Neuro:
Which type of sensory information is compromised by lesions in the portion labelled X?
Unconscious Proprioception
Differentials?
Conscious proprioception, vibratory sense and 2 point discrimination are all conducted by? the dorsal columns.
Pain sensation, temperature and crude touch is regulated by? spinothalamic tract
23 year old woman burns her hands and feels little pain. There is decreased pain sensation in both upper extremities and weakness and atrophy of intrinsic muscles in both hands. What best explains these findings?
Cystic lesion involving midline structures and both ventral horns in the cervical enlargement.
Patient has Syringomyelia
When do ghrelin levels peak? On consumption of a meal. They drop once the meal is done, to promote satiation.
Ganciclovir interferes with the function of which enzyme?
DNA polymerase
Differentials:
How do integrase inhibitors work?
Prevent integration of proviral DNA into host DNA.
Which drugs then affect integrase? Raltegravir
How does a fungus with thymidine kinase develop resistance?
Thymidine kinase activates ganciclovir via phosphorylation. In mutation of thymidine kinase, in the fungus, there will be no activation of the medication.
Which muscle is responsible for supination?
Biceps Brachii
Which muscle is responsible for pronation?
Pronator teres
Flexor of the wrist? Flexor carpi radialis
Which vessel is at greatest risk during operative removal of the right cervical rib?
Right subclavian artery
Radial Nerve | Innervates extensors of elbow, wrist and hand. |
Ulnar Nerve | Innervates intrinsic muscles of hand (except distal 2 lumbricals) |
Tibial Nerve | Intrinsic muscles of the foot and sensory to the bottom of the foot via plantar nerves |
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WOman with sensorineural hearing loss is undrgoing cochlear surgical implant. . Conversion of sound energy to electrical signals (in the cochlea), results in stimulation of which structure?
Auditory nerve endings in the cochlea
What is damaged in sonsorineural hearing loss? Hair cells within the cochlea
Skin
75 year old woman with expanding lesion, on her face, Atypical melanocytes seen on skin biopsy, spread along basilar layer of epidermis. Cause?
Lentigo maligna:
Which skin lesion can progress to squamous cell carcinoma? Actinic keratosis
Acanthosis nigrans: hyperpigmented, velvety patehes on axillar, neck, breast, back and abdomen.
25 year old woman with 3 year hx of celiac disease has itchy rash on scalp, buttocks, arms and legs for 5 weeks. Crusted papules surrounded by excoriations over the upper and lower extremities and a few vesicles on the buttocks. Vesicles are subepidermal and show granular deposits of IgA in the epidermal-dermal junction. Most likely diagnosis?
Dermatitis herpetiformis:
60 year old woman with a 1cm mass on her nose has neoplastic cells that exhibit dense pigment granules. Diagonsis?
Melanoma: diameter of mass greater than 6mm
Lesions are present for 3 days and are exacerbated by spicy, salty and acidic foods. What triggers development of sores? Aphthous ulcers
65 year old woman, proximal weakness in her arms and legs, mass in her right frontal lobe of lung. Biopsy of mass shows malignant small, blue cell neoplasm that expresses cytokeratin, chromogranin and synaptophysin. Dx?
Pulmonary small cell carcinoma.
Lambert Eaton syndome
28 year old woman, unable to climb stairs due to muscle weakness, has 1 month hx of rash on race, elbows and knuckles. Bilateral weakness of lower extremity muscles. Diagnosis?
Dermatomyositis
A patient who is recommended a colonoscopy to check for colon cancer says she just wants her stool checked. The physician is concerned about what, regarding this test?
Low sensitivity: ability to detect if a disease is present or not. (has a high likelihood of disease detection, aka a low likelihood of false negativity).
Useful to rule out a disease.
Why not low specificity? because it describes a test that is subject to false positive errors (a positive test does not have a high likelihood of the disease).
Infliximab inhibits what to help treat TB? Maintainance of granulomas:
TNF-a supports granuloma formation and is secreted by macrophages. Infliximab is a monoclonal antibody against TNF-a (as well as adalimumab and cetrolizumab).
Humoral antibodies mediate protection against reinfection of the same virus strain, primarily by this mechanism?
Blocking of viral attachment to cell receptors;
What does Barrette's esophagus look like histologically? Intestinal metaplasia.
50 year old man, shortness of breath with normal pulse and BP. Explanation for the following findings?
