UWorld Practice Questions #4 Flashcards
1
Q
How is the filtration fraction (GFR/RPF) affected by a decrease in renal perfusion pressure? Why?
A
The filtration fraction will increase. This is because GFR autoregulation causes the afferent arteriole to dilate and efferent arteriole to constrict in response to decreased perfusion pressure. This means that GFR is maintained at the expense of decreased RPF so the fraction increases.
Note that glomerular capillary oncotic pressure rises in response to increased filtration fraction –> more stuff filtered so there is a higher concentration of protein left in the capillary.
2
Q
What does stimulation of D1 receptors do?
A
Causes relaxation of vascular smooth muscle.
3
Q
What is acitretin and what is it used for?
A
It is in the retinoid family (like isotretinoin used for acne) and is the preferred drug in this class to treat psoriasis.
4
Q
What is xerosis? How do you treat it?
A
Xerosis is a dry, itchy rash with cracked skin. It is most commonly seen in elderly pt in the winter months, as heaters reduce air humidity and promote dry skin.
Tx = focus on maintaining the barrier and replenishing skin water losses –> lukewarm instead of hot baths, neutral or acidic cleansers as opposed to alkaline soaps, and moisturizing immediately after bathing.
5
Q
What are the positively charged amino acids at physiological pH?
A
Histidine, lysine and arginine
6
Q
What are the negatively charged amino acids at physiological pH?
A
Glutamate and aspartate
7
Q
What are the non-polar amino acids?
A
Alanine, valine, leucine, isoleucine, phenylalanine, tryptophan, methionine, proline and glycine.
8
Q
What is the mechanism of action of probenecid? As such, how can it be used?
A
It inhibits organic acid transporters in the kidney. By inhibiting the transporter that reabsorbs uric acid it can be used to tx gout. Additionally, by inhibiting the organic acid transporter thru which antibiotics like pencillin is secreted into the lumen, it can be used to raise levels of abx (by preventing its secretion at the kidneys).
9
Q
What is the pathophysiology of cough syncope? In what population does it typically occur?
A
In cough syncope, during a coughing fit there is increased intrathoracic pressure such that venous return to the heart is decreased and this reduces CO and cerebral blood flow leading to syncope.
This most commonly occurs in male COPD pts who are overweight.
10
Q
Xeroderma pigmentosum is a failure of what process?
A
Failure of the nucleotide excision repair process.
11
Q
What causes Bloom syndrome and how does it present?
A
Defect in DNA helicase RecQL3 gene. Presents with photosensitivity, short stature, erythema and telangiectasias. Pts are predisposed to GI and lymphoproliferative disorders.
12
Q
Bcl-2 overexpression is characteristic of what malignancy?
A
Follicular lymphoma
13
Q
C-Myc overexpression is characteristic of what malignancy?
A
Burkitt lymphoma
14
Q
What causes spider angiomata in patients with cirrhosis?
A
It is the hyperestrogenemia of cirrhosis that causes them.
15
Q
What are the manifestations of hyperestrogenemia in liver failure?
A
Spider angioma, palmar erythema, gynecomastia, testicular atrophy and decreased body hair.
16
Q
Histologically, what do neurofibromas consist of?
A
Loose, disorganized proliferations of Schwann cells, fibroblasts, and neurites.
17
Q
What are Merkel cells?
A
They are the neuroendocrine receptor cells in the skin associated with a sense of touch.
18
Q
For which malignancy does endometriosis increase risk?
A
Ovarian epithelial cancer. NOT endometrial cancer.
19
Q
What is the purpose of using drug-eluting coronary stents (i.e. ones covered in mTOR inhibitors like everolimus)?
A
To prevent intimal hyperplasia that would lead to re-stenosis.
20
Q
In a distal clavicle fracture, what muscle(s) pull the distal segment inferior-laterally? What muscle(s) pull the proximal segment medially and superiorly?
A
Inferior and lateral –> Deltoid
Medial and superior –> SCM and trapezius
*This displaces the fracture and increases the risk of non-union.
21
Q
How do patients with ornithine transcarbamylase deficiency present? What is the inheritance pattern?
A
Newborns present shortly after birth w/ poor feeding and vomiting. They have normal blood glucose, hypotonia, hyperammonemia and increased urinary orotic acid. Pts can lethargy/coma, cerebral edema and seizures from the accumulation of ammonia.
X-linked inheritance pattern.
22
Q
What is most commonly seen in uncle herniation of the brain?
A
CN3 palsy and contralateral hemiparesis due to compression of the ipsalateral cerebral peduncle by the herniated temporal lobe.
23
Q
What are early signs of hypokalemia?
A
Weakness, muscle cramps, myalgias and fatigue
24
Q
Describe the pathogenesis of osteoarthritis?
A
It is an interplay between inflammatory and non-inflammatory processes that cause deterioration of the joint cartilage. Repeated biomechanical stress seems to be of etiologic importance (as evidenced by increased incidence of this in obese people).
25
What is enfurvitide?
It is a fusion antagonist used to tx HIV
26
What are dolutegravir and raltegravir?
Integrase inhibitors used to tx HIV
27
Name the most common manifestations of VHL syndrome?
Cerebellar and retinal hemangioblastomas, renal cell carcinoma and pheochromocytoma
28
Decribe HbC?
It is a hemoglobin variant where the hemoglobin forms hexagonal crystals. Pts get mild anemia but are usually asymptomatic and the oxygen binding properties are not that different from adult hemoglobin.
