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  • Blood

    Blood is a kind of liquid connective tissue. It consists of intercellular substance – plasma, and blood cells.

    Blood has following functions:

  • respiratory (supplies oxygen to body cells)
  • nourishing
  • excretory (mainly harmful metabolism products – carbon dioxide and nitrogen)
  • immunological and thermoinsulating.

    Blood cells are produced in red bone marrow (that is between bone trabeculi of spongy bone tissue).

    Plasma - chemical composition:
  • 90% water
  • 9% organic compounds (immunological proteins, fibrinogen proteins, hormones, glucose, urea, amino acids)
  • 1% mineral substances (e.g. sodium chloride, calcium and potassium ions)

    Division of blood cells:

    Erythrocytes (red blood cells)

  • they are the smallest, but the number of them is the biggest (about 5 million in 1 cubic millimetre)
  • they cannot move themselves, so they are transported with the blood current
  • they have no nuclei
  • they live for a very short period of time – about 100-120 days
  • they die eaten by spleen that resolves haemoglobin, contained in them.

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