesis**, and secrete **mullerian inhibitory factor** during male embryogenesis. Inhibin suppresses FSH production by AP but does not feedback on hypothalamus. Thus, *selective impairment of Sertoli cell fxn would lead to decreased inhibin and increased FSH.* 1902

Answer 96

**_Asthma_**: bronchial biopsy typically demonstrates a thickened mucosa with eosinophilic infiltrates. Flares occur following exposure to airborn allergens that interact with IgE bound to pulmonary mast cells. Extrinsic allergic asthma provoked by **inhaled allergens such as animal dander** is the most common type. 1925

Answer 97

Patients who are heterozygous for sickle cell trait (Hb AS) have Hb composd of 35-40% HbS; they are generally protected from sickle cell crises, aplastic crises, and sequestration crises by presence of \>50% normal hemoglobin (HbA). Usually have normal peripheral smears and indies, reticulate counts, and MHCH values. Also enjoy relative **protection from Plasmodium falciparum**. However, sickle cell trait RBCs will sickle when **sodium metabisulfite** is added. 895

Answer 98

_True diverticulum_ has all 3 gut wall layers outpouch (mucosa, submucosa, and muscularis) vs. _False diverticulum_ where only **mucosa and submucosa** outpouch (occur esp. where vasa recta perforate muscularis externa). 328 _Zenker_: pharyngoesophageal **false diverticulum**. Herniation of mucosal tissue at Killian triangle b/w thyropharyngeal and cricopharyngeal parts of inferior pharyngeal constrictor. Dysphagia, obstruciton, halitosis; elderly males _Meckel_: **true diverticulum**; persistence of the vitelline duct. May contain ectopic acid-secreting gastric mucosa and/or pancreatic tissue. Can cause melena, RLQ pain, intussuscpeption, voluvlus, or obstruction near terminal ileum; first 2 years of life.

Answer 99

**Alanine** is the major AA responsible for transferring nitrogen to the liver for disposal. During the catabolism of proteins, alanine is transaminated by alanine aminotransferase to pyruvate with the amino acid group being transferred to **alpha-ketoglutarate** to form **glutamate**. Glutamate is further metabolized by glutamate dehydrogenase, which liberates free ammonia and regenerates alpha-ketoglutarate. Ammonia then enters urea cycle to form urea, the primary disposal form of nitrogen in humans. Free ammonia is also excreted into urine by kidney for regulation fo acid-base status. 1369

Answer 100

**AR disorder** d/t mutation of a gene that codes for protein frataxin, which is essential for normal mitochondrial fxn. An increased number of **trinucleotide repeats** is present in the mutated gene, causing **diminished levels of frataxin**. 5-15 y/o with gait ataxia (progressively slow and clumsy walking), wide-based gait, and dificulty maintaing balance. 672 * *Ascending and descending spinocerebellar tract degeneration* causes **gait ataxia** * *Degeneration of dorsal columns and DRG* causes **loss of position and vibration sense** * **Kyphoscoliosis** and foot abnormalities (**pes cavus**) * **Hypertrophic cardiomyopathy** and CHF * **Diabetes mellitus**

Answer 101

Unethical to discuss any information regarding the patient's diagnosis, treatment, prognosis, etc with a physician who is not involved in the patient's care. Likewise, the physician should neither confirm nor deny whether the person of interest is, in fact, a patient. 7733

Answer 102

Binding of morphine to **mu receptors** results in G protein-coupled activation of K+ conductance. **K+ eflux** increases and causes hyperpolarization of postsynaptic neurons effectively blocking pain transmission. 776 ## Footnote Other possible secondary messenger pathways of mu opioid receptor activation include inhibition of AC, inhibition of Ca2+ conductance, and inhibition of transmitter release.

Answer 103

Used in treatment of prostate cancer in combo with GnRH agonists. Non-steroid anti-androgen that **competes with testosterone and DHT for testosterone receptors.** Prevention fo androgen-receptor binding blocks the stimulatory effect of androgens on the primary tumor and metastases and leads to reduction in their size. 657

Answer 104

**Prolonged hypoxia**. It can be secondary to the following chronic conditions: * _Lung diseases_: lung cancer (esp. large-cell), TB, CF, bronchiectasis, pulm HTN, empyema * _Heart diseases_: cyanotic congenital heart diseases (esp. TOF) and bacterial endocarditis * _Other_: IBD, hyperthyroidism, malabsorption 820

Answer 105

Acquires virulence via **bacteriophage-mediated**"infection" with the Tox gene, which codes for **diphtheria AB exotoxin**. This process, whereby a bacteriophage infects a host bacterium and integrates its genome into the host bacterium's genome is termed **lysogenization**. 1389

Answer 106

_Low-frequency sound_ is best detected at the apex of the cochlea near the **helicotrema**. _High-frequency sound_ is best detected at the base of the cochlea near the **oval and round windows**. 1520

Answer 107

Involves enzymes fructokinase, aldolase B and triokinase. 1067 _Essential Fructosuria_: AR **asymptomatic** disorder d/t **fructokinase deficiency**. Fructose (reducing sugar) from the diet is absorbed in gut and secreted in urine unchanged. _Fructose Intolerance_: AR disorder of **aldolase B** (converts fructose-1-phosphate to DHAB and glyceraldehyde). Infants present after consumption of fruit, juice, or honey with hypoglycemia, jaundice, cirrhosis and vomitting. Tx: decrease intake of both fructose and sucrose (glucose + fructose).

