uWorld 25 Flashcards
what defines a sarcomere
the distance between two Z lines
the thin ACTIN filaments in the I BAND (light color surrounding darkest line) are bound to structural proteins at the Z LINE (darkest line on EM)
what part of the sarcomere is always the same length during muscle contraction
A band (myosin filaments in the sarcomere)- region contains the overlap of myosin and actin as well as non-overladed myosin
(H band is ONLY MYOSIN)
(M Line is light parallel lines on EM in A band = where myosin anchors to structural elements) in MIDDLE of sarcomere)
what is the most common cause of retinal artery occlusion (cause of acute, painless, monocular vision loss)
thromboembolic complications of atherosclerosis in the INTERNAL CAROTID
(retinal artery is branch of ophthalmic artery, which is a branch off the internal carotid)
retinal artery travels with retinal nerve to supply INNER RETINA and the SURFACE of the OPTIC NERVE
4 yr old with recurrent skin and respiratory infections
light skin and silvery hair
horizontal nystagmus
giant cytoplasmic inclusions in neutrophils and monocytes
the fuck he got?
CHEDIAK-HIGASHI Snydrome
Autosomal RECESSIVE
neurologic defects: nystagmus, peripheral and cranial neuropathies
defect in neutrophil phagosome lysosome fusion (large CYTOPLASMIC INCLUSIONS)
recurrent PYOGENIC (staph and strep) infections
abnormal MELANIN STOREAGE in melanocytes causes PARTIAL OCULOCUTANEOUS ALBINISM
complete albinism presents how and is due to what
lack of TYROSINASE
white hair, blue eyes and pink or white skin
what skin lesions are seen in sarcoidosis, also what part of the liver is fucked up by the granulomas
subcutaneous nodules (erythema nodosum), erythematous plaques, macules that are slightly reddened and scaling
PORTAL TRIADS fucked more than lobular parenchyma
when is hepatic centrilobular necrosis seen
death of hepatocytes immediately surrounding the terminal hepatic vein
ISCHEMIC INJURY (as in right sided heart failure), drugs, toxins, and fulminant hepatitis
portal hepatic fibrosis is a pathologic finding seen in what
CHRONIC viral hepatits
what is the major cause of morbidity in sarcoidosis
pulmonary fibrosis, which can progress to COR PULMONALE
what does klebsiella granulomatis cause
granuloma inguinale (donovanosis)
painLESS GENITAL papule that eventually ulcerates
lymphadenopathy is UNCOMMON
deeply staining gram-negative intraCYTOPLASMIC cysts (DONOVAN bodies) are diagnostic
base may have GRANULATION TISSUE
how is lymphogrnauloma venereum (LGV) caused by Chlamydia treated
DOXY
oral thrush is common in people with what
denture wearers diabetics immunosuppressed steroids antibiotics chemotherapy
if patient seems normal- proly HIV and immunocompromised
hospice care requires what
prognosis of LESS THAN or equal to 6 MONTHS
what is systemic mastocytosis
clonal mass cell proliferation occurs in the bone marrow, skin, and other organs
often assisted with mutation in the KIT receptor TYROSINE KINASE
prominent expression of mast cell TYRPTASE
excessive HISTAMINE release mediates symptoms:
syncope, flushing, hypotension, pruritus, urticaria, maculopapular rash
GASTRIC ACID SECRETION- ULCERS and inactivated pancreatic and intestinal enzymes (DIARRHEA)
can also have nausea, vomiting, and cramps
what is special about the bronchial circuit (supplies oxygen and nutrients to pulmonary parenchyma)
drains mostly to LEFT ATRIUM as opposed to right atrium
creates a RIGHT-to-LEFT shunt that acts as a partially independent circuit from the pulmonary-systemic circuit
what balance is necessary to maintain continuous blood flow through the body (and exists at both rest and during exercise)
volume of output of the left ventricle must closely match the output of the right ventricle
(blood flow per minute in systemic circulation should be the same as pulmonary)
what change in the post-synaptic cell most likely explains myasthenia gravis
