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Usmle > Block 11 > Flashcards

Block 11 Flashcards

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USMLE® Step 1 flashcards
1
Q

Rule of 2 meckels diverticulum

A
  • 2% of population
  • 2% symptomatic
  • 2 feet from illicecal valve
  • 2 inches in length
  • 2 time more common in males
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2
Q

Carbon tetrachloride can lead to

A

Free radical injury, its oxidized by pc450 in the liver –> reuslt is formation of radical CCL3 which leads to –> lipid degeneration and H2O2 formation (lipid peroxidation). –> swelling of ER , destruction of mitochondria. And increased permaibilty of cell membrane leading to hepatocytes necrosis. And fatty changes.

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3
Q

Coagulase negative staphylococci:(CoNS)

  • feature
  • consequences
  • treatment
A
  • they are major cause of infection in patients with indwelling catheters or implanted foreign bodies and a common cause of prosthetic valve endocarditis.
  • S.epidermidis can cause indolent endocarditis following valve replacement –> intracardiac abscess, prosthetic valve dehiscence and septic emobilization.
  • most of CoNS are methicillin resistant (80%) thats why CoNS infection should be regarded as methicillin resistant until proven otherwise.
  • treatment is with vancomycin, others like gentamicin or rifampin may be used
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4
Q

Laryngeal edema: part of anaphylactic shock

A
  • life threatening
  • initially can present as throat tightness, difficulty swelling, and dyspnea and hoarseness.
  • the condition may quickly progress to compromise airways and cause anaphylaxis
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5
Q

Statin induced myopathy

A

Myopathy is the most common complication of statin use, and symptoms range from myalgia or myopathy, with or without myonecrosis (elevated serum creatine kinase), to frank rhambdomylesis.

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6
Q

RAO(retinal artery occlusion)

A
  • acute, painless, monocular vision loss
  • thromboembolic complication of ATH in the internal carotid are the most common cause.
  • the retinal artery is one of the first branches of ophthalmic artery, which receives its supply from internal carotid.
  • fundoscopic examination shows cherry red spot, with surrounding retinal whitening.
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7
Q

Hot flushes and warmth after niacin is an increase in

A

Prostaglandinds

Use aspirin to prevent

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8
Q

IL-3

A

Stimulate the growth and differentiation of bone marrow stem cells and produced by T helper cell

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9
Q

Pes anserinus

A

group of tendons

  1. Semitendinosus
  2. Gracilis
  3. Sartorious

pes anserinus brusitis can form.

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10
Q

Respiratory epithelium in terms of layers

A

Bronchi :cilliated cells, mucus, goblet cells, submucosal glands and cartialges
Proximal tubule: same but no cartilage
Terminal bornchioles: contain only serous fluid and club cells, along with cillia
Respiratory bronchioles: serous fluid, club cells , and alveolar macrophages
Alveoli: type I alverolar cells , type II alveolar cell , and alveolar macrophages.

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11
Q

EP vs NE and dopamine

A
  1. EP is made predominantly in the adrenal medulla while NE and dopamine are produced in CNS as well as in the peripheral nervous system.
  2. Expression of PNMT in the adrenal medulla is upregulated by cortisol.
  3. Cortisol concentration in the adrenal medulla are high –> PNMT expressed at very high levels —> EP production ( in case of pituitary resection, ACTH secretion and subsequent cortisol production will be low —> decreased PNMT activity –> low EP)
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12
Q

Rat poision contains ?

A

rodenticides contains brodifacoum –> (superwarfarin)

Treatment FFP

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13
Q

K-1 capsular antigens

A

E.coli strains that cause neonatal meningitis synthesize K-1 capsular antigens.

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14
Q

Niacin Side effects

A
  • Flushing ,warmth, and itching .
  • mediated by release of prostaglandins.
  • aspirin which inhibits PG synthesis can be given with niacin to prevent this. (Administration 30-60 min)
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15
Q

Brown adipose tissues

-features, importance and function

A

Comprises 5% of body mass in neonates. The main function of brown tissues is heat production. Neonates have many physiological traits that make them more susceptible to hypothermia, such as immature CNS, high body surface area to volume ratio and decreased ability to shiver for heat production .

