Important Biology Notes on Human Blood Blood is a bodily fluid in humans and other animals that delivers necessary substances such as nutrients and oxygen to the cells and transports metabolic waste products away from those same cells. Blood contains antibodies, nutrients, oxygen and much more to help the bodywork. Let us have a look at the Composition of Human Blood in detail. Human Blood The blood constitutes 7% of the total weight of the human's body . Its pH value is nearly 7.4, so it is considered base in nature. There is an average of 5-6 litres of blood in the human body. Blood consists of two parts:- (1) Plasma (2) Blood Corpuscles (1) Plasma It is the liquid part of blood. It constitutes 60% part of the blood. The plasma has 90% parts is water, 7% protein, 0.9% salt and 0.1% is glucose. Its main function is to Transport of digested food, hormones, the excretory product from one part of the body to another part of the body. When Fibrinoge...