Asked by Brendan Morgan on May 11, 2024
Verified
A reduction in extracellular Ca2+ levels would lead to
A) increased force of cardiac muscle contraction due to increased interactions between actin and myosin.
B) decreased force of cardiac muscle contraction due to a lack of release of Ca2+ from the sarcoplasmic reticulum.
C) heart block due to depolarization of the sarcolemma.
D) heart block due to hyperpolarization of the sarcolemma.
Extracellular Ca2+
Calcium ions found outside of cells, crucial for various cellular processes including muscle contraction, neurotransmitter release, and blood coagulation.
Cardiac Muscle Contraction
The process by which heart muscle cells contract to pump blood, regulated by electrical impulses and calcium ions.
Sarcoplasmic Reticulum
A network of tubules and sacs found within muscle cells, involved in the regulation of calcium ions to facilitate muscle contraction and relaxation.
- Identify the relevance of extracellular ions in cardiac muscle function.
Verified Answer
MN
Mariam NasrullahMay 13, 2024
Final Answer :
B
Explanation :
Decreased extracellular calcium levels lead to a reduced influx of calcium into cardiac muscle cells during action potentials, which in turn results in a decreased release of calcium from the sarcoplasmic reticulum. This reduced release of calcium diminishes the interaction between actin and myosin, ultimately decreasing the force of cardiac muscle contraction.
Learning Objectives
- Identify the relevance of extracellular ions in cardiac muscle function.