Blood

Blood is a circulating tissue composed of fluid plasma and cells (red blood cells, white blood cells, platelets). Medical terms related to blood often begin in hemo- or hemato- (BE: haemo- and haemato-) from the Greek word "haima" for "blood".

Physiology of blood

Production and degradation

Blood cells are produced in the bone marrow; the process is termed hematopoiesis. The proteinaceous component is produced overwhelmingly in the liver, while hormones are produced by the endocrine glands and the watery fraction maintained by the gut and the kidney.

Related Topics:
Bone marrow - Hematopoiesis - Liver - Endocrine gland - Gut - Kidney

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Blood cells are degraded by the spleen and the Kuppfer cells in the liver. The liver also clears proteins and amino acids (the kidney secretes many small proteins into the urine).

Related Topics:
Spleen - Kuppfer cell - Amino acid - Urine

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Transport of oxygen

The amount of oxygen dissolved in blood is directly proportional to the PO2 of the blood.

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The hemoglobin molecule is the primary transporter of oxygen. 98.5% of the oxygen is chemically combined with the Hb. Only 1.5% is physically dissolved.

Related Topics:
Hemoglobin - Hb

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Transport of carbon dioxide

When systemic arterial blood flows through capillaries, carbon dioxide diffuses from the tissues into the blood. Some carbon dioxide is dissolved in the blood. Some carbon dioxide reacts with hemoglobin to form carbamino hemoglobin. The remaining carbon dioxide is converted to bicarbonate and hydrogen ions. Most carbon dioxide is transported through the blood in the form of bicarbonate ions.

Related Topics:
Carbamino hemoglobin - Bicarbonate - Hydrogen ion

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Transport of hydrogen ions

Some oxyhemoglobin loses oxygen and becomes deoxyhemoglobin. Deoxyhemoglobin has a much greater affinity for H+ than does oxyhemoglobin so it binds most of the hydrogen ions.

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