M&R Session 5- Intracellular Calcium Control Flashcards Preview

SOPHIE'S ESA 2 > M&R Session 5- Intracellular Calcium Control > Flashcards

Flashcards in M&R Session 5- Intracellular Calcium Control Deck (13)
Loading flashcards...
0
Q

At basal calcium levels which way is the concentration gradient?

A

From out to in

1
Q

Why does calcium have to be regulated?

A

Because calcium can’t be metabolised.

2
Q

What is the advantage of a large inward calcium gradient?

A

An increase in calcium intracellularly can increase rapidly without much movement of calcium.

3
Q

Why is a large inward gradient of calcium a disadvantage?

A

Because high intracellular calcium is toxic to cells.

4
Q

What four things does a calcium gradient rely on?

A
  • membrane impermeability
  • calcium expulsion
  • calcium buffers
  • intracellular calcium stores.
5
Q

What do calcium buffers do?

A

They limit diffusion by binding to calcium. Calcium diffusion then depends upon the concentration of the binding molecule and their saturation.

6
Q

What are the two categories of intracellular calcium stores?

A
  • rapidly releasable stores

- non-rapidly releasable stores

7
Q

What are the two main methods of expelling calcium across the membrane?

A
  • calcium ATPase - if intracellular calcium is high, calcium binds to calmodulin and this complex binds to the ATPase and calcium is then expelled from the cell.
  • NCX- transports three sodium in for one calcium to be expelled.
8
Q

What are the two ways that calcium enters the cell from outside?

A
  • VOCC- is triggered by membrane depolarisation and open to allow the movement of calcium ions into the cell.
  • receptor operated calcium channels- a ligand or agonist binds to the receptor, causing it to open and allow calcium to move in.
9
Q

What are the 2 ways that calcium is rapidly released from stores?

A
  • G protein coupled receptors. - a ligand binds to the GPCR in the cell membrane, activating the G alpha Q subunit, which binds to PIP2, releasing IP3. IP3 binds to receptors on the SR, causing Calicut to be released.
  • CICR- calcium binds to ryanodine receptors on the side of SR, stimulating further release of calcium into the cell.
10
Q

What is the non rapidly releasable method of calcium expulsion into the cell?

A

When intracellular calcium levels are high, the mitochondria take it up using a uniporter, as a protective mechanism.

11
Q

What 3 factors are required for returning calcium to basal levels?

A
  • signal termination
  • calcium removal
  • calcium store refilling.
12
Q

How are calcium stores refilled? (2)

A
  • calcium recycling

- store-operated calcium channels between mitochondria and the SR.

Decks in SOPHIE'S ESA 2 Class (74):