High Yields Week 1 Flashcards
Describe the absorption of glucose in the kidney in states of NORMAL serum glucose and HIGH serum glucose
Normal serum glucose = completely reabsorbed
High serum glucose = some glucose excreted in urine
The complete or partial loss of an X chromosome in Turner syndrome results from what genetic abnormality?
Paternal meiotic nondisjunction
What is the most common cause of sporadic encephalitis?
HSV-1
Chromaffin cells of the adrenal medulla and parafollicular C cells of the thyroid arise from what embryonic tissue and layer?
Neural crest tissue from the Ectoderm
Prostatectomy (accidental nerve severing) or injury to the prostatic plexus can cause what consequence?
Erectile Dysfunction
What is the most common non-nuclear DNA found in eukaryotic cells?
Mitochondrial DNA (mtDNA)
- small circular DNA resembling a bacterial chromosome
- maternal mtDNA is passed down from the mother to all of her offspring
What are the 3 most important predisposing factors for hypoglycemia in patients with Type 1 Diabetes Mellitus?
- Excessive insulin dose
- Inadequate food intake
- Exercise/physical activity (muscle contractions also cause glucose uptake by muscle cells via GLUT4)
What is Conversion Disorder?
Conversion disorder is characterized by neurological symptoms (voluntary motor and sensory deficits) that cannot be explained by another medical or mental disorder.
Neural tube defects occur during the 4th week of fetal development and can be detected by what diagnostic markers?
↑ a-fetoprotein (AFP) in maternal serum
↑ acetylcholinesterase (AChE) in amniotic fluid
These appear due to leakage of fetal CSF through the neural tube defect.
Clinical presentation and seromarker associations for ankylosing spondylitis
Young men Morning stiffness, low back pain Tender sacroiliac joints NO rheumatoid factor Associated with HLA-B27 (MHC Class I)
List the conduction speed of the following cardiac tissue from fastest to slowest: Ventricular muscle, Atrial muscle, AV node, Purkinje fibers
Purkinje fibers (fastest)
Atrial muscle
Ventricular muscle
AV node
Cleft lip results from failure of what intrauterine process?
Cleft results when the MAXILLARY prominence fails to fuse with the intermaxillary segment during the 5th-6th week of embryonic development.
Prevention of reinfection with a similar strain of influenza virus can be attributed to antibodies against what influenza viral antigen?
Hemagglutinin (promotes viral entry)
A humoral response with antibodies directed against hemagglutinin is generally the most important source of protection (this goes for the vaccine as well).
Universal Start Codon
AUG
Stop Codons
UGA
UAG
UAA
(U Go Away, U Are Gone, U Are Away)
What does right dominant coronary circulation mean?
It means the right coronary artery gives rise to the posterior descending artery (inferior wall of heart)
85-90% of people have right dominant coronary circulation
Clinical features and pathophysiology of hypercalcemia
Muscle weakness, constipation, mental status changes, increased thirst and urination
Hypercalcemia causes impaired depolarization of neuromuscular membranes (neuro/muscular symptoms) and impaired concentration of urine in the distal tubule (urination/thirst)
Dry beriberi vs. Wet beriberi
Dry beriberi - symmetrical peripheral neuropathy (sensory and motor impairments)
Wet berberi - high-output congestive heart failure (dilated cardiomyopathy, peripheral edema, etc.)
Beriberi (dry and wet) is caused by thiamine (B1) deficiency.
What is the embryologic origin of melanocytes?
Neural crest cells
Patient presents with fever, fatigue, anorexia, tachycardia, tachypnea, hypotension and a new holosystolic murmur. Disease/Dx?
Acute rheumatic fever resulting from an untreated Group A Strep infection.
- Early lesion is mitral valve regurgitation
- Aschoff body may be seen on cardiac biopsy
- (Latel lesion is mitral stenosis)
What fungus produces thin, septate hyphae with acute angle V-shaped branches?
Aspergillus fumigatus
Maple syrup urine disease results from the defective breakdown of branched chain amino acids because of a defective branched chain a-ketoacid dehydrogenase complex. What five cofactors are required for proper function of this enzyme complex?
Thiamine Lipoate Coenzyme A FAD NAD (Tender Loving Care For Nancy)
5 year old child presents with palpable purpura, abdominal pain, arthralgias and hematuria a week following upper respiratory infection. Disease/Dx?
Henoch-Schonlein purpura (IgA immune-complex mediated vasculitis)
What two factors play an important role in osteoclast differentiation?
Macrophage colony-stimulating factor (M-CSF) and activated nuclear factor kappa-B ligand (RANK-L)
Both M-CSF and RANK-L are produced by osteoblasts and bone marrow stromal cells
Define Pleiotropy
Pleiotropy describes instances in which multiple phenotypic manifestations (‘symptoms’) result from a single genetic mutation
- most genetic illnesses exhibit pleiotropy
- TLDR - pleiotropy is where a single gene mutation fucks a lot of shit up
What type of immune response do inactivated (killed) vaccines invoke (B cell/T cell)? Live-attenuated vaccines?
Inactive (killed) vaccines - B cell (humoral) response ONLY
Live-attenuated vaccines - T cell (cellular) AND B cell response
What causes infertility in cystic fibrosis?
Infertility is due to absent vas deferens bilaterally (azoospermia)
In metabolic acidosis, urinary pH decreases due to increased excretion of what substances?
H+, NH4+, H2PO4-
What embryologic dysfunction causes a patent foramen ovale?
Incomplete fusion of atrial septum primum and secundum
A patent foramen ovale can result in a very rare cryptogenic stroke in which an embolus of venous origin can travel through the heart defect into systemic circulation up into the brain.
What do RNA polymerase I, II and III produce?
RNA polymerase I - ribosomal RNA (rRNA -> in the nucleolus)
RNA polymerase II - messenger RNA (mRNA)
RNA polymerase III - transfer RNA (tRNA)
Where are T3 and reverse T3 (rT3) derived from?
T3 (active form) - small amount release from thyroid gland but the majority of T3 arises from T4 conversion to T3 in peripheral tissues.
reverse T3 (inactive form) - generated almost entirely from peripheral conversion of T4
T4 is the major secretory product of the thyroid gland
What enzyme deficiency can cause severe combined immunodeficiency (SCID)?
