2015.04.09 Flashcards by Amy Zhou

Rough endoplasmic reticulum functions

protein modification, folding, and transfer.

Synthesis of secretory proteins.

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Smooth Endoplasmic Reticulum

Lacks surface ribosomes, and functions in lipid synthesis, carbohydrate metabolism, and detoxification of harmful substances.

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Malignant Mesothelioma

Neoplasm that arises from the pleura or peritoneum.

Associated with asbestos exposure.

Hemorrhagic pleural effusions and pleural thickening are characteristic.

EM = gold standard: numerous, long, slender microvilli and abundant tonofilaments.

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Prostacyclin (Prostaglandin I2)

Produced from prostaglandin H2 by prostacyclin synthase in vascular endothelial cells

It vasodilates, inhibits platelet aggregation, and increases vascular permeability.

Opposes thromboxane A2.

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Thromboxane A2 (TXA2)

Prostaglandin that enhances platelet aggregation and causes vasoconstriction.

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Meyer’s Loop

Contains lower fibers of the optic radiation that carry information from the lower retin (upper/superior contralateral visual field)

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Lesions in Temporal Lobe

Disrupt Meyer’s loop - contralateral superior quadrantanopia.

Aphasia (dominant hemisphere lesions)

Memory deficits

Seizures (complex partial and tonic-clonic)

Hallucinations (auditory, olfactory, and visual)

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Delayed-type Hypersensitivity Reactions (DTH)

Include: contact dermatitis, granulomatous inflammation, tuberculin skin test and Candida extract skin reaction.

Mediated by T-lymphocytes.

Antigen is taken up by dendritic cells and presented to CD4 Th1-lymphocytes on MHC Class II. Th lymphocytes secrete IFN-r which recruit macrophages, leading to monocytic infiltration of the area where the antigen is introduced.

Takes 1 -2 days following antigen exposure.

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Hypersensitivity Types

Type I - IgE mediated (asthma, anaphylaxis)

Type II - Antibody mediated (ABO incompatibility hemolysis)

Type III - Immune complex (PSGN)

B-lymphocytes are involved. Stimulated by IL-4 release from Th2-lymphocytes.

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Alcohol Withdrawl Syndromes

Symptoms: Tremors, agitation, anxiety, delirium, psychosis

Exam findings: Seizures, tachycardia, palpitations.

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Benzodiazepine Withdrawal Syndromes

Symptoms: Tremors, anxiety, perceptual disturbances, psychosis, insomnia

Exam findings: Seizures, tachycardia, palpitations (same as alcohol ws)

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Opioid/Heroin Withdrawal Syndromes

Symptoms: NV, abdominal cramping, muscle aches

Exam findings: Dilated pupils, yawning, piloerection, lacrimation, hyperactive bowel sounds

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Stimulants (Cocaine, Amphetamines) Withdrawal Syndromes

Symptoms: Increased appetite, hypersomnia, intense psychomotor retardation, severe depression (“crash”)

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Nictoine Withdrawal Symptoms

Dysphoria, irritiability, anxiety, increased appetite/weight gain.

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Generalized Anxiety Disorder

Excessive worry over several different issues lasting at least 6 months.

Treated with antidepressants (SSRIs - paroxetine, sertraline; buspirone, venlafaxine) and benzodiazepines (short-term use)

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HIV Entry into Cells

HIV viruse uses CD4 protein as primary receptor and chemokine receptor CCR5 as a coreceptor.

CD4 and CCR5 are bound by the viral outer envelope protein gp120.

Deletion of both genes that code CCR5 results in resistance to HIV infection; one gene deletion leads to delayed manifestations.

Cricopharyngeal Muscle Dysfunction

Due to diminished relaxation of pharyngeal muscles during swallowing.

More force is required to move the food bolus down, thus increasing contractions which increase oropharyngeal intraluminal pressure.

Pharyngeal mucosa will herniate through muscle fibers in the zone of weakness and create a Zenker Diverticulum (false diverticulum).

Oropharyngeal dysphagia, coughing, choking, and recurrent aspiration.

Duodenal S-cells

Secrete secretin in response to increasing H+ concentrations.

Increases pancreatic bicarbonate secretion.

The chloride content of pancreatic secretions decreases in proportion to bicarbonate concentration increases.

Vasopressin (ADH)

V2 receptor-mediated increase in permeability to water and urea at the luminal membrane of the inner medullary collecting duct.

