role of Ca2+ in the nervous system

Question 1

What role does soluble Ca2+ play in the nervous system?

Answer 1

Acts as a charge carrier and signaling molecule

Examples include cardiac action potentials and cellular metabolism.

Question 2

What is the concentration of free calcium in most intracellular environments?

Answer 2

Very low

Most intracellular Ca2+ is buffered.

Question 3

In what form is Ca2+ a major structural constituent of bones and teeth?

Answer 3

Insoluble form

Question 4

What is the electrochemical equilibrium in the context of the Nernst equation?

Answer 4

No net movement of ions across the membrane

Question 5

What happens to the membrane potential if it is only selective for K+?

Answer 5

It would be at EK

Question 6

How does Ca2+ facilitate neurotransmitter release at the NMJ?

Answer 6

By triggering neurotransmitter release from the presynaptic cell

Question 7

What effect does low extracellular Ca2+ concentration have on EPP generation?

Answer 7

Reduces likelihood of EPP generation

Question 8

What role does Ca2+ serve during neurotransmitter release?

Answer 8

Second messenger

Question 9

What happens to Na+ and K+ channels during presynaptic Ca2+ entry?

Answer 9

They become inactivated

Question 10

What is observed in Cell 1 during moderate depolarization?

Answer 10

Presynaptic Ca2+ current followed by inward postsynaptic current

Question 11

What occurs in Cell 2 during strong depolarization?

Answer 11

Doesn’t trigger presynaptic Ca2+ & no postsynaptic current

Question 12

What is synaptotagmin’s role in neurotransmitter release?

Answer 12

Ca2+ sensor for synaptic vesicle fusion

Question 13

List the three models of presynaptic neurotransmitter release.

Answer 13

• Synchronous: within several ms after an AP terminus
• Asynchronous: up to several seconds
• Spontaneous: in the absence of depolarization

Question 14

What happens when Syt1 is removed?

Answer 14

Abolishes synchronous but not asynchronous release

Question 15

What behavioral abnormalities are associated with synaptotagmin-7 deficiency in mice?

Answer 15

Bipolar-like behavioral abnormalities

Question 16

What pathologies are associated with impaired presynaptic vesicle exocytosis?

Answer 16

• LEMS (lambert-Eaton MS)
• Cognitive dysfunction/ageing
• Increased presynaptic Ca2+ in the ageing brain
• Toxins like latrotoxin, tetanus, and botulinum toxins

Question 17

What mediates muscle contractions in skeletal muscle?

Answer 17

Interactions between myosin and actin

Question 18

What is required for myosin-actin interactions?

Answer 18

Ca2+

Question 19

Where is Ca2+ released from during muscle contraction?

Answer 19

Sarcoplasmic reticulum

Question 20

What model describes muscle contraction involving Ca2+?

Answer 20

Sliding filament model

Question 21

What characterizes cardiac muscle potentials?

Answer 21

Longer & sustained repolarization plateau

Question 22

What produces the plateau in cardiac muscle potentials?

Answer 22

Ca2+ entry through voltage-gated calcium channels

Question 23

In cardiac muscle, where does a larger amount of Ca2+ initiated contraction come from?

Answer 23

Outside the cell

Question 24

What are calcium transients?

Answer 24

Local, short-lived, spontaneous intracellular Ca2+ spikes

Question 25

What do calcium transients regulate in neuronal development?

Answer 25

• NT phenotype
• Dendritic morphology
• Axonal growth and guidance

Question 26

What influences the timing and frequency of calcium transients?

Answer 26

Location and identity of Ca2+ channels & receptors

Question 27

What do calcium transients activate that transduces ionic signals into biochemical ones?

Answer 27

Enzymes

Question 28

What is the relationship between the incidence of Ca2+ transients and rates of axon outgrowth?

Answer 28

Inversely related