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67 Cards in this Set
- Front
- Back
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List the ends of the epithelial cell
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Apical end
Basal end Lateral sude |
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Where is the basal end located?
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interstitial space
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What is Paracellular transport?
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solutes and fluid move between tubular epithelial cells
OR between tight junction |
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Where is the apical end located?
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lumen
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What is transcellular transport?
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solutes and fluid move THROOUGH tubular epithelial cells
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What does the transcelluar toute include?
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3 pathways:
transapical transbasal translateral |
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Water and solutes must cross which membrane of the epithelial cell?
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apical (luminal) membrane
basolateral membrane |
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List the passive transports in the trancelluar transport
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pores (always open)
ion channels (gated) carriers (facilitated diffusion) |
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List the carriers (facilitated diffusion) in the trancelluar transport
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cotransporters (symporters)
exchangers (antiporters) |
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List the active transports in the trancelluar transport
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ATP-dependent pumps (ATPases)
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Solutes and fluid movement in paracellular transport is goverened by:
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permeability of tight junctions
transepithelial chamical gradient transepithelial electrical gradient solvent drag |
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"leakiness" of tight junctions in paracellular transport decreases where?
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proximal tubule to collecting duct
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What is solvent drag?
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water flow sweeps dissolved solutes
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What are the biggest ions moved across epitheial cell membrane?
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Water and Na
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Waht is reabsorbed in the Proximal tubule?
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Na+
HCO3 or Cl- counterions |
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What solute does the Proximal tubule reabsorbed the most?
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67% Na reabsorbed osmotically (same # of water and Na)
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What is reabsorbed in the TAL- Thcik ascending limb?
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Na+,
NaCl without water |
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What is reabsorbed in TAL - Thick ascending limb the most?
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25% Na+
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What is reabsorbed in the DT (Distal tubule) and initial part of CCT Collecting tubules-- (includes distal convuluted tubule, and connecting tubule)
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5% filtered Na+ reabsorbed with Cl-
Varibale water reabsorption |
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What is reabsorbed in the MCD Medullary collecting duct?
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3% filtered Na+ reabsorbed with Cl-
Variable water reabsorption |
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How is Na+ transported?
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Through:
Passive apical Na+ entry Active basolateral Na+ extrusion Paracellular Na+ transport |
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What are the passive apical Na+ entry transporters?
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symporters and antiporters (PT, TAL, DCT)
Na+ channels (CCT & MCD) |
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List the Active basolateral Na+ extrusion (pushed):
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Na+ -K+
AtPase pump |
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What happens to NA+ transport in the Early Proximal Tubule? Does it go up or down the gradient?
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Apical Na+ influx DOWN its electrochemical gradient
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What does Proximal tubule have high density of?
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high density of aquaporin 1 (AQP1) water channels in apical and basal.
67% water reabsorbed osmotically |
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Which sectio on the tubule has the highest water permeability?
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Thin decending limb.
d/t AQP1 apical and basolateral membranes. Water reabsorbed by osmosis |
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Which tubule has the highest solute of Na+ ?
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Thick Ascending Limb
100% tanscelllular Cl- reabsoprion 50% transcellular Na+ reabsorption |
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Where is Furosemide filtered and secreted?
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filtered in glomerulus and secreted in Proximal tubule.
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Where does Thiazide work at this tubule?
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Distal Tubule at the Apical side (Na+/Cl symporter)
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Where does Amiloride work on in the tubule?
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Inhibits apical Na+ channels at the CCT cortical collecting tubules
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What type of drug is Amiloride?
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potassium sparing diuretic
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Where does loop diruteics (furosemide) work in which tubule?
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Loop of Henle
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What is the function of Angiotensin?
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Na+ retaining hormone
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How is Angiotension 2 made?
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Renin secreted by granular cells --> conversion of angiotensiongen to angiotensin 1 converted to angiotensin 2 by ACE (angiotensin converting enzyme)
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What stimulates Angiotensin 2?