Adenosine deaminase deficiency
Adenosine accumulation is toxic to lymphocytes leading to widespread death of T and B lymphocytes
What is the most common site of injury in a traumatic aortic rupture (car accident)?
Aortic Isthmus (located right as the aorta begins its descent to the abdomen, 2 o’clock position)
What physiologic function compensates for moderate central venous pressure increases, (due to mildly decreased cardiac function) thereby preventing peripheral edema?
Increased tissue lymphatic drainage
What effect does deacetylation of histones have on gene expression?
Deacetylating histones INHIBITS gene expression.
-causes chromatin to tightly shut, disabling transcription
(acetylating histones would increase gene expression)
5 y/o girl presents with neurologic abnormalities, partial albinism and immunodefiency. Peripheral blood smear shows giant cytoplasmic granules in neutrophils and monocytes. Disease/Dx?
Chediak-Higashi syndrome
Autosomal recessive disorder causing defect in neutrophil phagosome lysosome fusion
What serum biomarker reflects osteoblastic activity?
Bone-specific alkaline phosphatase
Patient presents with pneumonia, low platelet count, fatigue, myalgias and retroorbital headaches. History reveals frequent exposure to animal waste product. What is the causative organism?
Coxiella burnetti (causes Q fever)
What is a paradoxical embolism?
Occurs when a thrombus from the VENOUS system crosses into arterial circulation via an abnormal connection between the right and left cardiac chambers (patent foramen ovale, atrial septal defect, ventricular septal defect)
What is kinesin?
Kinesin is a microtubule-associated, ATP-powered motor protein that facilitates the anterograde transport of neurotransmitter-containing secretory vesicles down axons to synaptic terminals.
TLDR - carries vesicles down axons for release at synaptic terminals
What are the pressures (mmHg) of the airways, alveoli and intrapleural space at the FRC (functional residual capacity)?
Airways - 0 mmHg
Alveoli - 0 mmHg
Intrapleural space - always negative (~-5 mmHg)
What is the most common mutation causing cystic fibrosis and its pathogenesis?
3-base pair deletion at Phe508
Causes abnormal posttranslational processing causing abnormal folding of CFTR protein. Abnormal CFTR is targeted for proteasomal degradation, preventing it from reaching cell membrane.
What are the two physiologic etiologies of polyhydramnios?
Decreased fetal swallowing (gastrointestinal obstruction or anencephaly)
Increased fetal urination (↑ cardiac output due to anemia or TTTS)
What is the name of the sound on cardiac auscultation that immediately precedes the first heart sound?
S4 heart sound (hypertrophic cardiomyopathy)
What treatment should be considered in severe asthmatics that are not responsive to short/long-acting beta agonists or oral corticosteroids?
Anti-IgE antibodies (Omalizumab)
What type of cell junctions exist at the blood-brain barrier?
Tight junctions
The BBB is formed by tight junctions between nonfenestrated capillary endothelial cells that prevent the paracellular passage of fluid and solutes
-lipid soluble diffusion or carrier-mediated transport only
Where in the nephron of the kidney is the majority of water reabsorbed?
Proximal tubule ( > 60% of H20)
What is the most common cause of viral meningitis?
Enteroviruses (coxsackie, echovirus, polio, etc)
- normal glucose (CSF)
- marginally elevated proteins (CSF)
What type of collagen is present in scar tissue?
Type I Collagen
- Can be seen following fibrosis of an infarcted organ (for example)
- Most prevalent collagen in the human body
What are the diagnostic markers for diabetes mellitus?
fasting glucose > 126 mg/dL
random glucose > 200 mg/dL
hemoglobin A1c > 6.5%
Given phenotypically normal parents, what is the probability that a female sibling of a male affected by an X-linked recessive disease will give birth to an affected child?
1/8
What is factitious disorder?
A psychological disorder in which the patient consciously creates physical and/or psychological symptoms in order to assume ‘sick role’ and get medical attention.
TLDR - they hurt themselves for attention
What cells contribute to the pathogenesis of centriacinar emphysema (associated with smoking)?
Alveolar macrophages and infiltrating neutrophils
-these inflammatory cells release proteases
The superantigenic property of toxic shock syndrome toxin (from Staph aureus) results in activation of what immunologic cells?
CD4+ T cells and macrophages
Mature erythrocytes cannot synthesize heme because they lack what cellular organelle?
Mitochondria
Mitochondria are necessary for the first and final 3 steps of heme synthesis
What complications can arise from atrial fibrillation in a patient with severe aortic stenosis?
Atrial fibrillation leads to decreased atrial contraction -> decreased LV filling -> decreased preload -> decreased CO (on top of ↓ CO from aortic stenosis) -> backup of blood into pulmonary veins -> pulmonary edema
Define sensitivity
Sensitivity is the probability of a POSITIVE test result in a person who actually has the disease
It is important to have high sensitivity in screening tests
t(15;17)
Acute Promyelocytic Leukemia (APML)
- involves translocation of retinoic acid receptor
- inhibits differentiation of myeloblasts into mature granulocytes
- symptoms - anemia, thrombocytopenia, neutropenia, DIC
- treatment - All-trans retinoic acid
What precursor amino acid is required for the synthesis of Nitric Oxide?
Arginine
Th2 helper cells stimulate B cell antibody production. What lymphokines released by Th2 cells promote B cell class-switching to IgE?
IL-4 and IL-13 promote IgE production
An immunosuppressed patient with meningitis has a lumbar puncture. CSF fluid shows gram-positive rods with tumbling motility. What is the causative organism?
Listeria monocytogenes
-typically from food poisoning (unpasteurized milk)
Is rabies virus vaccine live attenuated or inactive (killed)?
Rabies virus vaccine is INACTIVE (killed)
-B cell humoral response only
Mutation of the ApoE4 gene is responsible for what disease?
LATE-onset familial Alzheimer disease
What enzyme deficiency is present in chronic granulomatous disease?
NADPH oxidase deficiency
(Deficiency of this enzyme leads to an inability of neutrophils to form the oxidative burst necessary to kill organisms in phagolysosomes)
Rubbing a person’s neck in an attempt to slow down their heart rate is stimulating what structure and nerve?
