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Phys. Exam 4 Renal Reabsorption
Renal Reabsorption
81
Physiology
Graduate
11/17/2010
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Term
The kidneys filter ____ml/min, so they filter ____ liters in a day.
 Definition
- 125
- 180
Term
Reabsorption of ___ ___ is incomplete, so large portions are excreted.
 Definition
- waste products
Term
Reabsorption of ___ ___ products is complete, so only small fractions are excreted.
 Definition
- useful plasma
Term
All ___ ___ are reabsorbed.
 Definition
organic nutrients
Term
Even though your body filters 180 L/day, you only urinate 1.5-2.0 liters/day, so ___ of ____ and ___ is reabsorbed.
 Definition
- 99%
- water and sodium
Term
In ultrafiltrate you have about ___mg glucose/100 ml, but you have no glucose in urine. Explain this.
 Definition
- 90
- this means that 100% of glucose should be reabsorbed
Term
Amino acids are ____ reabsorbed.
 Definition
100%
Term
Most of the ultrafiltrate is reabsorbed in the ___ ___.
 Definition
renal tubule
Term
___ ___ cannot be reabsorbed at all.
 Definition
Uric acid
Term
Transported substances undergoing reabsorption pass through what 3 membranes?
 Definition
- luminal membrane of tubule cells
- basolateral membrane of tubular cells
- endothelium of peritubular capillaries
Term
2 mechanisms for reabsorption:
 Definition
- active requiring ATP
- passive following electrochemical or osmotic gradient
Term
There are two pathways for reabsorption: paracellular and transcellular. The paracellular pathway is ___, ____, ___ ___ used for ___, ___, ___, ___, and ___. The transcellular pathway can be used for ___ and ___ transport.
 Definition
- passive, osmotic, solvent drag
- calciium, potassium, chloride, sodium, and water
- active and passive
Term
Between the epithelial cells it is called the ___ space, which contains ___ ___, which allow ____ and some other substances to pass through.
 Definition
- intracellular
- tight junctions
- water
Term
Sodium reabsorption uses ___ ___transport.
 Definition
- primary active
Term
Sodium is the most abundant molecule in plasma, and is the most important for reabsorption.
 Definition
Term
Reabsorption of sodium in the proximal tubule on the apical membrane is ____ via a contransporter that also absorbes ___, ___ ___, and some vitamins. Then on the basolateral side of the tubule epithelial cell, the ___ ___ ____ pumps sodium out of the cell to maintain the concentration gradient. So ultimately reabsorption in the proximal tubule is done by ___ ___ ___.
 Definition
- passively
- contransporter
- glucose, amino acids, and some vitamins
- sodium potassium ATPase
- primary active transport
Term
As sodium is reabsorbed into the blood, other substances like chloride follow it, which will result in an increased osmolarity. Water always moved to concentrated areas, so you have a huge osmotic gradient, so water moves from lumen into the interstitial space. This will increase the hydrostatic pressure in the interstitial space, making water and substances move the the capillary. This is ____.
 Definition
reabsorption.
Term
Sodium reabsorption is almost always by __ ___ ___.
 Definition
primary active transport
Term
To summarize, sodium moves into tubular cell and is transported out of the tubule by ______. It then moves into peritubular capillaries due to __ ___ ___ and ___ ___ ___ of the blood.
 Definition
- Na+K+ ATPase
- low hydrostatic pressure of the blood
- high osmotic pressure of the blood
Term
___ reabsorption provides the energy and means for reabsorbing most other solutes.
 Definition
Na+
Term
Active pumping of Na+ reabsorption drives reabsorption of :
 Definition
- water by osmosis, aided by water filled pores called aquaporins
- anions and fat soluble substances by diffusion
- organic nutrients and selected cations by secondary active transport
Term
In the first half of the proximal tubule, sodium reabsorption is coupled with ___ and ___ reabsorption. Mainly ___ though, which is very important to regulation of acid-base balance.
 Definition
- glucose and bicarbonate
- bicarbonate
Term
The major sodium transporter in the first half of the proximal tubule is the ______ ____, which pumps ___into the tubular lumen and brings ___ into the tubular cell. This transporter promotes the formation of ____ within the tubular cell.
 Definition
- Na+H+ Antiporter
- hydrogen
- sodium
- bicarbonate
Term
In the second half of the proximal tubule, sodium reabsorption is coupled to ___ reabsorption.
 Definition
chloride
Term
In the second half of the proximal tubule, the ___ concentration is higher in the lumen. But in the tubular cell the concentration of chloride is low b/c on the basolateral surface of the cell there is a ______ ____ that pumps ___ and ___ out of the cell. This creates an electrochemical gradient so that ___, ____, and ____are all reabsorbed here.
 Definition
- chloride
- chloride potassium cotransporter
- chloride and potassium
- chloride, sodium, and water
Term
Chloride is only absorbed in the ___ portion of the proximal tubule.
 Definition
- second
Term
Chloride causes an ___ and ___ gradient in the second portion of the small intestine.
 Definition
- electrical
- chemical
Term
The proximal tubule is the only portion of the renal tubule that can absorb ___ and ___ ___. If ___ doesn't get fully reabsorbed here, then it will be in the urine.