29
Where are Kayser-Fleischer rings found in Wilson disease?
These are fine granular copper deposits in the cornea.
30
Where are Lisch nodules found? In what condition?
Lisch nodules are located in the iris and are found in NF-1
31
What does aldehyde dehydrogenase deficiency lead to?
The classic alcohol flush reaction. (As such, I think this is the enzyme that antabuse inhibits).
32
What is a galactocele?
A milk-filled cyst due to an obstructed breast duct.
33
What mutation is dysplastic nevus syndrome (resulting is significantly increased lifetime risk of melanoma) associated with?
CDKN2A which is on chromosome 9p21.
34
What are the histopathological characteristics of a dysplastic nevus?
Nests of nevomelanocytes w/ angulated, hyperchromatic nuclei and bridging w/ nests in neighboring rete pegs
35
What sort of nevi are papular (raised) and what sort of nevi are flat (macular)
Papular --> intradermal
Macular --> junctional
36
Which GABA channel acting drugs does flumazenil NOT affect?
Does not affect barbiturates
37
What does the prosencephalon give rise to?
Telencephalon --> cerebral hemispheres and lateral ventricles
Diencephalon --> thalamus and third ventricle
38
What does the mesencephalon give rise to?
Midbrain and cerebral aqueduct
39
What does the rhombencephalon give rise to?
Metencephalon --> pons, cerebellum, and upper 4th ventricle
Myelencephalon --> medulla and lower 4th ventricle
40
Where does de novo purine and pyrimidine synthesis occur?
In the cytosol.
41
How does p57 staining vary btwn compete and partial moles?
Complete stain negative. Partial stain positive.
42
What is the mechanism of retinoids in treating acne?
They act to decrease sebum production and normalize keratinocyte differentiation. They also increase cell turnover and shedding of cells from the stratum corneum which reduces hyperkeratinization, opens blocked pores and prevents the formation of microcomedones.
43
Where is the esophageal hiatus and what passes thru it?
It is located in between fibers of the right crus of the diaphragm. The esophagus and the vagal branches pass through it.
44
What passes thru the aortic hiatus in the diaphragm?
The aorta, the thoracic duct, and the azygos vein.
45
What sort of drug is amlodipine?
It is a dihydropyradine CCB. Note that this class selectively vasodilates arterioles in order to decrease BP (decreasing afterload which decreased myocardial O2 demand).
46
What is one way to distinguish between glucose-6-phosphatase deficiency (Von Gierke disease) and debranching enzyme deficiency (Cori disease)?
In Cori disease the pt's hypoglycemia resolves w/ admin of fructose whereas w/ Von Gierke it does not as these pts can't convert fructose or galactose to glucose.
47
How does pontine hemorrhage present?
Pinpoint pupils, loss of horizontal gaze, quadraparesis, deceberate posturing and rapidly evolving coma that rapidly progresses to death.
48
What are the most common areas affected by non-traumatic intracranial hemorrhage (seen in the setting of HTN)?
Basal ganglia, lobar regions, thalamus, pons and cerebellum.
Putamen and thalamus are most common.
49
What are the mechanisms by which intracranial neoplasms lead to increased ICP?
Can obstruct CSF flow and cause a non-communicating hydrocephalus. Can disrupt the blood-brain-barrier that leads to increased vascular permeability and plasma filtration into the brain parenchyma, resulting in vasogenic edema.
50
Describe cytotoxic edema of the brain and what typically causes it?
Cytotoxic edema is an increase in intracellular fluid w/in neurons, endothelial cells and glial cells as a result of injury that damages the functioning of the Na/K ATPase. It usually occurs following ischemic injury to the brain.
51
Where does the tetany of tetanus infection classically first present?
In the jaw producing lockjaw
52
What is the timeframe for when papillary muscle rupture occurs post-MI?
Typically 3-5 days after. Same timeframe as inter-ventricular septum rupture/defect
53
What is PECAM-1 involved in?
The transmigration step of neutrophil recruitment.
54
What enzyme is defective in hereditary orotic aciduria and how does it present?
Enzyme defect of UMP synthase (in the de novo pyrimidine synthesis pathway). Why uridine supplementation can bypass this defect and improve sxs.
Presents w/ physical and mental retardation, megaloblastic anemia, and elevated urinary orotic acid levels.
55
What are important parameters to look at in distinguishing a cause of metabolic alkalosis?
Want to look at pt's volume status, and the urine Cl.
Urine Cl will be low (<10) in conditions like vomiting and NG suctioning. Urine Cl will be high (>20) in conditions like diuretic use and mineralocorticoid excess states (i.e. Conn syndrome)
56
Which common metabolic alkalosis presentations are saline responsive and which are not?
Saline responsive --> vomiting, diuretics
Saline unresponsive --> mineralocorticoid excess
57
Why do patients w/ C1 inhibitor deficiency (presenting w/ facial swelling, angioedema and GI manifestations) have high levels of bradykinin?
Because in addition to preventing C1 mediated cleavage of C2 and C4, C1INH also inhibits the conversion of kininogen to bradykinin.
58
What causes type 4 renal acidosis?
Either hyperaldosteronism or aldosterone resistance.
59
How are the following agents antiseptic: alcohol? clorhexadine? iodine?
