S7 - Calcium Homeostasis

Question 1

Why is a high intracellular calcium ion concentration bad?

Answer 1

Calcium is toxic in high concentrations

Question 2

What 6 things do Ca2+ play a part in?

Answer 2

1. Muscle contraction
2. Neurotransmission
3. Cell death
4. Regulation of metabolism
5. Learning and memory
6. Fertilisation

Question 3

How are Ca2+ concentration gradients set up and maintained?

Answer 3

• relative impermeability of plasma membrane to Ca2+
• pumps and transporters that move Ca2+ out of cytoplasm
• Ca2+ buffer proteins (bind to Ca2+ and decrease free Ca2+)

Question 4

What are the pumps and transporters in the cell plasma membrane to set up and maintain Ca2+ gradients?

Answer 4

• PMCA (plasma membrane calcium ATPase)

* NCX (sodium calcium exchanger)

Question 5

What is the pump/transporter in the sarcoplasmic reticulum plasma membrane to set up and maintain Ca2+ gradients?

Answer 5

SERCA (SR/ER calcium ATPase)

Question 6

What are the mechanism used to increase the intracellular calcium ion concentration?

Answer 6

• VOCC (voltage operated calcium channels) - cell plasma membrane
• CICR (calcium induced calcium release)/ryanodine receptors - SR/ER plasma membrane
• IP3 receptors - SR/ER plasma membrane