NBME 19 Flashcards
How does water get reabsorbed in the kidney?
It diffuses across- no energy needed
What does histone acetyltransferase do?
Decreases the affinity of histones for DNA, so it weakens the DNA-histone bond and makes DNA segments more accessible for transcription factors and RNA polymerases
In a viral infection, what is critical for the initial establishment of the infection?
Presence of viral receptor molecules on epithelial cells
Sildenafil mechanism of action
Inhibits PDE5 => increases cGMP => smooth muscle relaxation
HOX gene products and retinoic acid bind to specific DNA sequences on different chromosomes. What is the function of these?
They act as transcription factors
Antibodies associated with Graves disease?
Thyrotropin receptor autoantibodies
Antibodies associated with Hashimoto’s?
Antithyroid peroxidase (antimicrosomal) autoantibodies. Antithyroglobulin autoantibodies
In hyperparathyroidism, mechanism of how it causes osteopenia?
Paracrine stimulation of osteoclasts by osteoblasts
Dereased lysosomal hydrolase activity in occurs in what diseases?
Lysosomal storage disorders (e.g. Neimann-Pick disease
Patient has a problem with the respiratory burst mechanism. Dx?
NADPH oxidase deficiency
Patient with weakness of her left leg, decreased muscle strength, no other abnormalities. When her eyes are closed, she can’t tell whether her left great toe is raised or depressed. Which vessel is affected?
Right anterior cerebral artery.
Because weakness of left leg is motor and/or sensory, the left great toe symptom is a distractor because everything else is normal. so the area affected is motor, sensory area of right frontal and parietal lobes => Right ACA
A mutant form of a voltage gated sodium channel inactivates more rapidly than normal. What property will the neuron have?
Decreases the amplitude of the action potential
In a damaged lung, what does the cell that is responsible for repair produce?
Surfactant ( because it’s type 2 pneumocytes)
If you upregulate bcl-2, what will happen?
Apoptosis is inhibited- e.g. decreased cell death in the thymic cortex
Xeroderma pigmentosa causes what type of DNA damage?
Formation of pyrimidine dimers
What is Marcus Gunn pupil?
Also called- relative afferent pupillary defect
When you shine light in to the normal eye, both eyes constrict.
And then when you swing the light to the affected eye, both pupils dilate instead of constricting. This is because of injury to the optic nerve ipsilaterally.
What makes the blood-testis barrier?
Tight junctions between adjacent Sertoli cells
Morphine adverse effect- facial flushing cause?
Histamine release
Picture frame vertebrae is seen in what?
Paget’s disease of bone
Lab values of Paget’s
Increased Alk. phos
Ca, phosphorous, PTH- normal
What is psychogenic polydipsia?
When a person drinks excessive water without being thirsty.
Lab- urine osmolarity increases during water deprivation
Features of polio
Destruction of anterior horn of spinal cord- LMN weakness. Decreased reflexes
Features of West Nile Encephalitis
Meningitis
Flaccid paralysis
Seizure
Coma
What is vascular conductance?
The flow of a volume of blood through the vasculature
What is confined placental mosaicism?
It’s when the chorionic villus sampling testing comes back showing trisomy in some cells. And all the subsequent tests show normal chromosomal counts. This is due to trophoblastic mutation, or trisomic rescue. This is when the trisomic cells that were supposed to be in the fetus confined to the placenta, so fetus is normal
In an elderly pregnant patient, at 11 weeks of gestation, what test can you do to test for chromosomal abnormalities?
Chorionic villous sampling
What are dysplastic nevi?
Pigmented skin lesions that occur in sun exposed and nonsun exposed areas
Nephrotic syndrome- Uniformly thickened glomerular capillary basement membrane. Immunofluorescence- granular deposits of IgG and C3. Dx?
Membranous nephropathy
68 y/o patient with 2 month history of inability to maintain an erection. Has fatigue and difficulty sleeping and concentrating. What happens to libido and nocturnal erections?
Patient has depresssion.
Libido- decreased
Nocturnal erections- normal
Patient with diarrhea. Colonoscop- multiple ulcers that have undermined and destroyed large areas of the intestinal epithelium. What parasite is causing this?
Entamoeba histolytica
Histological changes you see in a biopsy of an ulcer of the vulva of syphilis?
Obliterative endarteritis with lymphocytes and plasma cells
Patient given penicillin. What kind of anemia do you see? Labs?
Direct Coombs positive hemolytic anemia
What does AMP do to breakdown of skeletal muscle glycogen phosphorylase?
AMP is an allosteric activator
What drugs cause photosensitivity?
SAT For Photo Sulfonamides Amiodarone Tetracycline 5-FU
Advantage of randomized controlled trial versus prospective cohort study
Better control for confounding variables
For PPD skin test, positive is usually 10 mm. If you change the induration to 5mm, what happens to incidence and prevalence of a positive PPD skin test?
They would both increase
75 y/o patient with Alzheimer’s, he has aspiration penumonia with compromised swallowing function. He has no advance directives. How should you address the feeding tube issue?
Encourage the family to come to a consensus based on their perception of the patient’s wishes
13 year old girl, comes to the doctor with her mother for general check up. You want to ask the patient about sexual activity. How do you do that?
Ask the mother to leave the room before asking the patient any questions
8 year old girl, unconscious. They were traveling in a truck overnight. She slept in the back, in an enclosed cabin. In the morning, she was hard to wake up, and had a severe headache and nausea. She has cherry red skin around the mouth. Dx? Tx?
Carbon monoxide posioning.
100% O2
Patient with dryness of skin, excessive freckling and keratoses with exposure to sun. What’s defective?
Nuclear excision repair of pyrimidine dimers