Alcohol --> disruption of cell membranes and protein denaturization
Chlorhexadine --> disruption of cell membranes and coagulation of cytoplasm
Iodine --> Halogenation of proteins and nucleic acids. ***Note that of the three, only this one is sporicidal (as is hydrogen peroxide)
60
What anastamosis is created to supply blood to a donated kidney in renal transplant?
Donated renal artery is connected to recipient external iliac artery.
61
Why can prolactinomas cause amenorrhea?
Elevated prolactin suppresses GnRH production.
62
What is milrinone and what is it used for?
It is a selective phosphodiesterase (PDE3) inhibitor. Prevents cAMP degradation in cardiac and smooth muscle leading to positive inotropic and vasodiliatory effects respectively. It can be used in HF.
63
What are the first generation anti-histamines? Second generation ones?
First gen --> hydroxyzine, promethazine, diphenhydramine, and chlorpheniramine
Second gen --> loratadine and ceterizine
64
What do homeobox genes do? What is a homeobox?
They typically code for transcription factors that alter expression of genes involved in the segmental organization of the embryo.
A homeobox is a conserved sequence of DNA, usually about 180 bases long. Homeobox genes have them.
65
What is an anal fissure? How do they normally occur? And how do they present?
Anal fissure = longitudinal tearing of the anal mucosa dital to the dentate line, most commonly in the posterior midline location.
Usually due to passage of hard stools and constipation leading to increased anal pressures and stretching of the mucosa.
Present w/ sharp pain and bright red rectal bleeding on defecation.
66
Chronic lymphedema is a RF for what?
Cutaneous angiosarcoma
67
Where is hepcidin made?
Liver parenchymal cells
68
What is the mechanism of action of vigabatrin? What is it used for?
It is an irreversible inhibitor of GABA transaminase (thus preventing GABA catabolism in the CNS). It can be used for tx resistant epilepsy.
69
When is pulmonary vascular resistance (PVR) at the lowest?
Near the FRC on respiration/PFT curves. At very high or low lung volumes, resistance is increased.
70
In what female neoplasm are Schiller-duval bodies seen?
In yolk sac tumors.
71
What does damage to the frontal eye field cause?
Causes the eyes to deviate to the ipsalateral side?
72
What are the physiological effects of dopamine at different drug levels?
At low doses it stimulates D1 receptors. At the kidney this leads to increased renal perfusion, increased GFR and increased salt excretion. At higher doses it stimulates B1 (increases cardiac contractility) and a1 (vasoconstriction increasing systemic vascular resistance) receptors.
Overall, in terms of receptor binding it is D1 > B1 > a1
73
Describe amyloid angiopathy and how it presents?
Amyloid angiopathy is where you have B-amyloid deposition in the walls of medium to large sized cerebral vessels. It weakens them are predisposes to rupture.
It presents w/ recurrent brain hemorrhage, often involving the parietal and occipital lobes. It is the most common cause of lobar hemorrhage, and commonly occurs in the elderly.
74
What is another name for folinic acid?
Leucorvin
75
What is the mechanism of amifostine and what is it used for?
It is a cytoprotective free radical scavenger that is used to decrease the nephrotoxicity associated with platinum containing and alkylating chemo. It is also used to decrease dry mouth.
76
What is filgastrim?
A granulocyte colony stimulating factor analog
77
What kind of vaccine is the rabies vaccine for humans?
A killed virus vaccine
78
What is the inheritance of von Willebrand disease?
Autosomal dominant
79
What is the effect of endogenous vasopressin acting on the V1 receptor?
Causes vascular smooth muscle contraction
80
What is the pathogenesis of alcohol induced hepatic steatosis?
Decreased free fatty acid oxidation due to excess NADH.
81
Where are B5 and B7 absorbed in GI tract?
In the small and large bowel via the Na dependent multivitamin transporter.
82
Where is B6 absorbed?
Jejunum and ileum
83
What are protective factors for ovarian epithelial neoplasm?
multiparity, combined oral contraceptives, and breastfeeding
84
What sorts of fibers does the posterior limb of the internal capsule carry? How about the anterior limb?
Posterior --> corticospinal motor and somatic sensory, visual and auditory fibers.
Anterior --> Portion of the thalamicocortical fibers.
85
What are the opioid side effects to which tolerance does not rapidly develop?
Constipation and miosis
86
Which gyrus of the occipital lobe receives upper field information? How about lower field info?
Upper field --> lingual gyrus of striate cortex
Lower field --> cuneus gyrus of striate cortex
87
Block of which adrenergic receptor causes bronchospasm and wheezing?
B2
88
What is the pathogenesis of increased lipoprotein synthesis by the liver in nephrotic syndromes?
There is all this protein loss and so intravascular oncotic pressure decreases and this causes the liver to increase lipoprotein synthesis leading to hyperlipidemia.
89
In blood, CO2 is transported as H2CO3 which dissociates. How is the H+ transported?
While the HCO3- mainly leaves the RBC in exchange for Cl- entering, the H+ generally stays in the RBC and is attached to Hgb by being buffered by histidine residues on the side chains of alpha and beta globin molecules.
90
What is the Haldane effect?
In the lungs, the binding of O2 to hemoglobin drives release of CO2 and H+ from hemoglobin.
91
What are possible complications of varicose veins?
This can lead to venous insufficiency producing stasis derm and skin ulceration.
92
Describe Peau d'orange. What does it indicate?
It is an erythematous, itchy breast skin rash w/ skin texture changes similar to an orange peel. It is the key dermatological presentation of inflammatory breast cancer and is caused by cancerous cells obstructing lymph drainage.
