Asked by Hazel Morris on Jun 17, 2024
Verified
When a pacemaker potential in the SA node reaches threshold,
A) the permeability to K+ increases.
B) many voltage-gated Ca2+ channels open.
C) voltage-gated Ca2+ channels close.
D) resting membrane potential has been restored.
E) permeability of the cell does not change.
Pacemaker Potential
Pacemaker potential refers to the spontaneous gradual depolarization of the membrane potential in pacemaker cells, leading to the initiation of action potentials in certain heart cells.
SA Node
The sinoatrial node, often described as the heart's natural pacemaker, initiating the electrical impulses that set the pace for cardiac rhythm.
Voltage-gated
Refers to ion channels that open or close in response to changes in electrical potential across a cell's membrane.
- Understand the electrical activity of the heart, including action potentials in cardiac muscle cells.
- Identify the factors influencing and modulating cardiac function.
Verified Answer
TM
Tiffany MasonJun 22, 2024
Final Answer :
B
Explanation :
When a pacemaker potential in the SA node reaches threshold, many voltage-gated calcium channels open, allowing calcium ions to enter the cell and initiate the action potential that leads to heart contraction. This process is crucial for the generation of heartbeats.
Learning Objectives
- Understand the electrical activity of the heart, including action potentials in cardiac muscle cells.
- Identify the factors influencing and modulating cardiac function.