Question

The true statement about \(\mathrm{RBC}\) is (a) RBCs have an average life span of 120 days. (b) \(\mathrm{RBCs}\) are destroyed in the spleen (graveyard of \(\mathrm{RBCs}\) ). (c) RBCs are devoid of nucleus in most of the mammals. (d) All the above

Short answer

The true statements about \(\mathrm{RBCs}\) are (a) RBCs have an average lifespan of 120, (b) RBCs are destroyed in the spleen, and (c) RBCs are devoid of a nucleus in most mammals. Therefore, the correct answer is (d) All the above.

Step-by-step solution

Analyzing option (a)

RBCs have an average lifespan of 120 days. This is a known fact in biology, so option (a) is correct.

Analyzing option (b)

RBCs are indeed destroyed in the spleen, which acts as a filter for blood. When RBCs are too old or damaged and can no longer perform their function, they are broken down in the spleen. Hence, option (b) is also true.

Analyzing option (c)

In most mammals RBCs are devoid of a nucleus. This is another less known fact about RBCs but it is true. Therefore, option (c) is correct.

Analyzing option (d)

Since all the individual statements (a), (b), and (c) are correct, the collective statement (d) 'All the above' is also correct.

Key concepts

RBC lifespan

Red blood cells, or RBCs, are critically important to the body's transportation needs, particularly for carrying oxygen. Did you know that each RBC in the human body does not live forever but has an average lifespan of about 120 days? During these 120 days, an RBC travels through your bloodstream seamlessly, executing its primary function to supply oxygen to your body's cells. Towards the end of their lifecycle, many physiological changes happen in RBCs. These changes make it more challenging for them to circulate efficiently. Additionally, they become more susceptible to getting caught in the capillary networks' narrow spaces. Because RBCs constantly need fresh nutrients and a chemical makeover due to the intense job they perform, our body naturally directs them towards retirement through biological processes, ensuring a new batch takes over for the old.

Spleen function

The spleen is a small but mighty organ tucked under your rib cage in the upper left side of the abdomen. It's sometimes nicknamed the "graveyard of RBCs" because it plays a vital role in getting rid of old or damaged red blood cells. When RBCs become frail or entire their lifespan, the spleen acts as a sort of filter. Here's what happens:

• As old RBCs pass through, they're recognized by the spleen as less flexible, often misshapen.
• These distinguished cells are broken down, and useful components like iron are recycled and sent back to the bone marrow to help form new RBCs.

The spleen doesn't only deal with RBCs; it deftly handles a plethora of duties including producing lymphocytes that protect the immune system, storing blood, and managing our body’s response to infections.

Nucleus absence in mammals

In many mammals, a unique characteristic distinguishes their red blood cells from those of other vertebrates: They lack a nucleus. While other cells have a nucleus that holds genetic material and helps control cell functions, mammalian RBCs are devoid of this organelle. This absence of a nucleus serves as a beneficial adaptation in several ways:

• It creates more room within each RBC, allowing for increased hemoglobin and thus more oxygen-carrying capacity.
• The biconcave shape that results from lacking a nucleus provides a large surface area relative to volume, favoring oxygen exchange.

This evolutionary trade-off ensures that oxygen is transported efficiently throughout mammalian bodies, backing up the high metabolic rates typical in these species.

Biology facts

Delving into the world of biology reveals some fascinating insights about blood and red blood cells. Here are a few intriguing facts to expand your knowledge:

• RBCs are produced in the bone marrow in a process known as erythropoiesis. Each second, the human body produces around 2 million RBCs!
• Despite their critical function, RBCs are quite tiny, measuring about 6-8 micrometers in diameter.
• An average adult has roughly 25 trillion RBCs circulating at any given time.
• Red blood cells appear red because of hemoglobin, a protein that binds with oxygen. When hemoglobin picks up oxygen, it turns bright red.

These simple cells perform the vital role of oxygen delivery, proving just how essential they are to our survival.

Blood filtration

Blood filtration is a vital process ensuring that our bloodstream remains free of unnecessary and potentially harmful substances. This intricate procedure is crucial for maintaining overall health and involves several organs acting in harmony.

• The kidneys are chiefly responsible for filtering the blood by removing waste and maintaining the balance of minerals and fluids. They filter your entire blood volume several times a day.
• The liver works as a "chemical factory," processing various toxins and aiding in digestion. It filters nutrients directly from the digestive tract to the bloodstream.
• Interestingly, the spleen adds to this cleansing lineup by eliminating old or faulty RBCs, ensuring the circulation of only healthy cells.

Together, these organs create a sophisticated network that protects the body, actively contributing to its efficient functioning by regulating, filtering, and recycling the essential components within our blood system.