93
How does T3 affect bone?
It increases bone turnover by osteoclasts.
94
What characterizes Rett syndrome? What is its inheritance pattern?
X-linked dominant disorder (affected males die in utero) characterized by progression neurodegeneration and stereotypical hand movements.
95
What is tryptase and when it is seen?
It is an enzyme that is relatively specific to mast cells (released along w/ histamine at degranulation) and elevated levels are seen in anaphylaxis.
96
What is 5-hydroxyindoleacetic acid? When is it used clinically?
A breakdown product of serotonin. High levels are used to screen for carcinoid syndrome.
97
Hyperactivity of the ________ pathway is associated w/ the positive sxs of schizophrenia, whereas underactivity of the ______ pathway is associated w/ the negative sxs?
Postive --> mesolimbic
Negative --> mesocortical
98
Stimulation of what nerve has been shown to be helpful for OSA?
Stim of the hypoglossal nerve. --> this increases the diameter of the oropharynx airway and reduces the freq of apneic events.
99
What muscles do Kegel exercises seek to strenthen in improving stress incontinence?
The levator ani muscles.
100
Where does lymph of the testes drain? How about the scrotum?
Testes --> para-aortic LNs
Scrotum --> superficial inguinal LNs
101
Where does lymph from the glans penis and the cutaneous portion of the posterior calf drain?
Deep inguinal LNs
102
What tendons border the anatomical snuff box?
Extensor pollicis longus medially and extensor pollicis brevis laterally
103
Describe Asherman syndrome?
It is secondary amenorrhea due to obstruction from scarring of the uterine cavity. It is typically a sequelae of uterine infection or procedures.
104
What is the germinal matrix?
It is a highly cellular and vascularized layer in the subventricular zone from which neurons and glial cells migrate out during brain development.
105
Where are most L atrial thrombi found?
Like 90% are found in the L atrial appendage.
106
What makes up the borders of the posterior triangle of the neck?
SCM, trapezius and the clavicle.
107
What nerve roots does the ansa cervicalis arise from? What does it innervate?
C1, C2 and C3. Innervates sternohyoid, sternothyroid and omohyoid.
108
Where is the carotid body located? What does it sense?
Lies at the bifurcation of the common carotid (just below the hyoid bone). It senses O2, CO2 and H+ w/ chemoreceptors for these things.
109
Where do nosebleeds most commonly occur?
At the watershed area of vessels (anastamoses of anterior ethmoidal, sphenopalatine, and superior labial arteries) at the nasal septum.
110
How do neprilysin inhibitors provide benefit in treating HF?
Neprisylin is a metalloprotease that degrades stuff like brain natriuretic peptide (BNP). By inhibiting it, there is more BNP around and it promotes diuresis, vasodilation and has a natriuretic effect.
111
How can one distinguish between 21-hydroxylase deficiency and aromatase deficiency?
In aromatase deficiency there is often maternal virilization (voice deepening, facial hair growth, etc.) because fetal androgens enter maternal circulation. In 21-hydroxylase deficiency, no such virilization occurs.
112
What sort of cancer therapy does an activating KRAS mutation make ineffective?
These activating mutations make EGFR inhibitors ineffective as this is upstream of where KRAS is acting in terms of cell proliferation.
113
What sort of meds are cetuximab and panitumumab?
Monoclonal antibody therapy that blocks EGFR
114
What can occur from rapid correction of hyponatremia? How about hypernatremia?
hyponatremia --> can lead to central pontine myelinolysis leading to quadraplegia (demyelination of CST in pons) and pseudobulbar palsy (demyelination of corticobulbar tracts of CN 9, 10 and 11).
Hypernatremia --> cerebral edema.
115
What do rivaroxaban and apixaban do?
They are direct factor Xa inhibitors.
116
What does eptifibatide do?
It is a GPIIb/IIIa receptor inhibitor that prevents platelet aggregation.
117
What does dabigatran do?
It is a direct thrombin inhibitor.
118
What causes uric acid to precipitate? Where is this most likely to occur in tumor lysis syndrome?
It is soluble at physiological pH but precipitates in an acidic environment. As such, during TLS stones are most likely to occur at the distal tubules and collecting ducts as these are the most acidic portions of the nephron.
119
What is the pathogenesis of apoplexy
It is acute intrapituitary hemorrhage, occurring most often in the setting of pituitary adenoma. Pts can develop cardiovascular collapse due to ACTH deficiency (in setting of panhypopituitarism) which is why tx is glucocorticoids.
120
What does a high Ki-67 ratio in cancer cells indicate?
That there is a high proliferation index.
121
What is the difference btwn chronic tic disorder and Tourette syndrome?
Chronic tic disorder --> motor or verbal tics but NOT both for at least one year.
Tourette syndrome --> Both motor AND verbal tics for at least one year.
122
What does inhibin B do?
Negative feedback to decrease FSH secretion.
123
WHy does hepatitis C virus demonstrate such great antigenic variation?
Because its RNA polymerase has no proofreading 3' to 5' exonuclease activity so it is very error prone.
124
Describe the pathogenesis of the FGRF3 mutation in achondroplasia?
It is a mutation that makes FGFR3 constitutively active such that there is exaggerated inhibition of chondrocyte proliferation. This limits endochondrial ossification, causing shortening of bones.
125
What are the two most important regulators of coronary blood flow for autoregulation of flow to myocardium?
