From USMLE Practice Test 1

Question 1

what is the term for:

1. disruption in organ morphogenesis that occurs after embryogenic period?
2. an error in organ morphogenesis that arises from the breakdown of an organ or body region that was developmentaly normal
3. intrinsic disruption in organ development

Answer 1

1. deformation
2. disruption
3. malformation

Question 2

How does a change in afterload or inotropy change a Frank-Starling curve?

Answer 2

increased afterload - shift down (for a given preload, there is a reduced cardiac output relative to normal)

decreased afterload - shift up

Question 3

How does AV malformation affect cardiac output?

Answer 3

increases venous return

leading to increased preload and therefore increased CO

Question 4

What is the affect on arterioles of severe, chronic hypertension?

Answer 4

hyperplastic arteriosclerosis (hyperplastic arteriolitis)

concentric thickening of the vessels with a laminar appearance caused by the proliferation of smooth muscles cells

Question 5

What ist he affect of sodium nitroprusside on the PV mechanics of the heart?

Answer 5

preferentially affects arterioles, so decreases afterload without really affectign preload

you have a shorter PV loop

Question 6

Central diabetes insipidus can result from a tumor involved what areas of the hypothalamus?

Answer 6

paraventricular & supraoptic nuclei

Question 7

Identify the functions of the following hypothalamic nuclei:

1. anterior hypothalamic nucleus
2. arcuate hypothalamic nucleus
3. dorsomedial hypothalamic nucleus
4. lateral hypothalamic nucleus
5. posterior hypothalamic nucleus
6. ventromedial hypothalamic nucleus

Answer 7

1. thermoregulation - specifically cooling
2. complex regulatory functions important in appetite stimulation
3. feeding & circadian rhythm
4. stimulating appetite under stimulation of ghrelin
5. thermoregulatino - specifically heating
6. stimulating satiety under stimulation of leptin

Question 8

What are the genetic mutations that can cause osteopetrosis?

Answer 8

channelopathies (CLCN7)

RANKL

RANK receptor

carbonic anhydrase deficiency (CA2)

net effect of all is impaired resorption by osteoclasts

Question 9

Osteoclasts differentiate from what precursor?

Osteoblasts?

Answer 9

osteoclast : monocyte/macrophage lineage

osteoblast : mesenchymal stem cells

Question 10

What is the mutation in porphyeria cutanea tarda?

Answer 10

decreased activity of uroporphyrinogen decarboxylase (used in the production of heme)

catalyzes the conversion of uroporphyrinogen III to copropophyrinogen III

so, this deficiency causes uroporphyrinogen III to accumulate in the skin

Question 11

What are the initial substrates for heme synthesis?

Answer 11

glycine

succinyl CoA

Question 12

What is the disorder that causes people to consciously produce symptoms for primary gain (to be cared for)?

Answer 12

factitious disorder

Question 13

Why are tyrosine supplements necessary in patients with PKU?

Answer 13

catecholamine production

Question 14

What is the effect on LH, FSH & testosterone of taking leuprolide in a non-pulsatile fashion?

Answer 14

b/c leuprolide is a GnRH analog, when taken non-pulsatile it acts as a GnRH receptor antagonist

decrease in LH, FSH which then causes a decerase in testosterone

Question 15

Definition of brief psychotic disorder?

Answer 15

acute onset of one or more psychotic symptom lasting less than one month

Question 16

What structures are responsible for producing progesterone throughout a pregnancy?

Answer 16

immediately following ovulation, corpus luteum form & produces progesterone that maintains the endometrial lining

if pregnacy occurs, the placeta develops from the embryo & makes human chorionic gonadotropin which maintains the corpus luteum & its secretion of progesterone

around 7-10 weeks, the placenta become primarily responsible for producing progesterone

Question 17

A nitroblue tetrazolium test screens for what condition?

Answer 17

chronic granulomatous disease (do not demonstrate color change)

NADPH odixase deficiency (can’t kill catalase positive organisms)

Question 18

What is the problem in Lambert Eaton Syndrome?

Answer 18

have antibodies to presynaptic voltage-gated calcium channels - this decreases calcium influx and therefore ACh release

presynaptic release of ACh

Question 19

OCP are contraindicated in what demographics?

Answer 19

patients with a history of DVT, PE, stroke, or MI

patients 35 or older who smoke 15+ cigarettes/day

patients diagnosed with hypertension, migraine with aura, severe cirrhosis, breast cancer

Question 20

What are the pores of Kohn?

Answer 20

form connections between alveoli & are present in normal lung tissue

aid in normal oxygenation & prevention of atelectasis

Question 21

Why is the PO2 in the renal vein relatively high compared to venous PO2 from other organs?

Answer 21

blood flow per gram of tissue is greater in the kidney than other organs

(receibes 1/2 to 1/5 of total cardial output)

Question 22

What is the general location of distribution for the following types of molecules:

large molecules or protein bound molecules

small hydrophilic molecules

small lipophilic molecules

Answer 22

• large molecules or protein bound molecules
  
  • vasculature
• small hydrophilic molecules
  
  • interstitial space
• small lipophilic molecules
  
  • adipocytes

Question 23

What cells secrete GIP? Where?

What is its function?

Its release is stimulated by what?

