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Physio Test I

Homeostasis, Kidney, and Electrophysiology

what is the marker used to measure total body water? tritiated water
what is the marker used to measure extracellular fluid? inulin and mannitol
what is the marker used to measure plasma? albumin and evans-blue
what is the equation for the anion gap? Na= Cl + HCO3 + 10
what is the anion gap? unmeasured anions
what must be present to see the effects of osmotic pressure? hindrance
what is the difference between osmolality and tonicity? osmolality- concentration of particles per solution; tonicity- refers to whether there is net movement of water
what are the starling forces? favoring filtration- hydrostatic (blood) pressure and COP of interstitial fluid; favoring reabsorption- COP of plasma and tissue pressure
what is the equation for plasma osmolality? P(osm)= 2(Na) + glucose/18 + BUN/2.8
what is the difference between garden variety capillaries and glomerular capillaries? garden variety- filtration and reabsorption so COP is always the same; glomerular- BP is always higher than COP so it's ALWAYS filtration, COP increases along length
how much fluid enters the tubule? ie. what is the GFR? approx. 20% of the RPF ~ 180 L/day
what happens to the GFR and RPF when you constrict the afferent arteriole? efferent arteriole? AA- GFR and RPF decrease; EA- GFR increases, RPF decreases
what is splay? the point where the plasma concentration exceeds the transport maximum
what is clearance? the volume of plasma that is free of a stated material in one minute; the ratio of amount of substance excreted to the plasma concentration
what is the equation of clearance? CL= UV/P = GFR
what is inulin and what is its clearance equal to? inulin is a substance that is filtered at the glomerulus but neither reabsorbed or secreted; its clearance is equal to GFR
what is the equation for flow? flow= UV/(arterial - venous difference)
what is the equation for RPF? RPF= UV/(arterial - 0)
what is PAH and what does its clearance equal to? PAH is a substance that is almost completely cleared from the kidney, thus almost equal to RPF; its clearance is equal to the ERPF (flow through the nephrons)
what is the filtration fraction? FF= GFR/ERPF ~ 20%
what is GFR usually measured by? creatinine
what are the 2 variables in creatinine clearance? GFR x P = k
what events happen in the first half of the proximal tubule? (1) Na/X symport; (2) Na/H antiport; (3) Na/K pump (4) Cl is not transported its concentration is increasing
what happens in the second half of the proximal tubule? (1) Na/H antiport; (2) Na/K pump; (3) Cl is transported in; (4) end result: NaCl reabsorption
what is the osmotic classification of reabsorption in the proximal tubule? isosmotic
what happens in the descending limb of the loop of Henle? passive transport; increased permeability to water
what happens in the thick ascending limb of the loop of Henle? (1) Na/2Cl/K symport; (2) Na/H antiport; (3) Na/K pump; (4) impermeable to water (known as diluting segment)
what is the osmotic classification of the thick ascending limb? limb is hypoosmotic to the solution
what happens at the early distal tubule? (1) Na/Cl symport; (2) Na/K pump; (3) impermeable to water
what is the osmotic classification of the early distal tubule? DT is hypoosmotic to solution
what happens in the late distal tubule and collecting tubule? principal cells secrete aldosterone; alpha intercalated cells secrete H and reabsorb bicarb; beta intercalated cells secrete bicarb and reabsorb H
in the distal tubule and collecting duct, what influences water reabsorption? ADH
what are the permeabilities of the descending and thin and thick ascending limbs? descending limb- highly permeable to water; thin ascending- highly permeable to salt (passive); thick ascending- impermeable to water, but site of very active NaCl transport
what happens in the presence and absence of ADH? presence- urine more concentrated; absence- urine more dilute
how is ADH release triggered? (2 ways) osmoreceptors in hypothalamus and volume receptors
what is free water clearance? the difference between urine volume and osmolar clearance; C(H2O)= V - C(osm)
what happens when the free water clearance is positive? negative? zero? urine is hypoosmotic, hyperosmotic, and isosmotic
