QuestionSBA
QuestionChoice
Calcium ions do not initiate the opening of sodium channels. Sodium channels are primarily regulated by changes in voltage potential, specifically by depolarisation which allows sodium ions to enter the cell and initiate action potentials.
10024017
c
Calcium ions initiate the opening of sodium (Na+) channels
QuestionChoice
In smooth muscle cells, calcium ions play a crucial role in initiating contraction. When calcium ions enter a cell, they bind to and activate myosin light chain kinase, which, in turn, phosphorylates myosin. This phosphorylation is a key step in the initiation of smooth muscle contraction. The other answer choices do not accurately describe the primary role of calcium ions in smooth muscle action potentials.
10024015
a
Calcium ions activate myosin light chain kinase
QuestionChoice
Whilst calcium ions do play a role in neurotransmitter release in neurons, this question is about calcium movement during action potentials in smooth muscle cells, where their primary function is related to muscle contraction, not neurotransmitter release.
10024018
d
Calcium ions trigger the release of neurotransmitters
QuestionChoice
The repolarisation phase of an action potential typically involves the efflux of potassium ions (K+), not calcium ions. Calcium ions primarily play a role in the initiation and maintenance of muscle contraction.
10024016
b
Calcium ions are responsible for the repolarisation of the cell membrane
QuestionChoice
Calcium ions promote, rather than inhibit, the contraction of smooth muscle. They activate myosin light chain kinase, which is a key step in the initiation of smooth muscle contraction.
10024019
e
Calcium ions inhibit the contraction of smooth muscle
Concept
Chapter
2693
5718
Muscle Movement
Topic
281
Muscles
17201
What is the primary role of calcium ions (Ca2+) during an action potential in smooth muscle cells?
a