Physiology (Urinary) Flashcards

Question

Reabsorbtion

Answer 1

The various nephron segments reabsorb most of the ultrafiltrate back into the blood - Process is the result of specific transport mechanisms located in the cell membranes of each individual nephron segment.

Answer 2

Some substances enter the final urine by moving across the nephron directly from the blood stream into the tubule lumen - The final amount of these particular substances which appears in the final urine is a combination of the amount filtered at the glomerulus and that secreted into the urine.

Answer 3

Glomerals (Bowmans capsul capillary Tufts) - Completes the intial filtration of urine Proximal tubes -- forst segment that urin encounters - Function - reabsorbes 65% of total filtrate (Includes all glucose and Amio acids_ - Secretion of organic solutes - Important in Acid/Base balance Loop of henele - Reabsorbes 25% of filtrate - Concentrating mechanism Distal Tubes - rabsorbes 5% of filtrate + secretes Collecting ducts - Reabsorbs 5% of filtrate - Acid/base balance - Controls Na+ and water extretion

Answer 4

Can secrete or absorb the rest of the filtrate

Answer 5

Chart - shows how much each parameter has in total ECF Kidney filters all ECF 12-13X per day - Amount extreted per day is lower than the amount filtered per day -- BECAUSE absorb 99% of it per day (rebsorb what you are filtering - If you were not able to reabsorb what you are filteing = you would dehdyraye very fast

Answer 6

Balance of Filtratiion + reabsoprtion + secretion = affects how much is extreted in the final urine Based on equation - Extretion = Filtration-reabsorption+secretion

Answer 7

When you apply hyrdostatic pressure (shove piston in on one side) = leads he pressure to shove water through the memebrane --> movement of water will cerate oppsoing osmotic pressure that favors water going back to the original comparent - Hydrosatic prssure pushing water from A to B will lead to osmotic pressure moving water from B to A Balance of the two pressures = determines how much filtration will happen

Answer 8

GFR = glomerular fltration rate Equation for GFR --> hydrostatic pressure diference that fvors filtration (PGc - PBs) ; subract from oncotic prssure differece that is oppsing filtratiion (Pic - Pibs) - Kf is the ultrafultration constant Use GFR to determine kidney function - GFR is dteermined by the balance of the two forces

Answer 9

Glamerular - capilariers that will filter --> filtrate will then go to tubule and evetually will be come urine Image NOTE - Numbers = hydrostatic pressures and oncotic (osmotic) pressure Hydrostatic pressure is high in on both sides of the the glamerular capilaries --> have filtering pressure from the hydrostatic pressure in capilaries themselces (hydrostatic pressure favors filteration) Oncotic pressure is high on the right side of the capilary BUT NOT at the bottom of the capilary MIGHT expect water to go back into the glameuli at the end of the capialry BUT based on hydrostatc pressure the water is able to go to the proximal tube

Answer 10

Hydrostatic pressure favors filtration

Answer 11

No oncotic pressure i the bottom of the glamerili because in a helathy person there is no proetin in the filtrate going through the glomerular = no protein in the glamerular capilaries BUT have high oncotic pressure at the end of the caplaries because proteins have been maimatined and the fluid is lost - At the end of the capilaries you have oncotic presure that is oposing the filtration (oppsoning hydrostatic pressure)

Answer 12

Organization of renal vaculature is unique Have artial + capilary bed THEN anotehr arterial + capilary bed This sturcture is the reason filtration can happen at the glamerular (because this organization allows the hydrostatic pressure to stay high on both sides) - IF had a vein on the other side = hydrostic pressure would drop - Kidney is able to filter because of the organization keeping this hydrstatic pressure high

Answer 13

Hydrstatic pressure drps because have vein on one side Have arty + capilary bed + vein --> presnece of the vein causes the hdyrostatic pressure to drop

Answer 14

PiBS (osmotic pressure (protein ressure) within the gameular) - should equal 0 BUT the term is still included in the equation becaue the value is equal to zero in health BUT not in disease