Answer 108

* CMV: cellular integrins * EBV: CR2 (CD21) * HIV: CD4 and CXCR4/CCR5 * Rabies: nicotinic ACh receptor * Rhinovirus: ICAM1 (CD54)

Answer 109

**dsDNA --\> template +RNA --\> progeny dsDNA** The HBV genome is a partially double stranded circular DNA molecule, and replication of this genome is accomplished through a reverse transcriptase DNA polymerase that creates an intermediate + single-stranded RNA template. The progeny of this process is dsDNA. 374

Answer 110

Pancreas! Pancreatic injury with formation of a retroperitoneal hematoma can occur d/t severe blunt or penetrating abdominal trauma. 838 _Retroperitoneal Structures_: **SADPUCKER** = Suprarenal (adrenal) glands, Aorta and IVC, Duodenum (2nd-4th parts), Pancreas (except tail), Ureters, Colon (descending and ascending), Kidneys, Esophagus (lower 2/3), Rectum (partially). NOTE: rupture of intraperitoneal organs would lead to hemoperitoneum (free blood in peritoneal space).

Answer 111

**Amphotericin B** - binds ergosterol in fungal cell membranes to form holes. Toxicity: renal vasoconstriction and reduction in GFR. Hypokalemia and hypomagnesemia are the two most serious electrolyte distrubances.

Answer 112

Affects young children and manifests with **acute renal failure, MAHA, and thrombocytopenia**. Labs include decreased RBC count, hematocrit and platelet count and increased bleeding time, LDH, BUN, and creatinine. Shiga toxin (verotoxin) enters circulation from bowels and induces vascular damage leading to capillary thrombus formation --\> consume platelets and cause mechanical damage to RBC --\> hemolytic anemia causes pallor, weakness, and tachycardia. Thrombocytopenia may lead to petechaie and purpura. 1851

Answer 113

_Sx of lithium toxicity_: neuromuscular excitability, irregular coarse tremors, fasicular twitching, agitation, ataxia, and delirium. HD is the most effective way of acutely reducing blood lithium level. 519 Lithium is almost exclusively excreted by the kidneys, with filtraiton and reasorption in the proximal tubules following sodium reabsorption. **Renal injury, toxins, and drugs that lead to increased proximal tubular absorption of sodium (e.g., NSAIDs, thiazides, ACE-I)** also increase lithium levesl and elevate risk of toxicity.

Answer 114

Antimycobacterial agent that **inhibits carbohydrate polymerization** by **inhibiting arabinosyl transferase**, thereby preventing peptidoglycan cell wall synthesis. AE is **optic neuritis**, which typically presents in conjuction with decreased visual acuity, central scotoma and color blindness. 1311

Answer 115

If deltaG is negative, Keq will be greater than 1, and the concentration of products at equilibrium will exceed that of substrates. If deltaG is positive, Keq will be less than 1, and the formation of substrates will be favored. An equilibrium constant of 1 would occur in a state where deltaG is zero.

Answer 116

Either **MAHA** (e.g. TTP, HUS, DIC) or **mechanical damage** (e.g. prosthetic valve). Both HUS and TTP come under same spectrum of dise with pentad: fever, neurologic manifestations, renal failure, thrombocytopenia, and microangiopathic hemolytic anemia. Usually TTP occurs in adults with predominant neuro sx vs. HUS in children with primarily renal involvement.

Answer 117

Cystic medial degeneration, which predisposes to the development of **aortic dissections** and **aortic aneurysms.** Medial degeneration is frequently seen in younger individuals with Marfan syndrome. 462

Answer 118

**Brown adipose tissue**, which contains several intracytoplasmic fat droplets and many more mitochochondria (provides the tan color) than white adipose cells. They fxn to **produce heat** by uncoupling oxidative phosphorylation with the protein thermogenin. 821

Answer 119

_Bacterial vaginosis_: thin, white discharge with fishy odor (positive "whiff" test on addition of KOH); clue cells at pH \>4.5. _Trichomoniasis (trichomonas vaginalis)_: frothy, grey-green, foul-smelling discharge; strawberry cervix; motile trichomonads with pH \>4.5

Answer 120

**FFA** (act to decrease insulin secretion and may also be d/t serine phosphorylation of the insulin receptor --\> serine kinase becomes activated instead of tyrosine kinase; mechanism of resistance induced by TNF alpha, glucagon, and glucocorticoids) and serum **triglycerides** are believed to increase insulin resistance in overweight individuals. 1328

Answer 121

PSVT is d/t re-enterant circuit in the AV node. Episodes are usually treated with adenosine in the hospital setting, but vagal maneuvers (increase cardiac PNS tone, which functions to slow the HR by slowing conduction through the AV node which will abolish the re-enterant circuit) such as carotid sinus massage and Valsalva can also be used. 1515

Answer 122

Adenomatous polyps: tubular, villous, and tubulovillous. **Tubular** tend to be smaller and pedunculated, while **villous** are larger and more commonly sessile. Sometimes villous adenomas can have **velvety or cauliflower-like projections**. Villous adenomas can cause **bleeding**, **secretory diarrhea** (villous adenomascan secrete large amounts of mucous), and partial **intestinal obstruciton**; high risk progression to adenocarcinoma. 430

