#blood

• Abacteriemic — A medical term describing the state of an organism or circulating blood in which no viable bacteria are present. It is used clinically to confirm the absence of a systemic infection disseminated through the bloodstream or to describe the complete remission phase of a patient successfully treated for bacteremia, where repeated blood cultures turn negative.
• ABO system — The major human blood group classification system (A, B, AB, and O), genetically determined by the presence or absence of specific antigens (agglutinogens) on the surface of red blood cells and antibodies (agglutinins) in the plasma. In modern medical lexicon, it functions as an invariable proper noun used to identify transfusion compatibility.
• Absorption — The physical or chemical process by which a substance (gas, liquid, or energy) enters the mass of another body; in clinical toxicology and pharmacokinetics, it represents the entry of a toxin or drug into the bloodstream through biological membranes.
• Acanthocyte — A pathologically altered erythrocyte (red blood cell) characterized by an abnormal spherical or star-like shape, displaying multiple rigid, sharp cytoplasmic protrusions (spicules) of irregular length and distribution across its membrane. This morphological change (acanthocytosis) is caused by membrane lipid abnormalities and is encountered in severe conditions such as abetalipoproteinemia, advanced liver diseases, or neuroacanthocytosis.
• Acanthocytosis — A pathological condition characterized by the presence of an abnormally high number of acanthocytes (spurred erythrocytes with rigid, irregular membrane protrusions) in the peripheral blood. This morphological anomaly is closely linked to altered lipid metabolism and cell membrane structure, serving as a major diagnostic indicator for rare hereditary disorders (such as abetalipoproteinemia or McLeod syndrome), advanced end-stage liver diseases, or neurodegenerative disorders within the neuroacanthocytosis group.
• Acapnia — A pathological or physiological condition characterized by an abnormally low concentration or partial pressure of carbon dioxide (CO2) in the arterial blood and tissues. Most frequently caused by alveolar hyperventilation, it leads to a profound disruption of the body's acid-base balance (respiratory alkalosis) and clinically manifests through dizziness, paresthesia, or muscle spasms.
• Achromatocyte — A pathologically degraded erythrocyte that has completely lost its hemoglobin content, appearing under the microscope as a pale, discolored, or empty cellular structure; a residual red blood cell (erythrocyte ghost) resulting from a severe hemolytic process or mechanical membrane trauma.
• Achromatocyte — A pathological erythrocyte cell form or degraded stage of a red blood cell that has partially or completely lost its normal hemoglobin content, appearing under the microscope as a pale, semitransparent, or fully pigment-depleted cellular structure. This structural phenomenon typically occurs following severe intravascular hemolysis, mechanical cell membrane trauma, or intense osmotic alterations, leaving behind a residual membrane known in specialized literature as an erythrocyte ghost.
• ACTH — International acronym for adrenocorticotropic hormone (or corticotropin), a peptide hormone secreted by the anterior pituitary gland. Its primary structural role is to stimulate the production and secretion of glucocorticoid hormones (especially cortisol) by the adrenal cortex. Monitoring ACTH levels in the blood is essential for diagnosing disorders of the hypothalamo-pituitary-adrenal axis, such as Addison's disease or Cushing's syndrome.
• Adventitia — The plural form (or feminine singular in specific variants) for the adjective adventiv, describing organs, structures, or elements appearing in an unusual, accidental, or secondary location. In human histology and anatomy, it functions as a feminine noun (the adventitia), denoting the outermost connective tissue tunic shielding a blood vessel or a tubular organ, rich in collagen and elastic fibers. In botany, it points to roots or buds arising at atypical locations.
• Aerotonometry — An experimental method or clinical laboratory procedure used to determine and measure the tension or partial pressure of gases (oxygen, carbon dioxide) dissolved in biological fluids, especially in blood, by equilibrating them with a determined volume of air or gas mixture. This structural process provides essential data for evaluating respiratory function and alveolocapillary gas exchanges.
• Aerotonometer — A laboratory apparatus or precision technical device used to measure the partial pressure or tension of gases dissolved in a liquid (such as blood) by means of hydro-gaseous equilibration. This structural instrument consists of sealed analysis chambers and fine barometric sensors, being essential in respiratory physiology research.
• To flow toward — To flow or move in a single and constant direction, used especially to describe the movement of liquid masses. In medical and physiological fields, the term defines the process by which blood or other biological fluids gather in much larger quantities in a specific point, organ, or tissue.
• Aglobulia — A marked decrease or total absence of red blood cells (erythrocytes) in the blood, representing a severe and critical form of structural anemia. This hematological condition severely disrupts the blood's capacity to transport oxygen to biological tissues and is often caused by a severe dysfunction of the hematopoietic bone marrow.
• Agglutination — The act of agglutinating or clumping and its result; the adhesion, union, or grouping of suspended particles. In immunology, it represents the specific reaction where antibodies cause the clumping of bacteria or erythrocytes, while in linguistics it is the welding of lexical and grammatical morphemes into a single word.
• Agglutinated — As an adjective and participle, having undergone the process of agglutination; cells, bacteria, or particles closely united, adhered, or grouped into clusters under the action of a specific biochemical agent. In linguistics, it describes elements or words formed by welding invariable affixes. As a neuter noun, it represents the product or compact mass resulting from this structural binding process.
• Agglutinin — A specific antibody or protein substance present in blood plasma or immune serum, capable of inducing the process of agglutination (clumping together) of foreign cells, bacteria, erythrocytes, or antigen-bearing particles. It plays a fundamental role in blood typing and in the immune defense mechanisms of the organism.
• Agglutinogen — An antigen substance, protein or carbohydrate in nature, located on the outer surface of the erythrocyte membrane, bacteria, or other biological cells. Its structural interaction with a specific agglutinin in the plasma triggers the agglutination reaction, serving as the core biochemical element that defines blood types within the ABO and Rh systems.
• Agranulocyte — A type of leukocyte (white blood cell) characterized by the absence of specific granules in its cytoplasm and a non-lobed nucleus; agranulocytes include lymphocytes and monocytes, playing a vital role in adaptive immunity.
• Agranulocytic — Relating to agranulocytes or agranulocytosis; describing cellular phenomena, immune reactions, or clinical syndromes associated with white blood cells that lack specific cytoplasmic granules or with conditions marked by a severe depletion of granulocytes.