Topic 1 Part B Flashcards by melissa griffith

Reabsorption – Proximal Tubule
__% of filtered load of sodium & water reabsorbed
-Cells of proximal tubule designed for ___ reabsorption capacity of ____ and ____

65% of filtered load of sodium & water reabsorbed

-Cells of proximal tubule designed for high reabsorption capacity of sodium and water

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Reabsorption – Proximal Tubule
Little less percentage for _____
-Quantity can be __________

Little less percentage for chloride

-Quantity can be increased or decreased as needed

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Proximal Tubule Cellular Ultrastructure

Contain large number of mitochondria to support

extensive active transport activity

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Proximal Tubule Cellular Ultrastructure

Luminal (apical) brush border provides

huge surface area for rapid diffusion

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Proximal Tubule Cellular Ultrastructure

Basolateral border contains

extensive number channels in between cells providing huge surface area

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Proximal Tubule Cellular Ultrastructure
Luminal border contains extensive number of _____
-Co-transport of ______ and ______
-Counter-transport of ______ (move a large quantity of them against a small ________)

Luminal border contains extensive number of protein carrier molecules

Co-transport of amino acids and glucose
Counter-transport of hydrogen ions (move a large quantity of hydrogen ions against small hydrogen ion gradient

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Proximal Tubule Cellular Ultrastructure

Basolateral border contains extensive amount of ____

N-K ATPase

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Early vs. Late Proximal Reabsorption
First half of tubule:
Extensive co-transport of sodium with

glucose and amino acids

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Early vs. Late Proximal Reabsorption
First half of tubule:
Sodium reabsorption carries ____, ____, ____ ions leaving _____ resulting in increasing [Cl-]
–____ mEq/L increases to _____ mEq/L

Sodium reabsorption carries glucose, bicarb, organic ions leaving chloride resulting in increasing [Cl-]
105 mEq/L increases to 140 mEq/L

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Early vs. Late Proximal Reabsorption
Second half of tubule:
High chloride concentration favors _______
-Some movement may occur through specific ______

High chloride concentration favors chloride diffusion

-Some movement may occur through specific chloride channels

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Early vs. Late Proximal Reabsorption
Second half of tubule:
Most ____ & _____ have been reabsorbed – ____ reabsorption drives _____ reabsorption
-_______ gradient

Most glucose & amino acids have been reabsorbed – sodium reabsorption drives chloride reabsorption
-Electrochemical gradient

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Changes in Solute Concentrations

Total _____ of sodium in tubule changes but ____ does not change because ____ reabsorption matches sodium reabsorption

Total quantity of sodium in tubule changes but concentration does not change because water reabsorption matches sodium reabsorption

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Changes in Solute Concentrations
Total osmolarity does not change for the same reason as sodium
-Proximal tubule _____ permeable to _____

Proximal tubule highly permeable to water

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Changes in Solute Concentrations

____ & _____ concentrations decrease due to extensive ________

Glucose & amino acid concentrations decrease due to extensive reabsorption

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Changes in Solute Concentrations
_____ & _____ are concentrated because they are not _______
Total amount of creatinine and urea in tubule does not ____

Creatinine & Urea are concentrated because they are not reabsorbed
Total amount of creatinine and urea in tubule does not change

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Changes in Solute Concentrations

Total amount of Na+, Cl-, HCO3-, glucose, amino acids in tubule _______

decrease

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Secretion of Organic Acids & Bases

Many end products of metabolism are secreted by proximal tubule (4)

Bile salts
Oxalate
Urate
Various catecholamines

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Secretion of Organic Acids & Bases

Many drugs & toxins secreted (2)

Penicillin

Salicylates

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Secretion of Organic Acids & Bases
Para-aminohippuric acid also secreted-
___% of PAH in renal blood flow is removed
Can be used to determine ____

90% of PAH in renal blood flow is removed

Can be used to determine renal blood flow

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describe the Thin Descending & Ascending Segment of the Loop of Henle (4)

Thin epithelial membrane
No brush border
Few mitochondria
Minimal metabolic level

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Thin Descending Segment of the Loop:
_____ permeable to water
_____ permeable to most solute

Highly permeable to water

Moderately permeable to most solute

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Thin Descending Segment of the Loop:
Allows diffusion of water and solutes: No active ____
___% of water reabsorption occurs in the loop of Henle