Answer 15

Glamerular capilary has arterial on both sides = keeps hydrostatic pressure high (Pc stays high) = drives fltration despite the fcat that osmotic preessire rises at the end of the glomerular capilary (Pic gets higher at the eend of the capilary) - have low GFR In peritubrlar capilaries - hydrostatic pressure is low and oncotic pressire is high (low Pc and High PiC) = allsows for reabsorption

Answer 16

There is no protein in the filtrate going through the glameular because of the structure of the filtration barrier Stucture includes obstacles that things ahve to go through to go from the capialry lumen to bowmans space (first part of tube) - Na and water can go through freely BUT larger things get stuck in the capilary lumen - Structure acts like a collender --> water goes through BUT bigger things get stuck (plasma proteins and larger molceules get stuck and can't go through)

Answer 17

Things are excluded because: 1. Size - Things are too big to get through 2. Charge - "collender" is filled with proteins with negative charge = repels negativley charged proteins 3. Shape - ONLY rod shaped things could get through at the right angle BUT globular things can neevr get through LIST are ALL characteristics of the ultrafiltrate

Answer 18

Chart - shows the weight + radius + Concetration ratio - Concentration ratio = filtrate/blood Value: 1.0 = no barier to being filters (goes from one side to another) - Example - urea and glucose are freely filtered - can pass through the barrier Larger mo;ecular weight OR large radius = the molecule would be exluded from urine and the concetration ratio decreases

Answer 19

If you ahve a lot of protein in urone = have glameular problem vecayse the barrier is broken = lets thorugh proteins that shoudn't fit

Answer 20

Clearance - aount of plsama that must be cleared of a substance to accoun for appreance of that substance in fineal urine

Answer 21

Estimate GFR --> meausres clearnce (shows how efficientley the kidney filters blood) GFR is assesed by measuring clearnce of a substance that is freely that is freely filtered by the golmerous but is niether reabsorbed or screyed in the nephrons (example - insulin and creatine) Urinary excretion rate = Filtration rate -rabsorption rate + secretion rate - maount extreted in the final urine = amount filtered at the glomerulus

Answer 22

Confounding factor = rabsorption and secrtion are happening at the same time Want to measure a sibstance that is filtered BUT not rabsorped and NOT filtered - BECAUSE ONLY want to know the amount filtered (not the rabsportion or the secretion) - Wnat the amount extreted in the urine to be the same as the amount filtered in the galmerous to know renal filtration function Have some substances that are not reabsorbed or secretion - Insuline does this - Give pateints a stead state infusion of insuline --> see how quickly they clear it = can know the filtration rate - Used in clincal studoes to asses drugs or used in labs - BUT in pateints giving patients an exogenous substance to know how the kidney is functioning is no prcatical = use creatine instead

Answer 23

I think she skipped but her notes: Inulin 90-120 ml/min Sinistrin also NOT creatinine

Answer 24

Chart: X-Axis - Different segemnts of the nephrone Y Axis - ratio of amounts (hard to know concetration because the water is always changing) Each line on the graph = different substance --> can see how the substance is handled in the nephron IF the line goes down = the substance is reabsorbed into the blood IF the line goes up = the substance is secreted into urine IN chart = see that a lot of reabsorption occurs in the proximal tube

Answer 25

Substance that is filtered BUT NOT screted and NOT reabsorbed = used for GFR - Has straight line in graph - Can easily know filtration rate

Answer 26

Used in the clinic to measure renal function Creatin = secreted a little by the proximal tubule (see line goes up) --> thsi complicates things - The amount scereted by the proximal tubule chnages in disease = it is not a perfect substance BUT it is easily measure --> it can give a genral idea of the glamaeular filtration rate (know the idea of if the genral glameular filtration rate is correct) Issue = creatine can't pick up mid defects in kdiney function

