THE BLOOD AND THE BLOOD VESSELS OF ANIMALS

_The blood is basically lymph with various pigments and substances dissolved in it, the main pigment and the most widespread is the red hemoglobin, its function is to collect oxygen from the respiratory membranes take it to the cells and remove the waste carbonic anhydride, transport nutrient substances, eliminate toxic products of metabolism, transport hormones and other important substances for the control of the organism and act as a defense against foreign elements, in addition in higher vertebrates serves to achieve homeothermia, blood also contains various cells such as are the amebocytes of invertebrates and white blood cells leukocytes and lymphocytes, red blood cells and platelets of vertebrates and also various proteins and mineral elements, blood vessels can be simple conduits as in lower invertebrates or differentiate into capillary and arterial blood veins heart, the first transports so the blood to the heart, the second leads from this to all the places of the cape and the cails unite both types and penetrate to the farthest points, the heart can be a contractile widening as in many insects or acquire the complexity of mammals with four differentiated chambers in all cases its essential function is to push blood or lymph through the entire body ...