Allows diffusion of water and solutes: No active reabsorption
20% of water reabsorption occurs in the loop of Henle

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Thin Ascending Segment of the Loop:
_______ to water
-Part of mechanism for _______

impermeable to water

-Part of mechanism for concentrating urine

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Thick Ascending Segment

____ epithelial cells with high concentration of _______- High level of _______ activity

Thick epithelial cells with high concentration of mitochondria- High level of metabolic activity

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Thick Ascending Segment | Able to reabsorb (6)

``` sodium chloride potassium (Approx 25% of filtered load) calcium bicarb magnesium ```

Thick Ascending Segment _______ to water As solute reabsorb ______ concentrations drop especially since water ____ reabsorbed – Fluid very ___

- Impermeable to water | - As solute reabsorb luminal solute concentrations drop especially since water NOT reabsorbed – Fluid very dilute

Sodium Reabsorption | Driven by _____ in ______ border of tubule cells

Driven by N-K ATPase in basolateral border of tubule cells

Sodium Reabsorption: how many transport mechanisms move sodium from tubular lumen

2 total 1 Na-2Cl-1K co-transport mechanism Na-H counter-transport mechanism

Sodium Reabsorption 1 Na-2Cl-1K co-transport mechanism= 1. _____ means of moving sodium out of ____ into ____ cells 2. Potassium reabsorbed _____ potassium concentration gradient 3. Cl- & K+ diffuse out of cell into _______ via specific _______

1. Primary means of moving sodium out of lumen into tubular cells 2. Potassium reabsorbed AGAINST potassium concentration gradient 3. Cl- & K+ diffuse out of cell into renal interstitial fluid via specific ion channels

Loop diuretics (furosemide, ethacrynic acid, bumetanide) inhibit the action of the

1Na-2Cl-1K co-transport mechanism

Loop Diuretics: | Less sodium reabsorption – less water reabsorption in

later segments of the nephron

Loop Diuretics: | Less sodium reabsorption – less potassium reabsorption with potential

loss of potassium

Na-Cl-K co-transport mechanism is isoelectric BUT K is able to diffuse back into lumen via potassium channels creating

+8 mV positive charge in tubule lumen

Electrical gradient drives diffusion of Na+, K+, Mg++ & Ca++ into the ________ via the tight junctions (paracellular diffusion)

renal interstitial space

Early Distal Tubule Macula densa forms ______ -Part of _______ complex -Provides feedback control for ____ and_____

Macula densa forms first part of tubule - Part of juxtaglomerular complex - Provides feedback control for GFR and blood flow (for this nephron)

Early Distal Tubule Next segment is the _______ -____ reabsorption – no _____ reabsorption -_______ segment of distal tubule

Next segment is the high convoluted - Solute reabsorption – no water reabsorption - Diluting segment of distal tubule

Early Distal Tubule | ___% of filtered load for sodium & chloride reabsorbed

Early Distal Tubule | Driven by ____ in _______ border of tubular cells

Driven by Na-K ATPase in basolateral border of tubular cells

Early Distal Tubule Na-Cl co-transport mechanism moves Na+ and Cl- _____ --Chloride _____ out of cell via ______

Na-Cl co-transport mechanism moves Na+ and Cl- into cell down [Na+] --Chloride diffuses out of cell via chloride specific channels

Early Distal Tubule Thiazide diuretics inhibit this _______ mechanism -Reduces sodium and chloride ______ and ultimately water reabsorption in _____segments of nephron

Thiazide diuretics inhibit this Na-Cl co-transport mechanism | -Reduces sodium and chloride reabsorption and ultimately water reabsorption in later segments of nephron

Functional Characteristics – Late Distal Tubule & Cortical Collecting Tubule: Membranes _______ to urea -All urea entering exits to _______ to be excreted -Some reabsorption of urea will occur in ______

Membranes impermeable to urea - All urea entering exits to collecting duct to be excreted - Some reabsorption of urea will occur in medullary collecting ducts

Functional Characteristics – Late Distal Tubule & Cortical Collecting Tubule: Sodium reabsorption controlled by various hormones but especially by

aldosterone

Functional Characteristics – Late Distal Tubule & Cortical Collecting Tubule: Potassium secretion controlled by various hormones but especially by

aldosterone