decreased ability of acetylcholine to bind and open post synaptic cation channels, thereby DECREASING the END-PLATE POTENTIAL and preventing the formation of muscular action potentials
(also see a reduction in compound action potential with repeated excitation)
what drugs are used to reduce the side effects caused by acetylcholinesterase inhibitors in myasthenia gravis
SCAPOLAMINE (anti muscarinic so it stops acetylcholine actions at M receptors but leaves the NMJ nicotinic receptors needed for treatment alone)
HYOSCYAMIN
what does the frontal eye field do
Brodmann areas 6 and 8
found near the caudal end of the middle frontal gyrus anterior to the pre central sulcus
damage causes EYES to DEVIATE to the IPSILATERAL SIDE
what is the lymph drainage of the male genitals
testis: para-aortic
glans penis (and superficial nodes): deep inguinal nodes (drain to external iliac nodes)
scrotum: superficial inguinal nodes
the inferior mesenteric nodes receive lymph form where
descending and sigmoid colon
upper rectum
(efferents drain into the pre-aortic nodes)
what passes through the inferior orbital fissure but do not enter orbit
V2 (maxillary branch)
infraorbital vessels
branches of sphenopalatine ganglion
the foramen rotunda transmits what
maxillary division (V2) from the skull to the pterygopalatine fossa
from there it courses through the inferior orbital tissue to appear on the face at the infraorbital foramen as the infraorbital nerve
what foramen is occluded by cartilage
foramen lacerum
internal carotid courses just superior to foramen lacerum in the lacerum portion of the carotid canal
what passes through the foramen ovale
V3 (mandibular branch)
what goes through the foramen spinosum
middle meningeal artery
what is seen in Treacher-Collins Syndrome (TCS)
fucked up 1st and 2nd pharyngeal arches
often get airway compromise and feeding difficulties from craniofacial abnormalities (mandibular, maxillary, and zygomatic bone hypoplaisa; muscles of mastication and facial muscle loss)
also have CONDUCTIVE hearing loss form absent or abnormal ossicles (incus, malleus, stapes)
where are the neuritic plaques found in alzhemiers
medial temporal lobe (hippocampus, amygdala, entorhinal cortex)
central amyloid beta core surrounded by dystrophic neuritis
the neurofibrillary tangles are in the neuronal cytoplasm (HYPERPHOSPHORYLATED TAU)
what is the difference between ADHD and a learning disorder
ADHD has to show inattention and/or hyperactivity/impulsivity across at LEAST 2 SETTINGS (multiple subjects, at home and school)
learning disorders can present with anxiety, inattention, or hyperactivity when under stress- like doing the subject they struggle in
what are the levels of cholesterol, bile acids, and phosphatidylcholine in patients with cholesterol gallstones (echogenic foci on ultrasound)
cholesterol: ↑
bile salts (or acids): ↓
phosphatidylcholine: ↓
(high levels of bile salts and phosphatidylcholine increase cholesterol solubility and decrease the risk of gallstones)
what is the rate limiting step of bile acid synthesis
cholesterol 7alpha-hydroxylase
starts series of chemical reactions that covers cholesterol into chalice and chenodeoxycholic acids
bile acids conjugated to GLYCINE or TUARINE to create bile slides
what change in MITRAL valve STENOSIS indicates a more SEVERE murmur (most reliable indicator of degree of stenosis)
if the opening snap is closer to A2 (time interval decreases)
done via mean transvalvular pressure gradients via 2-D Doppler echocardiography
if pre-systolic accentuation (due to left-atrial contraction) of the mitral valve stenosis disappears what does that indicate
the mitral valve stenosis has become bad enough to precipitate ATRAIL FIB
reddish color urine that darkens on standing is seen in what
acute PORPHYRIES
ari and light and air exposure oxidize the excess PBG (porphobilinogen)
what is seen in acute intermittent porphyria (what causes it)