Answer 27

Once substanes are fltered = things can happen

Answer 28

IF the line goes down = the substance is reabsorbed into the blood - Glucose + AA + Porteins, Na are reabsorbed in the proximal tube IF the line goes up = the substance is secreted into urine - Urea is secreted in the Loop of henele LOOK at chart to see where secreted and where absorbed

Answer 29

Things that the body spent ATP to make you do NOT want to pee out - 99% of what is filtered is reabsorbed Example - Glucose + Amino Acids + Protein should NOT be in final urine Diabetes = have glucose in urine

Answer 30

Small moleuclar weight proteins can get into filtarte (MOST proteins are not in filtrate) BUT the small proetsin are all reabsorbed by the proximal tubule IF have trace amount of protein in the urine = defect in proximal tube IF have massive amount of protein in urine = glameular defect

Answer 31

Diabetes = have glucose in urine Have glucose in urine because the amount of glucose is above the transport maximum (transport capicity) of the proximal tubule = glucase can't be rebasobred = glucose goes to urine Glucose act as an osmotic diaretic = pee more + get thristy (BOTH classic symptoms of diabetes) - Both because the glucose in the blod exceeds the transport maximum of glucose reabsorption

Answer 32

Morvment of Urea is imoortant for how kidneys concetrated Urine Urea (or urine?) is cycling through the nephron by being reabsorbed --> secreted --> reabsrobed - Cycling is required for concetrating

Answer 33

Chart - Na line and water line overlap until the distal tube --> after the distal tube they become seperate - In the proximal tube and the Loop of Henle the Na and water are reabsored together (Na and water are isoosmotic) - Na and water have to be seprated in later part of nephrone - Na and water are reabsorbed together earyy BUT then have fine tubed conrtol that the kidney needs to have in toder to maintain homoestasis so you seperate the handling of Na and water later in the nephron

Answer 34

Proximal tubule = absorbs 2/3 Loop of henle = absorbes 1/4 Distal part of neprhone = absorbs the rest

Answer 35

Most important part for Na = last part of absorption BECAUSE the 65% and 25% in teh promxinal tube and Loop of henle won't change (always the same amount) BUT the last segemnt is about fine tubing how much to reabsorbe (will make small adjustments) - Regulation happens in teh distal fine tuning (last segment does the fine tuning in repsonse to hormones coming for otehr parts of the body to tell the nephron how much Na and water is needed) - 65% and 25% = values for males ; females rely less on the proximal tubule and more on the loop (differnces in how salt and water are hanlded in males and females) The kdiney filters all blood 12-13X per day = small adjustments make a bog difference in Extracellular fluid

Answer 36

Na+ handling is regulated by: 1. ANP (atrial natriuretic peptide) 2. Aldostrone 3. Renin 4. Angiogenstin Regulation = primarily hromonal signals that tell the ditsal part of the nephron what to do

Answer 37

Start of nephron - water is reabsorbed isomoticly with Na THEN have seperation - Seperation can occur in different places How much water you absorb is different based on how much water you drink - How concetrated urine is = based on how much you drink (diference in final osmolarity in urine is based on how much as been reabsprbed) - At the end of the nephron water is either reabsorbed more or not depending on how much water you drink

Answer 38

T/P - osmoalrity of the forming urine/osmolarity of the plasma - line going up be reabsorption T/P doesn't chnage in the proximal tubule because Na and water are isomatic --> ratio is indifferent In loop of henle = urine is initially conetarted - Different lines in chart show different hydration status = have different urine concetration - High water or low water = affects the final omolarity of the urine

Answer 39

Postasum = reabsorbed in the proximal tubule ; Fine tuning occurs in the dstal part of the nephron Chart - have 2 lines depending on the amount of K in the body (amount of K in body affects how K is handled in the nephron) - Kidney can reabsorb K if you need more or can extrete K to get rid of it Healthy K = 4 Milimolar (if have wrong concetraton then you can die so it is regulated well)

