Why are rbc anucleate

Do blood cells have nuclei? What are two functions of Red Blood Cells? What is the function of red blood cells? Where are old red blood cells destroyed? Why do red blood cells have no nucleus?

Is DNA found in red blood cells? How do red blood cells reproduce? What are the functions of human red blood cells? Reticulocytes tend to be larger than RBCs and have a bluish tinge; an increased number of such cells on the blood film is termed polychromasia. The normal reticulocyte level is about 0.

Modern cell counters normally give an absolute reticulocyte count. If none is present this is abnormal and indicative of disease. An increase in reticulocyte number is often the first indication of successful treatment of deficiency anaemia - this is particularly true of vitamin B12 or folate deficiencies.

This is produced mainly in the kidney in response to tissue hypoxia Kern, b. The role of the kidney in regulating RBC synthesis means anaemia is a common consequence of renal disease; recombinant EPO has been used successfully to treat anaemia in renal failure, cancer and other conditions.

In treating renal patients with cardiac disease, target Hb levels must be chosen carefully to avoid increased mortality Strippoli et al, Function Although metabolically active, the only function of RBCs is to contain and transport the respiratory pigment Hb, which makes up 95 per cent of the content of a mature RBC. Hb is a complex of four protein chains globins each complexed with a haem group Fig 3. Haem is an iron-containing ring molecule, which can differentially bind and release oxygen O2 in response to O2 saturation, pH and temperature.

The differential binding capacity enables Hb to bind to O2 in the pulmonary alveoli and then release O2 in peripheral vessels. Secondary functions of Hb include transport of carbon dioxide from the tissues to the lung for excretion, and a buffer effect to help control blood pH. The chains of the Hb molecule act cooperatively in binding and releasing O2. When a fully deoxygenated Hb molecule binds a single molecule of O2 the shape of the entire Hb molecule changes to assist binding of the second O2 molecule.

A similar process occurs in binding the third and fourth molecules of O2. This process is reversed in tissue so that release of each O2 molecule triggers the easier release of each subsequent one.

Because of this, the O2 affinity curve of Hb has a distinctive sigmoid shape. Hb binds easily to O2 at high O2 concentrations in the pulmonary alveoli and O2 release is efficient at low O2 concentrations in hypoxic tissues.

Invertebrates that utilize hemolymph rather than blood use different pigments containing copper or iron to bind to the oxygen. Hemocyanin, a blue-green, copper-containing protein is found in mollusks, crustaceans, and some of the arthropods b.

Chlorocruorin, a green-colored, iron-containing pigment, is found in four families of polychaete tubeworms.

Hemerythrin, a red, iron-containing protein, is found in some polychaete worms and annelids c. Despite the name, hemerythrin does not contain a heme group; its oxygen-carrying capacity is poor compared to hemoglobin. The small size and large surface area of red blood cells allow for rapid diffusion of oxygen and carbon dioxide across the plasma membrane.

In the lungs, carbon dioxide is released while oxygen is taken in by the blood. In the tissues, oxygen is released from the blood while carbon dioxide is bound for transport back to the lungs. Studies have found that hemoglobin also binds nitrous oxide NO. Nitrous oxide is a vasodilator: an agent that causes dilation of the blood vessels, thereby reducing blood pressure. It relaxes the blood vessels and capillaries which may help with gas exchange and the passage of red blood cells through narrow vessels.

Nitroglycerin, a heart medication for angina and heart attacks, is converted to NO to help relax the blood vessels, increasiing oxygen flow throughout the body.