Answer 123

Inactivated viral vaccines predominately generate a humoral immune response. Live-attenuated can generate a strong cell-mediated and humoral response. Inactivated versions of influenza fxn by inducing **neutralizing antibodies against the hemagglutinin antigen**. Upon exposure to influenza virus through natural infection, these antibodies inhibit binding of hemagglutinin to sialylatd receptors on host cell --\> **prevents virus from entering cells** via endocytosis. 1466

Answer 124

Splenic artery originates from celiac artery and gives off several branches to stomach and pancreas (pancreatic, short gastric, and left gastroepiploic) before reaching spleen. D/t poor anastomoses, the gastric tissue supplied by the **short gastric arteries** is vulnerable to ischemic injury following splenic artery blockage. 8574

Answer 125

**Duodenal ulcers** d/t increased gastric acidity from unchecked gastric production secondary to destruction of somatostatin-secreting cells in the gastric antrum. H. pylori is also strongly associated with gastric adenocarcinoma and lymphoma. 1603

Answer 126

Can occur via atherosclerosis and chronic chemical and inflammatory exposures. Vascular reaction to injury, including endothelial injury, involves migration of medial smooth muscle cells (SMCs) across internal elastic lamina and into the intima followed by **SMC proliferation and collagen synthesis --\> reactive intimal hyperplasia. ** Injured endothelial cells release PDGF which promotes SMC migration and proliferation. Also express surface vascular cell-adhesion molecules (VCAMs) that allow adherence of monocytes and lymphocytes as well as their diapedesis into intma. 443

Answer 127

Shiga-like toxin produced by EHEC are nearly identical to the shiga-toxin produced by Shigella dysenteriae. These toxins fxn to inhibit the 60S RSU in human cells, thereby blocking protein syntheis by preventing bindign of tRNA. This mechanism differs from that of diphtheria toxin and exotoxin A of Pseudomonas in that the latter toxins act on EF-2. 1098

Answer 128

**Syringomyelia**: cystic dilation in cervical spinal cord slowly enlarges, characteristically causing damage to ventral white commissure (decussation of lateral spinothalamic tract neurons) and anterior horns (site of LMN cell bodies). Most commonly above C8-T1 cord levels. Further expansion can produce lower extremity weakness and hyperreflexia (UMN defect) by affecting lateral corticospinal tract. 1904

Answer 129

Can occur as the result of **hematogenous or lymphatic seeding** from a distant site or by spread from an adjacent site. Patients can present with fever, back or flank pain, inguinal mass, and difficulty walking. Inflammation of psoas muscle causes **pain when hip is extended** (psoas sign). Patients typically position themselves to minimize psoas stretching and discomfort, with hip flexion and lumbar lordosis. 8710

Answer 130

**AV nodal cells **can become pacemakers. In a _complete (third-degree) AV block_, the atria and ventricles depolarize independently of each other. **QRS complexes are narrow** since ventricular depolarization proceeds normally. AV node produces a **HR of 45-55 bpm**. When electrical impulse is generated below the AV node and His bundle, the HR can slow to 20 bpm and the EKG will show prolonged abnormally shaped QRS complexes. 1976

Answer 131

**Most common type of thyroid cancer**. Cells are large with overlapping nuclei containing finely dispersed chromatin, given them a ground-glass appereance (**Orphan Annie eye**). Numerous **intranuclear inclusions and grooves** can be seen d/t invagination of nuclear membrane. **Psammoma bodies** are also found within tumor. 1658

Answer 132

Progressive dysphagia. Major risk factors include EtOH consumption and tobacco. Consists of solid nests of neoplastic squamous cells with abundant eosinophilic cytoplasm and distinct borders. Areas of keratinization are easily identified. 287

Answer 133

Tells us that the total flow of mass into a contained system must be equal to the total flow of mass from the system in steady state. 245 Total Flow = Flow Velocity \* Cross Sectional Area e.g. Vol_in= A1 \* V1 = Vol_out = A2 \* V2

Answer 134

_Rotundum_: CN V2 (maxillary nerve) _Ovale_: CN V3 (mandibular nerve), lesser petrosal nerve, accessory meningeal artery, emissary veins _Spinosum_: middle meningeal artery and vein, meningeal (recurrent) branch of CN V3 _Jugular Foramen_: CN IX, X, and XI, the inferior petrosal and sigmoid sinuses, and posterior meningeal artery

Answer 135

**N-acetylation **in the liver. Patients who are slow acetylators are at greater risk for developing lupus-like syndrome. ***Having Lupus is "SHIPP-E"***: Sulfa drugs, Hydralazine, INH, Procainamide, Phenytoin, Etancercept

Answer 136

Triazolam or alprazolam ## Footnote 1352

Answer 137

Proportinal to the molecules concentration difference across the membrane, the total membrane surface area, and the solubility of the substance . Inversely proportional to the total membrane thickness and MW of the molcule. 1988

Answer 138

High peaking LV and aortic pressures during systole and steep diastolic decline in aortic pressure, resulting in an increased pulse pressure. The peak intensity of an AR murmur occurs after closure of the incompetent aortic valve, at the point when the pressure gradient between the aorta and LV is at its maximum. Murmur is typically best heard along left sternal border, with the patient leaning forward and at end expiration. 227

