Which is the most accurate statement?
- Adults generally have 2-4 litres of blood.
- Adults generally have 3-5 litres of blood.
- Adults generally have 4-6 litres of blood.
- Adults generally have 5-7 litres of blood.
About Blood (Saladin, 2018, p.671-673):
- It is a liquid connective tissue composed, like other connective tissues, of cells and an extracellular matrix.
- Its matrix is the blood plasma, a clear, light yellow fluid constituting a little over half of the blood volume.
- Suspended in the plasma are the formed elements — cells and cell fragments including the red blood cells, white blood cells, and platelets.
- The term formed element alludes to the fact that these are membrane-enclosed bodies with a definite structure visible with the microscope.
- Strictly speaking, they cannot all be called cells because the platelets are merely fragments torn from certain bone marrow cells.
- There are seven kinds of formed elements:
- Erythrocytes (red blood cells).
- Leukocytes (white blood cells): granulocytes (neutrophils, eosinophils, and basophils); and agranulocytes (lymphocytes and monocytes).
- The volume in an adult body varies between gender: 4-5 litres for women; and 5-6 litres for men.
- Blood is about 8% of bodyweight.
- Blood, by weight, is approximately 92% water.
- Sodium is more important than any other solute for the osmolarity of the blood. As such, it has a major influence on blood volume and pressure; people with high blood pressure are often advised to limit their sodium intake.
Saladin, K.S. (2018) Anatomy and Physiology: The Unity of Form and Function. 8th Ed. New York: McGraw-Hill Education.