Functional Characteristics – Late Distal Tubule & Cortical Collecting Tubule: - Able to secrete _____ ions against large concentration gradient of _____ - Proximal tubule moves hydrogen ions against ____ gradient of _____

- Able to secrete hydrogen ions against large concentration gradient (1000:1) - Proximal tubule moves hydrogen ions against small gradient (4 to 10:1)

Functional Characteristics – Late Distal Tubule & Cortical Collecting Tubule: Water permeability controlled by concentration of _____ -No ADH - no ____ permeability – excrete ____ urine -Increased concentrations of ADH increase permeability of ____ and decrease the volume of ____and increase the ________ of the urine

Water permeability controlled by concentration of antidiuretic hormone (ADH, aka vasopressin) - No ADH - no water permeability – excrete dilute urine - Increased concentrations of ADH increase permeability of water and decrease the volume of urine and increase the concentration of the urine

Late Distal Tubule & Cortical Collecting Tubule | two types of cells

Principal cells | Intercalated cells

Late Distal Tubule & Cortical Collecting Tubule | principal cells=

Reabsorb sodium & water | Secrete potassium

Late Distal Tubule & Cortical Collecting Tubule | intercalated cells=

Reabsorb potassium | Secrete hydrogen

Principal Cell Activity | _____ in _____ borders of tubule cells drives activity

Na-K ATPase in basolateral

Principal Cell Activity | Sodium follows _______ gradient – _____ through sodium specific channels

Sodium follows concentration gradient – diffuses through sodium specific channels

Principal Cell Activity | Potassium follows ______ gradient out of cell into _______ via potassium specific channels

Potassium follows concentration gradient out of cell into tubular lumen via potassium specific channels

Potassium Sparing Diuretics (Aldosterone antagonists): | What type of antagonist

Mineralocorticoid receptor

Potassium Sparing Diuretics (Aldosterone antagonists) | Compete with aldosterone receptor sites which inhibits

sodium reabsorption & potassium secretion

Potassium Sparing Diuretics (Aldosterone antagonists) drug names

Spironolactone & eplerenone

Potassium Sparing Diuretics (Sodium Channel Blockers) | Inhibit entry of sodium into cell which reduces amount of

sodium transported by Na-K ATPase

Potassium Sparing Diuretics (Sodium Channel Blockers) | reduces secretion of potassium as action of Na-K ATPase

decreases

Potassium Sparing Diuretics (Sodium Channel Blockers): | drug names

Amiloride & triamterene

Intercalated Cell Activity – Hydrogen Ions: | Secretion controlled by

H-ATPase transporter

Intercalated Cell Activity – Hydrogen Ions: | Presence of carbonic anhydrase allows conversion of

CO2 and H2O to hydrogen ions and bicarb ions

Intercalated Cell Activity – Hydrogen Ions: | Chloride also secreted following

electrochemical gradient

Intercalated Cell Activity – Hydrogen Ions: | Bicarb reabsorbed using Cl-HCO3- counter-transport mechanism following the

Cl- gradient into the cell

Intercalated Cell Activity – Hydrogen Ions: - _____moved freely between cell and interstitial fluid - ______ is also reabsorbed

- CO2 moved freely between cell and interstitial fluid | - Potassium is also reabsorbed

Meduallary Collecting Ducts: | Reabsorb ___% of filtered water and sodium

<10%

Meduallary Collecting Ducts: | Determine final concentration of

solutes and urine concentration

Meduallary Collecting Ducts: | Epithelial cells smooth with few

mitochondria

Meduallary Collecting Ducts: | Water permeability controlled by

ADH

Meduallary Collecting Ducts: | Urea is reabsorbed via specific urea transporters which moves urea into the

interstitial spaces thus affecting osmolarity

Meduallary Collecting Ducts: | Secretes

hydrogen ions (like cortical collecting tubule)

Solute Concentrations: | Change in solute concentration depends on rate of

reabsorption (secretion) versus rate of water reabsorption

Solute Concentrations: | Y-axis: Ratio of

[tubular] / [plasma]

Solute Concentrations: | Items highly concentrated are

not needed by body

Solute Concentrations: | Inulin neither secreted or reabsorbed provides indication of

water reabsorption

Solute Concentrations: - Inulin conc of 3 means that - Inulin conc of 125 means that

- Inulin conc of 3 means that 1/3 of water remains in tubule (2/3 has been reabsorbed) - Inulin conc of 125 means 1/125 of water remains while 124/125 has been reabsorbed

Topic 1 Part B Flashcards

(73 cards)