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BIOL 204 > Lecture 14 > Flashcards

Lecture 14 Flashcards

1
Q

Blood is filtered at the __________ and it produces a cell- and protein-free filtrate (glomerular filtration)

A

glomerulus

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2
Q
  • _____________: process of selectively moving substances from the blood into the filtrate
  • _____________: process of selectively moving substances from the filtrate back into the blood
A
  • tubular secretion
  • tubular reabsorption
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3
Q

the ______ is the most metabolically active part of the nephron, reabsorbs most of what was filtered….
- 100% _________
- 65% __________

A

proximal convoluted tubule (PCT)
- glucose; amino acids
- water; Na

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4
Q

Tubular Secretion
- the transfer of materials from the ___________ capillaries (blood) to the renal tubule _______ (tubular fluid)
- opposite process of reabsorption

A
  • peritubular; lumen
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5
Q

Tubular Secretion is important for urine formation because….
- it helps gets rid of molecules NOT filtered at the _________ due to _____ size
- it is a major mechanism for elimination of most administered ________ and their _________
- it helps maintain the ______, _____-______, and other bodily fluid balances (secretion of K+, H+, NH4+, creatinine, urea)

A
  • glomerulus; large
  • drugs; metabolites
  • ionic; acid-base
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6
Q

2 routes that substances can follow to cross tubule cells and get reabsorbed into blood…
1. ______________: BETWEEN the cells
2. ______________: THROUGH the cells

A
  1. Paracellular route
  2. Transcellular route
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7
Q

Structures that substances inside the renal tubular lumen must pass to be reabsorbed into the blood
- _____________ of tubular epithelial cells
- __________
- _____________ of tubular epithelial cells
- _______________
- ________________ of capillary

A
  • apical membrane of tubular epithelial cells
  • cytosol
  • basolateral membrane of tubular epithelial cells
  • interstitial fluid
  • endothelial cells of capillary
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8
Q

_____________: the maximum rate of reabsorption
- there are a _________ number of transport proteins–> limits the amount of solutes the renal tubule can ________
- Tm is reached when the transporters are _________
- each solute has its _____ ______

A

Transport maximum (Tm)
- LIMITED; reabsorb
- saturated
- own Tm

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9
Q

Factors that limits the amount of solute the renal tubule can reabsorb and therefore the Tm
- the ________ of transport proteins available for that solute
- transport ___________ which occurs when all protein transporters are being used for the transport of that molecule

A
  • number
  • saturation
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10
Q

________: the main function is to _______ all these things (such as glucose, amino acids, electrolytes) that your body did NOT intend to get rid of in the first place

A

PCT (proximal convoluted tubule); RECLAIM

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11
Q

In the PCT…
- _________: generates a strong concentration gradient for sodium reabsorption; located on ______________

A
  • Na+/K+ pump= Renal Na-K-ATPase; basolateral membraneD
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12
Q

Direction of movement in Sodium-Potassium Pump
- it moves Na+ and K+ against large concentration gradients
- it moves ____ ions into the tubule cell where ____ levels are high
- it pumps _____ ions out of the cells and into ________ fluid

A
  • potassium; K+
  • sodium; interstitial
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13
Q

How are organic solutes such as glucose and amino acids, as well as phosphates reabsorbed at the PCT
- via ____________ which transport _____ from the filtrate with another ______ (glucose, AAs)
- once solutes are inside the tubular epithelial cells… they cross the _________ membrane via _____ _________ _______

A
  • solute-specific transporter; Na+; solute
  • basolateral; specific membrane transporters
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14
Q

3 ways Na+ is reabsorbed at the PCT
1. ___________ transport through the luminal (_____) membrane via a variety of __________ (transport Na+ with other ______, such as ______)
2. ____________ transport by _______ ____________ (=exchangers) which links secretion of ________ with reabsorption of ________
3. ____________ route across tubular epithelial cell _____ ________ (together with ______ ions) in _______ PCT

A
  1. Transcellular; apical; symporters; solutes; glucose
  2. Transcellular; Na-H antiporters; hydrogen; sodium
  3. Paracellular; tight junctions; chloride; late
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15
Q

The concentration gradient to move Na+ from tubular lumen to the cell is generated by…. _____________
- which continuously pumps Na+ _________ the cell; ________ Na+ inside the cell