Nitrous oxide --> important for dilation of large arteries and pre-arteriolar vessels
Adenosine --> vasodilation of small coronary arteries
126
Describe systemic mastocytosis, what mutation is commonly present, and some common presenting sxs:
In systemic mastocytosis there is clonal mast cell proliferation in bone marrow, skin and other organs. It is often associated w/ mutations in KIT receptor tyrosine kinase. There is usually massive release of histamine and common sxs include syncope, flushing, hypotension, uticaria, pruritis, and gastric acid hypersecretion.
127
What are 3 signals to increase gastric acid secretion?
1. Histamine (H2 receptor)
2. Acetylcholine (M3 muscarinic receptor)
3. Gastrin
128
What are the two subtypes of anorexia nervosa?
Restricting subtype and binge eating/purging subtype
129
What is the key difference btwn anorexia nervosa binge eating/purging subtype and bulimia nervosa?
In the anorexia nervosa subtype weight is at an unhealthly low level whereas in bulimia nervosa weight is maintained at or above a normal BMI.
130
Name 3 serious medical complications of anorexia nervosa
```
1 = amenorrhea
2 = osteoporosis
3 = cardiac atrophy, cardiomyopathy and arrhythmias
```
131
How does carbon tetrachloride (CCl4) damage cells?
Thru free radical injury
132
What is teriparatide?
Recombinant PTH
133
Where does most H20 reabsorption occur in the nephron?
The majority (> 60%) is reabsorbed by the proximal tubule, regardless of the patient's hydration status
134
What are two equations for cardiac output (CO)?
CO = HR x SV
CO = rate of O2 consumption / arteriovenous O2 content difference
*Note that the later can be calculated using swan-ganz catheterization based on application of the Fick principle.
135
Lambert Eaton Syndrome is associated w/ what malignancy?
Small cell lung cancer
136
How it listeria most commonly transmitted?
Through contaminated food ingestion.
137
Which vessel is most commonly involved in atherosclerosis?
The abdominal aorta.
Next most common (in order) are the coronary arteries, popliteal arteries, internal carotid arteries, and the circle of Willis.
138
What are colchine's important ADRs?
Nausea, abdominal pain, and diarrhea (most common at higher doses).
139
What is the pathogenesis of hydrocephalus ex vacuo?
It is enlargement of the ventricles due to neuronal volume loss. Generally, this results in a normal pressure hydrocephalus as it is a slow/chronic process.
140
What is the pulse pressure?
Systolic BP - Diastolic BP
141
When administered IV, how does epinephrine affect the peripheral vascular resistance? Why?
It lowers PVR b/c it preferentially acts at B2 over a1 receptors in vasculature when given IV.
142
Where does cryptococcus typically establish its primary infection?
In the lungs
143
What are the teratogenic effects of warfarin?
Nasal bridge hypoplasia (i.e. depression of the nasal bridge) and epiphyseal stippling.
144
What are the teratogenic effects of isotretinoin?
Microcephaly, small ears, thymic hypoplasia, and hydrocephalus.
145
What can develop in untreated obstructive sleep apnea? What is the pathogenesis?
Pts w/ OSA can get systemic HTN. This is due to the apneic episodes causing hypoxia and hypercapnia that stimulate systemic and pulm vasoconstriction and sympathetic cardiac stimulation. Untreated, these pathophysiologic changes can also lead to development of pulmonary HTN and R heart failure.
146
What tumors do pts w/ NF-2 develop?
Bilateral CNVIII schwannomas and multiple meningiomas.
147
What is the inheritance of Osler-Weber-Rendu syndrome? What characterizes it?
It is autosomal dominant and is characterized by the development of telangiectasias in the skin and mucus membranes of the lips, oronasopharynx, respiratory tract, GI tract and urinary tract.
148
21 hydroxylase catalyzes the reaction of progesterone to _______ and catalyzses the rxn of 17-OH-progesterone to ________?
progesterone --> 11-deoxycorticosterone
17-OH-progesterone --> 11-deoxycortisol
149
Leads I and aVL correspond to what area of the heart on ECG?
These are the lateral leads. Infarct of the L circumflex artery would affect them.
Note that V5 and V6 are lateral leads as well and can sometimes be affected.
150
What are the anterior leads on ECG? Of these, which are the septal leads (and thus sometimes spared in distal left anterior descending occlusion)?
Anterior leads = V1-V4
Septal leads = V1 and V2
151
What are the inferior leads on ECG?
II, III and aVF
152
Decreased choline acetyltransferase activity in the nucleus basalis corresponds to what neurodegenerative disorder?
Alzheimer's.
*This is most noticable in the basal nucleus of Meynert, which participates in cognition and memory.
153
Describe the golgi tendon organ (GTO) and what it is used for
The GTO are sensory receptors located at the junction of the muscle and the tendon. A muscle actively contracting against resistance is transmitted thu the GTO and the GTO contacts inhibitory interneurons in the spinal cord in order to regulate and maintain muscle tension. When a muscle exerts too much force, the GTO inhibits contraction to prevent damage.
154
What are A-delta fibers?
They are thin, myelinated nerve fibers whose nerve endings sense temp and nociceptive stimuli. They are part of the reflex arc that mediates withdrawal from noxious stimuli.
155
Decribe intrafusal muscle fibers
They are arranged in parallel w/ the extrafusal fibers and sense stretch. They contract when stretched, which produces our DTRs.
