6/21 UWorld

Question 1

What is the name and cause of damage to the superior trunk of the brachial plexus

Answer 1

• Erb-Duchenne Palsy (“waiter’s tip”)
  
  • Injury to superior trunk (C5-C6)
  • Causes:
    
    • Lateral neck traction during delivery of babies
    • Trauma in adults

Question 2

Muscle/functions innervated by superior gluteal m/

Answer 2

• Innervates:
  
  • Hip abduction and medial rotation of thigh = tensor fasciae lata, gluteus minimus, gluteus medius
• Lesion:
  
  • Posterior hip dislocation, polio
  • Leads to Trendelenburg sign:
    
    • Contralateral hip drops when you are standing on leg ipsilateral to lesion

Question 3

Muscle/function innervated by inferior gluteal

Answer 3

• Innervates:
  
  • Hip extension and lateral rotation of thigh à gluteus maximus
• Lesion:
  
  • Posterior hip dislocation
  • Hard time getting up from sitting position

Question 4

Damage to what nerve caused Trendelenberg gait

Answer 4

Superior gluteal (respsonsible for gluteus medius and minimus, which do hip abduction)

Question 5

What nerve gets damaged with knee injury

Answer 5

Tibial (is located posterior to knee)

Question 6

What nerve gets damaged with fibula neck fracture

Answer 6

Deep or superficial peroneal

Question 7

What nerves are involved in each of the following reflexes?

• Achilles
• Patellar
• Biceps/brachioradialis
• Triceps
• Cremasteric
• Anal wink

Answer 7

Clinical reflexes:

• Achilles reflex = S1, S2 (“buckle my shoe”)
• Patellar reflex = L3, L4 (“kick the door”)
• Biceps and brachioradialis reflexes = C5, C6 (“pick up sticks”)
• Triceps reflex = C7, C8 (“lay them straight”)
• Cremasteric reflex = L1, L2 (“testicles move”)
• Anal wink reflex = S3, S4 (“winks galore”)

Question 8

Innervation of teres minor

Answer 8

Axillary nerve

Question 9

Defect and presentation of Atazia telangectasia

Answer 9

• Immunodeficiency = decreased T-cells and IgA
• Defect in ATM gene = failure to repair DNA double strand breaks = cell cycle arrest
  
  • THINK: the “T” in aTaxia and Telangiectasia is a dsDNA
• Triad:
• · Cerebellar defects – ataxia
• · Spider angiomas – telangiectasia
• · IgA deficiency

Question 10

Structures formed by meso- and metanephros

Answer 10

• Mesonephros
  
  • Forms temporary kidney during 1^st trimester
  • Later contributes to male genital system – Wolffian ducts
  • Caudal end becomes the ureteric bud which gives risk to ureter, pelvises, calyces, collecting ducts
• Metanephros
  
  • Interaction with the ureteric bud (caudal portion of mesonephros) induces differentiation and formation of glomerulus, Bowman’s space, proximal tubule, loop of Henles, and distal convoluted tubule

Question 11

What type of drug is Chlordiazopoxide

Answer 11

Benzo

Question 12

Histology of granulosa-theca cell tumor

Answer 12

Call-Exner bodies

Granulosa cells arranged haphazardly around collections of eosinophilic fluid, resembling primordial follicles

Question 13

Histology of Sertoli-Leydig cell tumor

Answer 13

Reinke crystals

Question 14

What does HELLP syndrome stand for and what is the reasoning behind the symptoms

Answer 14

• Stands for:
  
  • H - Hemolysis (anemia)
  • EL - Elevated Liver enzymes (RUQ pain, jaundice)
  • LP - Low Platelets (bruising bleeding)
• Preeclampsia + thrombotic microangiopathy
  
  • Hemolysis = thrombi causing schistocytes
  • Liver enzymes = lack of RBCs leads to infarction of liver tissue
  • Platelets = all used up in thrombi

Question 15

What is Meigs syndrome

Answer 15

Triad of: ovarian fibroma, ascites, pleural effusion

Question 16

Mutation and presentation of Williams syndrome

Answer 16

Microdeletion of long arm of chromosome 7 (deletion includes elastin gene)