Answer 23

secreted by K cells in the duodenum & jejunum

decreases acid production & stimulates insulin secretion by the pancreas

release stimulated by presence of fatty acids, amino acids, & intestinal glucose in the

Question 24

How does acromegaly effects glucose homeostasis?

Answer 24

increasing peripheral insulin resistance, impairing muscle and adipose uptake of glucose, increasing adipose lipolysis, increasing hepatic gluconeogenesis

Question 25

What is the classic triad of HIV encephalopathy?

Answer 25

movement disorders, psychomotor impairment, memory deficits

Question 26

What factor provides the migration pathway for fibroblasts durign migration in the process of wound healing?

Answer 26

fibronectin

Question 27

What immunologic process is primarily affected by the proteosome inhibitor bortezomib?

Answer 27

presentation of antigens to CD8+ T lymphocytes (by altering antigen presenation on the surface of MHC I molecules)

Question 28

What heart defect is most likely to be seen in a patient presenting with a DVT?

Answer 28

patent foramen ovale, allowing a thromboembolism to bypass the pulmonary circulation & cause a thromboembolic cerebrovascular accident or stroke

Question 29

What is the cause of twin-twin transfusion syndrome (TTTS) & twin anemia polycythemia sequence (TAPS)?

Answer 29

arteriovenous (less comonly artery-artery) anastamosis in the chorion of the placenta that allows blood to pass from one fetus to another

Question 30

Downregulation of what hormone leads to testicular atrophy in the setting of exogenous steroid use?

Answer 30

results in increased negative feedback on gonadotropin releasing hormone (GnRH) this subesquently decreased the amount of LH (leads to decreased testicular stimulation of testosterone & therefore leads to testicular atrophy) & decreased FSH

Question 31

What are the laboratory findings you would expect to see in a patient with autoimmune hemolytic anemia?

Answer 31

normo- or microcytic anemia incrased reticulocyte count (b/c increased hematopoiesis) unconjugated hyperbilirubinemia positive DAT

Question 32

Rheumatic heart disease classically causes what type of stenosis? Sound upon cardiac auscultation? It can result in what furher complications?

Answer 32

mitral stenosis diastolic murmur radiating to the axilla atrial enlargement, cardiogenic pulmonary edema, arrhythmias (afib/flutter)

Question 33

What is the first morphologic change that would occur at the cellular level after coronary artery ischemia?

Answer 33

swelling of the endoplasmic reticulum (and other organelles) d/t the cessation of the Na/K-ATPase which impairs the osmotic gradient of the cell and leads to swelling

Question 34

Herpetic infections are treated with drugs that inhibit what enzyme? MOA?

Answer 34

guanine analogs - ie. acyclovir, valacyclovir, famiciclovir first need to be polymerized by thymidine kinase inhibit viral DNA polymerase

Question 35

What type of hypersensitivity is seen in patients with tuberculosis?

Answer 35

type IV, delayed hypersensitivity reaction

Question 36

How do fibrinolytics work?

Answer 36

catalyzing the formation of plasmin from plaminogen plasmin is a serine protease that cleaves fibrin clots

Question 37

Renal papillary necrosis can be precipitated by what incidents?

Answer 37

infections, diabetes mellitus, sickle cell disease, NSAID

Question 38

What is Zellweger syndrome? Symptoms?

Answer 38

genetic mutation that leads to absence of peroxisomes (synthesize cholesterol, bile acids, and membrane substrates) seizures, intellectual disability, hypotonia, hepatomegaly, jaundice, kidney disease, cataracts, hearing loss, craniofacial abnormalities

Question 39

What is the purpose of positive end-expiratory pressure for patients on a mechanical ventilator? This is implemented in the case of acute lung injury to prevent what complication?

Answer 39

prevent pressure in the alveoli from dropping to zero or becoming negative during the respiratory cycle keeps alveoli stented open & therefore able to participate in gas echange w/ acute lung injury, the patient has impaired gas exchange caused by fluid filling the alveoli, which can result in **absorptive atelectasis**

Question 40

What signalling is decreased in alzheimer's dementia? Treatment?

Answer 40

decreased cholinergic signaling in the cerebral cortex & basal forebrain donezepil / other cholineresterase inhibitors (slow rate of cognitive decline, but not curative)

Question 41

What is Cleidocranial Dysplasia? Mutation? Symptoms/presentation?

Answer 41

mutation of CBFA1 gene - impaired osteoblast differentiation dimunition or absence of the clavicle (abnormal movement of shoulders anteriorly), impaired skull development, wormian (intrasutural) bones, supernumery teeth, hypoplasia of the maxilla, frontal bossing, hypertelorism, delayed ossification of the pubic symphysis life expectancy & neurologic development are normal

Question 42

what are the cells responsible for maintaing the barrier between the blood and the seminiferous tubule?

Answer 42

sertoli cells

Question 43

What is the most likely diagnosis of a man with pancytopenia, gingival hypertrophy, and 42% blasts on peripheral smear?

Answer 43

acute myelogenous leukemia

Question 44

What peripheral blood smear findings are characteristic of lead poisoning? Marrow? Lead inhibits what enzyme?

Answer 44

basophilic stippling ringed sideroblasts w/in the bone marrow inhibits ferrochelatase & delta-ALA dehydratase

Question 45

Cause of familial hyperchylomicronemia?

Answer 45

lipoprotein lipase deficiency