Answer 40

Proximal Tubule = reabsorbe 80% of K - Always 80% in proximal tubuls no matter if have high dietray K or low K - Reabsorpton in the oop is similar in both high and low K - Males - 70% ; females 55% in PT Distal part of nephron = can absorbe 2% and then 6% OR you can extrete more K to protect plasma K levels Urine secretes more or less K to make sure the blood vlume K stayes steady

Answer 41

Mucle cell = non-polar cell Muscle cell = just moves ions in/out of cell (simple) Epithelial cells = regulates itercellular concetration AND has to move colutes across the basolateral and apical sides without affecting the interceullar concetration = more complicated - Epithelial cell = polar cell

Answer 42

Epithelial cells trasnport salts and water into or out of a compartment - Have polar/direction vectroial transport Need to localize proteins in certain parts of the cell (basal or apical) --> cell needs to idetofy basolateral protein --> traffic them --> keep them there using tight junction/oculins)

Answer 43

Vectroral transport requires structural polarity --> have structrial polarity on the apical and basalateral sides = localize proteins differentley = can transprt in tandmen Can transport in tansem - one transprt of substance in teh basalateral side and then pass to apical side trasnprter and transprort on the apical side - Need to know if apical or basal to traffic proepry

Answer 44

Distrubutions of ion trasnprt proteins determines the functional properties of epithelial cells - Can have the same transporters but build TWO diffreent types of epithlium Example (BOTH use the same trasnporters but orented diferentley): 1. Absorptive epithelium - have all Na/K ATPase on the basolateral side ; have cotraspoerter in the apical side to move fluids in + for K recycing - Na goes out to ECF ; K goes out in lumen - Na and K can be reabsorbed by oritenting trasnprters this way 2. Lung epithlum - Cl is in the apical memebran ; co-trasnpter on the basal memebrane with K recycling chabel --> allows for secretion of K Cells know what the cell type is and what job to do = an have the transporters in the right place

Answer 45

Epithelial surface specilization facilitate transprt Proximal tubule = has a brush boarder (microvill) --> Increases the SA of linear distance = can pack in trasnprters - Proximal tubule needs to reabsorb a lot = need a lot of SA = have microvill Basal side = has invaginations to pack in all of teh Na/K ATPase pumps that drive transprt

Answer 46

Image - looking down at Proximal tubule --> see brush boarder as ring all around the tubule Shows need a lot of SA for the transport to happen

Answer 47

Water follows Na Distal nephron = absorbe Na and Secrete K In Distal nephron (NaCl is reabpsrbed ; K is secreed) - Have Na/K pump on basal side ; have Na chanel and K chanel on apical side -- Na will goe down the concetration gradient into the cell AND K goes down the concetration gradinet out of the cell - Basal side maintains the concetration gradient (using Na/K pump) - K is secreted to apical side - Cl transprt is para cellulaer (goe sto basal) ; Na goes to basal Thick ascedning limb (NaCl reabsprtion) - Use Na/K/2Cl trasnprters on the apical side --> drive the reabsprtion of Na and Cl - K is reccyling through recycling chalen - na gets reabsprbed by the Na/K ATPase on basal side (Na goes out to basal side) - Cl exits through chael on basal side (Cl goes out to basal side)

Answer 48

Water transport is passive Water follows salt

Answer 49

When Na is rebasorbed in the proximal tubule --> water will follow (have isosmotic reabsrtion) - In proximal Tubule = when Na + Glucose + AA are reabsorbed = water follows NOTE - in proximal tubule)

Answer 50

Because when salt move water follows --> valie of compartments chnage BUT the concetrayion is not chnaging ONLY the volume is chnaging - Compartmnet A gets small BUT teh concetratino stays the same = iso-osmotic absortion