Coagulopathies vs. Platelet Defects

Coagulopathies present with deep-tissue bleeding (joints, muscles, subcutaneous tissue).

Platelet defects present with mucocutaneous bleeding (epistaxis, petechiae).

DNA Polymerases Proof reading activity

All 3 prokaryotic DNA polymerases have proof reading activity and remove mismatched nucleotides via 3’ to 5’ exonuclease activity.

DNA polymerase I has 5’ to 3’ exonuclease activity which is used to excise and replace RNA primers and damaged DNA sequences.

Rb gene

Tumor suppressor gene whose protein product regulates the cell cycle at the G1-S phase transition.

Inactivation mutations are found in retinoblastomas, osteosarcomas, and cancers of the breast, lung and colon.

RAS gene

Works with MAP kinase pathway to control cell proliferation.

Mutations found in follicular thyroid cancer and follicular adenomas.

Bcl-2

Anti-apoptotic gene that enhances cell survivial.

Expression is upregulated in many cancer cells.

Common in follicular lymphomas.

p53

Tumor suppressor gene like Rb. Inactivating mutations seen in anaplastic thyroid cancer.

RET proto-oncogene

Membrane-bound tyrosine kinase receptor involved in cell cycle regulation. RET mutations are common in sporadic medullary thyroid cancers.

Stages of Acute Tubular Necrosis

1. **Initiation stage** - ischemic injury to renal tubules precipitated by hemorrhage, acute MI, sepsis, surgery. 2. **Maintenance stage** - Decreased urine output, fluid overload, increasing creatinine/BUN, hyperkalemia. High anion gap metabolic acidosis. 3. **Recovery phase**: Gradual increase in urine output leading to high volume diuresis. Electrolyte abnormalities may include decreased concentrations of K, Mg, PO4, and Ca due to slowly recovering tubular function.

Methylmalonic Acidemia (Methylmalonic aciduria)

Defect in isomerization reaction (methylmalonyl CoA mutase + Vitamin B12) that transforms methylmalonyl CoA to succinyl CoA, prior to succinyl CoA entering the TCA cycle.

Lactic ACidosis in patients with septic shock

Tissue hypoxia results in impaired oxidative phosphorylation and shunting of pyruvate to lactate following glycolysis. Hepatic hypoperfusion also contributes to the buildup of lactic acid, as the liver is the primary site of lactate clearance.

Cystic Fibrosis and Steatorrhea/Failure to Thrive

Due to malabsorption secondary to pancreatic insufficiency, which can be corrected by pancreatic enzyme supplementation.

Nitroglycerin

Acts as a venodilator. Decreases preload which decreases myocardial oxygen demand and thereby treats angina pectoris.

Streptococcus Bovis

Nonenterococcal Group D streptococci Part of normal flora. Bacteremia or endocarditis is associated with colon cancer. S. bovis endocarditis occur do so in patients with no preexisting valvular abnormality.

Ethambutol

Effective component of the multi-agent antibiotic regimen used in the treatment of M. tuberculosis and atypical mycobacterial infections. Side effect: optic neuritis. Decreased visual acuity, central scotoma, or color-blindness. (Reversible with discontinuation)

Isoniazid

Antimycobacterial agent that specifically inhibits the synthesis of mycolic acids. Mycolic acids are essential components of the unique mycobacterial peptidoglycan cell wall. Without mycolic acids, they lose their acid-fastness and become unable to synthesize new cell walls or multiply.

Isoniazid and Pyridoxine (Vitamin B6)

Chemically similar. Isoniazid can compete with vitamin B6 in the synthesis of multiple neurotransmitters, resulting in defective end products. Clinically manifests as peripheral neuropathy. Vitamin B6 needed in conjunction in elderly, alcoholics, or kidney/liver dysfunction.

Fragile X Syndrome

Second most common cause of genetic mental retardation in males after Down syndrome. Dysmorphic face (long, thin, prominent forehead and jaw), large testes, large protruding ears, tooth crwoding, arched palate. Mutation in FMR1 gene on X-chromosome. \>200 CGGG repeats leads to hypermethylation of cytosine bases and gene inactivation.

Acanthosis Nigricans (AN)

Hyperkeratotic, hyperpigmented plaques with a classic "velvety" texture in flexural areas. Skin tags (acrochordons) are pedunculated outgrowths of normal skin that are commonly present. Associated with insulin-resistant states (diabetes mellitus, acromegaly, obesity) and GI malignancies.