This action is stimulating baroreceptors in the carotid sinus
Parasympathetic impulses from this carotid sinus reflex travel to the medullary centers via the glossopharyngeal nerve
This carotid sinus reflex eventually results in a signal carried to the heart via the vagus nerve resulting in decreased CO and SVR (BP)
What embryonic structure does the thymus arise from?
3rd pharyngeal (branchial) pouch
What embryonic structure does the parathyroid gland arise from?
3rd and 4th pharyngeal (branchial) pouches
Patient presents with double vision (diplopia) that is worse when walking down stairs or reading. Does not affect vision when walking up stairs. Disease/Dx?
Trochlear nerve (CN IV) palsy
- innervates the superior oblique m., which causes the eye to internally rotate and depress (looks in and down)
- hence the patient has trouble walking down stairs while looking down
What cephalosporins should be used to treat Pseudomonas aeruginosa?
Ceftazidime (3rd gen) or Cefepime(4th gen)
Vitamin B12 deficiency is associated with which two elevated serum markers?
Elevated homocysteine AND methylmalonic acid
Patient presents with nocturnal palpitations, head pounding with exertion, involuntary head bobbing and widened pulse pressures. Disease/Dx?
Aortic regurgitation
widened pulse pressure/head bobbing is particularly helpful
What does a Northern blot detect?
mRNA
What does a Southern blot detect?
DNA sequences
What does a Western blot detect?
Protein
What does a Southwestern blot detect?
DNA-binding proteins
What are the crescent formations seen in RPGN actually composed?
Notably - Fibrin deposits
Crescents consist of glomerular parietal cells, monocytes, macrophages, as well as abundant fibrin
What ion flows into the cells during Phase 0 in cardiac pacemaker cells? cardiomyocytes?
Cardiac Pacemaker Cells - Calcium (Ca2+) influx (slow)
Cardiomyocytes - Sodium (Na+) influx (fast)
In a normal (bell-shaped/Gaussian) distribution, what percentage of observations lie within 1 SD? 2 SD? 3 SD?
68/95/99 rule
1 Standard Dev - 68%
2 Standard Dev - 95%
3 Standard Dev - 99%
Note, 68% encompasses a total from both sides of the mean
What gene mutation is associated with achondroplasia (dwarfism) and what is its inheritance pattern?
Gain-of-function mutation in FGFR3
Autosomal Dominant
What region of lymph nodes do T lymphocytes reside?
Paracortex
What region of the lymph nodes do B lymphocytes reside?
(cortical) Follicles
What artery supplies the distal 1/3 of the transverse colon, descending colon, sigmoid colon and rectum?
Inferior Mesenteric Artery
What is adenomyosis?
The presence of endometrial glandular tissue within the myometrium
(heavy menstrual bleeding and uniformly enlarged uterus are common clinical findings)
Which two major arterial beds are the most susceptible to atherosclerosis?
Coronary arteries and lower abdominal aorta
Down syndrome is associated with increased risk of what leukemias?
Acute lymphoblastic leukemia (10-20x ↑ risk)
Acute myelogenous leukemia
What is the wobble hypothesis (relating to protein translation)?
The first 2 nucleotide positions on the mRNA codon require traditional base pairing, but the third “wobble” nucleotide position may undergo less stringent base pairing
(this fits into concept of ‘degenerate’ genetic code in that multiple codes exist for 1 amino acid)
What is a Krukenberg tumor?
A gastric tumor that has metastasized to the ovary
- presents with unintentional wt loss, epigastric pain and adnexal masses
- will appear as mucin-secreting signet cells
Graft-versus-host-disease can occur after transplantation of what organs?
Allogeneic bone marrow transplantation
-donor bone marrow makes leukocytes that target host tissue
Organs rich in lymphocytes (liver)
-immunocompetent donor T cells from the graft survive and migrate into host tissues
Valproate is an anti-seizure drug that is teratogenic. What type of birth defects occur from valproate?
Neural tube defects (such as meningocele)
Patient biopsy reveals thickened bronchial walls, lymphocytic infiltration, mucous gland enlargement and patchy squamous metaplasia of the bronchial mucosa. What disease process did this patient die from?
Chronic bronchitis - likely due to lifelong cigarette smoking
Do the majority of Down syndrome cases arise from nondisjunction during maternal meiosis I or meiosis II?
Meiosis I
What is nondisjunction?
The failure of chromosome pairs to separate properly during cell division
What regions of the body does HPV infect?
Anus, vagina, cervix, true vocal cords (infants)
HPV ‘prefers’ stratified squamous epithelium
What is another name for B cell class switching?
Isotype switching
IgM, IgG, etc. are different heavy chain isotypes
When is myocardial perfusion the greatest?
Diastole
During diastole, the intraventricular pressure is lower than the aortic pressure, allowing for coronary perfusion
Why is the Haemophilus influenzae vaccine conjugated with tetanus toxoid (similar to S. pneumoniae vaccine)?
To elicit a T cell-dependent immune response
(B cell response from H flu vaccine is not effective in small children who have not developed a mature humoral immune system)
Patient presents with recent onset fatigue and dyspnea. Pt has hypotension, tachycardia and distended jugular veins. Heart sounds are muffled on auscultation and pulse becomes undetectable during inspiration. Disease/Dx?
Cardiac Tamponade
Beck’s Triad (acute tamponade)
- hypotension
- distended neck veins (JVD)
- muffled heart sounds
What is the inheritance pattern of neurofibromatosis type 1 (NF1)?
Autosomal dominant
What vitamin supplement is given during (and before) pregnancy to prevent neural tube defects?
Folic acid supplementation
Where are serotonin-releasing neurons of the CNS located?
Raphe nuclei
Which transmembrane glucose transport protein is responsive to insulin and what type of cells are these glucose transporters predominantly found in?
GLUT-4 is responsive to insulin
GLUT-4 transport proteins are found in skeletal muscle cells and adipocytes
After what period of time does myocardial ischemia cause permanent damage to cardiomyocytes?
30 minutes
After 30 minutes of ischemia, ischemic injury to cardiomyocytes becomes irreversible and they forever lose function
Proteases (such as elastase) in alveolar fluid are derived from what cells?