Answer 139

Low doses: stimulate D1 receptors in renal and mesenteric vasculature resluting in vasodilation and increased blood flow to these sites Higher doses: increase cardiac contractility by stimulating beta-1 adrenergic receptors Higher Higher doses: generalized vasoconstriction by an alpha-1 adrenergic effect. 1365

Answer 140

The most highly oxygenated blood is carried by the **umbilical vein** (forms ligamentum teres in adult) --\> liver, where it bypasses the hepatic circulation via the **ductus venosus** and enters the **IVC**. From the IVC, blood goes to heart where it is either pumped into pulmonary circulation or crosses from R to L heart via **FO**. Fraction of blood pumped into pulmonary circulation may bypass lungs via **ductus arterosus** (ligamentum arteriosum) and pass directly into **descending aorta** --\> fetal tissues --\> **umbilical arteries** carry deoxygenated blood back to the placenta. 1833

Answer 141

The Fragile X Mental Retardation 1 (FMR1) gene is located on the long arm of X chromosome. An increased number of CGG trinucleotide repeats lead to **hypermethylation** of cytosine bases and subseuent **gene inactivation**. 1421 _Sx_: mental retardation, long thin face with prominent forehead and jaw, post-pubertal macroorchidism, large protruding ears, tooth crowding, arched palate.

Answer 142

CFTR protein normally secretes Cl- into the lumen, and also has a tonic inhibitory effect on opening of the apical Na+ channel (which absorbs Na+ into the cell). Impaired CFTR functioning directly reduces ductal epithelial Cl- secretion and indirectly increases Na+ absorption by releasing the inhibitory effect on apical Na+ channel. These changes occur in most exocrine glands (other than sweat glands). 804 _Overall_: **reduced luminal Cl- secretion** and **increased Na+ and net H₂0 absorption** --\> **dehydrated mucus**.

Answer 143

Many viruses bind to normal host cell plasma membrane receptors in order to enter host cells. 1375 CD4 and HIV gp120 C3d complement component (CR2 or **CD21**) and EBV gp350: CD21 is normally present on the surface of B cells and nasopharyngeal epithelial cells. erythrocyte P antigen (globoside) and Parvovirus B19

Answer 144

Allows a physician to treat an incapacitated patient without consent in an emergency setting (i.e. patient is unresponsive and not carrying a blood refusal card, and communication with the next of kin surrogate decision maker is not possible). In an emergency situation in which the patient does not have capacity, consent is not required to provide life-saving treatment. In an emergency, the physician should always provide potentially life-saving therapy to a minor. 783

Answer 145

High levels of prolactin **supress GnRH secretion**, leading to **hypogonadism** (can also cause galactorrhea in females) and thus **low estrogen** in females. Estrogen maintains bone mass in females, so any loss of estrogen - whether from menopause, hormone imbalances, or surgical removal of ovaries-leads to loss of bone density (**osteoporosis**). 233

Answer 146

**Abciximab** is a **blocker of GPIIb/IIIa receptor**; useful for treatment of unstable angina and acute coronary syndrome, particuarly those undergoing percutaneous coronary intervention. **Glanzman thrombasthenia**: deficient or defective GPIIb/IIIa. Present in childhood with mucocutaneous bleeding. Peripheral smear shows no platelet clumping. 1079

Answer 147

**Oculomotor dysfunction** (e.g. horizontal nystagmus and bilateral abducens palsy d/t damage of CN III and VI, and vestibular nuclei), **ataxia**, and **confusion** form the triad. Most of these symptoms usually resolve after **thiamine (vitamin B1)** administration. Commonly involve **mammillary bodies**. Korsakoff syndrome is a complication of Wernicke encephalopathy associated wtih damage to **anterior and dorsomedial thalamic nuclei**, the hallmarks of which are **permanent memory loss** and **confabulation**. 63

Answer 148

ADH acts primarily on the collecting ducts, increasing their permeability to water. In the abscence of ADH, the tubular fluid is more concentrated at the junction between the descending and ascending limbs of the loop of Henle and most dilute in the collecting ducts. 1607

Answer 149

* _Proximal Tubule_: H20 passively rebsorbed along with active transport of solutes; fluid in lumen is **isoosmotic** with plasma. * _Descening Limb_: permeable to H20 but not solutes; H20 moves down its concentration gradient from lumen into highly osmotic medulla. Fluid in lumen becomes **hypertonic**. In abscence of ADH, tubular fluid is more concentrated at end of descending limb * _Thick Ascending_: impermeable to H20. Electrolytes are reabsorbed by NK2Cl cotransporter, causing osmolarity of tubular fluid to decrease; tubular fluid becomes **hypotonic** * _DCT_: reabsorption of solutues continues thru NaCl symporter. B/c the early DCT is impermeable to H20, tubular fluid increases in **hypotonicity**. * _Collecting Ducts:_ In abscence of ADH, collecting ducts are impermeable to water and tubular fluid can become as **hypotonic** as 50 mOsm/L while solutes continue to be removed.

