Uworld29 Flashcards
Late onset familial Alzheimer disease is associate with?
apoplipoprotein E4 genotype
Dysfunction of CNIII leads to?
The oculomotor nerve (CNIII) provides innervation to many of the extraocular muscles (superior rectus, medial rectus, inferior rectus, inferior oblique), parasympathetic innervation to the pupil, and somatic innervation of the levator palpebrae superioris.
Dysfunction of CN III leads to a characteristic triad of a “down and out” pupil, an efferent pupillary defect, and ptosis.
When can angiosarcomas occur?
Angiosarcomas classically occur after the treatment of breast cancer from either radiation exposure or chronic lymphedema with firm, violaceous nodules on the ipsilateral extremity.
Lack of vitamin D effect (eg, vitamin D def, vitamin D receptor mutation) causes?
hypocalcemia due to inadequate calcium absorption.
The compensatory rise in parathyroid hormone causes increased bone resorption, renal calcium reabsorption, and renal phosphorus wasting.
PTH also induces 1-alpha-hydroxylase acitivty, leading to elevated 1,25-dihydroxyvitamin D levels.
What is orthostatic hypotension?
a frequent cause of lightheadedness and syncope and is define as a decrease in systolic (>20 mmHg) or diastolic (>10mmHg) blood pressure on standing from the supine position.
Medications (alpha-1 adrenergic antagonists, diuretics), volume depletion, and autonomic dysfunction are common causes of orthostatic hypotension.
What is infantile hemangioma?
a common, benign vascular tumor that presents soon after birth as a bright red, raised, sharply demarcated plaque.
The natural course of hemangiomas is proliferation in infancy followed by regression in early childhood.
What is myositis ossificans?
characterized by the formation of lamellar bone in extraskeletal tissues (ie, heterotopic ossification), often triggered by trauma.
It typically presents as a painful, firm, mobile mass within a muscle (eg, quadriceps).
Histo: benign metaplastic bone and proliferating fibroblasts without mitotic atypia.
What is EBV mononucleosis?
Presents as fever, pharyngitis, lymphadenopathy, splenomegaly, and atypical lymphocytosis.
EBV is generally transmitted from an asymptomatic virus shedder to a susceptible individual through saliva transfer (eg, kissing)
Which tumors can present at the cerebellopontine angle?
Tumors at the cerebellopontine angle can cause unilateral progressive hearing loss due to compression of the vestibulocochlear nerve (CNVIII).
These tumors are most likely vestibular schwannomas or meningiomas.
MOA of ethosuximide
prevents neuronal burst firing by blocking thalamic T-type Ca2+ channels.
The first line treatment for absence seizures.
MOA of phenytoin, carbamazepine, and valproic acid
inhibit high frequency neuronal firing by blocking Na+ channels.
The contractile mechanism in skeletal muscle depends on?
proteins (myosin II, actin, tropomyosin, and troponin) as well as calcium ions.
What can be injured when you horizontally transect the rectus abdominis muscle?
Horizontal transection of the rectus abdominis muscle must be performed with great caution as the inferior epigastric arteries enter this muscle at the level of the arcuate line.
The inferior epigastric arteries below the arcuate line are susceptible to injury (eg, hematoma) due to lack of a supporting posterior rectus sheath.
What is the power of a study?
indicates the probability of seeing a difference when there is one.
The formula is Power= 1- beta, where beta is the type II error rate.
What are the labs seen in lactose intolerance?
Lactose intolerance presents with flatulence, crampy abdominal pain, and watery diarrhea after dairy product consumption.
It can be acquired by inflammatory/infectious conditions that injure the mucosal brush border of the small intestine where lactase is expressed.
Studies can show increased breath hydrogen content, reduced stool ph, and elevated stool osmolality.
What is acute monoarthritis?
characterized by pain, erythema, swelling, and reduced range of motion in a joint.
It may represent serious pathology such as septic arthritis, especially if accompanied by fever.
Urgent synovial fluid analysis should be performed to evaluate for infection.
Atherosclerosis is initiated by?
repetitive endothelial cell injury, which leads to a chronic inflammatory state in the underlying intima of large elastic arteries as well as in large and medium sized muscular arteries.
Traits of pseudomonas
nonlactose-fermenting, oxidase+, motile, gram-negative rod.
What is the most common cause of malignant otitis externa?
Pseudomonas.
MOE is a serious infection of the ear seen in elderly diabetic patients.
Presents with exquisite ear pain and drainage, and granulation tissue is often seen within the ear canal.
What is seen on physical examination of pulmonary hypertension?
A loud pulmonic component of S2 and an accentuated, palpable impulse at the left sternal border (left parasternal lift due to right ventricular heave)
Umbilical hernias are caused by?
a defect in the linea alba and present as protrusions at the umbilicus that are soft, reducible, and benign.
