Red Blood Cells

1551 Words Aug 28th, 2010 7 Pages
Red blood cell
From Wikipedia, the free encyclopedia
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Human red blood cells (6-8μm)
Red blood cells (also referred to as erythrocytes) are the most common type of blood cell and the vertebrateorganism's principal means of delivering oxygen (O2) to the body tissues via the blood flow through thecirculatory system. They take up oxygen in the lungs or gills and release it while squeezing through the body'scapillaries.

These cells' cytoplasm is rich in hemoglobin, an iron-containing biomolecule that can bind oxygen and is responsible for the blood's red color.

In humans, mature red blood cells are flexible biconcave disks that lack a cell nucleus and most organelles. 2.4 million new erythrocytes are produced per second.[1] The cells
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Membrane composition

The membrane of the red blood cell plays many roles that aid in regulating their surface deformability, flexibility, adhesion to other cells and immune recognition. These functions are highly dependent on its composition, which defines its properties. The red blood cell membrane is composed of 3 layers: the glycocalyx on the exterior, which is rich in carbohydrates; the lipid bilayer which contains many transmembrane proteins, besides its lipidic main constituents; and the membrane skeleton, a structural network of proteins located on the inner surface of the lipid bilayer. In human erythrocytes, like in most mammal erythrocytes, half of the membrane mass is represented by proteins and the other half are lipids, namely phospholipids and cholesterol.[29]

[edit]Membrane lipids

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The most common erythrocyte cell membrane lipids, schematically disposed as they are distributed on the bilayer. Relative abundances are not at scale.
The erythrocyte cell membrane comprises a typical lipid bilayer, similar to what can be found in virtually all human cells. Simply put, this lipid bilayer is composed of cholesterol andphospholipids in equal proportions by weight. The lipid composition is important as it defines many physical properties such as membrane permeability and fluidity. Additionally, the activity of many membrane proteins is regulated by interactions with lipids in the bilayer.

Unlike cholesterol which is
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