Ca2+ regulation

Question 1

Blood serum calcium levels

Answer 1

1.9-2.3 mmol

8-10mg/dL

Question 2

What is whole body Ca2+ homeostasis regulated by?

Answer 2

Intestinal Ca2+ uptake
Ca2+ reabsorption by kidneys
Bone calcium

Question 3

Endocrine control over Ca2+ levels

Answer 3

Ca2+ sensing receptors in parathyroid gland
Parathyroid hormone (increases levels)
1,25 dihydroxyvitamin D3
Calcitonin (reduces Ca2+ levels)

Question 4

Extracellular Ca2+

Answer 4

1-2 x 10^-3 M

Question 5

Cytoplasmic/intracellular Ca2+

Answer 5

1 x 10^-7 M (or even 100nm)

Question 6

ER/SR Ca2+ concentration

Answer 6

2-3 x 10^-4 M

Question 7

What is Ca2+ used for?

Answer 7

Muscle contraction
Neurotransmission
Fertilisation
Cell death (apoptosis, necrosis)
Regulation/metabolism
Learning/memory

Question 8

What are changes in Ca2+ like?

Answer 8

2-10 fold increase

within microdomains eg synaptic vesicles could be much greater

Question 9

Patterns of Ca2+ change

Answer 9

Peak-plateau

Oscillations

Question 10

How are Ca2+ set up and maintained?

Answer 10

Plasma membrane impermeability to Ca2+
Pumps/transporters move Ca2+ out
Ca2+ buffer proteins

Question 11

ATP dependent mechanisms of maintaining Ca2+ levels

Answer 11

Ca2+ ATPase: SERCA PMCA

Na+Ca2+ exchanger (requires Na+ gradient from Na+K+ATPase)

Question 12

What increases intracellular Ca2+ from across membrane?

Answer 12

Ligand gated ion channels

V gated Ca2+ channels

Question 13

What increases intracellular Ca2+ from ER stores?

Answer 13

IP3 receptors
Ca2+ induced Ca2+ release (CICR)

• CICR aka Ryanodine receptors