“Elfin” facies, intellectual disability, hypercalcemia, well-developed verbal skills, extreme friendliess with strangers

THINK: Will Ferrel in the movie elf

Question 17

Describe presentation of Tuberous sclerosis

Answer 17

• Due to mutated hamartin (or tuberin) gene
  
  • TSC1/TSC2 mutation on chromosome 16
• Triad:
  
  • Angiofibromas, mental retardation, seizures
    
    • Vs. VHL which is angiomatosis
• Other symptoms: Ash-leaf spots, hamartomas of CNS and skin, angiomyolipoma
• Incomplete penetrance and variable presentation

Question 18

What is the equation for incidence

Answer 18

• Incidence = number of new cases during a specific time period
  
  • (# of new cases) / (# of people at risk)

Question 19

Equation for number needed to treat

Answer 19

1/ARR

NOT 1 - ARR!!

Question 20

Differentiate between case-control study and cohort study

Answer 20

Case control = compare a group with disease to group without disease and look for prior exposures/risk factors (is retrospective)

Cohort study = compare a group with risk factor to a group without risk factor and look for likelihood of disease (can be prosepective or retrospective)

Question 21

Describe difference between T-test, ANOVA, and chi-square

Answer 21

• T-test:
  
  • Tests for differences between means of 2 groups with continuous variables
  • THINK: Tea is meant for 2
• ANOVA:
  
  • Tests for differences between means of 3 or more groups with continuous variables
  • THINK: 3 words in “Analysis Of Variance”
• Chi-square:
  
  • Checks differences between 2 or more percentages or proportions of categorical outcomes (not mean values)
  • THINK: Chi-tegorical

Question 22

Medicare vs. Medicaid

Answer 22

Medicare = elderly + those with certain conditions and end-stage disease

Medicaid = low income

Question 23

What is a Cushing ulcer

Answer 23

Gastric ulcer due to brain injury

Brain injury = increased vagal stimulation = increased ACh = increased H+ production

Question 24

What is Menetrier disease

Answer 24

• Menetrier disease:
  
  • Gastric hyperplasia of mucosa cells of the stomach
    
    • Leads to hypertrophied rugae which look like brain gyri
  • Atrophy of parietal cells à decreased gastric acid production
  • Increased risk of gastric carcinoma

Question 25

Where is VIP produced and what is its function

Answer 25

* Produced by smooth muscle cells in gut and parasympathetic ganglia * Relaxes smooth muscle and sphincters throughout the GI tract * Causes copious diarrhea

Question 26

Presentation of tropical sprue

Answer 26

* Unknown cause – probably infectious * Looks like celiac but: * Affects the entire small bowel * Vs. Celiac which mainly affects distal duodenum and proximal jejunum * Responds to antibiotics

Question 27

Presentation of Whipple disease

Answer 27

* Infection with Tropheryma whipplei * Symptoms: * Weight loss, lymphadenopathy, hyperpigmentation, cardiac symptoms, arthralgias, neurologic symptoms * Histology: * PAS (+) foamy macrophages in intestinal lamina propria

Question 28

What is boerhaave syndrome

Answer 28

Transmural, usually distal esophageal rupture Due to violent retching Surgical emergency

Question 29

What is the enzyme that converts glucose to sorbitol? Sorbitol to fructose?

Answer 29

Glucose --\> (aldose reductase) --\> Sorbitol Sorbitol --\> (sorbitol dehydrogenase) --\> Fructose

Question 30

What bug stains with aniline dye

Answer 30

Diptheria Metachromatic granules will stain red and the rest of the cell will stain blue

Question 31

What are the possible karyotypes of a partial mole

Answer 31

69, XXX (1 X from egg and 2 X from sperm) 69, XXY (1 X from egg, 1 X from sperm, 1 Y from sperm) 69, XYY (1 X from egg, 2 Y from sperm)

Question 32

What are the possible karyotypes of a complete mole?