Alveolar macrophages and infiltrating neutrophils
In statistics, what is power?
Power (1 - Beta) is the probability of rejecting a null hypothesis when it is truly false
(a study’s ability to detect a difference when one actually exists)
What are the two most important opsonins in the human body?
IgG and complement C3b
(Opsonins bind to the surface of foreign cells and act as a handle for receptors on phagocytes to grasp, enhancing phagocytosis)
What is the difference between a true and false diverticulum
True diverticulum - intestinal outpouching containing all 3 layers; mucosa, submucosa, muscular layer
(Meckel’s diverticulum is a true diverticulum)
False diverticulum - contains only 2 layers; mucosa and submucosa
(Zenker’s diverticulum is a false diverticulum)
Patient presents with 6 months of persistent watery diarrhea with no accompanying abdominal pain, fever or vomiting. Her gastric contents show a total lack of gastric acid. Her symptoms are relieved by somatostatin treatment. Disease/Dx?
VIPoma
VIP hypersecretion by VIPoma stimulates sodium, chloride, and water secretion into the bowel
What are ‘confounders’ which cause confounding bias?
Confounders are extraneous factors that correlate with both the exposure and the disease
What cardiac abnormalities are associated with Turner syndrome (45,XO)?
Bicuspid aortic valve (most common)
Coarctation of aorta (preductal)
How are the fingers/digits of the hand numbered?
Thumb - 1st digit
Pinky finger - 5th digit
What is negative selection in T cell maturation process?
Negative selection is a process of T cell maturation in the thymus by which apoptosis is induced in develop T cells that bind to self MHC/antigens with overly high affinity
(this prevents autoimmune reactions)
What intra-abdominal organ is most commonly injured during blunt trauma?
Spleen (intraperitoneal organ)
What antibiotics are first line treatments for Clostridium difficile infection?
Metronidazole and vancomycin
Primary biliary cirrhosis causing biliary obstruction can result in malabsorption of what vitamins?
Fat soluble vitamins - A, D, E, K
Pt presents with night blindness and thickened, dry skin (hyperkeratosis). What deficiency is present?
Vitamin A deficiency
What is rheumatoid factor?
Rheumatoid factor is an IgM antibody specific for the Fc component of self IgG
(in RA, it is thought that RF binding of IgG creates immune complexes that eventually deposit in synovium and cartilage resulting in the chronic inflammation seen in rheumatoid arthritis)
Multiple ring-enhanced lesions are seen on MRI of an HIV patient. What is the likely cause of these brain lesions?
Toxoplasmosis
Pt presents with symmetrical muscles weakness in his hips and shoulders for 6 weeks with difficulty rising from chairs and climbing stairs. Muscle biopsy shows CD8+ lymphocyte infiltration and serum shows elevated creatine kinase. Disease/Dx?
Polymyositis
progressive symmetrical muscle weakness
What is the most common cause of unilateral fetal hydronephrosis?
Obstruction at the ureteropelvic junction
caused by inadequate canalization of the ureteropelvic junction, the connection site between the kidney and the ureter
Who does medicare cover?
Elderly (> 65 yrs) and Disabled
MedicarE is for Elderly
Who does medicaid cover?
Homeless, undocumented immigrants, pregnant women, low-income families
MedicaiD is for Destitute
What cell surface markers do immature T-lymphocytes express?
Both CD4 and CD8
Staph saprohyticus frequently causes what infection? Is it catalase +/-? coagulase +/-? Novobiocin sensitive/resistant?
S. saprophyticus causes UTI in young women
Catalase +
Coagulase -
Novobiocin resistant
Which hypothalamic nucleus regulated the circadian rhythm (sleep cycle)?
Suprachiasmatic nucleus
What type of immune cell is likely to be found in bronchoalveolar lavage fluid of a patient with sarcoidosis?
CD4+ lymphocytes
What would be the p-value of a study that shows a 95% confidence interval that does not cross the null value?
p-value
Pt presents with blistering on the back of hands and forearms that has progressively gotten worse over the years. Disease/Dx?
Porphyria cutanea tarda
- the most common disorder of porphyrin synthesis
- results from a uroporphyrinogen decarboxylase deficiency
- causes itchiness and photosensitivity on sun-exposed areas
What is the function of haptoglobin?
Haptoglobin binds circulating hemoglobin and reduces renal excretion of free hemoglobin, preventing tubular injury
Low haptoglobin levels are seen in hemolysing diseases (like sickle cell) because it is being used to bind all the free hemoglobin
What are the most common cancers in women in order of incidence?
- Breast cancer
- Lung cancer
- Colon cancer
What cancer causes the high mortality in women?
Lung cancer
Visceral obesity, measured as increased waist circumference is an important predictor of what metabolic disorder?
Type 2 diabetes mellitus / insulin resistance
A 12 yo girl shows up with a history of arguing with teachers, refusing to follow rules, fighting with siblings, disobeying her parents and resisting homework and chores. Disease/Dx?
Oppositional defiant disorder
differentiate from conduct disorder which involves aggression and cruelty towards people/animals
Glutathione reductase deficiency causes a similar clinical picture and pathophysiology to what other disease/deficiency?
Glucose 6-phosphate dehydrogenase deficiency (G6PD)
Both result in a deficiency of reduced glutathione which increases the susceptibility of RBCs to oxidative damage
Where in the lymph node do B cells proliferate and class switch?
Germinal centers
What is commonly used to stimulate surfactant production in premature infants with surfactant deficiency?
Corticosteroids (dexamethasone)
corticosteroids increase surfactant production by accelerating maturation of type II pneumocytes
What is the most commonly injured muscle in rotator cuff syndrome (injured rotator cuff) and what movement will particularly cause pain?
Supraspinatus muscle
Injury to the supraspinatus muscle will cause pain on abduction of the arm
What immune cells release IFN-y
T lymphocytes produce and release IFN-y
IFN-y activates macrophages
A 50 yo patient presents with a heart murmur, bounding femoral pulses and carotid pulsations that are accompanied by head-bobbing. Disease/Dx?
Aortic regurgitation
Stimulation of what nerve has been used as a potential treatment for obstructive sleep apnea?