Answer 150

**Increase in LV preload** (i.e. LVEDV) in association wtih **eccentric LV hypertrophy** (adaptation to volume overload; "in series" synthesis of new myocardial sarcomeres). 237 ## Footnote NOTE: concentric hypertrophy is the response to pressure overload (e.g. aortic stenosis or systemic HTN) and involves "in parallel" deposition of new sarcomeres, which produces net ventricular wall thickening and a reduction in ventricular chamber size (decreased EDV)

Answer 151

Failure of chromosomes pairs to seperate properly during cell division. This could be d/t failure of homologous chromosomes to seperate in meiosis I or failure of sister chromatids to seperate during meosis II or mitosis. Monosomies or trisomies can result from nondisjunction in meosis I or II. 8328 ## Footnote On restrictrion fragment length polymorphism (RFLP) each band represents a homologous chromosome, thus the presence of an extra band indiciates extra homolgous chromsome (problem in meiosis I when homolgous chromsomes are seperated). Presence of a darker, thicker band significes inheritance of both sister chromaids, which produce equal-size restriction fragments (but twice the normal amount)

Answer 152

Increase in levels of thyroid binding globulin (TBG) lead to increase in circulating total T4 and T3. However, the level of free thyroid hormones remains normal, so patients remain euthyroid and have normal TSH levels. Increase in TBG is typically seen in pregnancy, with use of oral contraceptives, or with HRT.

Answer 153

**Nitric oxide (endothelium derived relaxation factor) **is the most important mediator of coronary vascular dilation in large arteries and pre-arteriolar vessels. It is synthesized from arginine and oxygen by endothelial cells and causes vascular smooth muscle relaxation by a guanylate cyclase-mediated cGMP second messenger system. **Adenosine**, a product of ATP metabolism, acts as a vasodilatory elemetn in small coronary arterioles. 1516

Answer 154

**One or more delusions for at least a month** in the **abscence of other psychotic symptoms**. Apart from behavior relating to the delusions, the patient's actions are not obviously bizarre or odd and general functioning is not significantly impaired. Subtypes (erotomanic, grandiose, jealous, persecutory, somatic). 2046

Answer 155

Causes HUS and is a common cause of bloody diarrhea. Associated wtih consumption of undercooked ground beef and elaborates a shiga-like toxin (phage encoded) capable of **inhibiting protein synthesis (inactivate 60S RSU)** in colonic mucosal cells and renal endothelial cells (EHEC does NOT invade the intestinal mucosa) This strain is unable to ferment sorbitol and does not produce a glucuronidase. 1100.

Answer 156

**Transketolase** and **Transaldolase** (involved in non-oxidative steps). 1035 ## Footnote NADPH (reduced form of NADP) is produced mainly when glucose is metabolized via the HMP. NADP, in contrast to NAD, is primarily used as a reducing equivalent in the cytosol rather than as a source of energy for ATP synthesis in ETC. The HMP shunt is also responsible for production of ribose 5-P needed for nucleotide synthesis. Conists of two types of reactions: oxidative (irreversible) and nonoxidative (reversible), both of which occur in the cytoplasm.

Answer 157

Segmental demyelination of peripheral nerves and an **endoneural inflammatory infiltrate** on LM. Ascending flaccid paralysis and areflexia; affects young adults and starts a few weeks after a febrile illness; associated with camylobacter jejuni infection. 1058

Answer 158

**Attrition bias** (if the lost subjects differ in thier risk of developing the outcome compared to the remaining subjects), which is a form of **selection bias** (i.e. systematic differences between groups in terms of treatment response or prognosis). 1188

Answer 159

**Anabolic steroids** (e.g. **methytestosterone**) are androgens. After conversion to dihydrotestosterone, androgens promote both follicular epidermal hyperproliferation and excessive sebum production --\> acne development. 7585 _Other drugs_: epidermal growth factor receptor inhibitors and lithium

Answer 160

Lactose in the diet is catabolized into glucose and galactose by an intestinal brush-border disaccharidase called lactase (a type of beta-galactosidase). Secondary lactase deficiency occurs in association with celiac sprue and viral gastroenteritis (i.e. diseases that damage the epithelial cells in the microvilli of the small intestine that contain lactase). Cause abdominal distention, flatulence, and diarrhea after lactose ingestion. 1072

Answer 161

Antimuscarinic agents (**ipratropium**). 170 NOTE: Methylxanthines like theophylline and aminophylline cause bronchial dilation by decreasing phosphodiesterase enzyme activity, thereby increasing intracellular cAMP.

Answer 162

Transformed to NO at the vascular smooth muscle cell membrane which leads to increased cGMP, decreased intracellular calcium, decreased activity of MLCK, and **myosin dephopshorylation** and smooth muscle relaxation. 136

Answer 163

Rotator cuff is made up of the tendons of the **supraspinatus**, **infraspinatus**, **subscapularis**, and **teres minor. ** Most commonly injured tendon is the **supraspinatus** (primarily an abductor of arm) because this tendon is prone to repeated impingement trauma between teh humeral head and the acromion. Thus, most commonly associated with **pain during abduction of the humerus**. 1733

Answer 164

Metabolized to FFAs and glycerol by hormone sensitive lipase. Glycerol is then transported to the liver where it is phosphorylated to glycerol-3-phopshate by the **liver-specific enzyme glycerol kinase**. Subsequently, glycerol-3-phosphate is converted to DHAP by glycerol-3-phosphate dehydrogenase. DHAP can be used to produce ATP through glycolysis or glucose through gluconeogenesis. Glycerol in the liver can also be utilized for triglyceride synthesis. 1889