  • heat production by brown adipose tissues are thus necessary for survival.
  • they have high amount of mitochondria that gives it the brown tan color.
  • in the brown tissues, the protons pumped out by the ETC returns to the matric via mitochondrioal membrane protein thremogenin (uncoupling agents), thus no ATP is synthesized rather energy released as heat.
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16
Q

Tendon of biceps femoris insert in fibula on

A

Styloid process of the head of fibula

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17
Q

Catecholamine synthesis

Steps

A
  1. Tyrosine –> DOPA (tyrosine hydroxylase)
  2. DOPA –> Dopamine (dopa decarboxylase)
  3. Dopamine —> NE ( dopamin -ß hydroxylase)
  4. NE –> epinephrine ( phenylethanolamine N- methyltransferase /also called PNMT ) (its stimulated by cortisol )
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18
Q

Giant cell arteritis
Pathogenesis
Clinical
TX

A

-the inflammtory infiltrate in affected vessels is composed of lymphocytes (CD4 positive) and MAC, and frequently contain multinucleated giant cells.
- the production of cytyokines , IL-6 in particular appears to closely correlate with severity of the diseaes.
- clinically: unilateral headache(temproal artery), jaw claudication, visual symptoms( optic disc edema, bilateral), enlarged temporal artery , elevated ESR, polymyalgia rheumatica, irreversible blindness if ophtalmic artery obstruction occurs
TX: IL-6 inhibitors

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19
Q

Osgood schaltter disease
Causes
Pathogenesis
Clinical

A

Overuse injury of the secondary ossification center (apophysis) of the tibial fracture.
Its very common cause of knee pain in young and adolescent athletes after a recent growth spurt.
- it present as pain and swelling in the tibial tubercle, in insertion point of patellar ligament.
- the patellar ligament connects the tibia to the patella, which in turn is connected to quadriceps muscle. Its a group of muscle involved in leg extension
- repetitive quadriceps contraction (eg, jumping ) and chronic avulsion cause the proximal patellar tendon to separate from the tibial tubercle during healing process, callous formation causes the tubercle to become elevated and prominent.

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20
Q

Red man syndrome- side effect of

A

Vancomycin

Its mediated by histamine release due to non IgE mediated mast cell degranulation.

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21
Q

Elevated systolic BP with normal DBP

A

Isolated Systolic hypertension –> responsible for 60-80% of HTA in population and seen at age >60.
- can result from aortic stenosis, aortic regurgitation, anemia ,hyperthyroidism .

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22
Q

Desmopressin in coagulation effect

A

Increase plasma levels of vWF –> increase factor VIII levels

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23
Q

Breast ture

A

Nipple –> sinus –> duct –> lobules

All surrounded by stroma

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24
Q

Kilnfilter syndrome features, clinical

A

Caused by meiotic nondisjunction.

  • 47,XXY karyotype.
  • Disorder usually not diagnosed until puberty
  • features:
    1. Primary testicular failure: hylanization and fibrosis of seminferous tubules. –> small testes with azoospermia –> leydig cells dysfunction (LH and FSH levels increased- hypergonadotropic hypogonadism)
    2. Testosterone deficiency results in eunchoid body habitués. (Tall stature, and gynecomastia)(facial and body hair is sparse or absent and muscle mass decreased)
    3. Mild intellectual disability is seen in some patients. (Psychosocial abnormalities also common)
25
Q

Pilocytic astrocytoma

A

Arise in the cerbellum, brainstem , hypothalamic region or optic pathways.
-they are well differentiated neoplasms comprimised of spindle cells with hair like glial processes that are associated with microcysts.
These cell are mixed with rosenthal fibers and granular eosinophilic bodies.

26
Q

Dobutamine
Indication
Mechanism
Side effect

A
  • indication : managment of refractory HF, with severe LV systolic dysfunction and cardiogenic shock
  • mechanism:
    1. ß stimulation–> increased cAMP –> positive inotropy and chronotropy –> increase CO , and decreased LV filling pressure –> improves pulmonary edema.
    2. Mild vasodilation : decreased SVR -> reduction in BP –> avoid the increase in afterload but on the other hand can be used in severe hypotension .
  • the strong inotropic effect of dobutamin –> increase O2 consumption –> can trigger or exacerbate myocardial ischemia.
27
Q

Tocilizumab

A

IL-6 inhibitor - used for GCA

28
Q

Familial hypocalciuric hypercalcemia

A

Benign autosomal dominant disoeder caused by defective Ca+ sensing by parathyroid and renal tubule cells.

