How Much Blood Is There in a Human Body?

There is a large amount of blood flowing through our vessels, which is extremely important. Apart from transporting nutrients to various organs and tissues in the body, blood also plays a role in regulating temperature, maintaining osmotic pressure, and providing defense mechanisms. Typically, blood contains many cellular tissues, such as the well-known platelets, red blood cells, and white blood cells.

In general, the blood volume in an adult body accounts for approximately 1/13 of their total body weight.

Plasma can be considered as the intercellular substance of connective tissue. Serum is a light yellow, translucent liquid. Besides containing a large amount of water, plasma also contains inorganic salts, fibrinogen, albumin, globulin, enzymes, hormones, various nutrients, metabolites, and other substances. These substances do not have a fixed form but possess crucial physiological functions. 1L of plasma contains 900-910g of water (90%-91%), 65-85g of protein (6.5%-8.5%), and 20g of low-molecular-weight substances (2%). The low-molecular-weight substances include various electrolytes and small-molecule organic compounds, such as metabolites and certain other hormones. The electrolyte content in plasma is basically the same as that in tissue fluid.

During the life process of the organism, blood cells constantly undergo metabolism. The average lifespan of red blood cells is approximately 120 days, while the lifespan of granular leukocytes and platelets generally does not exceed 10 days. The lifespan of lymphocytes varies greatly, ranging from hours to several years. The production of blood cells and platelets originates from hematopoietic organs. Red blood cells, granular white blood cells, and platelets are produced by red bone marrow, while agranular white blood cells are produced by lymph nodes and the spleen.

Blood cells are classified into three types: red blood cells, white blood cells, and platelets.

1. Transporting oxygen to various parts of the body, primarily through red blood cells.
2. Transporting nutrients, such as glucose, amino acids, and fatty acids.
3. Removing waste products, such as carbon dioxide, uric acid, and lactic acid.
4. Providing immune functions, mediated by white blood cells and antibodies.
5. Serving an informational role, such as transmitting hormone signals and tissue damage alerts.
6. Regulating the acid-base balance within the body.
7. Regulating body temperature.
8. Maintaining hydraulic pressure.