tests 22 Flashcards
narcolepsy treatment
stimulants during the day (amphetamines, modafinil). nighttim sodium oxybate (GHB).
What is the chemical problem in narcolepsy?
not enough hypocretin (aka orexin) production by the lateral hypothalamus. these neuropeptides promote wakefulness and inhibit REM sleep-related phenomena. hypocretin-1 is measurable in the CSF (though not in narcoleptic people) but not in the serum.
Which immunoglobulins fix complement? What is the function of IgA and IgE?
IgM and IgG fix complement
IgA prevents attachment of bacteria and viruses to mucous membranes. it is a monomer in the circulation and a dimer when secreted.
IgE: binds mast cells and basophils. cross-links when exposed to antigen. mediates type I hypersensitivity. activates eosinophils.
Piriform recesses: where is it? relevant injuries?
small cavities on either side of the laryngeal orifice. they are bounded medially by the aryepiglottic folds and laterally by the thyroid cartilage and thyrohyoid membrane. a thin layer of mucosa overlying the piriform recess is all that protects the superficially coursing internal laryngeal nerve (branch of csuperior laryngeal nerve). It mediates cough reflex by carrying sensation from the mucosa superior to the vocal cords. it is easily injured when food gets stuck in the piriform recesses.
Describe normal gas exchange, including numbers
- ambient air has a pO2 around 160
- tracheal air has a pO2 around 150 (smaller because of partial pressure of water vapor).
- alveolar pO2 should be around 100 (or 104). This is the equilibration point between the pressure in the trachea and the pressure in venous blood (40). pCO2 in alveoli should be around 40 (between tracheal pressure- 0 mmHg- and venous pressure- 45 mmHg).
If equilibration occurs at it should, it is perfusion limited (limited by how much blood can flow through the lungs). If perfusion is poor, equilibrium will occur slowly or may not occur at all.
treatment for S. epidermids
IV vancomycin with gentamicin or rifampin or both. S epidermidis is usually resistant to methicillin (and cephalosporins, etc).
How do you reduce the likelihood of confounding in case-control studies? How is it different from selection bias?
MATCHING based on potential confounders.
primary biliary cirrhosis vs. primary sclerosing cholangitis
primary biliary cirrhosis: autoimmune reaction that causes lymphocyte infiltration and periductal granulomas. It usually involves middle aged women and is insidious in onset. It may begin with hepatosplenomegaly, choelestasis, itchiness at night. increased serum mitochondrial antibodies. may have high IgM.
primary sclerosing cholangitis: onion skin bile duct fibrosis, with beading of intra and extra hepatic ducts on ERCP. associated with hypergammaglobulinemia (IgM) and ulcerative colitis. can lead to secondary biliary cirrhosis and cholangiocarcionma. often pANCA positive.
What heart sounds are associated with ASD? VSD?
ASD: loud S1; wide, fixed, split S2.
VSD: may be associated feta alcohol exposure. causes turbulent high velocity blood flow across a small VSD, producing a loud, holosystolic murmur heard over the left sternal border of the third or fourth intercostal space.
murmur may be absent if the VSD is big enough.
Integrins: function, binding partners
integrins are membrane proteins that maintain ibasolateral membrane integrity by binding to collagen and laminin in the basement membrane. they also bind fibronectin, which helps mediate cell adhesion and migration.
post strep glomerulonephritis histo
hypercellular, inflammed glomeruli on H and E.
mediated by immune complex deposition with subepithelial humps on EM.
How do you treat DKA?
give SHORT ACTING, regular insulin. (this takes longer to work than rapid acting but is the second fastest). it will be continuous, IV regular insulin. regular insulin starts working within 30 min, peaks at 2-4 hrs, and lasts 5-6 hours
Other than hepatocellular carcinoma, what are three other important liver tumors?
- cavernous hemangioma: most common benign liver tumor. thought to be a congenital lesion that expands via ectasia (dilation). histo shows cavernous, blood filled vascular spaces lined by a single epithelial layer. biopsy is contraidicated because of bleeding risk.
- hepatic adenoma: rare but benign tumor. related to OCPs or anabolic steroids. may regress spontaneously or rupture (causing shock and abdominal pain).
- angiosarcoma: malignant tumor of endothelial origin related to exposure to arsenic or vinyl chloride.
What does the femoral nerve do? How would an injury present?
femoral nerve innervates the muscles responsible for flexion of the thigh at the hip (iliacus and sartorius muscles) and extension of the leg at the knee (quadraceps). It also supplies sensory innervation to the skin on the anterior thigh and medial leg. injury causes loss of knee reflex and anterior thigh sensory loss.
What muscles and nerves are involved in the Trendelenberg sign?
remember, trendelenberg means that the the hip dips toward the unaffected side when the patient stands on the affected leg. it is usually due to weakness of the gluteus medius and gulteus minimus, which are supplied by the superior gluteal nerve.
