n. 1. Physical or mental weariness resulting from effort or activity. 2. Something, such as tiring effort or activity, that causes tiredness or weariness: the fatigue of a long hike. 3. Physiology The decreased capacity or complete inability of an organism, organ, or part to function normally because of excessive stimulation or prolonged exertion. 4.
blood - the fluid (red in vertebrates) that is pumped through the body by the heart and contains plasma, blood cells, and platelets; blood carries oxygen and nutrients to the tissues and carries away waste products; the ancients believed that blood was the seat of the emotions
The blood is the means whereby all nourishment is transported to the cells. 2. Transport of respiratory gases: The blood transports Oxygen as oxy hemoglobin from the lungs to the blood cells and returns carbon dioxide from the cells to the lungs for excretion. 3. Acts as a Vehicle: The blood transports hormones and enzymes from their place of origin to their target organs and tissues (place of activity).