156
What is septic abortion? How does it present? What are the common causative organisms?
Septic abortion is any abortion that results in infected retained products of conception in the uterine cavity. Presents w/ fever, abdominal pain, uterine tenderness, and/or a foul smelling vaginal discharge. Most commonly caused by S. aureus and gram negative bacilli.
157
What is the most frequent mechanism of sudden cardiac death in the first 48 hours of acute MI?
Ventricular fibrilation.
158
Where do axons of the second order neurons of the lateral spinothalamic tract ascend?
In the contralateral lateral funiculus. They come here by crossing at the anterior white commissure and rise to synapse w/ third order neurons in the ventral posterior-lateral thalamus.
159
If there is suspicion of child abuse, what is the immediate next step?
Ask permission to interview the child alone.
160
Involuntary head bobbing can be a sign of what?
Widened pulse pressure
161
Name 5 risks of secondhand smoke exposure
- prematurity and low birth weight
- sudden infant death syndrome
- middle ear disease (i.e. otitis media)
- asthma
- respiratory tract infections
162
The levels of _______ correlate w/ the severity of sxs of giant cell arteritis?
cytokines, particularly the levels of IL-6.
163
What is tocilizumab?
It is an antibody therapy against IL-6 that is used to treat giant cell arteritis.
164
Highly soluble (in the blood) anesthetics have a ______ blood/gas partition coefficient?
high blood/gas partition coefficient
165
Define potency of an inhaled anesthetic
It is determined by the minimum alveolar concentration (MAC). It's the concentration in the lungs at which desired effects are seen in 50% of pts.
166
What does DNA glycosylase do?
It removes the nitrogen base from the sugar-phosphate backbone as part of base-excision repair.
167
What are the congenital manifestations of congenital CMV?
Chorioretinitis, sensorineural deafness, seizures, jaundice, hepatomegaly, splenomegaly and microcephaly.
168
How is chronic mesenteric ischemia analagous to stable angina?
In CMI, there is atherosclerosis that diminishes bowel blood supply such that when a pt eats and there is more blood flow needed for the bowel, this can lead to ischemia and pain. Similarly, stable angina is pain due to ischemia in the setting of increased myocardial oxygen demand.
169
How do amiloride and triamterene work?
They block the ENa channels in the apical membrane of principal cells to prevent Na reabsorption at the collecting duct.
170
Give examples of 3 intrinsic tyrosine kinase receptors
receptors for insulin, insulin-like-growth-factor, and epidermal growth factor.
171
Describe how JAK2 signaling works
JAK2 is a cytoplasmic tyrosine kinase. It interacts w/ receptors when ligand is bound (i.e. when EPO binds to its receptor) and then is activated. This in turn causes it to phosphorylate and thus activate STAT which will then go affect transcription.
172
What enzyme activates 6-mercaptopurine into its active metabolites?
Hypoxanthine-guanine phosphoribosyl transferase (HGPRT)
173
Describe a complete atrioventricular canal defect
It is composed of a ASD, a VSD, and a combined AV singular/common valve.
174
What is the pathogenesis of HUS?
Microthrombi in small vessels leads to microangiopathic hemolytic anemia that damages renal vessels and causes AKI
175
What cells make somatostatin and what does somatostatin do at the stomach?
D cells make somatostatin. It inhibits gastrin secretion (which is why loss of these cells from antral gastritis secondary to H. pylori can increase predilection to get duodenal ulcers).
176
Pneumobilia (air in the biliary tree) is a common radiographic finding for what?
Gallstone ileus
177
What is the mechanism of paroxysmal nocturnal hemoglobinuria?
Episodic hemolysis by a complement mediated mechanism.
178
Which hormone leads to the maternal insulin resistance seen in the 2nd and 3rd trimesters of pregnancy? What is another effect it has?
Human placental lactogen (does it by increasing insulin secretion by B cells). HPL will also increase lipolysis in the mother to provide nutrients to the fetus.
179
Describe physiologic changes due to exercise as they pertain to cardiac output (CO), LV end-diastolic volume and pressure, mean arterial pressure (MAP), total systemic vascular resistance (TSVR), and pulmonary artery systolic pressure.
- CO --> increases, primarily due to increased HR
- LV end-diastolic volume and pressure --> increase due to increased venous return
- MAP --> increases, due to sympathetic discharge causing contraction of arterioles, except for those in exercising skeletal muscle.
- TSVR --> decreases, due to substantial arteriolar vasodilation in exercising skeletal muscle
- pulm artery systolic pressure increases
180
What are the names of the carpal bones in the acronym, "some lovers try positions that they can't handle"
scaphoid, lunate, triquietrum, pisiform, trapezium, trapezoid, capitate, and hamate
181
What is the mechanism of action of methimazole and propylthiouracil (PTU)? Which one is safe during pregnancy?
Methimazole and PTU both inhibit thyroid peroxidase and thus inhibit the coupling of iodinated tyrosine residues to make T3 and T4. PTU also inhibits the peripheral conversion of T4 to T3.
PTU is preferred for pregnancy as methimazole is a possible teratogen (can cause cutis aplasia).
182
What do perchlorate and pertechnetate do?
They both are competitive antagonists of the Na/iodide symporter that does iodide uptake in the thyroid.
183
What primary cell lines are increased in COPD?
Neutrophils, macrophages and CD8+ lymphocytes
184
What is the most common mechanism of resistance to aminoglycosides?