They can occur in isolation or in association with other conditions (eg, Down syndrome)
What are the 3 types of population pyramids?
expansive= young and growing population, high birth and mortality rates
stationary= stable population, declining birth rates and low mortality rates
constrictive= shrinking population, significantly low birth and mortality rates
How does glucocorticoids effect bone?
Chronic or recurrent glucocorticoid (eg, prednisone) use can lead to loss of bone density.
Glucocorticoids inhibit replication and differentiation of osteoblast precursor cells, increase osteoclast activity, and promote intestinal and renal calcium wasting.
What is buprenorphine?
a semisynthetic opioid with mixed/partial agonist-antagonist activity, resulting in a therapeutic ceiling.
Relative to full opioid agonists, this reduces the risk of dose-dependent adverse effects such as respiratory depression
Innervation of external hemorrhoids
External hemorrhoids, which originate below the dentate line, are covered by modified squamous epithelium and have cutaneous (somatic) nervous innervation from the inferior rectal nerve, a branch of the pudendal nerve.
What confirms the diagnosis of menopause?
Menopause occurs on average at age 51 and is diagnosable retrospectively after 12 months of amenorrhea.
An elevated serum FSH level confirms the diagnosis.
Lymphatic drainage of the rectum proximal to the anal dentate line occurs via?
the inferior mesenteric and internal iliac lymph nodes.
Lymphatic drainage of the rectum distal to the dentate line drain primarily into?
inguinal nodes.
What uses the JAK-STAT pathway?
Growth hormone binds to cell surface receptors, leading to intracellular activation of the JAK-STAT pathway.
Cytokines (eg, interferon) and hematopoietic growth factors (eg, erythropoietin, G-CSF) also use this pathway.
Function of tumor necrosis factor-alpha
TNF-alpha is released from activated macrophages and is one of the most important mediators of the systemic inflammatory response in sepsis.
Other cytokines responsible for inducing the systemic inflammatory response include IL-1 and IL-6
Patients with severe burn injury commonly develop?
a hypermetabolic response that results in an increased basal metabolic rate and often lean muscle wasting.
Administration of oxandrolone, a synthetic testosterone analogue, enhances muscle protein synthesis and decreases protein catabolism, reducing lean muscle loss.
Primary (idiopathic) membranous nephropathy is associated with what antibodies?
IgG4 antibodies to the phospholipase A2 receptor, which might play a role in the development of the disease.
Antibody titers are useful for diagnosis and correlate with disease activity.
What causes an accessory nipple?
Incomplete involution of the mammary ridge during fetal development can lead to an accessory nipple, a well-circumscibed, hyperpigmented papule located anywhere from the axilla to the thigh.
Similar to hormone induced changes in normal breast tissue (eg, due to puberty/menses), they may grow larger and become tender/swollen
What causes gynecomastia in men with hypogonadism (low testosterone)?
The adrenal cortex produces estrogen precursors (eg, androstenedione, dehydroepiandristerone (DHEA), DHEA sulfate, which are subsequently aromatized to estrogens in peripheral tissues
In men with hypogonadism, the resulting elevation in the estrogen/testosterone ratio can produce gynecomastia.
Black gallstones form due to?
supersaturation of the bile with bilirubin, which precipitates with calcium to form calcium bilirubinate stones.
This typically occurs in the setting of chronic hemolysis (eg, sickle cell disease) or altered enterohepatic circulation of bilirubin (eg, Crohn disease, ileal resection)
What is the cause of cholelithiasis in women who are pregnancy or using oral contraceptives?
Estrogen induced cholesterol hypersecretion and progesterone induced gallbladder hypomotility
What should be implemented in patients receiving chronic red blood cell transfusions?
Chelation therapy with deferoxamine.
Deferoxamine prevents iron-induced cardiotoxicity and congestive heart failure from developing in this patient population.
Acute lesions to the cerebellar vermis typically cause?
truncal and gait ataxia due to impaired modulation of the medial-descending moto systems.
Involvement of the lower vermis and the flocculonodular lobe also causes vertigo/nystagmus due to dysregulation of the vestibular nuclear complex.
Massive, life-threatening hemoptysis is typically due to?
hemorrhage from the high-pressure bronchial circulation.
Bronchiectasis is a common etiology because chronic airway inflammation causes hypertrophied bronchial arteries that are prone to rupture with coughing.
What is syringomyelia?
The combination of fixed segmental loss of upper extremity pain and temperature sensations, upper extremity lower motor neuron signs, and/or lower extremity upper motor neuron signs in the setting of scoliosis suggests syringomyelia.
