Blood and blood disorders
Structure and Functions (Magill’s Medical Guide, Sixth Edition)
Blood provides a common communication channel for all organs in the body. It is responsible for the transport of oxygen, enzymes, hormones, drugs, and many other substances, as well as for the transfer of heat produced by chemical reactions in the body. The average-sized adult has about 10 pints of blood. At rest, 10 pints a minute (and up to 40 pints during exercise) are pumped by the heart via the arteries to the lungs and all other tissues. This blood then returns to the heart through the veins, in a continuous circuit.
About half the volume of blood consists of cells, which include red blood cells (erythrocytes), white blood cells (leukocytes), and platelets (thrombocytes). The remainder is a fluid called plasma, which contains dissolved proteins, sugars, fats, and minerals.
All types of blood cells are formed within the bone marrow by a series of divisions from a single type of cell called a stem cell. Red blood cells, or erythrocytes (from the Greek eruthros, “red”), are very small, have no nucleus, and consist almost completely of hemoglobin. Very little oxygen is needed for the survival of these cells. They have a large surface relative to their volume, which allows oxygen and carbon dioxide to diffuse in and out of the cell rapidly. This large surface also allows the cell to swell and shrink and to be squashed through narrow capillaries without its surface being subjected to shearing or...
(The entire section is 1654 words.)
Disorders and Diseases (Magill’s Medical Guide, Sixth Edition)
Blood tests can be used to check on the health of major organs as well as respiratory functions, hormonal balance, the immune system, and metabolism. They can reveal not only the blood cell abnormalities characteristic of some diseases but also healthy variations in blood induced by response to infections. Blood tests can be classified into three categories. Hematological tests involve studying the components of blood itself by looking at the number, shape, size, and appearance of its cells, as well as by testing the function of clotting factors. The most important tests of this type are the blood count, blood smear, and blood-clotting tests. Biochemical tests look at chemicals in the blood such as sodium, potassium, uric acid, urea, vitamins, gases, and drugs. In microbiological tests, blood is examined for microorganisms, such as bacteria, viruses and viral particles, fungi, and parasites, and for antibodies that form against them.
Known causes of blood disorders include genetic reasons (an inherited abnormality in the production of some blood component), nutritional disorders (such as a vitamin deficiency), infections by microorganisms, tumors (such as bone marrow cancer), poisons (carbon monoxide, lead, and snake and spider venoms), drugs (which can produce blood abnormalities as a side effect), and radiation.
Abnormalities can occur in any of the components of blood, including some constituents of plasma....
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Perspective and Prospects (Magill’s Medical Guide, Sixth Edition)
Blood is a liquid of complex structure and vital functions that has been considered the essence of life for centuries. There is no shortage of irrational or unscientific ideas about the supposed properties of human blood—one can speak of “blood brotherhood,” “blood feuds,” “blood relations,” and of someone being “bloodthirsty.”
The present medical understanding of blood has developed over the past two or three thousand years. The study of blood began in Egypt and Mesopotamia, around 500 b.c.e., and it moved to the countries around the Mediterranean that had become intellectually active. Ancient Greek thinkers noted that there were differences between arteries and veins, and that the blood moved through them. According to whether the heart, the liver, or the brain was thought to be the prime organ controlling the rest of the body, various functions were tentatively ascribed to blood, such as its relation to sleep, the distribution of heat, and the animation of the body.
The Greek school of medicine became personified in Hippocrates. He denied the widely accepted theory of the existence of spirits and proposed that the body followed natural laws. He presented the concept of body juices, or humors. There were four of them: blood, lymph or phlegm, yellow bile (or choler), and black bile (or melancholy), with blood being the most important one. The philosopher Aristotle accepted the humoral...
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For Further Information: (Magill’s Medical Guide, Sixth Edition)
Bick, Roger L. Disorders of Thrombosis and Hemostasis: Clinical and Laboratory Practice. 3d ed. Philadelphia: Lippincott Williams & Wilkins, 2002. An excellent introduction to the diagnosis and management of clotting and bleeding disorders.
Leiken, Jerrold B., and Martin S. Lipsky, eds. American Medical Association Complete Encyclopedia of Medicine. New York: Random House, 2003. An excellent presentation on blood—its components, illnesses, and treatments.
Lichtman, Marshall, et al., eds. Williams Manual of Hematology. 7th ed. New York: McGraw-Hill, 2006. An accessible handbook that covers the pathogenetic, diagnostic, and therapeutic essentials of blood cell and coagulation protein disorders.
Litin, Scott C., ed. Mayo Clinic Family Health Book. 4th ed. New York: HarperResource, 2009. Good presentation of blood; concentrates on illnesses, their causes and treatments.
Loscalzo, Joseph, and Andrew I. Schafer, eds. Thrombosis and Hemorrhage. 3d ed. Philadelphia: Lippincott Williams & Wilkins, 2003. Covers an array of relevant topics including the basic elements of hemostasis, the normal function and response of platelets, and specific clinical disorders and laboratory approaches, thrombotic disorders, and management of patients with hemorrhagic and thrombotic conditions.
Provan, Drew, and John Gribben, eds. Molecular Haematology....
(The entire section is 291 words.)