Arterial PCO2 | 30 mmHg |
Arterial PO2 | 96 mmHg |
Arterial O2 content | 12 vol% (N= 17-21%) |
Mixed Venous PO2 | 36 mmHg |
Mixed Venous O2 content | 8vol % (N = 10-16%) |
Anemia: Reduced arterial and venous O2 content. Reduced O2 content and mixed venous circulation with normal arterial PO2. With no abnormalities, the patient's O2 saturation should be normal. However, in anemic patients, the Hb levels are decreased and arterial CO2 levels are decreased due to hyperventilation. This is expected due to the decreased O2 delivery to tissue.
What kind of hormones are thyroid hormones? Lipophilic hormones.
How do T3 and T4 enter liver cells? Both T3 and T4 enter the nucleus: unlike other lipophilic hormones, they contain charged amino acids that prevent passive diffusion across the cell membrane
What kind of receptors are thyroid hormone receptors? Nuclear receptors that contain DNA-binding domains. Once they bind to their hormones, they translocate into the nucleus.
A newborn is in respiratory distress and has a congenital diaphragmatic hernia. There is small bowel and stomach herniation into the left hemithorax. Breath sounds are decreased on the left. Which complication is life threatening to the newborn?
Pulmonary hypoplasia
Where do we see alveolar edema? NRDS
An 18 hour old newborn is 12 lbs and his mom has type 1 diabetes. His serum glucose is 20. Which fetal condition immediately prior to birth most likely precipitated the newborn's postnatal hypoglycemia?
Decreased gluconeogenesis
Increased fetal production of insulin causes a decrease in gluconeogenesis. The insulin acts now as a growth factor, causing the macrosomia and inhibits the production of surfactant, which leads to NRDS.
Woman is diagnoised with gestational diabetes during pregnancy. THis hapened to her mother and sister as well. Her serum glucose is 100. This patient has decreased activity of which enzyme?
Glucokinase
The synthesis of enzymes necessary for replication of the genome occurs during which phase of the cell cycle?
C: The synthesis of enzymes necessary for replication of the genome occurs in G1 (in preparation for the S phase). In G1, cell contents (except chromosomes) are duplicated. Chromosome duplication occurs in S phase. Fidelity of replication is checked in phase G2.
Which opioid receptor is responsible for neuronal adaptations that lead to addiction? Delta
Which opioid receptor opposes the reward signalling of mu receptors? Kappa (leads to dysphoria under stressful conditions).
Activation of which opioid receptor causes apnea? mu
Which drug inhibits platelet interaction with fibrinogen? Abciximab
Lesch -Nyhan syndrome (X-linked recessive) is seen in 1/100,000 males. Expected prevalence of heterozygous females? 1/50, 000
Hardy Weinberg principle: p2 + 2pq + q2 = 1 and p +q = 1
p = frequency of dominant allele
q = frequency of recessive allele
2pq = probability of heterozygosity
p2 = probability of dominant homozygote
q2 = probability of being a recessive homozygote
Affected males only carry a single gene in X-linked recessive diseases.
So in this circumstance, the frequency of affected males is represented by q rather than q2.
2pq is the maternal carrier frequency
So q = 1/100,000
and p=(1-1/100,000) = 1/99,999
2pq = 2 x 1/100,000 x 1/99,999 = 1/50,000
Another example;
A 21 year old woman has a 3 year old sister who was recently diagnosed with CF. What best approximates the patient's risk of being a heterozygote for CF?
2/3
CF is autosomal recessive therefore for her to not be affected, we can rule out aa. So we are left with 3 other options and 2 of those are Aa.
And another: (Probability but it's biostats)
After 5 minutes of rowing, a man experiences fatigue of upper left extremity, lightheadedness and vertigo. When he stopped rowing, all symptoms resolved. What is seen on physical examination?
Supraclavirular bruit
This patient is experiencing subclavian steal syndrome. Due to atherosclerotic disease of the subclavian artery, proximal to the vertebral artery, leads to decreased pressure in the distal subclavian artery. During exercise of upper ipsilateral extremity, atherosclerotic disease of that subclavian artery may prevent sufficient blood supply to the arm.
So how can the arm be perfused? Through retrograde flow in the ipsilateral vertebral artery. Blood from the contralateral subclavian and vertebral artery may flow in the retrograde direction at the vertebrobasilar confluence instead of continuing to ascend the basilar artery.
Motor fibers from the vagus nerve innervate all the muscles of the pharynx except the? stylo pharyngeus
Which function in mRNA synthesis and processing, is most likely encoded by the sequence AATAAA? Cleavage and polyadenylation: the AATAAA sequence encodes the polyadenylation signal. Mutations here would result in polyadenylate the 3' end of the mRNA transcript and lead to early degradation within the nucleus prior to translation.
