what is blood? why is it nessessory?how does it help in respiration?can you explain it in detail?
Blood is a fluid connective tissue contained in the heart and blood vessels of the circulatory system.
Importance of blood:
Blood forms a clot which serves to prevent the loss of blood and the entry of disease-causing germs.
It transports digested food from the alimentary canal to the tissues.
Blood helps in keeping the temperature of the body uniform by distributing heat.
It transports excretory materials from the tissues to the liver, kidneys or skin for elimination.
Endocrine glands secrete hormones into the blood so that they are transported to target sites.
Haemoglobin is a respiratory pigment present in the stroma of RBCs.
It is formed of an iron-containing part haemin and a protein globin.
It combines readily with oxygen to form an unstable compound oxyhaemoglobin. This compound delivers oxygen to tissues.
Hb + O2 = Hb.O2 (Oxyhaemoglobin)
Haemoglobin can carry a very small quantity of carbon dioxide in the form of carbaminohaemoglobin.
Hb + CO2 = Hb.CO2 (Carbaminohaemoglobin)