Answer 165

Due to calcium-mediated myophosphorylase activation. Increasd calcium in the cytosol allosterically activates phosphorylase kinase, which then phosphorylates (Activates) muscle phosphorylase. 1028

Answer 166

Increased neutrophil count and decreased lymphocyte, monocyte, basophil, and eosinophil counts. The increase in neutrophil count results from "demargination" of neutrophils previously attached to the vessel wall. 549

Answer 167

Due to gravity, _supine_ patients typically aspirate into the **posterior segments of the upper lobes** and **superior segments of the lower lobes**. Patients who are _upright_ tend to aspirate into the **basilar segments of the lower lobes**. Aspirated material is more likely to travel down the **right main bronchus** (mnemonic: "swallow a bite, goes down the right"). 1745

Answer 168

_Big particles (10-15um)_: trapped in URT _Medium (2.5-10um)_: enter trachea and bronchi and are cleared by **mucociliary transport** _Small (less than 2um)_: reach terminal bronchioli and alveoli and are phagocytized by **macrophages** --\> activated alveolar macrophages release cytokines; also PDGF and IGF stimulate fibroblasts to proliferate and produce collagen --\> inflammation + fibrosis --\> **pneumoconiosis** (interstital lung fibrosis secondary to inhalation of inorganic dust). 536

Answer 169

Actin filaments are anchored into the Z-line of the sarcomere. The Z-line lies in the center of the lucent region referred to as the I-band. _Mnemonic_: **A**n **I**nteresting **Z**oo **M**ust **H**ave **M**ammals (**A**ctin in the **I**-band attaches at the **Z**-line, **M**yosin in the **H**-band attaches at the **M**-line). 1734

Answer 170

1. _Margination_: neutrophils contact endothelial lining 2. _Rolling_: neutrophils roll on endothelium via loose binding of sialylated carbohydrate groups to **L-selectin **on neutrophils or **E-selectin/P-selectin** on endothelial cells (*cytokines* induce endothelial expression of selectins) 3. _Activation_: slow rolloing allows leukocytes to sample *chemokines* secreted by inflammed tissue; this activates integrins resulting in a conformational change 4. _Tight adhesion and crawling_: neutrophils become firmly attached to endothelium via binding of **CD18 beta 2 integrins** (**Mac-1** and **LFA-1**) to **ICAM-1** on endothelial cells. 5. _Transmigration_: neutrophils migrate out of vasculature by squeezing b/w cells via integrin attachments and adherence to **PECAM-1**

Answer 171

AR disorders; leukocytes cannot leave the vasculature to migrate into tissues under conditions of inflammation. 8480 _LAD type 1_: abscence of **CD18**. Recurrent skin infections **without pus formation, delayed detachment of umbilical cord,** and poor wound healing.

Answer 172

**Perchlorate** and **pertechnetate ions** (as well as iodide isotopes) are absorbed in the thyroid gland via the sodium-iodide symporter. High levels of any one substance will signficiantly reduce the uptake of the others d/t competitive inhibition. 766

Answer 173

Relationship with **current** patients are unethical. Relationships between **non-psychiatric** physicians and former patietns may be ethically acceptable provided the physician-patient relationship is terminated prior to initiating a relationship with a patient. 10464

Answer 174

Co-infection of a host cell by two viral strains, resulting in progeny virions that contain nucleocapsid proteins from one strain and the genome of the other strain. Since there is no change in the underlying viral genomes (no genetic exchange), the next generation of virions revert to thier original, unmixed phenotypes. 1462

Answer 175

**Radial nerve injury** (C5-T1) can occur d/t **improperly fitting crutches** (d/t its superficial location within the axilla). Can also be injured (along with the **deep brachial artery**) by **midshaft humerus fractures. ** Results in weakness of all forearm, wrist and finger extensors ("**wristdrop**"). 1685

Answer 176

Metabolized via **hepatic acetylation**. Individuals who are "slow acetylators" are at greatest risk of drug-induced lupus, while those who metablize the drug more rapidly are less likely to experience this AE. 1505

Answer 177

Glucose is normally freely filtered at the glomerulus and completely reabsorbed by the proximal tubule. Inhibition of sodium-coupled, carrier-mediated transport of glucose by the proximal tubule would cause the glucose clearence to approach the value of GFR (i.e. **inulin** which is also freely filterd at the glomerulus and is neither reabsorbed nor secreted by the renal tubules). 1559

Answer 178

Occurs just after S2 (best heard at cardiac apex in left lateral decubitus position) and is commonly associated with increased **LVESV**, which occurs in the setting of **LV systolic failure**. 2108 with audio

Answer 179

Characterized by high arterial blood pH, HCO3-, and pCO2. Determining **volume status and measuring urinary Cl- concentration** can help identify the cuase. 956 * Vomitting/nasogastic suctioning and thiazide/loop diuretic use cause volume and Cl- depletion (saline-responsive) * Excess mineralocorticoid activity (e.g. primary hyperaldosteronism, cushing disease, ectopic ACTH production) as well as Barrter/Gitelman cause high urine chloride (saline-unresponsive)

Answer 180

**Sudden, painless, and permanent monocular blindness**; fundoscopic exam shows **pale retina and chery-red macula** (macula has seperate blood supply from choroid artery, while rest of retina is supplied by central retinal artery). CRA is a branch of the opthalamic artery, which arises from the internal carotid artery. **Embolism** is the MCC of CRAO. Predisposing conditions include AFib and carotid artery stenosis. 360

Answer 181

Urea's nitrogen is derived from NH3 and **aspartate** in the urea cycle. CPS1 is the rate-limiting enzyme in the urea cycle and is activated by NAG (produced from glutamate and acetyl CoA in a reaction activated by arginine) --\> produces carbamoyl phosphate within the mitochondria, which combines with ornithine to produce citrulline.

