psychologicalblogspot

All living cells require nutrients, oxygen, and other essential substances, as well as the continuous removal of waste or harmful substances for healthy tissue functioning. Different groups of animals have evolved various methods of transport for these substances. Simple organisms like sponges and coelenterates circulate water from their surroundings through their body cavities to facilitate substance exchange with cells. More complex organisms, including humans, use special fluids within their bodies for transport. Blood is the most commonly used body fluid for this purpose. Blood is a vital fluid that circulates throughout the body, delivering oxygen, nutrients, and hormones, and removing waste products. Blood is composed of plasma, red blood cells, white blood cells, and platelets. Plasma is the liquid component of blood, consisting of water, proteins, hormones, electrolytes, and other substances. Red blood cells (erythrocytes) carry oxygen from the lungs to the body tissues and tra...