Block 30 Flashcards
Multiple myeloma effect on Ca+ metabolism
Hypercalcemia in MM is the result of osteolysis induced by tumor cells, which release osteoclast activating factor.
- elevation of Ca+ leads to decreased PTH —> low levels of PTH -> increased Ca+ in urine.
- hypercalcemia and light chain nephropathy in MM causes progressive renal failure. This leads to depletion of 1a hydroxylase, the activity of which is already supressed by hyperphosphatemia and low PTH —> low 1,25 dihydroxyvitamin D levels
PTH related protein
Its the most common cause of hypercalcemia in malignancy.
Nitrates side effects
Main adverse effects seen are
- headache
- cutaneous flushing
- lightheadedness
- hypotension
- reflex tachcardia.
Anaphylaxis
Triggers:
-food
-medication
-insect stings
Clinical manifestation:
-cardiovascular -> hypotension and edema with tachcarida
-respiratory -> stridor hoarsness and wheezing
-cutaneous -> urticarial rash, pruritus, flushing
-GI -> nausea,vomiting, and abdominal pain.
Tx:
-intramuscular epinephrine
-airway management
-adjuvent therapy such as antihistaminic and steroids.
Anaphylaxis pathophysiology
It result from widespread mast cell and basophil degranulation and resultant histamine and tryptase release.
- tryptase is an enzyme that is relatively specific to mast cells and elevated serum levels support diagnosis of anaphylaxis.
- anaphylaxis occurs usually within minutes or seconds after intravascular exposure to an inciting factor, but can take up to 2 hours in oral trigger.
Fructose 2,6 bisphospate and glucose metabolism
It helps to control the balance between gluconeogenesis and glycolysis, through inverse regulation of PFK-1, and 1,6 bisphosphatase. Fructose 2,6 bis activates PFK-1 the main ergulatory enzyme involved in glycolysis, which converts fructose 6 phosphate into fructose 1,6 bisP.
-this substrate is inolved in increasing glycolysis thus decreasing gluconenogenesis.( inhibit conversion of alanine to glucose )
Thyroid cancer - nests of polyglonal cells with congo red positive deposits
Medullary cancer
Thyroid cancer - branching structure with interspersed calcified bodies (psammoma bodies)
Also follicular hyperplasia with tall cells forming interfollicular projections is found in papillary thyroid cancer
High affinity IgE receptor is
Found on most mast cells and basophils and plays a primary role in mediating the allergic response. The receptor normally binds the Fc portion of circulating IgE , coating the cell with various antigen specific IgE molecule
- when a multivalent antigen comes in contact with the cell, multiple IgE antibodies become cross linked resulting in aggregation of the FcERI receptors on mast cell surface.
- this clumping of receptor leads to activation of non-receptor tyrosine kinases triggering an intracellular cascade that ultimately results in mast cell and basophil degranulation.
Insulin acts on which receptors
- the surface receptor for insulin is transmembrane receptor protein with intrinsic tyrosine kinase activity in its cytoplasmic domain.
- insulin binding activates tyrosine kinase, leading to phosphorylation of insulin receptor substrate 1(IRS-1).
- activation of PI3K stimulates metabolic functions such as translocation of GLUT-4 to cell membrane, glycogen synthesis and fat synthesis.
How insulin stimulate glycogen synthesis
PI3K stimulation promotes glycogen synthesis by activating protein phosphatase, enzyme that dephosphorylates glycogen synthase leading to its activation, and inhibit glycogen phosphorylase.
Adenosine mechanism of action
It affect phase 4 of the action potential of pacemaker, reducing the rate of spontaneous depolarization in cardiac pacemaker cells.
- adenosine interacts with A1 receptors on the surface of cardiac cells, activating K+ channels and increasing K+ conductance, causing membrane hyperpolarization.
- it also inhibits L-type Ca+2 further prolonging depolrization time.
- this result in slowing the Sinus rhythm and increase AV conduction delay.
Risk factor for nephrolithiasis
Dietery intake: -low fluid - low calcium -high oxalate -high protein -high sodium - high fructose Diseases: 1. increased PTH 2. Chrons disease 3. Distal renal tubular acidosis (hypo-citrate-uria) 4. Gout
S.aureus normally present in
-commonly found in the nares.(epidimiologist usually check the nares for colonization)
Meckles diverticulum - mucosa of other organs present in it is a termed
Ectopy (not metaplasia), normally functioning cells in abnormal location