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Low BP
Low extracellular fluid volume (hemorrhage, loss of salt and water d/t lots of sweat and severe diarrhea) |
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What is the Angiotensin 2 effects?
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vasocontrict in kidney.
stimulate Na+ reabsorption in loop of Henle, distal, and collecting tubules Stimulate aldosterone secretion (RAA the renin angiotension aldosterone) |
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How does Angiotensin 2 vasoconstrict in the kidney?
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it constricts afferent and efferent.
Overall: raise filtration fraction --> higher colloidal osmotic pressure in peritubular capillaries raising reabsorption forces. |
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How does Angiotensin 2 stimulate Na+ reabsorption in the different areas of the tubules?
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stimulate Na+ K+ pum and Na+ HCO3 on basal side.
Stimulate Na+ H+ exchanger |
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When is Atrial Natriretic Peptide (ANP) released and how?
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Released by specialized cells in cardiac atrium, realse ANP (peptide) when distended d/t increased blood volume
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What is the function of ANP?
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inhibit renin secretion and Angiotensin 2
inhibit reabsorption of NaCl and water, esp collecting duct. LEAD to natriuresis & pressure diuresis inhibit ADH release |
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Define Natriuresis
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excretion of sodium
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DEfine Pressure Diuresis
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secretion of urine due to high arterial pressure
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What is the most abundant intracellular cation?
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K
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What does K regulate?
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Call volume
intracellular pH |
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Why is Low extracellular K essential?
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Determines:
resting membrane potential cardiac rhythmicity vascular resistance |
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What is K balance?
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K consumed = K excreted
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What that renal handling of depends on?
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dietary intake
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Where is K reabsorbed mostly in which tubule?
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90% reabsorbed in proximal tubule and loop of Henle
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Where is low K diet reabsorbed?
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CCT (collecting duct) by a-intercalated cells
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Where is normal to high K diet sercretion made?
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CCT by principle cells.
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What is Aldosterone?
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Steroid mineralocorticoid secreted by adrenal gland (outer layer of adrenal cortex)
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What happens is there is a total lost of aldosterone?
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DEATH d/t high K+ extracellular and loss of NaCl fro body.
Fluid and blood volume drops. Patient goes into SHOCK and diets. |
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Aldosterone is stimulated by what?
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increase K+ extracellular and increase Angiotensin 2
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Which cell does Aldosterone act on?
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Principle cells
** stimulates NaK pump on basal membrane and increases Na+ permeability on apical membrane = Na increase absorption and increase K secretion |
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What is the normal fasting glucose level?
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70-100 mg/dL in plasma and 0 mg/dL in urine
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Glucose is regulated by what?
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insulin remediated glucose uptake
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Glucoss is found in which part of the tubule?
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freely filtered
100% reabsorbed in transcellular Proximal tubule EArly 98% LAte 2 % |
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In EArly PT, glucose use which transporter?
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Apical SGLT 2
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In Late PT, glucose use which tarnsporter?
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Apical SGLT 1
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List the causes of Glucosuria
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Diabetes mellitus
Gestational diabetes Mutations in SGLT1 and SGLT2 |
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What is diabetes mellitus?
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increase plasma glucose
plasma glucose exceeeds glucose threshold |
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In DM, how is plasma glucose caused?
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absolute insulin deficiency (type 1) or
relative insulin deficiency and insulin resistence type 2 |
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What leads to gestational diabetes?
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increase GFR --> filtered glucose load to exceed glucose tranport maximum
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Waht is mutations in SGLT 1 or SGLT 2 lead to?
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Rare hereditary conditions that decrease glucose transport maximum
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SGLT2 mutation lead to what type of glucosuria?
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severe glucosuria
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SGLT1 mutation lead to what type of glucosuria?
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mild glucosuria
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Where is amino acid reabsorption occur in the tubule?
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99% reabsorbed transcellularly in Proximal tubule.
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