Question

In the absence of oxygen, which tissue will experience damage most rapidly? (A) Skin (B) Brain (C) Red blood cells (D) Liver

Short answer

Brain

Step-by-step solution

Understand the conditions of the problem

The problem asks about the effects of the absence of oxygen on different tissues. Oxygen is crucial for cellular respiration, a process that produces energy.

Identify tissues and their oxygen requirements

Different tissues in the body have varying levels of dependency on oxygen. Tissues with high metabolic rates and high energy demands will be more susceptible to damage in the absence of oxygen.

Evaluate the metabolic rates of the given tissues

Consider the metabolic rates of the options provided: (A) Skin - lower metabolic rate; (B) Brain - very high metabolic rate; (C) Red blood cells - do not consume oxygen since they carry it; (D) Liver - moderate metabolic rate.

Determine which tissue is most sensitive to low oxygen

The brain has the highest metabolic rate among the given options and requires a constant and substantial supply of oxygen. Without oxygen, brain cells will start to experience damage rapidly.

Conclusion

Based on the metabolic demands of the tissues, the brain will experience damage most rapidly in the absence of oxygen.

Key concepts

cellular respiration

Cellular respiration is a vital process that our cells use to turn nutrients into energy. This energy is crucial for every function our bodies perform.

During cellular respiration, cells use oxygen to convert glucose into adenosine triphosphate (ATP), the main energy carrier in cells. Without oxygen, this process cannot proceed efficiently.
In the absence of oxygen, cells resort to anaerobic respiration, leading to significantly less ATP production and causing potential build-ups of lactic acid, which can be harmful.

• Oxygen is the final electron acceptor in the electron transport chain, a key step in cellular respiration.
• Without oxygen, many cell processes either stop or slow down significantly, leading to energy shortages.

Understanding cellular respiration helps us see why tissues with higher energy needs suffer more in low oxygen conditions.

metabolic rate

Metabolic rate refers to how quickly an organism's cells perform their various chemical reactions.

Tissues with high metabolic rates require more energy and thus, more oxygen.

Brain cells, for instance, have a very high metabolic rate and consume a lot of oxygen to maintain their functions.

• Your metabolic rate determines how efficiently your body uses nutrients to generate energy.
• Different tissues have varying metabolic rates. For example, muscle cells during exercise have higher metabolic rates than when at rest.
• High metabolic rate tissues need constant oxygen supply because they are continually active.

When oxygen is limited, tissues with higher metabolic rates—like the brain—are quickly affected because their energy demand cannot be met.

oxygen requirements

Oxygen requirements vary greatly between different tissues in the body.

Tissues that are more active or constantly working usually need more oxygen.
This is because they need more energy, and oxygen is crucial for efficient energy production.

• The brain requires about 20% of the body's total oxygen intake even though it makes up only 2% of body weight.
• Red blood cells carry oxygen but don't consume it. They lack mitochondria where cellular respiration occurs.
• The liver has a moderate oxygen requirement due to its role in detoxification and metabolism.

Without sufficient oxygen, high-demand tissues can't produce enough ATP, leading to rapid dysfunction and damage. This helps us understand why the brain is so susceptible to damage without oxygen.

brain susceptibility

The brain is incredibly susceptible to oxygen deprivation, more so than other tissues.

This high sensitivity is due to its constant high metabolic rate. The brain is always active, whether you're awake or sleeping, constantly processing information and regulating body functions.

• Brain cells have a high demand for ATP because they are constantly transmitting signals, even at rest.
• Deprivation of oxygen for even a few minutes can cause significant damage to brain tissues.
• Symptoms of brain oxygen deprivation include confusion, loss of consciousness, and, if prolonged, permanent damage.

Therefore, understanding how essential oxygen is for brain function is crucial. In medical settings, ensuring continuous oxygen supply to the brain is a priority during emergencies.