Antibiotic modifying enzymes (i.e. ones that acetylate the antibiotic such that it isn't effective)
185
Where is protein A expressed in S. aureus?
It is part of the outer peptidoglycan layer (aka on the outer surface of the bacterium).
186
What are some ADRs associated w/ mercaptopurine use?
Cholestasis and hepatitis leading to abdominal pain and jaundice.
187
What are 6 absolute contraindicates for oral contraceptive pill use?
Pregnancy, prior hx of thromboembolic event or stroke, hx of an estrogen dependent tumor, over 35 and smoke heavily, hypertriglyceridemia, active or decompensated liver disease.
188
The sympathetic nervous system releases acetylcholine at pre-ganglionic synapses and norepi at post-ganglionic synapses. What are the 2 notable exceptions to this?
One is that at the adrenal gland, the chromaffin cells of the adrenal medulla release epi and norepi directly into circulation after ACh stimulation from preganglionic neurons.
The other exception is that both the pre and post-ganglionic neurons that supply eccrine sweat glands are cholinergic and release ACh.
189
What is the most common cause of death of Marfan syndrome patients?
Aortic dissection (due to cystic medial degeneration of the aorta).
190
What are the first line meds for WIlson disease?
Copper chelators like d-penicillamine and trientine
191
What characterizes polyarthritis rheumatica?
Sudden onset stiffness, pain and tenderness of the musculature (especially shoulders, hip, neck and torso). Pts classically usually have an elevated ESR too.
192
What innervates the posterior part of the external auditory canal?
A small auricular branch of the vagus nerve.
193
What is the treatment of congenital adrenal hyperplasia?
*I think this is specifically for the 21 hydroxylase form.
Administration of low (physiologic) doses of corticosteroids. This will suppress ACTH release such that there isn't more signaling on the adrenal gland leading to excess androgen production. Overall you are causing reduced stimulation of the adrenal cortex.
194
What makes up ther blueish network (on Wright-Giemsa stain) in reticulocytes? These are reticular precipitates.
Ribosomal RNA.
195
In terms of cardiology, what is the Kussmaul sign and when is it sign?
Normally JVP drops during inspiration but the Kussmaul sign is where it paradoxically rises during inspiration. This occurs during constrictive pericarditis because the volume restricted R ventricle is unable to accommodate the increased venous return of inspiration.
196
When is a mid-systolic click classically heard?
In mitral valve prolapse
197
What does sucralfate do?
It binds to the base of mucosal ulcers and protects them from gastric acid
198
Which cells synthesize and form the fibrous cap of mature atheromas in atherosclerosis?
Smooth muscle cells.
199
How do you calculate Vd?
Vd = dose / Cp
200
What is prazosin and how can it be used?
It is an selective a1 blocker that can be used to tx nightmares in PTSD
201
Describe granuloma inguinale
It is an STI caused by klebsiella granulomatis and causes extensive ulcerative genital lesions that are usually not painful and usually there is no lymphadenopathy.
202
What genital ulcer is associated w/ having a grey exudate?
Chancroid from H. ducreyi
203
What is the main blood supply to the femoral head and neck? When are they vulnerable to damage?
Main blood supply is branches of the medial circumflex artery. These arteries are especially vulnerable to damage from fractures to the femoral neck
204
Where are the terminal sequences of collagen cleaved by N and C terminal procollagen peptidases? This converts _____ to ______.
This happens extracellularly and converts procollagen to tropocollagen.
205
Where and when does glycosylation of selected hydroxylysine residues occur in collagen formation?
Occurs in the RER after hydroxylation of proline and lysine residues and before assembly of pro-a chains into the triple helix of procollagen.
206
What is the specific enzymatic defect in Ehlers-Danlos syndrome?
Defect of procollagen peptidase which cleaves the C and N termini of procollagen to form tropocollagen.
207
What does a defect in the GH receptor lead to?
Laron dwarfism - pts have decreased linear growth.
208
What is bone-specific alkaline phosphatase a marker for?
Osteoblast activity. They release it into circulation as they are synthesizing bone matrix.
209
What are urinary levels of deoxypyridinoline and hydroxyproline excretion markers for?
Osteoclast activity w/ deoxypyridinoline being the better/ideal marker as pyridinoline is what covalently cross-links collagen fibers.
210
What are the three treatments of acute C. diphtheriae, in order of importance for improving prognosis?
```
1 = diphtheria antitoxin
2 = antibiotics
3 = DPT vaccine
```
211
What is the most common cause of death from diphtheria?
Cardiomyopathy. Note that the exotoxin can affect cardiac and neural tissue which is how it can have sequelae in these organ systems.
212
What is flunisolide?
An inhaled glucocorticoid
213
What is the mechanism of action of methylxanthine meds like theophyline and aminophyline?
They are phosphodiesterase inhibitors that increase bronchial dilation by increasing intracellular concentration of cAMP.
214
What are anti-mitochondrial antibodies specific for?
Primary biliary cirrhosis (PBC)
215
What lymphoma classically has a waxing and waning course of lymphadenopathy and is the most indolent non-Hodgkin lymphoma?
Follicular lymphoma
216
Name 2 non-hodgkin lymphomas that have rapidly expanding nodal masses
Burkitt lymphoma and diffuse large B cell lymphoma.
217
What is mycoses fungoides?
It is a cutaneous T cell lymphoma that manifests w/ plaques.
218
Where does scabies usually present?
