Cardiac muscle has high caloric demands. The following are all ways in which the cardiac cells get energy for their cells except:
A myoglobin
B high vascularization
C high content of lipid in vessels
D a lot of mitochondria
E heart is capable of using multiple sources for energy
The correct answer and explanation is:
The correct answer is C: high content of lipid in vessels.
Cardiac muscle has high metabolic and caloric demands because of its continuous activity in pumping blood throughout the body. The heart requires an abundant and consistent supply of energy to maintain its function. Several mechanisms enable the heart to meet its energy needs, but the high content of lipid in the vessels is not one of them. Here’s why each of the other options contributes to the heart’s energy demands:
- A. Myoglobin: Myoglobin is a protein found in muscle cells, including cardiac muscle. It binds oxygen and helps to store it within muscle cells, making oxygen available during intense muscle activity. This is particularly important for cardiac cells, which need constant oxygen supply to maintain their activity and energy production.
- B. High vascularization: The heart is richly supplied with blood vessels, particularly the coronary arteries, which deliver oxygen and nutrients required for the cells’ energy production. This high level of vascularization ensures that cardiac muscle cells have a steady and reliable supply of energy substrates.
- D. A lot of mitochondria: Cardiac cells are rich in mitochondria, the cellular structures responsible for generating ATP, the energy currency of the cell. These mitochondria help to ensure that the heart has sufficient energy to contract continuously and efficiently. Mitochondria generate ATP through aerobic respiration, which requires oxygen, making the presence of mitochondria crucial for the heart’s energy demands.
- E. Heart is capable of using multiple sources for energy: The heart can use various substrates to generate energy, such as fatty acids, glucose, and lactate. This metabolic flexibility allows the heart to adapt to different conditions, like fasting or exercise, ensuring it has a continuous energy supply.
In contrast, C is incorrect because while lipids play a role in energy production in cardiac cells (as they can be broken down for ATP), the heart’s blood vessels themselves don’t necessarily have a “high content of lipid.” The heart’s energy production relies more on oxygen delivery through the vascular system and mitochondrial function rather than the lipid content of the vessels themselves.