PSC2002/L19 Calcium Signalling III

Question 1

What is a Ca2+ puff?

Answer 1

A short occurrence of Ca2+ with ~10 IP3R releasing Ca2+
Does not become a wave

Question 2

What is the diameter and duration of a Ca2+ puff?

Answer 2

~5um diameter
~200ms duration

Question 3

What is a Ca2+ spark?

Answer 3

Cluster of ~10 RyR releasing Ca2+

Question 4

How are RyR and IP3R dispersed?

Answer 4

Highly localised in time and space

Question 5

What is the diameter of a Ca2+ spark?

Answer 5

~5um

Question 6

Describe the hierarchical organisation of intracellular Ca2+ signalling.

Answer 6

Low stimulus - Blip (quark)
Intermediate stimulus - puff (spark)
High stimulus - abortive wave, Ca2+ wave

Question 7

What is a calcium blip/quark?

Answer 7

Release of calcium ions from just 1 IP3 receptor in response to low level stimuli

Question 8

What is propagation?

Answer 8

Puff becoming a wave due to increased stimulus

Question 9

Describe what occurs when a Ca2+ spark occurs within proximity to Ca2+ activated K+ channel. (4)

Answer 9

Activates K+ channel
Hyperpolarisation
Relaxation
Contraction

Question 10

Describe what occurs in the trachea when an intercellular Ca2+ wave occurs.

Answer 10

Signal stimulated by glass pipette
Signal spreads throughout monolayer of cell
Cilia on these cells beat in same manner to remove foreign particles

Question 11

What is the relationship between Ca2+ spike frequency and hormone concentration? Give an example of when this occurs

Answer 11

Ca2+ spike frequency increases with increased hormone concentration
E.g., glycogen breakdown in liver

Question 12

How can different frequencies of Ca2+ spikes be decoded?

Answer 12

Into different amounts of enzyme activity