Hypoglossal nerve
Hypoglossal nerve stimulation causes the tongue to move forward slightly, increasing the diameter of the oropharyngeal airway (decreasing apnea)
Aside from hygenic delivery, what is currently done to prevent neonatal tetanus infection?
Vaccination of pregnant women with TDaP
Immunized mothers provide passive immunity to infants via transplacental IgG (this protects infants until they receive their own immunization at age ~2 months)
The main purpose of double blinding in clinical trials is to prevent what kind of bias?
Observer bias
Blinding prevents patient and researcher expectations from interfering with an outcome
Patients have the right to refuse to receive medical information regarding diagnosis (or anything else). True or False?
True
Physicians must understand and respect different cultures that may not want to know about a diagnosis which may cause stress/depression/pain/etc.
What are the two most common anatomic locations where the ulnar nerve may become injured?
- medial epicondyle of the humerus (“funny bone”)
2. Guyon’s canal near the hook of the hamate bone
In what state of acetylation will histones prevent replication/transcription of DNA?
Deacetylated histones (maintain a tight hold on DNA wrapped in chromatin, preventing DNA replication/transcription)
What enzyme carries out nucleotide excision repair following DNA damage such as thymine dimers formation due to UV light exposure?
Endonuclease
Endonuclease recognizes distortions in the structure of DNA caused by thymine dimers and excises the damaged DNA containing defects
Wide, fixed splitting of the second heart sound (S2) is associated with what heart defect?
Atrial septal defect (ASD)
Valine, alanine and isoleucine are examples of what kind of amino acids?
nonpolar, hydrophobic amino acids
These amino acids carry no charge
Contact dermatitis, granulomatous inflammation, tuberculin skin test and Candida extract skin reaction are examples of what type of immune reaction mediated by what immune cell?
Delayed-type hypersensitivity reaction (Type IV)
The cells mediating this type of immune reaction are T cells (Th1 specifically)
What is the most posterior part of the heart?
Left atrium
Enlargement of the left atrium can cause dysphagia due to pressure on the esophagus
Patient presents with a sore on his leg that appears to be an ulcer with central black eschar and surrounding edema. Culture reveals chains of large Gram-positive rods. Disease/Dx?
Bacillus anthracis infection
Cutaneous anthrax is most commonly contracted through exposure to infected animals or animal products
Explain the mnemonic for the femoral triangle AND how to properly apply this medially to laterally.
VAN - Vein -> Artery -> Nerve (all femoral)
The femoral vein is most medial and the femoral nerve is most lateral
What role does carnitine play in biochemisty?
Carnitine is responsible for transport of fatty acids into the mitochondria (from the cytosol) for beta-oxidation of fatty acid
What is the difference between Schizoid and Schizotypal personality disorder?
Schizoid - prefers to be a loner, detached, unemotional
Schizotypal - eccentric; odd thoughts, perceptions and behaviors, social anxiety
Patients with chronic granulomatous disease experience frequent reinfection by organisms that have what characteristic?
Catalase positive organisms
catalase positive organisms can destroy hydrogen peroxide
How do you calculate the alveolar-arterial (A-a) gradient and what is the A-a gradient in a healthy person?
A-a gradient = Alveolar O2 - Arterial O2
A-a gradient in a healthy person is 5-15 mmHg (a normal A-a gradient can help rule out certain types of hypoxemia)
What (2nd line) treatment is in patients with gout that cannot take NSAIDs due to renal failure or peptic ulcer disease?
Colchicine
Colchicine inhibits tubulin polymerization and microtubule formation in leukocytes, reducing the inflammatory response (this also causes diarrhea, nausea and vomiting)
How long does it take to reach steady state concentration for a given first-order kinetic drug?
4-5 half-lives (during continuous infusion)
What is the most common type of kidney stone?
Calcium stone
usually due to hypercalciuria
What is the single most preventable cause of death and disease in the United States?
Smoking (tobacco)
On lifestyle modification questions, the answer is almost always smoking cessation
What hormone is responsible for gallbladder contraction?
Cholecystokinin
Its main functions are to:
- increase pancreatic enzyme secretion
- gallbladder contraction
- decrease gastric emptying
(fatty foods increase CCK production/release)
In males, incomplete fusion of the urethral (urogenital) folds results in what congenital abnormality?
Hypospadias
A urethral opening on the ventral (underside) of the penis)
A 1 yo female presents with recurrent, pus-less skin infections and gingivitis. The patient also had delayed separation of the umbilical cord for 10 weeks following delivery. Disease/Dx?
Leukocyte adhesion deficiency
- autosomal recessive genetic absence of CD18
- inability to synthesize integrins resulting in a defect in leukocyte ability to adhere to endothelium and exit bloodstream
- highly associated with delayed detachment of umbilical cord
What statistical test is used to compare the difference between the means of 2 groups? and 2 or more groups?
2 group - Two-sample t-test
2 or more groups - Analysis of variance
How is net filtration calculated?
Net filtration = (difference in hydrostatic pressure) - (difference in oncotic pressure)
What is characteristic of the psychologic defense mechanism splitting?
Seeing others as all bad or all good; all or nothing thinking
What physiologic effect do nitrites have on blood?
Nitrites cause poisoning by converting reduced ferrous (Fe2+) heme to the oxidized ferric (Fe3+) state
Fe3+ heme, called methemoglobin, is unable to bind oxygen (resulting in a functional anemia)
What are the name of antigen presenting cells that possess tennis racket shaped intracytoplasmic granules?
Langerhans cells (tennis racket inclusions are Birbeck granules)
Langerhans cells are dendritic cells found in the skin
What complication may occur following a scaphoid bone fracture, typically occurring after a person falls with an outstretched hand?
Avascular necrosis (due to little blood supply to this area)
What is the most common complication following a varicella zoster virus (reactivation) infection?
Persistent dermatomal pain that may persistent for several months (post-herpetic neuralgia)
What ion channel do Class 3 antiarrhymics block?
