M&R 2.2 - ATP Dependent Pumps And Ion Exchangers Flashcards Preview

ESA 2 > M&R 2.2 - ATP Dependent Pumps And Ion Exchangers > Flashcards

Flashcards in M&R 2.2 - ATP Dependent Pumps And Ion Exchangers Deck (33)
Loading flashcards...
1
Q

What are the functions of the sodium ion pump?

A
  • Form Na+K+ gradient (used in membrane potentials)

- Promotes secondary active transport (pH control, cell volume and Ca2+ regulation, Na+ absorption and nutrient uptake)

2
Q

What is the Na+Ca2+ exchanger otherwise known as?

A

NCX

3
Q

What is the ratio of ion transport of NCX? What happens as a result of this?

A
  • 3 Na+ into cell : 1 Ca2+ out of cell

- Membrane becomes electrogenic so the current runs in the direction of the Na+ gradient

4
Q

What is the function of NCX?

A

Expels intracellular Ca2+ during cell recovery from signalling

5
Q

What happens when NCX becomes depolarised?

A
  • Works in reverse (3Na+ out, 1Ca2+ in)

- Lead to a high concentration of extracellular Na+ and high concentration of intracellular Ca2+

6
Q

What happens to NCX during ischaemia/ after reperfusion?

A

The depletion of ATP causes it to become partially depolarised which can produce toxicity

7
Q

What is the Na+H+Exchanger otherwise known as?

A

NHE

8
Q

What is the ratio of ion exchange of NHE?

A
  • 1 Na+ in: 1 H+ out so is electroneutral
9
Q

What are the functions of NHE? What is it activated by?

A
  • pH regulation (is an acid extruder)
  • Cell volume regulation
  • Drug target for Amiloride
  • Activated by growth factors
10
Q

Name the two bicarbonate transporters and give their shorthand terms

A
  • Na+bicarbonate-chloride cotransporter (NBC)

- Anion exchanger (AE)

11
Q

What is the function of NBC and how is this achieved?

A
  • Alkalinises cell

- 1 Na+ and 1 HCO3- in : 1 H+ and 1 Cl- out

12
Q

What is the function of AE and how is this achieved?

A
  • Acidifies cell

- 1 HCO3- out : 1 Cl- in

13
Q

What the full name of PMCA?

A

Plasma membrane Ca2+ ATPase

14
Q

What are the functions of PMCA?

A
  • Removes 1 Ca2+ from cell and brings 1 H+ in

- Removes residual Ca2+ by having a high affinity but a low capacity

15
Q

What is the full name of SERCA?

A

Sarco(endo)plasmic reticulum Ca2+ ATPase

16
Q

What are the functions of SERCA?

A
  • Removes 1 H+ and brings 1 Ca2+ in

- Accumulates Ca2+ in sarcoplasmic/endoplasmic reticulum by having a high affinity but a low capacity

17
Q

What kind of active transporter are SERCA and PMCA?

A
  • Primary active transporter

- Use ATP

18
Q

What are the intracellular and extracellular concentrations of Ca2+?

A
  • Intracellular = 50-100nM

- Extracellular = 2mM

19
Q

Which three transport methods contribute to the transport of calcium ions? Why does there need to be so many?

A
  • Primary active transport e.g. SERCA
  • Secondary active transport e.g. NCX
  • Facilitated transport e.g. VOCC
  • If only one was used, the appropriate concentrations wouldn’t be able to be reached
20
Q

Which transporters contribute to the control of cellular calcium levels?

A
  • PMCA
  • SERCA
  • NCX
  • Mitochondria Ca2+ uniports
21
Q

What is the function of the mitochondrial Ca2+ uniports?

A
  • Buffer away from cytoplasm when concentrations of Ca2+ are high
  • Move H+ into inter membrane space which causes an electrical gradient
22
Q

Which transporters are acid extruders?

A
  • NHE - removes H+ so is protective in highly metabolising tissues
  • NBC
23
Q

Which transporters are base extruders?

A

AE - chloride is also brought in therefore acidifying

24
Q

How is cell volume regulated? In what environment can this be achieved?

A
  • Transport of osmotically active ions e.g. Na+ to which water follows
  • Has to be done in an ELECTRONEUTRAL environment
25
Q

What causes swelling and shrinkage of the cell?

A
  • Swelling = INFLUX of ions therefore more water inside

- Shrinkage = EXTRUSION of ions therefore more water outside

26
Q

Where does renal bicarbonate absorption happen? What is the aim of this?

A
  • Proximal tubule of the kidney

Goals are:

  • H2CO3 retention for pH buffers
  • pH and cell volume regulation
27
Q

How is Na+ retained in the proximal tubule?

A
  • NHE transports Na+ into cell from lumen of proximal tubule
  • Na+ pump transfers Na+ into the capillary from the cell
28
Q

How is H2CO3 retained in the proximal tubule?

A
  • NHE exchanges H+ for Na+
  • H+ combines with HCO3- to make H2CO3
  • H2CO3 is broken down by carbonic anhydrase to form H2O and CO2
  • Diffuse readily across membrane and recombine in cell
  • H2CO3 transported into capillary by AE
29
Q

Which transporter is targeted in the thick ascending limb of the kidney during diuretic treatment? What is the effect of this?

A
  • NKCC2 (Na+K+Cl- move in)
  • Is inhibited when loop diuretics bind
  • Limits reuptake of Na+ therefore less water reabsorbed
  • Blood volume is decreased
  • Decreases blood pressure
30
Q

Which transporters are targeted in the distal convoluted tubule of the kidney during diuretic treatment? What is the effect of this?

A
  • Thiazide inhibits Na+Cl- cotransporter and does the same as loop diuretics
  • Amiloride inhibits Epithelial Na+ Channel and does the same as loop diuretics
31
Q

Which transporters are targeted in the cortical collecting duct of the kidney during diuretic treatment? What is the effect of this?

A
  • ENaC
  • Na Pump
  • ROMK
  • Spironolactone inhibits therefore inhibiting aldosterone
32
Q

What is the function of aquaporin? What stimulates this?

A
  • A water channel, ensures efficient water uptake along with Na+
  • Stimulated by ADH
33
Q

What is Na+K+ATPase otherwise known as?

A

Sodium pump

Decks in ESA 2 Class (63):