Question• How Red Blood Cell Destroyed

and what happens next?

Life Span and Destruction of Red Blood Cells

When red blood cells are delivered from the bone marrow into the circulatory system, they normally circulate an average of 120 days before being destroyed. Even though mature red cells do not have a nucleus, mitochondria, or endoplasmic reticulum, they do have cytoplasmic enzymes that are capable of metabolizing glucose and forming small amounts of adenosine triphosphate.

What Dose Adenosine Triphosphate Do?

These enzymes also:1. maintain pliability of the cell membrane2. maintain membrane transport of ions3. keep the iron of the cells’ hemoglobin in the

ferrous form rather than ferric form4. prevent oxidation of the proteins in the red cellsEven so, the metabolic systems of old red cells become progressively less active, and the cells become more and more fragile, presumably because their life processes wear out.

Once the red cell membrane becomes fragile, the cell ruptures during passage through some tight spot of the circulation. Many of the red cells self-destruct in the spleen, where they squeeze through the red pulp of the spleen.There, the spaces between the structural trabeculae of the red pulp, through which most of the cells must pass, are only 3 micrometers wide, in comparison with the 8 micrometer diameter of the red cell.

And Next…

What Happens When The Spleen Is Removed From Body?

One Question From You

When the spleen is removed, the number of old abnormal red cells circulating in the blood increases considerably.

Destruction of Hemoglobin

When red blood cells burst and release their hemoglobin, the hemoglobin is phagocytized almost immediately by macrophages in many parts of the body, but especially by the Kupffer cells of the liver and macrophages of the spleen and bone marrow. During the next few hours to days, the macrophages release iron from the hemoglobin and pass it back into the blood, to be carried by transferrin either to the bone marrow for the production of new red blood cells or to the liver and other tissues for storage in the form of ferritin. The porphyrin portion of the hemoglobin molecule is converted by the macrophages, through a series of stages, into the bile pigment bilirubin, which is released into the blood and later removed from the body by secretion through the liver into the bile.

Bile

bilirubin is the greenish yellow pigment. This is a major end product of hemoglobin degradation, Briefly, when the red blood cells have lived out their life span (on average, 120 days) and have become too fragile to exist in the circulatory system, their cell membranes rupture, and the released hemoglobin is phagocytized by tissue macrophages (also called the reticuloendothelial system) throughout the body. The hemoglobin is first split into globin and heme, and the heme ring is opened to give (1) free iron, which is transported in the blood by transferrin, and (2) a straight chain of four pyrrole nuclei, which is the substrate from which bilirubin will eventually be formed. The first substance formed is biliverdin, but this is rapidly reduced to free bilirubin, which is gradually released from the macrophages into the plasma. The free bilirubin immediately combines strongly with plasma albumin and is transported in this combination throughout the blood and interstitial fluids. Even when bound with plasma protein, this bilirubin is still called “free bilirubin” to distinguish it from “conjugated bilirubin,” which is discussed later.

Bilirubin in the Bile

Within hours, the free bilirubin is absorbed through the hepatic cell membrane. In passing to the inside of the liver cells, it is released from the plasma albumin and soon thereafter conjugated about 80 per cent with glucuronic acid to form bilirubin glucuronide, about 10 per cent with sulfate to form bilirubin sulfate, and about 10 per cent with a multitude of other substances. In these forms, the bilirubin is excreted from the hepatocytes by an active transport process into the bile canaliculi and then into the intestines.

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At The End

Abstract

Resources guyton & hall textbook of medical physiology

11th edition Wikipedia free encyclopedia

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