 Definition
- glucose and amino acids
- glucose
Term
About __% of sodium is absorbed in the proximal tubule.
 Definition
67%
Term
___ is the main ion that determines osmolality.
 Definition
Sodium
Term
In the proximal tubule, sodium reabsorption is ____ and ____. Chloride reabsorption is ___ ___ and ___ ___, but is always coupled with sodium. Water absorption is passive and always follows solutes.
 Definition
- active and transcellular
- passive paracellular
- active transcellular
Term
The thin descending loop of Henle has ___ water reabsorption and __ NaCl reabsorption. The thin ascending loop has ___ water reabsorption and ___ NaCl reabsorption. The thick ascending loop of Henle has __ water reabsorption and very ___ NaCl reabsorption.
 Definition
- passive
- no
- no
- passive
- no
- active
Term
The only portion of the loop of Henle where water is reabsorbed is the __ ___ portion.
 Definition
thin descending
Term
Concentration of sodium chloride is at its max at the ___ part of the loop of Henle b/c at this point only water, no sodium chloride, has been reabsorbed.
 Definition
- bending
Term
In the thin ascending loop of Henle, the method of NaCl reabsorption is __ ___.
 Definition
not clear
Term
NaCl reabsorption is very important in the thick ascending loop of Henle. The transporter used for this is a ____ that transports 3 ions at the same time: _ ___, _ ___, _ ___.
 Definition
- cotransporter
- 1 sodium
- 1 potassium
- 2 chloride
- all into the cell
Term
If you block the cotransporter for sodium reabsorption in the thick ascending loop of Henle, what happens?
 Definition
- you inhibit sodium reabsorption> lose lots of sodium> decreased blood osmolarity> decreased blood volume> decreased blood pressure
Term
What transporter is a big target for diurectics?
 Definition
- 3 ion contransporter in the thick ascending loop of Henle
- you block this> you lose lots of sodium and water follows
Term
In the distal tubule there is ___ water reabsorption and ___ NaCl reabsorption. This is where ____ act.
 Definition
- no
- active
- thiazides
Term
The collecting duct is divided into the ___ portion and the ___ portion.
 Definition
- cortical
- medullary
Term
In the cortical portion of the collecting duct, water is ___ reabsorbed and is regulted by ___. Also NaCl is ___ reabsorbed and regulated by ___.
 Definition
- water is passively reabsorbed and regulated by ADH
- actively reabsorbed and regulated by aldosterone
Term
In the medullary portion of the collecting duct, water is ____ reabsorbed and is regulated by ___, and urea is ___ reabsorbed and is regulated by ___.
 Definition
- passively
- ADH
- passively
- ADH
Term
The thin and thick ascending loop of Henle as well as the distal tubule is ___ to water. But the descending loop of Henle and the collecting duct are ___ to water.
 Definition
- impermeable
- permeable
Term
The collecting duct is permeable to water depending on ___. If there is ADH in the plasma, it will be permeable to water. If there is not ADH in the plasma, it will not be permeable to water.
 Definition
Term
Both the cortical and medullary portions of the collecting duct are permeable to ___, but the cortical is also permeable to ____, while the medullary portion is permeable to ____.
 Definition
- water
- NaCl
- urea
Term
In the collecting duct, everything depends on ____.
 Definition
hormones
Term
The Distal tubule, is impermeable to water, but is permeable to NaCl. On the apical membrane in the distal tubule, there is a ___ ____ ____ that brings ___ and ___ into the tubule cell, while the ____ ___ pumps the sodium out into the interstitial space.
 Definition
- Na Cl cotransporter
- Na and Cl
- Na+K+ ATPase
Term
The ___ membrane is where you have differences in absorption, but you always have the ___ ___ on the basolateral membrane.
 Definition
- apical
- Na+K+ ATPase
Term
Epithelial cells in the distal tubule can be divided into two types of cells. Most are the ____ cells, and the others are the ___ cells.
 Definition
- Principal
- Intercalated
Term
Principal cells are responsible for ___ reabsorption and ___ secretion.
 Definition
- sodium
- potassium
Term
Intercalated cells are responsible for ____ secretion and ____ reabsorption, so they are imporant for ____ balance.
 Definition
- hydrogen secretion
- bicarbonate reabsorption
- acid base balance
Term
On principal cells )in the late distal tubule and collecting duct)have lots of ___ ___ on their apical membranes, not transporters, just ____.
 Definition
- sodium channels
- channels
Term
___ determines if the sodium channels are opened or closed in the late distal tubule and collecting duct.
 Definition
Aldosterone
Term
Na+K+ ATPase on basolateral surface of principal cells maintains gradient that favors sodium moving in through channels in late distal tubule and collecting duct. But whether or not these channels are open is dependent on aldosterone.