Usually presents w/ an intensely pruritic rash in the flexural surfaces of the wrist, lateral surface of the fingers, and the finger webs.
219
Necrotic keratinocytes in the epidermis suggest what skin disorder?
Steven-Johnson-Syndrome
220
When CMV infection in immunocompotent individuals does cause sxs, how does it present?
Presents as a mononucleosis-like illness with fever, myalgia, malaise, atypical lymphocytosis, and elevated transaminases
221
What do "mycotic aneurysms" refer to?
Local destruction and dilation of a arterial wall due to infection (rarely fungal which is confusing given the name)
222
What enzyme converts oxaloacetate to phosphoenolpyruvate as part of gluconeogenesis?
Phosphoenolpyruvate carboxykinase
223
In general, how long into fasting does it take to deplete hepatic glycogen stores?
About 12-18 hours, after that gluconeogenesis takes over as the primary source of blood glucose.
224
What is the first fatty acid produced from acetyl CoA during lipogenesis in the fed state?
Palmitic acid
225
How long must excessive worry and anxiety be present in order to make a dx of generalized anxiety disorder?
At least 6 months
226
What is the mechanism by which voltage gated Na channel blockers achieve use dependence?
They block channels in the open and inactivated state but not in the resting/closed state. As such, tissue undergoing frequent depolarization will be preferentially affected.
227
When is the Rb protein in its active state? What does it do when this is the case?
It is in its active state when it is hypophosphorylated and when this is the case it acts to halt the transition from G1 to S in the cell cycle.
228
Characterize hairy cell leukemia
Indolent B-cell neoplasm of middle-aged men typically that presents w/ bone marrow failure and massive splenomegaly.
229
What can be used as a surgical landmark during appendectomy?
The teniae coli (the three fibrous bands along the colon converge on the appendix).
230
Which form of IBD has thickening of the muscularis mucosae?
Crohn disease
231
What type of granulomas are seen w/ Crohn disease?
Non-caseating granulomas.
232
What can the hydrogen breath test be used to dx?
Lactose intolerance
233
POMC is a polypeptide precursor that goes through enzymatic cleavage and modification to produce what three things?
MSH (melanocyte stimulating hormone), ACTH, and beta-endorphins.
234
What is somatostatin C?
It is insulin like growth factor (aka IGF)
235
What are brown and black pigment gallstones associated with.
Both are associated w/ conditions that increase the amount of unconjugated bili in the bili.
Brown --> biliary tract infections (microbes producing B-glucuronidases)
Black --> conditions of hemolytic anemia
236
What sort of viral genomes are infectious all by themselves, that is, without any additional proteins or anything else being put in a cell?
+ sense ssRNA viruses. Others like - sense RNA viruses need an RNA polymerase too to be infectious.
237
Anesthetics w/ a high anteriovenous concentration gradient have _____ blood solubility?
High blood solubility. This is because this means a lot of anesthetic is being extracted from the blood by tissues and so it will take a while to saturate the blood.
238
What is the triad of abnormalities seen on ECG in wolf-parkinson-white syndrome?
Due to ventricular pre-excitation there is: shortened PR interval, delta wave, and a widened QRS complex.
239
Describe acute and chronic lung rejection presentations
Acute --> dyspnea, dry cough and low grade fever. Occurs due to vascular damage.
Chronic --> inflammation and fibrosis of the bronchiolar walls leading to narrowing and obstruction of the small airways (bronchiolitis obliterans). Presents w/ dyspnea, wheezing and non-productive cough.
240
Contrast chronic rejection of kidneys vs. lungs in transplant pts
Renal --> it is primarily vascular obliteration
Lungs --> primarily small airway obliteration
241
What is a leukemoid reaction? What can you see on blood smear?
It is a benign leukocytosis (count > 50,000) that occurs in response to underlying conditions infection/hemorrhage, solid tumors or acute hemolysis.
Smear can show increased bands, early mature neut precursors, Dohle bodies (light blue peripheral granules in neuts), toxic granulation and cytoplasmic vacuoles.
242
How does lecithinase (main virulence factor of C. perfringens) work?
It catalyzes the splitting of phospholipid molecules.
243
What enzyme does fomepizole inhibit?
Alcohol dehydrogenase (first step in alcohol metabolism)
244
Where does the trigeminal nerve exit the brainstem?
At the level of the mid-pons aka the level of the middle cerebellar peduncle.
245
Of PBC and PSC, which has granulomatous destruction of intrahepatic bile ducts and which has "onion skinning" appearance?
PBC --> granulomatous desctruction
PSC --> onion skinning fibrosis.
246
What is the pathogenesis w/ which L sided HF causes pulmonary HTN?
Increased pressure leads to pulm venous congestion which causes endothelial damage and capillary leak. This causes decreased NO and increased endothelin production which leads to vasoconstriction. Additionally, over time there is remodeling of pulm vasculature as smooth muscle proliferation and collagen deposition occur.
247
What does histo of Hashimoto thyroiditis classically show?
Mononuclear infiltrate of lymphs and plasma cells, often w/ germinal centers.
248
Why do selective COX-2 inhibitors (i.e. celecoxib) not inhibit platelet aggregation?
Because platelets primary express COX-1 only.
249
What is a common mutation seen in melanoma?
Activating BRAF mutation
250
Why is a VSD usually not detectable until about 4-10 days after birth?
Because it takes time for PVR to lower and then allow L to R shunting of blood.
