What is the underlying pathophysiology of ARDS?
- ARDS: acute onset lung dsfxn, pulmonary edema, normal LA pressure, PaO2/FIO2 < 200.
- Pathophys: damage to the endothelial cells lining the pulmonary capillaries –> leakage of fluid into alveoli (exudative stage). Primary cause of injury = inflammatory cytokines and neutrophils (DAD = diffuse alveolar damage).
- Causes: trauma, pulmonary contusions, infection/sepsis, fat embolism.
Rank the cardiac tissue conduction velocity from fastest to slowest.
- Purkinje
- Atrial
- Ventricular
- AV node
Mnemonic: Park At Venture Avenue
- Impulses begin at SA node (RA wall near SVC): 1.1 m/s
- Internodal tracts carry AP to AV node(interatrial septum near tricuspid orifice): 0.05 m/s (slowest)
- AP enters bundle of His/right and left bundle brances (interventricular septum): 2.2 m/s (fastest)
- AP trasmitted through ventricular myocardium: 0.3 m/s
Patient presents with “lump in throat” but exam shows no abnl and barium swallow is unrevealing. What is the dx?
Globus hystericus: the sensation of a lump in the throat without accompanying physical, endoscopic, or radiologic findings of esophageal obstruction.
How does vitamin A ingestion manifest in fetal growth?
- Microcephaly
- Cardiac anomalies
- Early epiphyseal closure
- Growth retardation
- Spontaneous abortion
The appearance of DNA fragments in multiples of 180 base pairs on gel electrophoresis is known as what?
DNA laddering: a lab phenomenon used to identify apoptotic cells and distinguish them from necrotic cells. During karyorrhexis, endonucleases degrade DNA into fragments that are multiples of 180 base pairs.
Confusion, blurred vision, dry mucous membranes, and intense thirst are associated with _____ toxicity?
Anticholinergic toxicity (atropine).
- Hot as a hare: fever
- Dry as a bone: dry skin and mucous membranes
- Red as a beet: flushing
- Blind as a bat: mydriasis, cycloplegia
- Mad as a hatter: confusion, excitation, disorientation, delirium, psychosis
Two children have osteogenesis imperfecta but parents are unremarkable family hx. What is responsible for the d/o?
- Germline mosaicism (2+ genetically different gamete cell lines) should be considered when a genetic mutation is IDed in offspring but not in parents.
- Pleitropy: single gene with multiple phenotypes
- Penetrances: extent to which gene is expressed.
What sturcutre is likely to be injured in a posterior displacement of the tibia?
Popliteal artery is the main concern with both anterior and posterior dislocations of knee joint. This vessel is rigidly fixed proximal and distal to the knee joint by the adductor magnus and soleus muscles, respectively.
What are the risk factors of endometritis and which bacteria is the most commonly isolated?
- RF: premature and prolonged rupture of the membranes, use of devices (scalp electrodes, intrauterine pressure catheters).
- S/S: fever, uterine tenderness, foul smelling discharge, leukocytosis
- Culture: bacteroides and other mixed aerobic/anaerobic flora
How does a heminephrectomy affect GFR immediately after surgery and six weeks after surgery?
50% –> 80% (not 100%)
What do the 4 heart sounds and mid-systolic click represent?
- S1: closure of AV valves at beginning of systole.
- S2: closure of semilunar (aortic and pulmonic valves) at end of systole. After this sound is isovolumetric relxation of ventricle before opening of AV valves.
- S3: blood turbulence within ventricle during period of rapid diastolic filling. In adults, it occurs most commonly in setting of cardiac failure (systolic or diastolic). It’s normal in children.
- S4: pathologic. Result of forceful atrial contraction pushing blood into overfilled or stiffened ventricle.
- Midsystolic click: mitral valve prolapse
Splenectomy can be performed on patient with hereditary spherocytosis to prevent what complication?
Splenectomy would improve anemia, decrease hemolysis and juandice, and reduce bilirubin gallstone formation.