A

Na-K ATPase
- outside; decreasing

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16
Q
  • Where is the Na+/H+ antiporter (Na+/H+ exchanger) located? _______________
  • What is the direction of ion movement in the Na+/H+ antiporter? _______________
  • Which hormone up regulates its expression and/or activity? ________________
A
  • apical membrane of epithelial cells at the PCT
  • H+ OUT; Na+ IN (contributes to Na+ reabsorption and body acid-base balance)
  • Angiotensin II
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17
Q

The reabsorption of salt and organic solutes creates a gradient favoring the passive movement of water by _________
- this is called “___________________________” because water is “obliged” to ________ solute movement

A

osmosis
- obligatory water reabsorption; FOLLOW

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18
Q
  • SGLT= ______________
  • they are found in the renal tubule segment: __________, _____% glucose reabsorbed here
  • function: responsible for the tubular _______________ of filtered glucose from the kidneys into the ___________
A
  • Sodium Glucose cotransporters
  • PCT; 100%
  • reabsorption; bloodstream
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19
Q

The primary. function of the Loop of Henle is to generate an _______ ________ that enables the collecting duct to concentrate the urine and conserve water

A

osmotic gradient

20
Q
  • Which segment of the Nephron loop is permeable to water? ___________
  • Which segment of the Nephron loop is impermeable to water? ____________
  • Which segment of the Nephron loop is permeable to solutes? ____________
  • Which segment of the Nephron loop is impermeable to solutes? ____________
A
  • descending limb
  • ascending limb
  • ascending limb
  • descending limb
21
Q

In the ____________ limb the reabsorption of large amounts __________ in the absence of water results in significant dilution of the tubular fluid—> this is why this segment of the nephron loop is considered “the ______ ________” of the nephron

A

ascending; sodium; diluting segment

22
Q

Thick Ascending Loop of Henle
- ___________ __________ are located on the ____________ membrane of epithelial cells

A
  • Na+/K+/2Cl- symporter; apical (or luminal)
23
Q

Direction of ion movement in the Na+/K+/2Cl- symporter:
- all 3 ions are transported in the ________ direction
- from the ______ to the ______ of the cell
- reabsorption of Na+ is powered by a __________ _______ __________: it generates low Na+ concentrations within the tubular epithelial cells

A
  • SAME
  • lumen; inside
  • basolatereal Na/K ATPase
24
Q

In the thick ascending loop of henle,
- how many potassium and chloride ions are transported together with sodium ions through co-transport?
Cl= ________
K= _______
Na= ______

A

2 (-2 charge)
1 (+1 charge)
1 (+1 charge)

25
Q

“Distal Tubule”
- it includes two nephron segments
1.
2.

A
  1. distal convoluted tubule (DCT)
  2. Connecting tubule (CNT)
26
Q
  • NCC= __________
  • Located in ___________, subsegments 1 (_______) and 2 (__________) on _________ membrane of tubule epithelial cells
  • Function: transport _____ and _____ from the lumen to the cell
A
  • NaCl Cotransporter
  • Distal convoluted tubule (DCT); early DCT; late DCT; apical
  • Na+; Cl-
27
Q

Main functions of cortical collecting duct
- ______ ______ the amount of _________
-________ cells play an important role in this process–> controlled by ___________
-reabsorb ______ and ____
-secrete ____
- _____ homeostasis–> important role for ____________ cells
-reabsorb ____
- secrete ____

A
  • fine tuning; electrolytes
    -principal; aldosterone
    -Na; H2O
    -K+
  • pH; type A intercalated
    -K+
    -H+
28
Q

Main functions of medullary collecting duct
- contributes to _____________ _________ _____ (_____ reabsorption)
- ______ decision point for ______ reabsorption (urine concentration)
- permeability to H2O depends on _____

A
  • hyperosmotic medullary ISF; urea
  • FINAL; water
  • ADH
29
Q

The late DCT and cortical CD are relatively impermeable to water and solutes unless influenced by _______________

A

hormones

30
Q

ENaCs= ___________
- located: __________ and ___________

A

Epithelial Sodium Channels
- late distal convoluted tubule (DCT 2) and cortical collecting duct (CD)

31
Q

3 regions of the nephron that are collectively termed the “aldosterone-sensitive distal nephron”
1.
2.
3.

