Page 701 - Fundamentals of anatomy physiology

688 Unit 4 Fluids and Transport Events Occurring in the Red Bone Marrow

Figure 19–4 Recycling of Red Blood Cell Components. Developing RBCs absorb amino
acids and Fe2+ from the bloodstream
Events Occurring in Macrophages and synthesize new Hb molecules.

Macrophages monitor the condition
of circulating RBCs, engulfing them
before they hemolyze (rupture), or
removing Hb molecules, iron, and
cell fragments from the RBCs that
hemolyze in the bloodstream.

Macrophages in spleen, RBC
liver, and red bone marrow formation

Fe2+ Fe2+ transported in bloodstream
by transferrin
Amino acids
Heme

90% Average life span of
RBC is 120 days

Biliverdin 10% Old and In the bloodstream, New RBCs
Bilirubin damaged released into
RBCs the rupture of RBCs bloodstream
is called hemolysis.

Bilirubin bound Hemoglobin that is not
to albumin in phagocytized breaks down,
bloodstream and the alpha and beta
chains are eliminated in urine.
19

Liver Kidney
Hb
Bilirubin
Urobilins
Absorbed into the bloodstream

Excreted Urobilins, Eliminated
in bile stercobilins in urine

Bilirubin

Events Occurring in the Liver Events Occurring in the Large Intestine Eliminated Events Occurring in
in feces the Kidney
Bilirubin released from Bacteria convert bilirubin to urobilins and
macrophages binds to stercobilins. Feces are yellow-brown or The kidneys excrete some
albumin and is transported to brown due to the presence of urobilins and hemoglobin, as well as
the liver for excretion in bile. stercobilins in varying proportions. urobilins, which gives
urine its yellow color.