Question

multiple choice question
why are only old rbcs destroyed in the spleen?

old rbcs have lower hemoglobin content which marks them for destruction by macrophages in the spleen.
old cells have markers on the membrane that indicate they are no longer functional; the spleen recognizes these markers, targ
old cells rupture in the narrow channels of the spleen because they are no longer flexible or resilient.
old rbcs swell so that they dont fit through the sinus spaces of the spleen.

Explanation:

To determine the correct answer, we analyze each option:

• Option 1: Hemoglobin content isn't the marker for destruction in the spleen.
• Option 2: While markers exist, the main reason for old RBC destruction in the spleen is mechanical.
• Option 3: Old RBCs lose flexibility/resilience. The spleen has narrow channels; old RBCs can't pass and rupture, which is the correct mechanism.
• Option 4: Old RBCs don't swell to not fit; they lose flexibility.

Answer:

The correct option is the one stating: "Old cells rupture in the narrow channels of the spleen because they are no longer flexible or resilient." (Assuming this is, for example, the third option in the list presented, with its full text as above.)