  • this defect prevents PTH from being suppressed in response to increase in serum Ca+ resulting in hypercalcemia with normal to high serum PTH levels.
  • although primary parahypothyrodism and FHH present with hypercalcemia and increased PTH, FHH also have hypocalciuria.
29
Q

Thiazide diuretics - electrolytes abnormalities

A

High dose thiazide leads to

  1. Hypokalemia,
  2. Hyponatremia
  3. Hypercalcemia
  4. Hyperglycemia,
  5. Hyperuricemia
30
Q

Acute congestive heart failure may lead to

A
  • DCM(it may be the cause)
  • exertional dyspnea
  • death
31
Q

IL-1

A

Activates naive TH0 cells and promotes their differentiation into TH1 and TH2

32
Q

Antibiotics that kills bacteria on foreign material (prosthetic valves and tubes)

A
  • rifampin

- gentamicin

33
Q

Hot tub folliculitis

A

Superficial pseudomonal infection of the hair follicle

  • pruritic papulopustular rash
  • pool water that have not been maintained
  • caused by gram negative oxiadse postive lactose negative pseudomonas aurigonosa
34
Q

Semimbrenous muscle,

Insertion site.

A

Its the most medial hamstring muscle, involved in knee flexion and hip extension (like all hamstring)
Attached to medial condyle

35
Q

Radial nerve deficits in the setting of mid shaft humerus fracture

A

Rise the suspicion for injury to deep brachial artery.
- the deep brachial artery branches of brachial artery high in the arm, passes inferior to teres major muscle and courses posteriorly along the humerus in close association with radial nerve.

36
Q

Travel to southwestern USA increase risk for

A

(Southern and central california, arizona, new mexico and western taxes), northern mexico and some regions of central and south america
Increase predisposition to C. Immitis.

37
Q

Phentolamine

A

Reversible nonselective å-blockers.
Can be used to prevent necrosis due to excessive vasoconstriction in response to NE.
-it leads to vasodilation

38
Q

Difference between methotrexate and 5-fluorouracil

A
  • methotrexate prevents the reduction of folic acid to THF, while 5-FU binds THF and thymidylate synthase in a stable reaction intermediate form, thereby effectively decreasing the amount of thymidylate synthetase available for thymidine synthesis.
  • 5FU has reduced cytotoxic effect in cells deficient in THF, because 5-FU requires folate in order to form complexes with thymidylate synthetase.
39
Q

Pigeon droppings –> predisposition of

A

C.neoformans

40
Q

Supracondylar fractures injures

A

Brachial artery

41
Q

5 p of lichen planmus

A
  1. Polyglonal
  2. Planar
  3. Pruritic
  4. Purpulish
  5. Plaques
    Found on wrist, trunk, legs
    Wickham striae may be present on plaque
42
Q

QT prolongation in otherwise healthy young individual

A
  • its probably due to membrane potassium channel proteins mutation. (Phase 2-3 disturbance)
  • 2 syndromes can cause this :
    1. Jervell and lange-nielsen syndrome: (AR, with neurosensory deafness)
    2. Romano-WARD syndrome: (AD, no deafness)
  • both may predispose to torsades de pointes at young age, syncope and sudden cardiac death.
43
Q

HCV features (envelope )

A
  • HCV have 6 or more genotypes and multiple subtypes that differ in genomic composition by as much as 30-35% . This is largely due to the fact the the virion encoded RNA-dependent RNA polymerase has no proofreading 3’–>5’ exonuclease activity. –> errors during replication.
  • the high mutation rates leads to development of distinct species within infected individual overtime.
  • these variants strains differ primarily at hypervariable genomic regions, such as those found in the sequence coding for its envelope glycoproteins.
  • the continuous generation of novel envelope, prevents infected individuals of making an effective immune response against the HCV.
  • when new antibodies produced against a quasispecies commences , the strain dies off and new ones take its place.
  • that is the reason vaccine hasn’t been made yet.
44
Q

Increase in symphatetic tone –>

A

Can result at elderly–> increased both SBP and DBP

45
Q

Patients with asthma have increased risk for developing allergic reaction to (yeast)

A

Aspergillus
Can lead to bronchopulmonary aspergillosis
Signs include cough, dyspnea, wheezing, fever, and migratory pulmonary infiltrates
- also N.B: aspergillus can colonize old lung cavities (formed by TB) to form fungal ball called aspregilloma.