Potassium (K+) channels
This prolongs phase 3 of the cardiomyocyte action potential, slowing repolarization
What amniotic fluid marker ~35 weeks gestation indicates appropriate fetal lung maturity?
lecithin (phosphatidylcholine)/sphingomyelin ratio > 2.0
Lecithin (phosphatidylcholine) production increases sharply in the 3rd trimester while the sphingomyelin level remains unchanged
What test can be used to diagnose abnormal hemoglobin in patients with thalassemia, sickle cell disease/trait or hemoglobin C disease/trait?
Hemoglobin electrophoresis
What tissue in the body has the highest oxygen extraction from blood?
Cardiac muscle (myocardium)
What bacterial pathogens can cause necrotizing fasciitis?
Staph aureus, Strep pyogenes and Clostridium perfringens are most common
S. aureus (G+ cocci, catalase +, coagulase +)
S. pyogenes (G+ cocci, catalase -, coagulase -)
C. perfringens (G+ rod/bacilli, obligate anaerobe)
Nitrates are used to treat chronic stable angina and cause systemic vasodilation. Do nitrates predominantly vasodilate arterial or venous vessels?
Nitrates preferentially dilate VEINS
calcium channel blockers preferentially dilate arteries
What treatment is provided to people with potential exposure to radioactive iodine-131 following nuclear reactor accidents to prevent tissue damage?
Potassium iodide (prevents thyroid carcinoma)
Potassium iodide competitively inhibits thyroid uptake of the radioactive iodine
What occurs with a missense mutation?
Single base substitution
Missense mutations are seen in sickle cell and hemoglobin C disease in which a single base substitution results in a codon for a different amino acid
What occurs with a silent mutation?
Silent mutations are point mutations that have NO EFFECT on the protein formed
What occurs with a frameshift mutation?
Frameshift mutations occur with the deletion or insertion of base pairs that are NOT A MULTIPLE OF 3
What occurs with a nonsense mutation?
Nonsense mutations INTRODUCE A STOP CODON, truncated proteins
What anatomical landmark can be used to distinguish between direct and indirect inguinal hernias?
Inferior epigastric vessels (essentially run down the middle)
Indirect (lateral) - Inferior epigastric - Direct (medial)
What are the classic symptoms of hyperparathyroidism?
Bone pain, renal stones, GI disturbances, depression
“stones, bones, abdominal groans, and psychic moans”
Concerning RAAS, where in the body is inactive angiotensin I converted into active angiotensin II?
AT I is converted to AT II by angiotensin-converting enzymes in the LUNGS
A 13 month old girl presents with initially normal development but has recently regressed via a loss of babbling, inability to sit up, deceleration of head growth and constant movements of twisting hands together. Disease/Dx?
Rett syndrome
(characterized by loss of speech and motor skills, deceleration of head growth and stereotypic hand movements after a period of normal development - mainly in girls)
What G protein-coupled receptor do TSH, glucagon and PTH act on?
Gs receptor
activates protein kinase A, increases intracellular cAMP
In statistics, what is the Hawthorne effect?
The tendency of study subjects to change their behavior as a result of their awareness that they are being studied (observer effect)
It is OK for physicians to accept expensive gifts from patients. True or False?
FALSE
It is ethically problematic for physicians to accept expensive gifts and should be declined (though small value gifts or cards are OK)
What hormone causes the closure of epiphyseal plates (growth plates) during puberty?
Estrogen
Estrogen initially increases linear bone growth but eventually stimulates the closure of epiphyseal growth plates
What drug is used to treat open-angle and closed-angle glaucoma that has physiologic action in both the eye and the kidney? What is its mechanism of action?
Acetazolamide - inhibits carbonic anhydrase
In the kidney - this blocks HCO3- reabsorption in the proximal tubule, alkalinizing urine (↑ pH)
In the eye - this decreases HCO3- and aqueous humor formation, relieving intraocular pressure
What congenital heart defect is associated with children squatting to make themselves “feel better”?
Tetralogy of Fallot
Squatting increases systemic peripheral resistance (↑ afterload) and decreases right to left shunting
What type of exocrine gland is responsible for acne?
Holocrine glands (sebaceous glands are a type of holocrine gland)
What two places in the body are B1 adrenergic receptors predominantly found?
Cardiac tissue and renal juxtaglomerular cells
Cardiac tissue - increases heart rate / contractility
Juxtaglomerular cells - increases renin release (↑ BP)
What is first-line treatment for panic disorder (recurrent panic attacks)?
SSRIs
benzodiazepines can also be used
Sore throat, diffuse erythematous rash and strawberry tongue are associated with infection by what bacteria?
Strep pyogenes (Group A Strep)
These symptoms describe scarlet fever
What is the difference between first generation and second generation antihistamines?
First gen antihistamines block H1 receptor in peripheral tissues AND the CNS (can cross BBB)
Second gen antihistamines block H1 receptors ONLY in the peripheral tissues (can’t cross BBB)
In statistics, what is characteristic of a reliable test?
Reproducible; it gives similar or very close results on repeat measurements
(basically synonymous with precision)
What is the difference between ribosomes attached to the RER and ribosomes freely floating in the cytosol?
Ribosomes synthesize proteins
Ribosomes attached to the RER synthesize proteins that are destined for the cell membrane or secretion/export from the cell
Ribosomes freely floating in the cytosol synthesize proteins that remain in the cytosol or other inner cell regions
What medication should be prescribed to patients experience transient ischemic attacks (brain) or stable angina in addition to antihypertensives and statins?
Aspirin!
Aspirin prevents platelet synthesis of thromboxane A2 which impairs platelet aggregation, reducing the risk of clot formation
What is the function of primase?
Primase is a DNA-dependent RNA polymerase that synthesizes the short RNA primers which DNA polymerase utilizes as a starting point for DNA replication
What complications can arise from chronic obstructive sleep apnea?
Systemic hypertension and eventually pulmonary hypertension and right heart failure
(due to blood gas fluctuations from the transient hypoxic states)
What type of abnormality occurs in Ehlers-Danlos syndrome?
Abnormal collagen formation
This manifests as hypermobile joints, overelastic skin and fragile tissue susceptible to bruising
A patient presents to clinic with an abnormal gait. On examination of gait, the patient leans to his right side while walking. When standing on the right leg, the patient’s left hip tilts downward. What nerve is injured?
Superior gluteal n.