Answer 32

* Empty ovum fertilized by sperm – 46 chromosomes(90% of cases) * Can be fertilized by one sperm which then duplicates * 46, XX * 46, YY zygote would not survive * Can be fertilized by two sperm * 46, XX or 46, XY

Question 33

What is the drug Baclofen used fo

Answer 33

GABA-B receptor agonist Treats spasticity secondary to both brain and spinal cord disease, including multiple sclerosis

Question 34

What is the pathogenesis of thrombotic thrombocytopenic purpura (TTP)

Answer 34

Platelets used up in pathologic formation of microthrombi in small vessels Due to decreased ADAMTS13, enzyme that normally cleaves vWF for degradation No vWF degradation = abnormal platelet adhesion = microthrombi

Question 35

What is the pathogenesis behind immune thrombocytopenia (ITP)

Answer 35

IgG autoantibodies to GP2b3a Antibodies produced by plasma cells of spleen and antibody-bound platelets consumed by macrophages of spleen

Question 36

What is the defect in Bernard-Soulier syndrome

Answer 36

Defect of glycoprotein 1b Platelet can’t bind to vWF on collagen = defect of platelet plug formation Platelet count is only slightly low – moderate thrombocytopenia Large platelets

Question 37

What is the defect in Glanzmann thrombasthenia

Answer 37

Genetic GP2b3a deficiency Defect in platelet aggregation Platelet count is normal (they aren’t being destroyed, just can’t aggregate)

Question 38

Describe drainage in pancreas divisum

Answer 38

* Ventral and dorsal parts fail to fuse * Dominant dorsal duct opens into the duodenum via the major papilla and is responsible for draining the majority of the pancreas * Smaller ventral duct opens into the major papilla and drains the inferior/posterior head and uncinated process

Question 39

Describe the role that troponin and tropomyosin play in muscle contraction

Answer 39

Tropomysin sits in the myosin-binding sites of actin Troponin molecules are situated alongside tropomyosin When Ca2+ binds to troponin C, the Troponin-Ca2+ complex pulls tropomyosin away, exposing the myosin-binding site

Question 40

What bases (A, G, T, U) are present at the 5' and 3' splice site of the intron

Answer 40

5' splice site = GU 3' splice site = AG

Question 41

What disorder is asociated with decreased levels of hypocretin

Answer 41

Narcolepsy * Diagnostic criteria * Recurrent lapses into sleep or naps * Minimum 3x per week for 3 months * At least 1 of the following: * Cataplexy: Brief loss of muscle tone precipitated by strong emotion (e.g. laughter excitement) * Low CSF levels of hypocretin * Shortened REM sleep latency

Question 42

What is the defect and presentation of multiple myeloma

Answer 42

* Malignant proliferation of monoclonal plasma cell within the marrow * Recall: Plasma cells = mature B-cells that produce immunoglobulin * Classic presentation: * Anemia – plasma cells packed in bone marrow inhibit production of other cells * Renal insufficiency – excessive antibodies plug up kidney and form casts * Back pain – plasma cells stimulate osteoclasts * Hypercalcemia – plasma cells stimulate osteoclasts

Question 44

What disease is associated with Bcl-2 mutation?

Answer 44

Follicular lymphoma t(14;18) THNK: 18 y/o is when you can buy a gun and start killing people (apoptosis) Apoptosis occurs in the follicle

Question 45

What is the MOA of Rifaximin in hepatic encephalopathy

Answer 45

Is a poorly absorbed antibiotic that will remain in the GI lumen and can eradicate ammonia producing intestinal bacteria Used to treat hepatic encephalopathy

Question 46

An interscalane nerve block, targeting the brachial plexus and used to anesthetize the shoulder and upper arm, may also cause paralysis to what structure?

Answer 46

Diaphragm Causes transient ipsilateral diaphragmatic paralysis in nearly all patients by anesthetizing the roots of the phrenic nerve as they pass through the interscalene sheath This nerve block should be avoided in patients with chronic lung disease or contralateral phrenic nerve dysfunction

Question 47

Is Zollinger-Ellison syndrome more likely to cause gastric ulcers or duodenal ulcers

Answer 47

Duodenal - ZE is a tumor of pancreas or duodenum