20.1 Functions and Composition of the Blood

• • Blood is a fluid connective tissue that circulates through the cardiovascular system. Blood consists of plasma and formed elements (red blood cells, white blood cells, and platelets).
• Blood is a fluid connective tissue distributing nutrients, oxygen, and hormones to each of about 75 trillion cells in the body
• Any cell deprived of circulation may die within minutes
• Blood is normally confined to the circulatory system
• Blood consists of

  • plasma
  • formed elements
• Plasma is the liquid component of blood.
• Plasma is denser than water
• Plasma contains dissolved proteins and other solutes (nutrients, electrolytes, wastes)
• Formed elements are blood cells (red and white) and cell fragments (platelets) suspended in plasma
• Red blood cells (RBCs) transport oxygen and carbon dioxide
• White blood cells (WBCs) are components of the immune system and are less numerous than RBCs
• Platelets are small, membrane enclosed packets of cytoplasm containing enzymes and clotting factors, proteins that play a role in blood clotting
• Whole blood is a mixture of plasma and formed elements
• Whole blood components can be separated or fractionated
• Whole blood is sticky, cohesive, and resistant to flow
• Sticky, cohesive, and resistant to flow are characteristics which determine the viscosity of a solution
• Water has 1.0 viscosity while plasma has 1.5 but blood has 5.0
• Adult males have more blood than adult females
• Blood is slightly alkaline with a pH range between 7.35 and 7.45 and a temperature of 100.4F, higher than the normal body temperature
• Hypovolemic refers to low, normovolemic refers to normal, hypervolemic refers to excessive blood volumes