Block 37 Flashcards
First and second Pharyngeal arches
The first pharyngeal arch is associated with CN V. It bony derivatives include the maxilla, zygoma, mandible, incus and malleus, its muscular derivatives include masseter and temporalis.
Second pharyngeal arch is associated with CN VII, give rise to stylod process of temporal bone, lesser horn of hyoid (the greater derived from 3rd) and stapes.
Tracher collins syndrome
Genetic disorder resulting in abnormal development of 1st and 2nd pharyngeal arches.
-craniofacial abnormalities and often result in airway compromise and feeding difficulties. In addition absent or abnormal ossicles lead to profound conductive hearing loss.
Large PDA
-they can present anytime during childhood with progressive pulmonary hypertension and reversal of the shunt to right to left.
-the characterestic continous murmur decreases as the pulmonary pressure rises and ultimately disappears.
Typical consequence include HF and eisenmenger syndrome.
-the cyanosis and clubbing are most pronounced in the lower extremities because PDA delivers unoxygeneated blood distal to subclavian artery.
Proximal tubular cell ballobning and vacuolar degeneration , presence of oxalate crystals
- the presence of oxalate crystals in the tubular lumen is highly suggestive of ethylene glycol poisoning.
- its rapidly absorbed from the GI tract and metabolized to glycolic acid which is toxic to renal tubules.
- patients initially manifests with toms of ethanol intoxication, signs of AKI develops about 24-72 hours later with high anion gap metabolic acidosis and osmolar gap also typically seen.
Liquefactive necrosis is seen in
- focal bacterial infections that stimulate massive leukocytes
- CNS infarcts due to the lack of substantive supporting stroma.
Train of four stimulation
-its used during anesthesia to asses the degree of paralysis induced by NMJ blocking agents.
-PNS is stimulated 4 times in quick succession and muscular response is recorded.
The highest of each bar represent the strength of each twitch, higher bars indicaties activation of increasing numbers of individual muscle fibers.
-nondepolarizing NMJ blocker such as vecuronium leads to progressive reduction in each of the 4 responses, fading pattern as a result of less Ach being released.
-depolarizing blockers such as succinylcholine initially function by preventing repolariztion of motor endplate and show equal reduction of all 4 twitches during TOF stimulation.
Succinylcholine
Commonly administred for rapid sequence intubation due to the rapid onset. The duration of action is determined by its metabolism by plasma cholinesterase and is typically <10 minutes.
-however some patients are homozygous for an atypical plasma cholinesterase —> in these patients blockage might perisit for hours and mechanical ventilation is necessary.
PE leads to which acid base disorders
PE causes hypoperfusion of affected parenchyma —> V/Q mismatch —>hypoxemia stimulate respiratory drive —> hyperventilation (whoch cant significantly improve blood oxygeneation) —> it decreases CO2 —> respiratory alkalosis with normal bicarbonate levels in the first 48 hours (no compensation).
Sternous exercise changes
Increase oxidative metabolsim of glucose and FA in skeletal muscle —>muscle increase their rate of O2 consumption and CO2 production.
-these increase are balanced by increases of the cardiac output/skeletal muscle perfusion and ventilation, respectively.
Homeostatic mechanisms maintain arterial O2 and CO2 contents and arterial PH near normal resting valeus, but there are significant changes in venous blood O2 and CO2 and PH.
Small cell lung carcinoma stains
Show evidence of neuroendocrine differentiation. These tumors stain for neuroendocrine markers such as neural cell adhesion molecules (NCAM (CD65)), neuron specifc enolase , chromogranin and synaptophysin.
Some small cell carcinoma express neurofilaments.
Nephrotic syndrome pathogenesis in edema
2 mechanisms , underfilling and overfilling contribute to the pathogenesis of edeme in nephrotic syndrome
The underfilling mechanism is particulary significant in minimal change disease in children and presents as follows:
1. Increased glomelular capillary permability to plasma proteins leading to loss of protein in urine
2. The large decrease in serum albumin causes a drop in intravascular oncotic pressure which results in fluid moving into the interstitial space and edema formation
3. The fluid shift results in intravascular volume depletion which triggers the RAAS system to increase aldosterone synthesis and ADH secretion. The result is intavascular sodium and water retention.
The fluid leaks back out into the interstitial space due to the low oncotic pressure exacerbating the edema.
4. Low intravascular oncotic pressure stimulates increased in lipoprotein production in the liver. Impaired catabolism due to decreased LPL and abnormal transport of circulating lipid particles leads to hyperlipidemia
Clamydia - lemphogranuloma venorum (LGV)
Serotypes A-C causes ocular infection (trachoma ) in children
Serotype D-K causes urogenital infections and inclusion conjunctivitis
L1-L3 causes lymphogranuloma venereum.
LVG charactrized initially by painless ,small shallow genital ulcer containing infected cells.
-painless nature helps distinguish LGV from other disease.
-the appearance of the ulcer is followed weeks later by swollen, painful, coalescing inguinal nodes (“buboes”) that can develop stellate abscess and rupture.
-if left untreated LGV can cause fibrosis, lymphatic obstuction and anogenital strictures and fistulas.
-histology shows contain areas of mixed granulomatous and neurophilic inflammation with intracytoplasmic chlamydial inclusion bodies in epithelial and inflammatory cells.
-Tx doxycycline.
Beta blockers effect on kidney (atenelol)
- at low doses atenolol is a selective B1 Adrenergic antagonist.ß1 receptors are found in cardiac tissue and on renal juxtaglomelular cells, but not in vascular smooth muscle.
- ß1 receptor is a G protein coupled receptor associated with Gs which increases intracellular cAMP levels. Blockade of the ß1 receptors leads to decreased cAMP levels in cardiac and renal tissue without significantly affecting cAMP levels in vascular smooth muscle.
- GPCRs comprise a large family of 7 transmembrane domain receptors that activates intracellular second messenger system involving GPCRs:
1. CAMP signaling pathway: the activated Gs a subunit activates the enzyme adenylyl cyclase which catalyzes the conversion of ATP into cAMP. Elevated cAMP leads to the activation of protein kinase A. Conversely, the Hi a subunit inhibit adenylyl cyclase therby reducing cAMP.
2. Phosphatidylinostiol signaling pathway: the activated Gq a subunit activates phospholipase C which degrades membrane lipids into DAG and IP3. Protein kinase C is activated by DAG, and Ca+ is released from SR under the influence of IP3.
Osteomyelitis hematogenous spread
- Presenting symptoms are vague and a high index of suspicion is required to make the diagnosing.
- initial symptoms such as malaise and fevers are non-specific.
- as the infection progress, infants and younger children may refuse to move the affected extremity.
- older children complain of pain over a long bone.
- bone pain develops as the abscess expands within the bone, leading to bone necrosis periosteal disruption and swelling of the surrounding soft tissue.
- s.aureus is implicated in most cases of acute hematogenous osteomyelitis in otherwise healthy children.
C.difficile colitis pathogenesis
Disruption of intestinal flora.
- toxina A and toxin B (cytotoxin) act synergistically in c.difficle colitis pathogenesis. Toxin inactivates Rho regulatory proteins involved in signal transduction and actin cytoskeletal structure maintenance.
- as a result the toxin cause disruption of intercellular tight junction leading to cell rounding/reaction as well as increased intestinal fluid secretion.
