Oxygen

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Top Contributors - Lucinda hampton and Aminat Abolade  

Introduction

Oxygen is a vital gas, responsible for life on earth. It generates energy and supports the life of all the living organisms. In order to survive, all of our cells need oxygen. The complex process of getting your body the oxygen it needs is a collaborative effort among your nervous system, lungs, blood, and heart.

• Your brain initiates breathing by sending a message through your nervous system to your muscles of respiration and ribs, which ultimately allows your lungs to expand.
• As you unconsciously breathe in, the air around you enters through your nose and mouth.
• Oxygen diffuses through membranes and into red blood cells after inhalation into the lungs.
• The heme group (that consists of an iron) of hemoglobin binds oxygen when it is present, changing haemoglobin’s color from bluish red to bright red.
• O2 is handed-off to an enzyme (monooxygenase) that also has an active site with an atom of iron. The enzyme uses oxygen to catalyze many oxidation reactions in the body (metabolism).
• The transport of oxygen is fundamental to aerobic respiration and the survival of complex organisms. The lungs, heart, cardiovascular network, and red blood cells play essential roles in oxygen transport..

The primary function of the cardiorespiratory system is to ensure that all metabolically active tissues are adequately oxygenated at all times. Hypoxemia and hypoxia may result when these systems fail and represent major immediate threats to organ function and patient survival.

Oxygen Transport

Oxygen is carried in the blood in two forms. The vast majority of oxygen in the blood is bound to hemoglobin within red blood cells, while a small amount of oxygen is physically dissolved in the plasma. A liter of blood can dissolve 200 cc of oxygen gas, which is much more than water can dissolve.

After being carried in blood to a body tissue in need of oxygen,

• The regulation of unloading of oxygen from hemoglobin at target tissues is controlled by several factors, including oxygen concentration gradient, temperature, pH, and concentration of the compound 2,3-Bisphosphoglycerate.
• The most critical measures of adequate oxygen transportation are hemoglobin concentration and oxygen saturation; the latter is often measured clinically using pulse oximetry.

A persistent reduction in oxygen transportation capacity is most often the result of anemia.

Hemoglobin (Hgb or Hb)

Hemoglobin (Hgb or Hb) is the primary carrier of oxygen in humans. Approximately 98% of total oxygen transported in the blood is bound to hemoglobin, while only 2% is dissolved directly in plasma. Hemoglobin is a metalloprotein with four subunits composed of an iron-containing heme group attached to a globin polypeptide chain. One molecule of oxygen can bind to the iron atom of a heme group, giving each hemoglobin the ability to transport four oxygen molecules. Various defects in the synthesis or structure of erythrocytes, hemoglobin, or the globin polypeptide chain can impair the oxygen-carrying capacity of the blood and lead to hypoxia.

Molecular oxygen, O2

Molecular oxygen, O2, is essential for cellular respiration in all aerobic organisms. Oxygen is used as an electron acceptor in mitochondria to generate chemical energy. For more on cellular respiration see ATP.