A
  1. Late Distal Convoluted Tubule (DCT 2)
  2. Connecting Tubule (CNT)
  3. Cortical Collecting Duct (CCD)
32
Q

___________: hormone that controls water reabsorption, and therefore, urine concentration in the _____

A

ADH (Antidiuretic hormone, aka vasopressin); CD

33
Q

Two factors that allow the kidney to produce concentrated (hypertonic) urine
1. _______ acting on the ___ and ____ to increase water permeability: “_________ water reabsorption”
2. a ________ _______ ________ in the interstitial fluid of the _____ ________ that drives the reabsorption of water by osmosis

A
  1. ADH; DCT; CD; “facultative”
  2. medullary osmotic gradient; renal medulla
34
Q

To produce concentrated urine… you need to reabsorb _________ water

A

MORE (the urine will contain less amount of water so the solutes will be concentrated)

35
Q

_____ in the ______ you can find more concentrated interstitial fluid

A

DEEP; medulla

36
Q

Three mechanisms that help create or maintain the medullary osmotic gradient
1. a _______ ______ _______ in the nephron ______ of _________ nephrons
2. The ________ of _______: it passively diffuses into the interstitial fluid of the medulla from the ______
- this ______ will be taken back into the tubular fluid at the nephron _______
3. A _________ ________ in the _____ ______

A
  1. countercurrent multiplier system; loops; juxtamedullary
  2. recycling; urea; CD
    - urea; loop
  3. countercurrent exchanger; vasa recta
37
Q

Countercurrent Multiplier System
- located: nephron _____ of __________ nephrons
- called multiplier because it multiplies the _________ deep in the ______
- establishing an interstitial osmolality gradient from ______ mosmol/kg (in the ____ similar to plasma) to >_______ mosmol/kg (in the ________ at the tip of the renal papilla)

A
  • loops; juxtamedullary
  • osmolarity; medulla
  • 300;cortex; 1200;medulla
38
Q

in the descending loop of henle, water is drawn from the tubular fluid through ___________, following an osmotic gradient created mainly by ________ ion

A

aquaporins; sodium (Na+)

39
Q

in which limb of the nephron loop is the tubular fluid more concentrated in solutes?

A

descending loop because water leaves and NaCl remains (filtrate becomes progressively more concentrated as it reaches bottom of the nephron loop)

40
Q
  • The descending limb is __________ to solutes, including Na+
  • The ascending limb we can find ________ transporters
  • this is why sodiums ion leave the ________ limb of the nephron and not before
A
  • impermeable
  • Na+/K+/2Cl
  • ascending
41
Q

What is responsible for increasing the interstitial fluid’s osmolarity of the medulla?

A
  • pumping sodium outside the tubule
42
Q

Countercurrent multiplier vs. Countercurrent exchange
- the countercurrent multiplier at the nephron loop is mainly responsible for creating the ______ ______
- the countercurrent exchanger does _____ create the _____ ________, but ________ it by
(1) preventing ____ removal of salt from the medullary interstitial
(2) removing reabsorbed ______

A
  • medullary gradient
  • NOT; medullary gradient; preserves
    (1) rapid
    (2) water
43
Q

The countercurrent exchange
- the water reabsorbed at the descending limb reenters the circulatory system through the ____ ______
- as the blood flow in these capillaries is _____, solutes that are reabsorbed into the bloodstream have _____ time to diffuse back into the interstitial fluid, maintaining the ______ concentration gradient in the _______

A
  • vasa recta
  • SLOW; ample; solute; medulla
44
Q

______ passively diffuses into the interstitial fluid from the CD, contributes to the _________ _______ _______

A

urea; medullary osmotic gradient

45
Q

Obligatory water reabsorption
- water is ______ by osmosis to follow ______ that have been reabsorbed
- takes place in the ______ and ______ _________
- _______ control this with _________
- _____ % of water

A
  • obliged; solutes
  • PCT; descending limb of nephron loop
  • CANNOT; hormones
  • 85%
46
Q

Facultative water reabsorption
- regulated by ______; water is reabsorbed considering the plasma osmolarity (fluid balance of the individual)
- takes place in the ___ ______ and _____
- ____% of water

A
  • ADH
  • late DCT; CD
  • 15%

BIOL 204 (28 decks)

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