Answer 182

Histidine, arginine, lysine, aspartic acid, glutamic acid, cysteine and tyrosine. 2121

Answer 183

The duration and extent of colitis are the most significant risk factors. Unlike sporadic colorectal carcinomas, colitis-associated carcinomas are more likely to arise from non-polypoid dysplastic lesions, be multifocal in nature, develop **early p53 mutations** and **late APC gene mutations **(*opposite that of sporadic disease*), and be of a higher grade. 411

Answer 184

* Glucose enters beta cells by faciltated diffusion using **GLUT-2** --\> oxidative metabolism through glycolysis --\> CAC, which generates ATP * **High ATP/ADP ratio** causes closure of **K+ ATP channels**, which are responsible for outward movement of K+ (closure occurs when ATP binds to regulatory subunit of KATP channel) --\> **depolarization** * Opening of **voltage-dependent calcium channels** --\> **insulin release** Defects of the KATP channel gene can result in T2DM. Sulfonylureas work by binding to regulatory subunits of KATP channels, causing them to close. 1009

Answer 185

**IL-1, IL-6 and TNF-alpha** mediate systemic inflammatory response and stimulate hepatic secretion of acute-phase proteins (e.g. fibrinogen). High levels of circulatign fibrinogen increase ESR, which is a nonspecific marker of inflammation. 1801

Answer 186

_Type I_: red muscle fibers that generate low-level sustained force (e.g. **postural maintenance**). Fxn via **aerobic metabolism**, meaning they have high myoglobin (oxygen storage) and mitochondrial (aerobic respiration) concentrations. Include postural skeletal muscles such as the **soleus and paraspinal muscles**. _Type II_: generate ra**pid forceful pulses of movement**. Derive ATP energy through **anaerobic** glycogenolysis and subsequent glycolysis. 1858

Answer 187

_Short (\<10h)_: alprazolam, triazolam, oxazepam _Medium (10-20h)_: estrazolam, lorazepam, temazepam _Long (days)_: chlordiazepoxide, chlorazepate, diazepam, flurazepam \* Long acting benzos cause more severe drowsiness than short-acting ones. However, long-acting benzos are far less likely to cause depedence. 348

Answer 188

**Clindamycin: **MOA simmiar to macrolides in binding to 50S RSU and disrupting protein synthesis. Alcoholics are more likely than the general population to develop pulmonary infections and abscesses (look for presence of *air-fluid levels*) involving a combination of anaerobic and aerobic bacteria. 1446

Answer 189

**Gluconeogenesis:**** **pyruvate is first converted to**oxaloacetate**through biotin-dependent carboxylation by the enzyme *pyruvate carboxylase* in the mitochondria. Oxaloacetate is then converted to**phosphoenolypyruvate** by *phosphoenolpyruvate carboxykinase (PEPK)*. The other two enzymes differening enzymes in gluconeogensis are *fructose 1,6-bisphosphatase* (bypassing phosphofructokinase) and *glucose-6-phosphtase* (bypass hexokinase). 997

Answer 190

**Epithelial surfaces** --\> invade the epithelium and gain access to vasculature where they can spread hematogenously. Antibodies that successfuly impair the pili would inhibit pilus-mediated attachment of the meningococcus to the mucosal epithelium of the nasopharynx, preventing colonization and subsequent invasion. 1005

Answer 191

Counting down from 100 by intervals of 3 or 7, reciting the months of the year in reverse order, and spelling "world" backwards. 8295

Answer 192

**Strep pyogenes** (Gram+ cocci that is coagulase negative, catalase negative, and pyrrolidonyl arylamidase [PYR] positive), **S****taph aureus, Clostridium perfringens** Sudden onset of severe pain (**out of proportion** to exam findings) and swelling at a site of trauma or recent surgery. Systemic symptoms (e.g. **fever, hypotension** --\> septic shock). 8857

Answer 193

Develop from lactotroph cells in the anterior pituitary, which is derived from **surface ectoderm**. 8702

Answer 194

All cause **dysphagia and/or odynophagia**. 283 * _Candida_: _Endoscopic_ shows patches of adherent, grey/white pseudomembranes on erythematous mucosa. _Microscopic_ shows yeast cells and pseudohyphae that invade mucosal cells. * _HSV-1_: _Endoscopic_ shows small vesicles that evolve into typical **"punched out" ulcers**. _Microscopic_ shows eosinophilic intranuclear inclusions (**Cowdry type A**) in multinuclear squmous cells at hte margins of ulcers. * _CMV_: _Endoscopic_ shows **linear ulceration**. _Microscopic_ shows both **intranuclear and cytoplasmic inclusions**

