Benders'dictionary of nutrition and food technology

Average blood volume is 5.3 L (78 mL/kg body weight) inmales and 3.8 L (56 mL/kg body weight) in females.blood cells Three main types of cell are present in blood: erythrocytesor red cells, leucocytes or white cells and platelets.Red blood cells contain haemoglobin, which is responsible forthe transport of oxygen from the lungs to tissues, and of carbondioxide from tissues. White blood cells are generally concernedwith protection against invading micro-organisms, and plateletswith the process of blood clotting.blood charcoal (or blood char) Charcoal prepared by treatingwhole blood or blood meal with activating agents and heating inairtight containers at 650–750 °C for 6–8 h. Contains 80% carbon,used for absorption of gases, as an industrial decolourising agent,and as an antidote for chemical poisoning.blood clotting The process by which the soluble protein fibrinogenin blood plasma is converted to insoluble fibrin, thus preventingblood loss through cuts, etc. vitamin k is required anddeficiency is characterised by excessive bleeding.See also anticoagulants; thrombosis.blood plasma The liquid component of blood, accounting forabout half the total volume of the blood. Plasma is a solution ofnutrients and proteins, mainly albumin and globulins, includingthe immunoglobulins which are responsible for defence againstinfection, as well as some adverse reactions to foods. Whenblood has clotted (see blood clotting), the resultant fluid isknown as serum.See also lipoproteins, plasma.blood pressure Blood pressure (bp) is measured as millimetres ofmercury (Hg) at systole (when the heart contracts) and diastole(when the heart relaxes), and increases with age due to loss ofelasticity of the arteries.Normal systolic bp is 120 mmHg at the age of 12 rising to 160(men) or 175 (women) at 70. Normal diastolic bp is 70 mmHg atage 12, rising to 85 (men) or 95 (women) at age 70.Diastolic bp above 105 is moderate, and above 115 severe,hypertension.blood sausage See black pudding.blood serum See blood plasma.blood sugar glucose; normal concentration is about 3.5–5mmol(60–90 mg)/L, and is maintained in the fasting state by mobilisationof tissue reserves of glycogen and gluconeogenesis (synthesisfrom amino acids). Only in prolonged starvation doesit fall below about 3.5 mmol (60 mg)/L. If it falls to 2 mmol(35 mg)/L there is loss of consciousness (hypoglycaemic coma,see hypoglycaemia).67