Symptoms unconsciously produced or exacerbated by psychological factors such as stress, but show no findings on physical examination? Somatic symptom disorder
Differential?
Conversion disorder: Patient is not preoccupied by symptoms
PAH concentration vs PAH secretion, which is lower at point Y than at point X?
PAH clearance: the absolute secretion of PAH at point Y, exceeds that at point X, the clearance is lower because the kidneys are unable to increase their rate of clearance despite an increasingly high concentration of PAH. Graph shows that plasma PAH concentrations increase, PAH clearance by kidneys into the urine increases in a linear fashion until an inflection point, where the slope of the graph become zero.
Patient undergoing furosemide therapy has persistent edema and hypokalemia. Mechanism of action of the drug that will help, is what?
Decreases the luminal permeability to Na+ in the collecting duct (potassium sparing diuretics: triamterene and amiloride)
Relative risk for exposure variable?
| Infection present | Infection absent |
Turtle exposure | 60 | 20 |
No turtle exposure | 40 | 80 |
(60/80)/(40/120)
A study measures the impact of exercise on the incidence of MI, subjects are placed into 2 groups based on their self reported exercise habits. After the study, subjects who reported exercising, had half the incidence of MI compared with the subjects who did not exercise. What describes this study design?
Cohort: whether an exposure is associated with an outcome of interest .
1000 workers checked to see which ones use computers and whether they have Carpal tunnel's syndrome or not. What type of study is this?
Cross sectional:
Obesity study: 5000 normal weight patients are followed from age 1o-15 years. Conclusion: 1,100 patients were obese. What best represent the incidence per 1000 patient-years of obesity during the course of this study?
Incidence rate: (# of new cases)/ (total population at risk per unit time).
{(1,100 cases of obesity)/(5000 patients at risk)}/5 years = 0.044
Multiply by 1000 to convert to units from cases per patient per year to cases per 1000 patients-years: 0.044 x 1000 = 44 cases per 1000 patient years
Which wbc type is increased in appendicitis (bacterial proliferation)? Neutrophils
Where would we see a rise in basophils? In myeloproliferative disorders like AML, PCV, myelofibrosis
Which cell type is increased in viral infections? Lymphocytes
Stroke:
Weakness in right lower 2/3 of face results from lesion to which site?
Broca's area?
Motor function of contralateral (right) lower extremity? UMN weakness of lower leg
Sensation of right (contralateral) leg?
Behanvioural dysregulation (learning, reading, problem solving, emotions)?
Left angular gyrus of inferior parietal lobe lesion: agraphia, acalcula, finger agnosia, L/R disorientation (Gertsmann syndrome)?
Superior temporal gyrus and lesion can lead to Wernicke aphasia?
Deficits in complex visual perception. and semantic memory processing?
Sensation of right upper extremity and face?
Superior temporal gyrus; auditory association area. Lesion disrupts spoken word recognition?
C, A, D, E, B, G, H, I, F, J
46 year old woman has chronic alcohol dependance, has several spider angiomas on her face, chest and back. There is shifting dullness to percussion and a firm liver edge is ballotable 3cm below costal margin. Mild anemia and increased hepatic tranasaminase activity and decreased albumin concentration. Peritoneal aspiration shows 80% of leucokytes to be neutrophils, and 100 rbcs. What is the cause for the febrile illness?
Spontaneous bacterial peritonitis: development of peritoneal infections in patients with ascites. Patient has incurred cirrhosis from alcohol use disorder
Differentials:
Not chonic pancreatitis: despite alcholi use, he also autoimmune pancreatitis. Represents with malabsorption, steatorrhea, and deficiencies of fat soluble vitamins.
Respiration:
After a vehicular accident, a man has trouble breathing even has pain when climbing up the stairs. He is cyanotic, tachypneic. What is most suggestive that fractured ribs are the cause of his respiratory difficulties?
Subcutaneous crepitus: Rib fractures can be complicated by tearing of the adjacent visceral or parietal pleura, allowing air in the lung, to escape into intrapleural space and subcutaneous tissue.
There is no improvement after bronchodilator therapy. How is airway resistance and lung compliance affected in patient with these findings?
They both increase. Based on these findings, patient has COPD from smoking. Outflow obstruction leads to increased airway resistance (reduced FEV1) and air trapping during expiration. The lung parenchyma lacks elasticity so leads to increased compliance. In conjunction with air trapping, this is demonstrated by in increase in TLC and RV. In COPD, no response to bronchodilators is expected (as opposed to asthma patients, where FEV1 would have increased).