Answer 51

Coach at UF noticed that players had issues at the end of games because they were dehydrated He had a nephrologost look at te places and teh noephrologist found that the players lost 17 pounds on the day fo practcie (water loss) = caused the players to be lethargic Giving players water wouldn't help because it would dilute the plasma Na = need to replace water and salts iso-osmotically = the coach make an electrolyte drink with Na and K in the same concetraion as plasma = replaced volume iso-osmotically --> called it gaterade Gaterade = also used in developing countries for kids with diarretic disorders

Answer 52

After the Proximal tubule you can reabsorbe na and water sepreatly BUT they are absorbed tgether in the Proximal Tubule - Can absorb salt and leave water in the lumen by not putting water chanels in the memebrane Hyperosmotic reabsprtion can happen - Take out water chanel = membrane is imermeale to water = water can't follow = get hyper-osmotic reabsorption - Volume of the compartment stays the same BUT concentration chnages

Answer 53

Have a big concentraton for Na to be absorbed Kidneys se secodary active trasnprt to absorb other things - Example - Na/Glucose --> use the concetration of Na to rebasorb glucose - Can do the same for reabsrbing AA If you have good Na pump activity = Take advantage of the Na Gradinet = can use secondary transport for the absorption of Glucose + AA + phosphate - Have antiporters that ise secondary active trasnprt (coupled to the secreyion of H+ ions) If absorb Na = use Na going down the gradinet to move other things NOTE - occurs in the proximal porton of the nephone

Answer 54

Occurs in the priximal part of the nephron Proximal tube uses na reabsprotion going down concetration gradeint on the appical side = drive reabsoprtion of other molecules Need faciliateted duffusion on basolateral side to get glucose out - Put a lot of pumps and mitocondria to keeo sodium low Exmaple - Protein receptor mediate endocytosis (magalin) , degrdaed in the lysosomes, trasnported acros BL with AA trasnorters

Answer 55

Need to keep sodium concetration high in the lumen because you can use this concetration to reaborb lots of other things - High Na in the lumen dirves many substances into the cell - Solute coupled water movment

Answer 56

Proximal portion of the nephron is heterogenous Proximal tubule = divided into different segments 1. S1 - does most of the transprt - Has bursh boader + more mitocondria + taller --> absorbs larger amounts in terms of total amount - Does more bulk transport 2/3. S2 and S3 are important for clean up - S3 - has high affinity trasnprters to get the last molecule of glucose = makes sure you don't lose molecules

Answer 57

Chart - shows that mos of the reabsprtion (in terms of amount) occyrs before 50% mark BUT you need the last bit (100% length) to get the line to zero

Answer 58

Proximal Tubule is important for secreting compounds the body wants to get rid of Image - shows the anions and cations the proximal tubules secretes Example - Penecilin anion is secreted by the proximal tubule - Created an issue in WW2 because had very little Pencilin and a lot was sceretd out = need more of it for it to work - made proveset = secreted by the same transprter as pencilin = competivley inhibits for teh same secretion machiner = can maintain higher pencilin levels

Answer 59

Loop of Henle = middle portion of the nephron Loop = has different reabsprotion of water vs. naCl to concetrate the urine Function of Loop = concetrate the Urine

Answer 60

Final protion of the nephron = absorbs Nacl + Absorbs/secretes K ADH determines if you have watwer chanels = detemrines if you reabsorb more water

Answer 61

Anti-diuretic hormone (vassopressin) Water permability is diffreent in diffrent portions of the nephron - Begining is water permeable - Middle = concetrating urine = not water permeable - End = water permeable or impermeable depending on if you have ADH Depending on if you ahev ADH the water permeability is different --> presence or absense of the hromone = allows you to secrete urine that is diluted or concetrated - No water transprters = extrete urine - Have water transporters = reabsorb water

Answer 62

ADH regulates urin concetration If dehyrated = change ADH = drives chnage in urine concetration + chnages in thrid drive (coordinates both together) IF you dirnk when you are thristy you will always be hydrated ; if you drink more or less the kidneys will correct for that

Physiology (Urinary) Flashcards

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