6/7 UWorld Flashcards
What structure is cut during a midline episiotomy
Perineal body
Midline episiotomy is a vertical incision from the posterior vaginal opening to the perineal body
Itr transects the vaginal submucosal tissue but not the external anal sphincter or the rectal mucosa
Describe the pathogenesis of Zenker diverticulum
- Thought to be due to abnormal spasm or diminished relaxation of pharyngeal muscles during swallowing
- Increased oropharyngeal intraluminal pressure eventually results in herniation of the pharyngeal mucosa through a zone of muscle weakness (false diverticulum) in the posterior hypopharynx
- Pulmonary aspiration of diverticular contents may lead to recurrent pneumonia
What causes differentiation of Th0 cells into Th1 cells
What is produced by Th1 cells
What inhibits differentation of Th1 cells
- Th1 cells
- Differentiation caused by IL-12 (secreted by macrophages)
- Produces IL-2 and IFN-y
- Inhibited by IL-10
What causes differentiation of Th0 cells into Th2 cells
What is produced by Th2 cells
What inhibits differentiation of Th2 cells
- Th2 cells
- Differentation caused by IL-4
- Produces IL-4, IL-5, IL-10
- Inhibited by IFN-y
The most common mutation of CFTR gene causes a defect in what process?
- Most common mutation (deltaF508) causes impaired post-translational processing of CFTR, which is detected by the ER, causing the abnormal protein to be targeted for proteasomal degradation, preventing it from reaching the cell surface
What is the presentation of a lesion to the dominant parietal cortex
- Gerstmann syndrome
- agraphia (inability to write)
- acalculia (inability to calculate)
- finger agnosia (inability to distinguish fingers)
- left-right disorientation
What is the treatment for organophosphate poisoning
Organophosphates are cholinesterase inhibitors found in pesticide = increased ACh
Treatment:
- Atropine
- Competitively binds ACh receptors
- Pralidoxime
- Sketchy = lid on toxic spray
- Regenerates acetylcholine esterase
What receptor does Clonidine work on
a1 agonist
Describe the receptors that dopamine acts on
D-B-A order of activation
Low doses of DA = DA receptors
Medium doses = Beta receptors
High doses = Alpha receptors
What receptors does Epinephrinw work on
Beta > alpha agoinst
Predominantly beta at low doses
More alpha at higher doses
What is the drug of choice for anaphylaxis
Epinephrine
What is the drug of choice for septic shock
Norepinephrine
What are the 2 main clinical uses of selective alpha-1 antagonists
HTN
BPH
What is the MOA of Acebutolol and Pindolol
Sketchy:
- Agonizing plastic bugle
- Agonizing pin
MOA: are partial beta-agonists, but funciton as beta blockers because their action on beta receptors is so low, and still prevents the binding of ligands that would strongly activate these receptors
What are the 2 drugs that act as beta-blockers and alpha-1 antagonists
Carvedilol (used in chronic heart failure)
Labetolol (used in HTN in pregnancy, hypertensive emergency, acute aortic dissection)
What is receptor does alpha-methydopa effect?
Alpha-2 agonist and analog of L-DOPA
Used to treat gestational HTN
Describe the steps of catecholamine synthesis (from phenylalanine to norepinephrine), including enzymes
What are the layers of the glomerular filtration barrier and which layer is responsible for size/charge?
- Fenestrated capillary endothelium
- Size barrier
- Basement membrane
- Negatively charged (contains heparin sulfate) and size barrier
- Podocyte foot process
- Visceral layer of Bowman’s capsule
- Negative charge layer
Describe the fluid composition/compartements of the body
- 60-40-20 rule
- 60% of body mass is water, of that 60%:
- 40% is ICF
- 20% is ECF
- Only 25% of ECF is plasma
What substance is used to measure renal plasma flow
- Renal plasma flow
- RPF = Blood going to the glomeruli + blood going to the tubules
- Can be estimated with PAH (Clearance of PAH > GFR)
When does glucose begin to appear in the urine
- Glucose is completely reabsorbed up until plasma glucose level ~200 mg/dL
- This is when glucosuria begins (threshold)
- At ~375 mg/min, all transporters are fully saturated
Describe the rates of absorption in the proximal tubule of:
Na+, Cl-, K+, HCO3-, Urea, Glucose, Inulin, amino acids, creatinine, and PAH
Be able to graph these on a Tubular fluid / plasma filtrate graph (specifically is HCO3- more reabsorbed or secreted?)
- Anything that falls below the horizontal line (1.0) – more of that soluble is being absorbed relative to water
- Anything that falls below the horizontal line – less of that solute is being absorbed relative to water
- The reason that Creatinine and Inulin levels within the tubule are rising is because they are not reabsorbed, but water is, so their relative levels go up
- PAH is not being reabsorbed and is also being secreted into the tubules
- Interpretation of graph:
- PAH is freely filtered and secreted
- Creatinine is also freely filtered but not secreted as much as PAH
- Inulin is freely filtered but not secreted or reabsorbed
- Clearance of Inulin = GFR
- Urea is freely filtered and poorly reabsorbed
- Na+ and K+ are reabsorbed at the same rate of water so their concentrations remain constant
- HCO3- is actively reabsorbed due to carbonic anhydrase
- Glucose and amino acids are almost 100% reabsorbed in the proximal tubule
What part of the nephron are divalent cations (Mg2+ and Ca2+) reabsorbed and how?
Thick ascending loop
- Indirectly induces reabsorption of Mg2+ and Ca2+
- K+ enters the cell from the lumen via NKCC but then leaks back into the lumen, giving the lumen a slight positive charge
- Cations flow from lumen into cell down the electric gradient
Describe how you get euvolemic hyponatremia in SIADH
Increased ADH leads to excessive water retention
Body responds to water retention with decreased renin and aldosterone, increased ANP and BNP
Causes increase urinary Na+ secretion - Euvolemic hyponatremia
