Maintaining the normal excitability of various tissues in the body requires a suitable and constant internal environment, such as temperature, pH, osmotic pressure and various ion concentrations. Blood plays a very important role in maintaining a constant internal environment.
For example, the buffer system in blood (such as sodium bicarbonate and carbonic acid, plasma protein, hemoglobin in red blood cells, etc.). ) has the function of buffering acidic or alkaline substances, and keeps the pH value of blood at 7.35 ~ 7.45. The content and proportion of various inorganic ions in plasma are very important to maintain the normal excitability of nerves and muscles, especially the excitability of myocardium.
Extended data
Blood is a tissue that circulates in the heart and blood vessels. Adult blood accounts for about one thirteenth of body weight, with a relative density of 1.050 ~ 1.060, a pH value of 7.3 ~ 7.4, and an osmotic pressure of 3 13mm per liter. It consists of plasma and blood cells.
Plasma contains plasma proteins (albumin, globulin, fibrinogen), lipoproteins and other nutrients, as well as inorganic salts, oxygen, hormones, enzymes, antibodies and cell metabolites.
Blood cells include red blood cells, white blood cells and platelets. Physiological and pathological changes of the body often cause changes in blood components, so the detection of blood components has important clinical significance. ABO blood group is the main blood group classification of human beings, which can be divided into A type, B type, AB type and O type.
Baidu Encyclopedia-Blood (opaque red liquid flowing in the heart and blood vessels)