Circulatory fluids are divided into plasma and cellular elements
Hematocrit is the percentage of blood volume occupied by cells
45% in human males, 42% in human females
30~40% in fish
Plasma is an aqueous medium for transport of inorganic ions, gases and organic solutes
90% water
Plasma proteins are the most plentiful organic solutes (6 - 8% of plasma)
Lipoproteins carry energy lipids (triglycerides) and structural lipids (phospholipids and cholesterol)
Respiratory pigments transport oxygen