Renal Physiology & Urinary System

hrdcorhrvivor's version from 2017-05-08 05:45

Section 1

Question Answer
functions of the kidneyregulates volume and comp of body fluids through urine formation. excretion: primary funx, regulation: blood volume and pressure, blood solutes, concentration, pH, RBC formation
renal papillaapex of renal pyramid
papillary ductsfiltrate from nephron flows through here to calyces
nephronfunctional unit of the kidney
cortical nephronrenal corpuscles located high in cortex, short loops of henle, 80% of nephrons
juxtamedullary nephronrenal corpuscles close to the base of medullary pyramid, long loops of henle, 20% of nephrons
renal corpusclesinitial filtrate is formed, glomerular (bowman's) capsule and glomerulus
collecting ductwater re-absorption and urine concentration
filtration fractionabout 1/5 of plasma enters the nephron
filtration barriers to get to bowman's capsulebasal lamina, fenestrated endothelium, bowman's epithelium. driven by pressure gradient
glomerular filtration rate (GFR)volume of fluid produced by both kidneys per minute, influenced by filtration pressure: renal blood flow and bp and filtration coefficient: ease fluid moves through capillaries. directly proportional
glomerular filtrationfiltration in glomerulus from blood to bowman's capsule, blood pressure driven
reabsorptionsolutes are removed from the filtrate and returned to the blood
tubular secretiontransport of certain molecules from blood to filtration
Cinsulinused in research settings, insulin=polysaccharide that is 100% cleared from the body
Ccreatinineused in clinical settings, byproduct of phosphocreatine, not reabsorbed, good estimate of GFR
Cglucose= 0 should not be found in urine
blood urea nitrogen BUNhigh numbers signals problem, shouldnt be present
creatinine clearanceshould be highly secreted, if low kidneys might not be working
clearancerate at which a solute disappears from the body. if Cx greater than GFR = secreted. if Cx less than GFR = reabsorbed

Section 2

Question Answer
afferent arteriole- radius, + resistance, - GFR. less blood enters the glomerulus, decrease filtration
efferent arteriole- radius, + resistance, + GFR. GFR increases as blood dams up in glomerulus
filtration regulation (4 steps)1. diameter of resistance vessels 2. neural regulation and myogenic reflex of a/e resistances 3. tubuloglomerular feedback 4. hormonal regulation
neural regulationSNS stimulates constriction of afferent arterioles, - GFR shunts blood to use somehwere else, + blood volume more o2
myogenic reflexsmooth muscles contract when stretched (high bp), protects kidneys against high bp
reninreleased by juxtaglomerular cells in response to low bp
what does renin do after its released?catalyses activation of angiotensin II, initiates cascade of events leads to release of aldosterone & antidiuretic hormone
atrial natriuretic peptide ANPacts to lower bp, released from myocardium, +GFR dilating aff arteriole, - Na reab, -renin, ADH, and aldosterone
juxtaglomerular apparatusmodification of tubular and arterial walls where they are in contact with one another
high osmolarity of filtrate (high flow)stimulates macula densa to release vasoconstrictors, act on afferent arteriole, - GFR
low osmolarity of the filtrate (low flow)- secretion of vasoconstrictor from macula densa singals granular cells to release renin
renin-angiotensin systemrenin released from juxtaglomerular cells, angiotensinogen released from liver and converted to angiotensis I via renin, angiotensis I converted to angiotensin II via angiotensis converting enzyme
angiotensis II actions 51. vasoconstrictor (-radius +pressure) 2. directly stimulates reabsorb (Na/H exchanger) indirectly stimulates (aldosterone production acting on principal cells) 3. aquaporin II (+ water reabsorb) 4. +SNS (+CO, +TPR, +MAP) 5. triggers thirst behavior
tubular reabsorptionmostly in PCT, Na: driving force for renal reabsorp active transport, anions: diffusion, water: osmosis, K, Ca, urea: passive
aldosterone+ reabsorp of Na by DCT & collecting ducts, more water following Na as it moves from filtrate to blood. + bv and pressure. concentrated urine
antidiuretic hormone+ permeability to water of collecting ducts, more water moving from filtrate to blood. + bv and pressure. concentrated urine.
atrial natriuretic hormone= reabsorp of Na by DCT & collecting ducts, more Na and water remaining in filtrate. - bv and pressure. dilute urine.

