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Flashcards in UWorld_2.28 Deck (10)
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1

Calculation of GFR & RPF

  • creatinine or inulin clearance
    • C = (( [urine] x urine flow rate)) / [plasma]
  • starling equation
    • GFR = Kf ((PG - PB) - (πG - πB))
      • Kf = filtration coefficient
      • PG = hydrostatic pressure @ GC
      • PB = hydrostatic pressure @ bowmans
      • πG = oncontic pressure @ GC
      • πB = oncotic pressure @ bowman's
  •  RPF = PAH clearance

2

Common cause of gas gangrene + mechanism of infection

  • clostridium perfingens
    • gram (+) bacillus
  • C. perfingens = abundant @ soil, spores enter penetrating injuries
    • germinate in anaerobic environment ==> toxin-producers
  • toxin = phospholipase that attacks cell membranes ==> cell death
    • metabolizes carbs ==> gas 
  • ==> extensive tissue damange, necrosis, reduction of blood supply to affected area

3

C. perfringens presentations

  • late-onset food poisoning ==> transient watery diarrhea
  • gas gangrene

4

Characteristics of caudal regression syndrome

  • rare
  • associated w/poorly controlled maternal DM
  • pt. born w/agenesis of sacrum and lumbar spine
  • flaccid paralysis of legs, dorsiflexed contractures of the feet
  • urinary incontinence

5

Wristdrop ==> dx?

  • radial n. injury

6

Characteristics of radial n. injury

  • common causes
    • improperly-fitted crutches
    • midshaft humerus fracture
  • radial n. = C5 - T1 spinal n.
    • branch of posterior cord of brachial plexus
    • can be injured due to superficial location @ axilla
  • ==> weakness of forearm, wrist and finger extensors

7

Attachment sites for complement and phagocytic cells to immunoglobulin

  • C1 ==< hinge region of constant segment
  • phagocytes ==< Fc receptor/initial segment

8

Causes of Down's sydnrome

  1. Meiotic nondisjxn ==> trisomy
  2. Robertsonian translocation = extra arm of chromosome 21 translocated to another chromosome
  3. Mosaicism

9

Sections of adrenal gland + products

  • angiotensin II ==> zona glomerulosa ==> mineralocorticoids (aldosterone)
  • ACTH ==> zona fasciculata ==> glucocorticoids (cortisol)
  • zona reticularis ==> androgens
  • preganglionic sympathetic neurons ==> ACh ==> medulla ==> epinephrine + norepinephrine

10

Most common gallstone + risks

  • caucasian
  • female sex hormones/OCPs ==> increased synthesis of cholesterol via increased activity of hepatic HMG-CoA reductase 
  • hypomotility of gallbladder
    • preg., adv. age, fasting
  • drugs: fibrates, octreotide, ceftriaxone
    • fibrates ==> reduced 7a-hydroxylase activity ==> less conversion of cholesterol to bile acids
  • obesity or rapid weight loss

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