 Definition
Term
Major roles of proximal tubule:
 Definition
- recovery of filtered load
- "mass reabsorber" from 50-100%
- major site of solute secretion, except K+
Term
Major roles of loop of Henle:
 Definition
- ion reabsorption, 15-35%
- some water reabsorption
Term
What happens beyond the loop:
 Definition
- fine tuning of most substances
- determines final amounts excreted
- major site of homeostatic control
Term
Angiotension II stimulates ___ reabsorption in the ___ ____, ___ ___ loop of Henle, ___ ___, and ___ ____. It also stimulates ___ reabsorption in the ___ ___.
 Definition
- NaCl
- proximal tubule
- thick ascending loop of Henle
- distal tubule
- collecting duct
- water reabsorption in proximal tubule
Term
Aldosterone stimulates ___ reabsorption in the ___ ___ __ and ___ ___ , specifically in the ___ ___. This is accompanied by ___ secretion.
 Definition
- Na+
- late distal tubule
- collecting duct
- principal cells
- potassium
Term
Aldosterone is a ___ hormone so it can pass through the cell membrane and bind to its receptor in the cytoplasm and then go to the nucleus. What actions does it have in the nucleus?
 Definition
- causes more channel proteins to be made
- causes increased transport and insertion of channels in plasma membrane
- increases activity of channels via SgK1 and CAP1 enzymes
- increases amount of Na+Cl- ATPase
Term
Besides targeting the 3 ion cotransporter in the thick ascending loop of Henle, what else may diuretics target?
 Definition
sodium channels on principal cells in the late distal tubule and collecting duct
Term
Anti-diuretic hormone stimulates ___ reabsorption in the ___ ___ by increasing ___ ___ of collecting duct.
 Definition
- water reabsorption
- collecting duct
- water permeability
Term
Atrial Natriuretic Peptide (ANP) and Brain Natriuretic Peptide (BNP), inhibit ___ ____ ____ reabsorption in the ___ ___ and ___ ___ and inhibit ___ ___ ____ reabsorption in the ___ ___.
 Definition
- inhibit aldosterone stimulated NaCl reabsorption in late distal tubule and collecting duct
- inhibit ADH stimulated water reabsorption in collecting duct
Term
Urodilatin is produced in the ___ and inhibits ___ and ___ ____ in the ___ ___ and ___ ___.
 Definition
- kidney
- inhibits NaCl and water reabsorption in the distal tubule and collecting duct
Term
Uroguanylin and Guanylin are generated in the ___ ___and inhibit ___ and ___ ___.
 Definition
- GI tract
- NaCl and water reabsorption
Term
Glomerular tubular balance just involves the ____ tubule. The percentage of reabsorption in the proximal tubule is always ___% of ultrafiltrates, this is fixed. So if filtration increases, reabsorption will increase, but it will always be this percent
 Definition
- proximal
- 67%
Term
Some substances cannot be filtered, thus ___ has to get rid of them, examples include:
 Definition
- secretion
- antibiotics
- toxins
Term
With tubular secretion, substances move from ____ ____ or ___ ___ to the ___ ____.
 Definition
- peritubular capillaries
- tubule cells
- tubular lumen
Term
Tubular secretion is important for:
 Definition
- disposing of substances not already in the filtrate
- eliminating undesirable substances like urea and uric acid
- ridding body of excess potassium ions
- controlling blood pH
Term
Major substances secreted in the renal tubule include:
 Definition
- potassium
- hydrogen ions
- ammonium
Term
Hydrogen and ammonium are secreted mostly in the ___ ___, while potassium is secreted in the ___ ___.
 Definition
- proximal tubule
- distal tubule
Term
Define renal clearance:
 Definition
- the volume of plasma that is cleared of a particular substance in a given time
Term
The amount of substance removed by the kideny with renal clearance, should be equal to the amount that is in the ____ .
 Definition
plasma
Term
Without reabsorption and secretion, the amount filtered is equal to what?
 Definition
- the amount excreted
Term
Renal clearance tests are used to:
 Definition
- determine the GFR
- detect glomerular change
- follow the progress of diagnosed renal disease
Term
equation for renal clearance:
 Definition
RC = UV/P

RC: renal clearance rate
U: concentration (mg/ml) of substance in urine
V: flow rate of urine formation (ml/min)
P: concentration of same substance in plasma
Term
Inulin is not made by the body, but is a substance that is infused into body to assess ___ and ___ ____. Inulin cannot be ___ or ___, so amount ___ should equal amount ____.
 Definition
- GFR and renal clearance
- cannot be reabsorbed or secreted
- amount filtered should = amount excreted
Term
Some patients aren't comfortable using inulin, so ___ ___ can be assessed instead. This is made by the body, it is not as pefect of measurement, but it is close.
 Definition
- creatinine clearance
Term
Bartter's Syndrome is a loss of _____ ____ in the ___ ___ loop of Henle. This manifests itself through ____, ____, and ____.
 Definition
- 1 Na, 1 K, 2 Cl contransporter
- thick ascending
- hypokalemia
- hyperaldosteronism
- alkalosis
Term
With Liddle's Syndrome, there is an increase in number of the ___ ___ ___ in the ___ ___ of the ___ ___ and ___ ___. This causes ___.
 Definition
- epithelial Na+ channels
- principal cells
- distal tubule
- collecting duct
- hypertension
Term
With diabetes you have ____.
 Definition
- diuresis
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