This nerve innervates the majority of gluteus muscles and stabilizes the pelvis. With nerve injury, the muscles cannot contract and so the patient is essentially walking with a peg leg on one side
12 month old male presents with eczema, increased bleeding time, petechiae and a history of recurrent, severe respiration infections. Disease/Dx?
Wiskott-Aldrich syndrome
WATER: Wiskott-Aldrich, Thrombocytopenia, Eczema, Recurrent infections (B and T cell deficiency)
Does total systemic vascular resistance increase or decrease with exercise?
DECREASE (even though BP increases)
Vasodilation within active skeletal muscle (B2) to increase perfusion to exercising muscles actually decreases the total systemic vascular resistance
A patient presents a week after dislocating their right shoulder playing flag football. The patient has trouble elevating (abducting) his right arm and has diminished sensation over the deltoid muscle/upper lateral arm. What nerve has been injured?
Axillary nerve
Axillary nerve injury occurs commonly in the setting of shoulder trauma
Prior to prescribing amiodarone (class III AR), what functional tests should be ordered due to potential adverse effects?
Pulmonary, Liver and Thyroid function tests
Amiodarone can cause adverse effects in all of these organs
What volume of distribution is larger in the body, fat or water?
Fat (41 L) is vastly larger
water is ~14 L, 3 L of which is plasma volume
What is the most dangerous adverse effect of Amphotericin B?
Nephrotoxicity
This can lead to anemia (↓ EPO production by kidney) and hypokalemia (causing weakness and arrhythmias)
What effects can dopamine have on the autonomic nervous system?
Dopamine is an adrenergic agonist (sympathetic)
At low doses, dopamine can stimulate B1 receptors
At high doses, dopamine can stimulate a1 receptors
What is the 1st line therapy for recurrent gout attacks (gouty arthritis, uric acid renal stones, etc.)?
Xanthine oxidase inhibitors (allopurinol, febuxostat)
-these drugs decrease uric acid production
9 year old girl presents with diplopia and headaches. A brain MRI shows a cystic, suprasellar lesion with calcifications. Disease/dx?
Craniopharyngioma
Craniopharyngioma is derived from remnants of Rathke’s pouch (embryologic predecessor of anterior pituitary)
A 45 yo male kidney transplant recipient presents with fever, night sweats, patchy lung crackles and lethargy. Brain MRI shows 2.0cm ring-enhancing focal lesion. Gram stain shows branching filaments of gram-positive rods. Disease/Dx?
Nocardia asteroides infection
Nocardosis typically affects LUNGS (similar to TB), BRAIN (abscess) and SKIN
What is the importance of the marginal artery, an artery found supplying the intestinal tract?
The marginal artery serves as an anastomosis between the superior and inferior mesenteric arteries
In sickle cell disease, what physiologic condition promotes aggregation and sickling of the HbS RBCs?
LOW OXYGEN state (or anything associated with hypoxia such as ↓ pH)
What is the most anterior part of the heart?
Right ventricle (mostly)
What is carbolfuchsin dye used for?
Acid-fast staining
Acid-fast staining identifies organisms with mycolic acid present in their cell walls which includes Mycobacterium and Nocardia
What is akathisia?
An extrapyramidal side effect of antipsychotic medication characterized by INNER RESTLESSNESS and an INABILITY TO SIT STILL
Irregular periods resulting from polycystic ovary syndrome can propagate what serious complication?
Endometrial carcinoma
Menstrual irregularity results in decreased progesterone secretion, a hormone that counters estrogen-driven proliferation of the endometrium
On light microscopy of lung tissue from a patient that experienced chronic dyspnea, alveolar macrophages containing golden cytoplasmic granules that turn dark blue with Prussian blue staining are found. What are the granules in the macrophages?
Hemosiderin (containing IRON)
Prussian blue stain detects intracellular iron
What types of tumors/cancers are associated with psammoma bodies?
PSaMMoma
Papillary carcinoma of thyroid
Serous papillary carcinoma of the ovary / endometrium
Meningioma
Malignant mesothelioma
What is the drug of choice for patients that experience absence seizures (staring blankly) AND tonic-clonic seizures (violent shaking)?
Valproate
Valproate can treat BOTH absence and tonic-clonic seizures
Describe hypoxic vasoconstriction and where it occurs.
Hypoxic vasoconstriction occurs in the LUNGS
In pulmonary vascular bed, tissue hypoxia results in vasoconstriction. This allows for blood to be diverted away from underventilated regions of the lung toward better-ventilated areas.
What cranial nerves are involved in the pupillary light reflex?
CN II (optic) - AFFERENT limb of pupillary reflex
CN III (oculomotor) - EFFERENT limb of pupillary reflex
What symptoms are seen in a cranial nerve III palsy?
Ptosis (drooping eyelid)
“down and out” gaze (unopposed CN IV and VI action)
Fixed, dilated pupil and loss of accommodation
What types of drugs or foods can precipitate G6PD deficiency hemolytic anemia?
Sulfa drugs, antimalarials, dapsone, fava beans
What is the most important component of therapy for a person with active diphtheria infection?
Administering ANTI-TOXIN (passive immunization)
While antibiotics may help in the long run (prevents production of new exotoxin), anti-toxin is needed to dispose of currently circulating exotoxin
Carotid sinus massage causes an autonomic nervous system response via what mechanism?
Carotid sinus massage leads to INCREASED baroreceptor firing rate leading to an increase in PARASYMPATHETIC tone
What three effects does parasympathetic activity have on the heart?
↓ heart rate at SA node
↓ contractility of the heart
↓ conduction velocity at the AV node (prolongs AV nod refractory period)
What is the most common substance causing overdose death in the United States?
Opioids
What does the pulmonary capillary wedge pressure measure?
Left atrial pressure
On auscultation, a holosystolic murmur is heard that is loudest over the left mid-sternal border. What is the cause of the murmur?
Ventricular septal defect
most common congenital heart defect
What are the possible toxic effects of furosemide (loop diuretic)?
OH DANG!
Ototoxicity Hypokalemia Dehydration Allergy (furosemide is sulfa drug) Nephritis (interstitial) Gout
In what ways are beta blockers therapeutic for thyrotoxicosis (severely increased thyroid hormone in circulation)?