46
Q

Anal fissure

A

Due to stretching of mucosa
Characterized by longitudinal tears in the anal canal distal to dentate line. Spasm of the sphincter can contribute to the pain and creates tension across the wound.
-most fissures > chronic constipation, high anal pressure and passage of hard stools.
-the majority of fissures especially those causing prolonged symptoms occur in the posterior midline of the anal verge.
-due to poor blood supply of posterior anal canal.

47
Q

Lipid A vs protein A

A

Lipid A in gram negative bacteria –> shock

Protein A –> in S.aureus –> inhibit phagocytosis and opsonization .

48
Q

Congeinital bilateral absence of vas deferns

A

CF

49
Q

What is the most toxic component of LPS

Mechanism of shock

A
  • LPS is released following a destruction of Gram - bacteria,
  • LPS long have 3 components: O antigen, polysaccharide and lipid A.
  • Lipid A is responsible for toxic properties of gram negative.
  • it induces shock by activation of MAC and granulocytes,–> synthesis of endogenous pyrogens such as IL-1, PGL, inflammatory mediators –> TNF-å and IFN –> febrile response on the hypothalamus by IL-1 as well as hypotension, increased vascular permability with third spacing of fluid, diarrhea, DIC and death.
50
Q

Meckles diverticulum

walls consists of

A

-it due to partial failure of the vitelline duct to obliterate (normally at week 7) –> formation of meckles diverticulum
Consists of :- mucosa, submucosa, and muscular layers.
- true diverticulum
-findings : blind pouch attached to the ileum, with a fibrous band seen attaching the end of the pouch to umbilicus

51
Q

Myelofibrosis

A

Caused by atypical megakaryocytic hyperplasia, which stimulate fibroblast proliferation resulting in progressive replacement of the marrow space by extensive collagen deposition.

  • in early stages –> marrow hypercellularity with minimal fibrosis –> pancytopenia can result. Hepatomegaly and massive splenomegaly develop because of loss of bone marrow hematopoiesis.
  • teardrop RBC
  • JAK2 kinase mutation –> constitutive tyrosine phosphorylation activity –> STAT pathway.
52
Q

ACL is present location on tibia

A

Intercondylar area (anterior)

53
Q

CF vs kartegner

A

extrapulmonary features:
CF: pancreatic insufecciency, infertillity due to absent vas deferns, failure to thrive.
kartegner: situs invertus (50%), infertility due to immotile spermatozoa, normal growth.

54
Q

Henoch-schonlein purpura

A

Pathogenesis :
-IgA immune complex-mediated vasculitis
-generally follows upper respiratory or other minor infection
Clinical manifestation:
1. Palpable purpura(generally limitid to lower extremity)
2. Arthlagia
3. Abdominal pain
4. Renal disease similar to IgA nephropathy (hematuria)
Diagnosis:
Usually made clinically
Skin biopsy showing IgA deposition in blood vessels.

55
Q

Seborrheic keratosis

A

Benign, tan or brown epidermal tumor.

-leser trelat sign = multiple seborrheic keratosis usually indicates gastric carcinoma or invasive carcinoma.

56
Q

Leaf like projection tumor in breast

A

Phyllodes tumor

57
Q

Gestational choriocarcinoma is

A

Malignant tumor that arises from the trophoblast.

  • its most commonly preceeded by normal pregnancy but can occur following any pregnancy (molar, actopic, aborted)
  • clinically : vaginal bleeding, uterine enlargment, and significantly increased ß-hCG.
  • histologically its composed of abnormal proliferation of mononuclear cytotrophoblasts and multinuclear synctiotrophoblasts. With “no villi”
58
Q

Cricothyrodictomy
Indication
Incision passes through which structures

A

Indications: when an emergency airway is required and orotracheal of nasotracheal intubation are either unsuccessful or contraindicated (due to massive hemorrhage,vomiting, facial trauma or airway obstruction).

  • the procedure establishes an airway through the placement of a tube between the cricoid and thyroid cartilages and requires incision through :
    1. Skin
    2. Superficial cervical fascia
    3. Investing and pre-tracheal layers of the deep cervical fascia
    4. Cricotyhroid membrane
59
Q

Inhibition of ß-receptors by catecholamines effect on K+

A

Impairs potassium entry into the cell and causes minor elevation in plasma potassium.
Stimulation of beta receptors leads to hypokalemia

Usmle (45 decks)

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