Section 3

Question Answer
regulation of potassium+ intake of K, + K excreted. if intake wxceeds excretion plasma K goes up, triggers aldosterone
glucose reabsorptionnot normally in urine, reabsorb via secondary active transport into capillaries
descending loHpermeable to water, not permeable to solutes, water flows down
ascending loHnot permeable to water, permeable to solutes, water flows up
countercurrent exchangermaintains gradient set up by countercurrent multiplier, prevents interstitium from becoming dilute by recirculating solutes
urea recyclingcauses a buildup of high urea concentration in the inner medulla, helps with countercurrent exchange/mult system leading to water reabsorb
loop diureticsact on ascending loH blocking Na transport, + urine volume
tubular secretionH, K, creatinine, PCT. disposes of substances attached to plasma proteins, removal of undesired substances, ridding body of extra K, controlling blood pH
micturition reflexurination, spinal reflex subject to higher brain control, int urethral sphincter: SM, PSNS activation. ext urethral sphincter: skel muscle, SNS. detrusor muscles lines the bladder
acidosispH too low
alkalosispH too high
under normal conditions the biggest source of acid is co2, why?bicarbonate buffer system, changes in co2 levels change H
hypoventilation+ co2, + H = acidosis
hyperventilation- co2, - H = alkalosis
renal compensation for acidosis in PCTH secreted into PCT via antiporter with Na, kidneys make HCO3, reabsorbed into blood at PCT with Na, glutamate metabolized into HCO3 and enters blood
intercalated cells+ concentration of carbonic anhydrase, rapidly converts co2 + h20 > H + HCO3
type a intercalated cellsactive during acidosis, secrete H and reabsorb HCO3
type b intercalated cellsactive during alkalosis, secrete HCO3 and reabsorb H
respiratory acidosiscause: hypoventilation, + co2. signs: - pH, +HCO3. compensation: renal-kidneys secrete H and reabsorb HCO3
metabolic acidosiscause: lactic acid buildup or ketoacidosis, loss of HCO3 from diarrhea. signs: -pH, - HCO3. compensation: resp-hyperventilation, renal-secretion of H and reabsorb of HCO3
respiratory alkalosiscause: hyperventilation - in Pco2. signs: +pH, -HCO3. compensation: renal-HCO3 secretion, H reabsorbed
metabolic alkalosiscause: prolonged vomiting. signs: +pH, +HCO3. compensation: resp-hypoventilation, renal-HCO3 secretion, H reabsorb

Section 4

Question Answer
calcitriolregulated calcium homeostasis
erythropoietinred blood cell production
renal hiliumindent where ureter, BV, lymphatic vessels, nerves exit kidney
renal capsuledeep, continuous with outer coat of ureter, protects against trauma, maintains shape of kidney
adipose capsulemiddle layer, protection
renal fasciasuperficial layer, thin CT, anchors kidney to ab wall and surrounding structures
kidney vasculature RSIACAGEPCAIRIrenal a, segmental a, interlobar a, arcuate a, cortical radiate a, afferent arteriole, glomerulus, efferent arteriole, peritubular capilarries/vasa recta, cortical radiate v, arcuate v, interlobar v, renal v, inf vena cava
glomerular capsulesimple squamous epi. visceral layer: podocytes-projections wrap around endothelial cells of glomerular capillaries. parietal layer: forms outer wall of capsule. fluid filtered from capillaries enters capsular space
glomerular filtratefluid that enters capsular space
filtration membraneendothelial cells of glomerular capillaries and podocytes encircling capillaries. 3 layers to pass: fenestrations, basal lamina, pedicles of podocytes
renal tubule histologyPCT: simple cuboidal epi with microvilli, LoH: descending simple squamous ascending simple cuboidal, DCT: simple cuboidal, last part of DCT and collecting duct: simple cuboidal with specialized cells
formation of urine 3 stepsglomerular filtration: glomerular capsule, tubular reabsorption: returns solutes we want to keep to blood, tubular secretion: secretes solutes we want removed into tubule
kidney stonesfrom crystals of salts in urine, low water intake and increased calcium ingestion, let it pass naturally, shock wave lithotripsy
ureterstransport urine from renal pelvis to urinary bladder, peristaltic waves and gravity move urine, no valve at entrance to urinary bladder
ureter layersmucosa: transitional epi, mucous protect ureter walls from solute and pH of urine. muscularis: SM layers, peristalsis. adventitia: anchors ureters in place
urinary bladderhollow muscular organ. floor of bladder: trigone
urinary bladder layersmucosa: transitional epi and rugae. muscularis: detrusor muscle, int and ext sphincters. adventitia: continuous with ureters. serosa
incontinencedue to ext urethral sphincter not being fully developed/weak pelvic floor muscles
development of urinary systemderived from mesoderm. pronephros: first to form, gone by 6th week. mesonephros: replaces pronephros, gone by 8th week. metanephros: ultimately form kidney. metanephric mesoderm forms nephrons. urogenital sinus: bladder