mechanism of cell injury: Hypoxia/Ischemia

What is hypoxia and how does it affect cells?

• Hypoxia is a condition of low oxygen availability that impairs cellular function and energy production.

• Hypoxia refers to the presence of toxins that improve energy production in cells.

• Hypoxia is a type of cell that thrives in high oxygen environments.

• Hypoxia is a condition of high oxygen levels that enhances cellular function.

Answer explanation

Hypoxia is correctly defined as a condition of low oxygen availability, which negatively impacts cellular function and energy production. The other options incorrectly describe hypoxia.

Which types of cells are most affected by oxygen deprivation?

• Adipocytes

• Neurons and cardiomyocytes

• Osteocytes

• Epithelial cells

Answer explanation

Neurons and cardiomyocytes are highly sensitive to oxygen deprivation due to their high metabolic demands. Unlike adipocytes, osteocytes, and epithelial cells, these cells cannot survive long without oxygen, making them the most affected.

How long can brain cells survive without oxygen before permanent damage occurs?

• 1 to 2 hours

• 30 seconds to 1 minute

• 10 to 15 minutes

• 3 to 5 minutes

Answer explanation

Brain cells can survive without oxygen for only 3 to 5 minutes before permanent damage occurs. After this time, irreversible injury begins, making this the critical window for brain health.

What role do hypoxia-inducible factors (HIFs) play during hypoxic conditions?

• HIFs decrease oxygen consumption in cells.

• HIFs inhibit gene expression to prevent cell damage.

• HIFs promote the production of carbon dioxide during hypoxia.

• HIFs activate gene expression to help cells adapt to low oxygen levels.

Answer explanation

HIFs are crucial during hypoxia as they activate gene expression that enables cells to adapt to low oxygen levels, promoting survival and metabolic adjustments.

What are some potential causes of hypoxia in the body?

• High protein diet

• Reduced oxygen availability (e.g., high altitude), respiratory diseases (e.g., COPD, pneumonia), anemia, circulatory issues (e.g., heart failure), carbon monoxide poisoning

• Excessive exercise

• Increased hydration

Answer explanation

Hypoxia can result from reduced oxygen availability, respiratory diseases like COPD and pneumonia, anemia, circulatory issues such as heart failure, and carbon monoxide poisoning, making this the correct choice.