Androgen insensitivity syndrome
- 46XY Male
- X-linked disorder
- Androgen receptor defect
- Free T is aromatized to E –> breasts
- Cryptorchid testes (secretes T)
- No axillary or pubic hair
- No penis/scrotum
- No uterus/ovaries: due to MIF
- Vagina ends in blind pouch
5-a reductase deficiency
- Autosomal recessive
- Ambiguous genitalia in newborns
- Testosterone cannot convert to DHT
What is a significant cause of brain injury in premature infants? Where does it usually arise from?
- Intraventricular hemorrhage (IVH) is common in premature infants in the first five days of life.
- RF: birth < 32 wks, <1500g, intrapartum asphyxia, respiratory distress syndrome, prolonged resuscitation.
- Begins in germinal matrix: highly cellular and vascular in the subventricular region that generates neurons and glia during fetal development.
Most head and neck cancers what ______ types of cancers? Where are they usually found?
- Squamous cell carcinoma
- HNSCCs are strongly a/w tobacco and alcohol.
- Usually ventral tongue, floor of mouth, lower lip, soft palate, gingiva
How are G protein coupled receptors anchored to cell membranes?
- Via palmitoylation
- Process in which FA are covalently anchored to plasma membrane cysteine residues, increasing the hydrophobicity of a protein.
How does nitroglycerin affect HR and end-systolic LV volume?
- Increases HR, decreases end-systolic LV volume
- Systemic venodilation –> myocardial oxygen consumption is decreased relative to coronary perfusion through a reduction of steady state ventricular volumes that overcome the associated reflexive increase in HR.
- Nitroglycerin relaxes vascular smooth muscles in veins more than arteries. This rapidly decreases ventricular preload (end diastolic volume), which reduces venous return to the heart, and decreases effective circulating blood volume through venous blood pooling.
- CV reflexes compensate for the drop in SV, CO, and MAP with sympathetic increases in HR and myocardial contractility.
- In the new steady state, preload, afterload, end systolic ventricular volume, and CO are somewhat reduced, while TPR is the same. Due to reduction in stroke work a/w smaller ventricular volumes, decreased ejection time, and decreased afterload during the cardiac cycle, the ratio of myocardial oxygen consumption to coronary blood flow is decreased in the new steady state.
Liver disease + hepatomegaly, skin hyperpigmentation (sun exposed areas) and DM is a sign of what pathology?
Hematochromatosis. The skin hyperpigmentation results from hemosiderin deposition in the dermis.
When protons are added to growth media, previously resistant bacteria are no longer resistant to specific abx. What is the likely mechanism?
Efflux pumping is an active, energy-requiring process. Most are powered by moving protons (H+) along their concentration grandeitn out of the cell, coupled with expelling the abx. When the medium is saturated with protons, the gradient is eliminated.
A prohormone peptide molecule has a signal sequence with a hydrophobic core. A alrge deletion in the hydrophobic core would result in protein accumulation in which compartment?
mRNA –> protein
- In the cytosol, mRNA binds to ribosome and initiates translation.
- Proteins destined for ER have N-terminal peptide signaling sequences, recognized by SRPs (signal recognition particles), which halt translation and target the ribosome to protein pores in the RER.
- Once bound to RER, the SRP dissociates and translation proceeds with the polypeptide being fed into RER through membrane pore.
- Signal sequences: 15-20 hydrophobic AA residues.
- Deletion of this hydrophobic signaling sequence: failure of SRP binding, failure to translocate appropriate proteins into the RER, accumulation of ER proteins int he cytosol.
23 yo male has normal secondary sexual characteristics and normal blood T, but T in seminiferous tubules and epididymis is abnl low. Which cell is dysfxn?
- Sertoli cells
- Seminiferous tubules and epididymis must contain high T relative to the testoterone in circulation for spermatogenesis and sperm maturation to occur.
- Androgen-binding protein (ABP) binds T and DHT to concentrate them in the luminal fluid.
- ABP is made by sertoli cells.
- Leydig cells: make T
Red safranin O is used to stain what?
- Cartilage
- Mast cell granules
- Mucin
How does PE affect pH, PaCO2, and PaO2?
- High pH, low PaCO2, low PaO2
- PE is characterized by hypoxemia secondary to pulmonary ventilation-perfusion (V/Q = infinity) mismatch.
- Hypoxemia –> hyperventilation and respiratory alkalosis.
- Increase in pH and reductions in PaO2 and PaCO2