Role of astrocytoma in the brain? uptake of amino acid neurotransmitters (like glutamate, GABA and glycine). They react to neuronal injury: During damage to the CNS, glutamate is released rapidly into synaptic clefts. This causes neuronal apoptosis to occur, but the high affinity for glutamate of receptors on astrocytes, prevents necrosis by removing glutamate from synapses.
Which cells in the brain form myelin sheaths? oligodendrocytes (damaged in MS)
Why is mean arterial pulmonary pressure increased in systemic sclerosis? Due to chronic hypoxic vasoconstriction (from fibrosis in the lungs). Coronary vascular resistance would increase and LV diastolic compliance would decrease due to fibrosis of heart walls.
How does lactic acid cause cramps? Regeneration of NAD+ from NADH produces acid. During levels of low oxygen, pyruvate is converted to lactic acid and this process requires formation of NAD+ from NADH.
How does Bordetella pertussis cause neutrophil chemotaxis and oxidative metabolism to be defective? Due to increased activity of adenylyl cyclase. It increases intracellular cAMP through inactivation of G-protein coupled receptors in respiratory epithelium and systemically, leading to uninhibited adenylyl cyclase activity. This causes impaired recruitment of neutrophils, migration and production of inflammatory mediators.
To remove a portion of the great saphenous vein, at which location should an inscision be made? At the medial side of the ankle joint
Malignant cells from the cervix drain first to which lymph nodes? Internal iliac.
INtestinal tumors
A child with painless rectal bleeding has multiple polyps in his intestine. Dx? Juvenile polyps
Hamartoma polyps in the intestine and pigmented macules in the mouth, lips, hands and genitalia.
Older patient with solitary tumor in intestine? Tubular adenoma
Which part of this traverse section of the penis, does sildenafil work on?
D: sildenafil is an inhibitor of cGMP specific PDE-5 (causing increase in nitric oxide concentration, thefore vascular dilation). D is the corpora cavernosa.
Low Hb and hematochrit and normal MCV. Blood smear is shown. Patient is a 3 year old boy of European descent. What does genetic testing show?
Heterozygous (AD) mutation in ankyrin gene: This is hereditary spherocytosis.
A man cuts himself while shaving and the bleeding stops almost immediately. What is the cause for this rapid cease in blood flow?
Localized secretion of endothelin: this is stimulated by thrombin at the site of bleeding.
Renal:
A new medication is given and then patient develops a petechial rash and blood and protein in the urine. What kidney problem has occurred? Acute interstitial nephritis
Some kind of toxicity or injury to the kidney is causing Granular, muddy brown casts into the urine. No hematuria: Acute tubular necrosis
Woman has hypotension and shortness of breath following a bee sting. After treatment, the hypotension resolves. Next day, she has minimal urine output. Which area of the kidney is most affected with the prolonged hypotension?
Proximal renal tubule. : patient has acute tubular necrosis.
Man with AML recently began undergoing treatment. He has pain and hematuria during urination. What will increase in the serum?
Uric acid: patient has Tumor lysis syndrome (common in patients just starting cancer treatement).
Woman of Japanese descent drank a glass of champagne for the first time and has had a 3 hour facial flushing. Most likely cause is a mutation in the gene for which enzyme?
Aldehyde dehydrogenase
The accumulation of acetaldehyde stimulates the release of histamine, causing facial flushing.
Fracture of neck of tibia causes what findings?
damage to common peroneal nerve. Dorsi flextion (1;5). Plantar flexion: ( 4/5).
How does ursodiol prevent gallstones? by inhibiting biliary cholesterol secretion.
18 year old woman has 3 day hx decreased ability to see in reduced light. Lifelong hx of chronic diarrhea. Has generalized muscle weakness and her 16 year old brother has similar symptoms. Has bilateral retinitis pigmentosa. Lab findings show erythrocytes with spiny projections and total serum cholesterol shows 40mg/dL. Which apolipoprotein is deficient in this patient?
Apo B: MTP is required for assembly and secretion of Apo B in the liver and GIT. Absence of Apo B means an inability to assemble IDL, VLDL and LDL. this causes malabsorption of dietary fats and fat soluble vitamins (ADEK), Subsequent symptoms lead to peripheral neuropathies.
COld inteolerance, firm, nodular thyroid gland, biopsy shows diffuse infiltration of lymphocytes with occasional lymphoid follicles. Most likely diagnosis?
Chronic autoimmune (Hashimoto) thyroiditis
Differentials: Granulomatous or viral thyroiditis:
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