Answer 195

Autoimmune disease triggered by an unknown antigen. Cartilage components serve as autoantigens that activate CD4+ T cells, which in turn stimulate B-cells to secrete **rheumatoid factor**, an **IgM antibody specific for the Fc component of self IgG**. Rheumatoid factor binds IgG and forms immune complexes that circulate in the serum. Deposition of IC on the synovium and cartilage activates complement in those locations and contributes to chronic inflammation. 754

Answer 196

Caused by mutations affecting the collagen genes or enzymes involved in collagen synthesis, such as **lysyl-hydroxylase** or **procollagen peptidase**. In the case of procollgen peptidase deficiency, impaired cleavage of procollagen N- and C-termini causes the formation of more soluble collagen that does not properly corsslink with other collagen molecules --\> joint laxity, loose skin, easy brusiability. 1246

Answer 197

**Increased ventricular preload** (i.e. a larger than normal volume is being placed into the ventricle during diastole). This can occur during any state of fluid overload: renal failure, CHF, or after **infusion of IV fluids**. 1511

Answer 198

By using the alveolar-arterial oxygen gradient (A-a gradient); normally the A-a gradient doesn't exceed 10-15mmHg. P_aO₂ is the partial pressure of oxygen in arterial blood; it is determined with an arterial blood gas analysis (usually \>92 mmHg). P_AO₂ is the partial pressure of oxygen in alveolar air and is calculated using the aveolar gas equation (usually 100 mmHg). **P_AO₂ = 150 - (P_aCO₂ / 0.8)** 1526

Answer 199

Calcium efflux prior to myocyte relaxation is accomplished through the use of **Ca²⁺-ATPase and Na⁺/Ca²⁺ exchange mechanisms**. The Ca²⁺-ATPase uses active transport to sequester calcium within the SR and re-establish the ion gradient. The sarcolemmal Na⁺/Ca²⁺ transmembrane protein does not require ATP and accepts 3 extracellular Na⁺ in exchange for 1 intracellular Ca²⁺ ion. 1931

Answer 200

**Psoas muscle**: originates from teh anterior surface of the transverse processes and lateral surface of correspondign vertebral bodies T12-L5. Acts primarily to flex the thigh at the hip. Contributes somewhat to lateral rotation and abduction of thigh as well. 1885

Answer 201

Chronic thiamine (B1) deficeincy leads to diminished ability of cerebral cells to utilize glucose. The mechanism is decrease function of the enzymes that use vitmain B1 as a cofactor (**pyruvate dehydrogenase, alpha-ketoglutarate dehydrogenase,** and **transketolase**). An increase in erythrocyte transketolase levels after thiamine infusion is diagnostic for thiamine deficeincy. 598

Answer 202

Acts via **tyrosine kinase second messenger system** to stimulate synthesis of glycogen, proteins, FAs, and nucleic acids. Tyrosine kinase leads to activation of **protein phosphatase** within cells, which dephopshorylates glycogen synthase thereby activing that protein and promoting glycogen synthesis. Protein phosphotase also dephosphorylates fructose 1,6-bisphosphate thereby inacting that enzyme and inhibting gluconeogenesis. 1121

Answer 203

Refractory hypotension and cardiac arrhythmias. **Inhibition of fast Na+ channels in cardiac myocytes** (and His-Purkinje system) is thought to be the major underlying cellular event. Fluid resuscitation with normal saline and hypertonic sodium bicarbonate administration is crucial. 574

Answer 204

AR d/t **lipoprotein lipase deficeincy**; without sufficient LPL activity, the body is unable to clear dietary lipid loads d/t defective hydrolysis of serum TGs (especially **chylomicrons**). Presents in childhood with recurrent episodes of acute pancreatitis. 782

Answer 205

**Fibrates**, which work by activating peroxisome proliferator-activated receptor alpha (PPAR-a) which increases LPL activity. Since these meds decrease triglycerides, they will decrease the risk of acute pancreatitis! 166

Answer 206

Include methimazole and propylthiouracil; act as antithyroid meds by decreasing the formation of thyroid hormones via inhibiton of the enzyme **thyroid peroxidase** (responsible for organification and coupling). PTU also decreases peripheral conversion of T4 to T3. 626

Answer 207

**Clomiphene**: estrogen receptor modulator that decreases negative feedback inhibition on the hypothalamus by circulating estrogen and thereby increases gonadotropin production and ovulation. 2094 ## Footnote _Sx_: persistently elevated estrogen, androgen, and LH levels resulting in hyperandrogenism, chronic anovulation, oligomenorrhea, and multiple ovarian cysts. Theca cell hyperplasia can result in excess androgen production. Obesity, insulin resistance, and dyslipidemia --\> increased risk of diabetes and CVD.

Answer 208

Inadequate blood supply to brain leads to ischemic stroke; MCC is arterial thrombosis or embolism. First microscopic changes occur 12-24h after cessation of blood supply and are described as **"red neurons"** (eosinophilic cytoplasm, pyknotic nuclei, loss of Nissl substance). 19

Answer 209

**Lidocaine** is a class IB antiarrhythmic agent which specifically binds rapidly depolarizing and depolarized cells. Ischemic myocardium is depolarized tissue; this is why lidocaine is specific for ischemic tissue and is the agent of choice for prevention and treatment of post-MI arrythmias. Amiodarone has replaced lidocaine in mangement of Vtach. 900

Week of March 23 Flashcards

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