AD deficiency in PORPHOBILINOGEN (PBG) DEAMINASE
accumulation of: porphobilinogen and delta-ALA, corporphobilinogen (urine)
Symptoms: 5 P's Painful abdomen Port wine-colored URINE Polyneuropathy Psychological disturbances Precipitated by drugs (CYp450 inducers), alcohol, and starvation
TX: GLUCOSE (or dextrose) and HEME (both INHIBIT ALA SYNTHASE)
how does botulism toxin work
prevents pre-synaptic release of acetylcholine
acute GI hemorrhage or diarrhea would cause what kind of fluid loss
ISOSMOTIC VOLUEM CONTRACTION
isotonic loss of ECF volume
no effects on osmolarity or ICF volume
what happens to the fluid compartment levels in adrenal insufficiency
HYPOSMOTIC VOLUME CONTRACTION (hypertonic loss of NaCl with some extracellular volume loss)
low osmolarity of ECF results in SHIFTING of free water into the ICF compartment, causing ICF expansion
what does infusion of large amounts of hypertonic saline do to the ECF and ICF (volume and osmolality)
HYPERTONIC VOLUME EXPANSION
both the volume and osmolarity of ECF are increased
high osmolarity of ECF leads to SHIFTING of water from from the ICF, further INCREASING the ECF volume
primary polydipsia does what to ECF and ICF (volume and osmolarity)
HYPOOSMOTIC VOLUME EXPANSION
expansion of both ECF and ICF compartments and decrease in the osmolarity of both
apparently also seen in SIADH but that should be euvolemic hypernatremia
prolonged use of NSAIDs can cause CHRONIC INTERSTITIAL NEPHRITIS, what is seen histologically
NSAIDs concentrate in renal medulla along the medullary osmotic gradient, with higher levels in the papillae
fibrosis
tubular atrophy
papillary necrosis and scarring
caliceal architecture distortion (calcifications)
NSAID also decrease prostaglandin synthesis, causing constriction of medullary vasa recta and ISCHEMIC PAPILLARY NECROSIS
GH binds what receptor
JAK/STAT pathway
(non receptor tyrosine kinase (JAK) with docking sites for signal transducer and activator of transcript (STAT))
in this case (with GH) STAT dimerizes and translocates into nucleus where it activates IGF-1 gene transcription by binding the promoter site
(cytokines like interferon and hematopoietic growth factors like erythropoietin and G-CSF use JAK-STAT pathway too)
what antibiotic has good coverage of ORAL ANAEROBES and covers Strep Pneumo too (good for lung abscess in alcoholic or seizure person)
CLINDAMYCIN (antibiotic of choice for lung abscess)
covers oral anaerobes: Bactericides, Prevotella, Fuscobacterium, Peptostreptococcus)
also covers AEROBIC bacteria
what is seen in McCune-Albright syndrome
cafe-au-alit spots (unilateral) endocrine abnormalities (precious puberty, hyperthyroidism) fibrous dysplasia (multiple osteolytic-appearing lesions of hip and pelvis)- from activation of fibroblast, IL-6 and osteoclasts
mosaic somatic mutation in GNAS gene encoding the stimulatory ALPHA SUBUNIT of G PROTEIN
constitutive ACTIVATION of ADENYLATE CYCLSE leads to OVERPRODUCTION of several hormones
what is Legg-Calve-PErthes disease
disease of young children that results in ISOLATED IDIOPATHIC OSTEONECROSIS of the HIP
what is omalizumab
monoclonal antibody (IgG1) to IgE
what is bortezomib
proteasome inhibitor
used to treat MULTIPLE MYELOMA and Waldenstrom macroglobulinemia
left circumflex occlusion would be seen in what leads
V6 and V6 (possibly I and aVL)
LAD occlusion is seen in what leads
V1 and V2 for interventricular septum
V3 and V4 for anterior left ventricular wall
rightt coronary occlusions are seen in what leads
II, III and aVF
supplementation with what can reduce erythroid precursor cell apoptosis in things with folic acid deprivation
THYMIDINE (can use the salvage pathway using thymidine kinase to partially compensate)
folate is necessary for THYMIDYLATE SYNTHETASE (THF + dUMP = DHF + dTMP)
what are homocysteine levels like in folate defieicency
elevated (can be reduced by folate deficiency)