- decrease catecholamine action at beta-adrenergic receptors
- decrease the rate of peripheral conversion of T4 to the more active T3
Niacin can be synthesized in the body but requires what precursor molecule?
Tryptophan
Niacin deficiency results in pellagra - 3 D’s
What are clinical features of post-traumatic stress disorder (PTSD)?
Exposure to a significantly traumatic event (life threatening)
Nightmares, flashbacks, intrusive memories
Avoidance of reminders of the event
Emotional detachment, negative mood
Decreased interest in activities
Sleep disturbance, irritability, hypervigilance
Describe 5 of the symptoms used to diagnose schizophrenia (need >2)
Delusions Hallucinations Disorganized speech Grossly disorganized behavior (bizarre behavior) Negative symptoms (flat affect)
What is the function of calcineurin?
Calcineurin is an essential protein in the activation of IL-2, which ultimately promotes growth and differentiation of T cells
How does Hepatitis B (or any hepatitis) cause damage to hepatocytes?
HBV does NOT! have a cytotoxic effect
The presence of viral HBsAg and HBcAg on the cell surface of infected hepatocytes stimulates host CD8+ T cells to destroy infected hepatocytes
The CD8 IMMUNE RESPONSE causes the liver injury
What is a common adverse effect of lamotrigine (Na+ channel blocker for generalized seizures) that can develop into a more severe complication?
Skin rash; typically benign but a life-threatening rash can be caused by Stevens-Johnson syndrome
CYP450 Inducers (increase drug metabolism)
Carbamazepine Phenobarbital Phenytoin Rifampin Griseofulvin
CYP450 Inhibitors (decrease drug metabolism)
Cimetidine Ciprofloxacin Erythromycin Azole antifungals Grapefruit juice Isoniazid Ritonavir (protease inhibitors)
A patient presents weeks after lower right leg injury in a floor hockey game. On examination, the patient has reduced sensation of the dorsum of the foot and lateral shin and displays “foot drop” while walking. What nerve injury is responsible for these findings?
Common peroneal nerve injury
This is the most commonly injured leg nerve
What is a common side effect of topical corticosteroid use?
Dermal atrophy - corticosteroids decrease the production of extracellular matrix collagen
What medical therapy is used for severe sickle cell anemia?
Hydroxyurea
Hydroxyurea increases fetal hemoglobin (Hb F) production which reduces polymerization (sickling) of sickle cells
What virus is particularly problematic in patients with sickle cell and other hemolytic disorders?
Parvovirus B19 (infects erythroid precursor cells)
Parvovirus B19 can cause aplastic crisis in which the patient is unable to produce new RBCs
What causes the early transient hypercoagulable state when warfarin therapy is started?
Protein C and S (anticoagulants) have shorter half-lives than the VitK dependent clotting factors II, VII, IX, and X
Because of this, there is a coagulant/anticoagulant imbalance for a short period of time, resulting in a hypercoagulable state
Recurrent infections with Neisseria species (many bouts of meningitis) may be indicative of what immune system deficiency?
Terminal complement deficiency (↓ C5-C9)
Patients deficient in C5-C9 complement cannot form the membrane attack complex and have recurrent Neisseria infections
What enzyme deficiency is seen in Lesch-Nyhan syndrome and what pathogenesis does this result in?
Defective/absent hypoxanthine-guanine phosphoribosyltransferase (HGPRT)
This results in defective purine salvage/recycling leading to increased purine degradation and excess uric acid production
In a female experiencing recurrent UTIs with eventual development of pyelonephritis in some cases, what is a predisposing factor to pyelonephritis?
Vesicoureteral urine reflux
Allows for retrograde flow of pathogens in the urine into the ureter, contributing to ascending infection
-frequent UTIs can contribute to development of vesicoureteral reflux
What are the pathologic functions of toxin A and B of Clostridium difficile?
Toxins A and B disrupt the actin cytoskeletal structure and intracellular signaling
This disrupts the intercellular tight junctions allowing for intestinal fluid secretion
When patients develop splenomegaly due to high amounts of hemolysis, what part of the spleen is enlarged?
Red pulp of the spleen (splenic parenchyma)
This area of the spleen contains reticuloendothelial cells involved in the removal of damaged RBCs
What anatomic structure is fluid accumulating within in hydrocele?
Tunica vaginalis (can be due to patent processus vaginalis)
What is the function of atrial and brain natriuretic peptides (BNP/ANP)?
ANP and BNP are both release in response to increases blood volume and blood pressure
They cause vasodilation and ↓ Na+ reabsorption in kidneys
Act via cGMP (relaxation of vascular smooth muscle)
What immunologic function does Leukotriene B4 serve?
Chemotaxis - stimulates neutrophil migration to sites of inflammation
(as does C5a and IL-8)
What molecule is a precursor for serotonin?
Tryptophan (for niacin as well)
What gram-negative bacilli, lactose fermenting (pink on MacConkey), encapsulated infectious agent is highly associated with pneumonia in alcoholics and immunocompromised?
Klebsiella pneumoniae
also associated with thick, mucoid, blood-tinged sputum - currant jelly sputum
What area of the brain is the first area damaged during global cerebral ischemia (from cardiac arrest, for example)?
Hippocampus
What is the most common cause of an irregularly irregular rhythm, detected on ECG as an absence of organized P waves?
Atrial fibrillation
A 70 yo man presents to clinic with persistent back pain. On examination it appears the pain is acutely due to bone pain in multiple vertebrae. Imaging indicates increased activity in these vertebrae due to osteoblastic activity. A metastatic cancer is suspected. Disease/Dx?
Metastatic prostate cancer
What malignancies are associated with Epstein-Barr virus (infectious mononucleosis)?
Burkitt lymphoma
Hodgkin lymphoma
Nasopharyngeal carcinoma
What co-morbidities are associated with coarctation of the aorta?
Turner syndrome
Bicuspid aortic valve (assc. w/ Turner syndrome)
Congenital berry aneurysms in Circle of Willis (adult-type)
What is a common complication of subarachnoid hemorrhage resulting from a ruptured saccular/berry aneurysm?
Vasospasm (> 50% experience)
Typically occurs 4-12 days after rupture and can cause additional cerebral ischemia
