(a) Lymphatic system: A system of tiny tubes called lymph vessels (lymphatics) and lymph nodes (lymph glands) in the human body which transports the liquid called lymph from the body tissues to the blood circulatory system is called lymphatic system.

Functions of lymphatic system:

(i) It takes part in the nutritive process of the body.

(ii) It protects the body by killing the germs drained out of the body tissues with the help of lymphocytes contained in the lymph nodes, by making antibodies.

(iii) It helps in removing the waste products like fragments of dead cells etc.

(b) Blood pressure: The pressure at which the blood is pumped around the body by the heart is called blood pressure. The two factors which expresses the blood pressure a person are systolic pressure and diastolic pressure.

(c) Urea is the main nitrogenous waste in human blood. It is removed from the body in the form of urine through the kidneys.