describe how to differentiate between primary polydipsia, central DI, and nephrogenic DI first you don't let the patient drink; if the urine osmolality rises, it's primary polydipsia; then you give ADH, if the urine osmolality rises, it's central DI, if not, it's nephrogenic DI
describe the renin-angiotensin-aldosterone system decrease in plasma volume leads to increased renin release from JG apparatus; renin cleaves angiotensinogen in the liver to angiotensis I; angiotensin I is converted to angiotensin II in the lungs; angio II stimulates aldosterone secretion
what factors influence renin secretion? (1) perfusion pressure; (2) sympathetic nerve activity; (3) sodium chloride delivery to macula densa
what are the functions of angiotensin II? (1) stimulation of aldosterone secretion; (2) vasocontriction increasing BP; (3) stiumulation of ADH from posterior pituitary
what is the function of aldosterone? reduces NaCl excretion by stimulating reabsorption by the thick ascend. limb, DT and CT
what are the functions of ANP? (1) vasodilation, increasing GFR and RPF; (2) inhibits renin, aldosterone, and ADH secretion; (3) inhibits NaCL reabsorption by CT
what is the stimulus for ANP secretion? atrial distension which occurs during plasma volume expansion
what do diuretics do? (1) increase rate of elimination of toxic substances; (2) mobilize and reduce edema; (3) control of hypertension
what do osmotic diuretics do? alot of ureabsorbed glucose (diabetics) stays in proximal tubules which holds alot of water, causing polyuria
what do carbonic anhydrase inhibitors do? it reduces reabsorption of bicarb teh secretion of hydrogen; this causes sodium to stuck in the proximal tubule; major side effect is hypokalemia
what do thiazides do? inhibits sodium reabsorption in early distal tubule by Na/Cl symporter
what do potassium sparing diuretics do? it blocks the action of aldosterone on the principle cell of the CT or blocks entry of Na through Na channels; never give to renal failure patients (increase K more)
what do loop diuretics do? they inhibit sodium reabsorption by blocking the Na/2Cl/K symporter in thick ascend limb; VERY potent!
what is Gitelman's? results from a genetic mutation that inactivates thiazide sensitive Na/Cl transport in EDT, leading to hypokalemia and metabolid alkalosis; similar to thiazide abuse
what is Barrter's? several mutations causing inhibition of Na/2Cl/K symporter in ascend limb; similar to loop diuretic abuse
what type of ATPases autophosphorylate? P-type ATPases
what are factors that influence ion movement in solution? diffusion and current flow
what the equation for the Nernst potential? Em= 62 log [K+]o/[K+]i
what is accomodation? the depolarizing shift of threshold with slow stimuli
what are some mechanisms responsible for states of membrane refractoriness? Na channel inactivation and increase in K as K channels open
in myelinated nerves, where are the voltage gated Na channels located? the K channels? Na channels are in the nodes of Ranvier, K channels are in the internodal regions
what produces myelin? Schwann cells (PNS) and oligodendrocytes (CNS)
what is the Lloyd/Hunt classification of muscle afferent nerve fibers? Group I: primary muscle spindle afferents and efferents from tendon organs; II: cutaneous mechanoreceptors; III: deep pressure sensors in muscle; IV: unmyelinated pain fibers
what are the presynaptic events in neuromuscular transmission? AP invades; influx of Ca through Ca channels; ACh released; diffusion of ACh across cleft
what are the post synaptic events in neuromuscular transmission? ACh binds with receptors; activation of cation channel that produces invward Na current (EPC); EPC depolarizes at end-plate region (EPP); EPP initiates AP; contraction of muscle
what do synpatotagmin and SNARE complex do? synaptotagmoin regulates synaptic vesicle exocytosis; SNARE complex causes the fusion so that neurotransmitter can be released
what do GABA and serotonin do to presynaptic responses? GABA inactivates Ca channels so less Ca enters and less ACh is released; serotonin activates Ca channels and causes more Ca and ACh to be released
what special thing must ACh do so that the Na and K channels open? it must bind to 2 sites on the channel
what are the 2 types of chemical synapses and what do they do? excitatory- depolarizes; inhibitory; hyperpolarizes
Created by: medchichi