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PCS2002 > lecture 5/6 - redone > Flashcards

lecture 5/6 - redone Flashcards

1
Q

sodium movement into the cell

A

enters through sodium channels down an electrochemical gradient by facilitated passive diffusion

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2
Q

sodium movement out the cell

A

removed by Na/K ATPase which requires ATP, into the blood

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3
Q

movement of chloride

A

chloride moves between the cells (paracellular diffusion) through tight junctions

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4
Q

water follows the NaCl by

A

osmosis through aquaporins or tight junctions

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5
Q

NKCC1 transporter transports

A

1 sodium
1 potassium
2 chloride
into the cell

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6
Q

on the apical membrane the chloride channels we have are

A

CFTR and calcium activated chloride channels (CaCC)

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7
Q

which part of the CFTR is phosphorylated by PKA and causes the channel to open

A

R domain

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8
Q

CFTR activity is regulated by

A

PKA and ATP

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9
Q

phosphorylation induces ATP binding to the

A

NBDs (nucleotide binding domains)

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10
Q

then a conformational change in NBDs

A

transmits to MSD (membrane spanning domains) causing the pore to open

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11
Q

ATP is hydrolysed and the pore

A

closes

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12
Q

protein phosphatases

A

dephosphorylate of the R domain

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13
Q

does the channel open if ATP is present but the R domain is not phosphorylated

A

no

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14
Q

patch clamp technique allows you to

A

make electrical measurements of ions moving through ion channels
showed ATP alone had no response

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15
Q

calcium activated chloride channels (CaCC) are activated by

A

a ride in calcium

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16
Q

examples of CaCCs are

A

TMEM16A and B

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17
Q

in TMEM16A what does the calcium bind to

A

glutamate residues in one of the alpha helices causing pore to open

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18
Q

SLC26A anion exchanger brings chloride into the cell in exchange for

A

bicarbonate

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19
Q

NBC (Na+ dependent HCO3- cotransporter) on basolateral membrane supplies

A

cytosolic HCO3- for the exchanger

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20
Q

cAMP/PKA activation of CFTR does what to AE activity

A

switches it on

21
Q

what is required for CFTR to regulate the activity of AE (e.g SLC26A3)

A

interaction of the 2 channels by scaffold protein CAP70

22
Q

in CF, AE activity is

A

inhibited

23
Q

what 2 cells is the pancreas made up of

A

duct and acinar cells

24
Q

what do acinar cells secrete into the ducts

A

digestive enzymes and low volumes of NaCl rich fluid (using TEM16A (CaCC) channel)

25
Q

duct cells transport

A

digestive enzymes to SI
produce a high volume of NaHCO3- rich solution using CFTR and SLC26A6 (AE)

26
Q

in CF what isnt secreted in the pancreas

A

NaHCO3- fluid (as CFTR and AE dont function)

27
Q

what does this cause

A

blockages in the ducts as the enzymes cant be solubilized

28
Q

why does the pancreas self digest

A

as the enzymes still get activates and start to degrade the pancreas

29
Q

role of ENaC in the kidney

A

sodium retention, controls body sodium and water balance and therefore blood pressure

30
Q

role of ENaC in the lungs

A

sodium and water absorption
controls ASL

31
Q

role of ENaC in the colon

A

sodium and water reabsorption from the diet

32
Q

how many subunits does ENaC have

A

3
alpha, beta and gamma

33
Q

how many transmembrane domains does each subunit have

A

2
they form the pore of the channel

34
Q

inhibitor of ENaC

A

amiloride

35
Q

CAPs cleave the loops and

A

increase activity

36
Q

SLUNC1 binds to beta subunit and

A

inhibits ENaC

37
Q

where is ENaC expressed in the kidney

A

aldosterone-sensitive distal nephron (ASDN)

38
Q

renin is released in response to

A

low blood pressure

39
Q

renin converts angiotensinogen to

A

angiotensin I

40
Q

ACE 1 cleaves angiotensin I to

A

angiotensin II

41
Q

angiotensin II increases levels of

A

aldosterone

42
Q

aldosterone increases

A

sodium reabsorption through ENaC which increases extracellular fluid
restores BP so renin stops being released

43
Q

aldosterone binds to cytosolic receptor and goes to nucleus to regulate transcription and translation of certain genes in order to increases

A
  1. surface ENaC levels
  2. Na/K ATPase density
  3. ATP supply to support increased Na/K activity
  4. K secretion across membrane
44
Q

aldosterone decreased rate of ______ for ENaC

A

retrieval

45
Q

retrieval of ENaC is regulated by ubiquitin ligase

A

Nedd4-2

46
Q

Nedd402 binds to

A

P-Y motif and adds ubiquitin group to a lysine residue signalling degradation of ENaC

47
Q

aldosterone stimulates production of

A

SGK1

48
Q

SGK1 phosphorylates Nedd4-2

A

prevents Nedd4-2 binding to ENaC inhibiting ubiquitination

PCS2002 (34 decks)

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