(a) What is lymphatic system? What are its function? (b) What is blood pressure? What are the two factors used to express the blood pressure of a person? (c) Name the main nitrogenous waste in the human blood. How is it removed from the blood?

• The lymphatic system consists of network of organs, lymph nodes, lymph ducts and lymph vessels in the human body that make and move the lymph from tissues to the bloodstream.

Following are the functions of lymphatic system:

• Collects and transports tissue fluid from the intercellular spaces in all the tissues, back to the veins in the bloodstream.
• The defense mechanism in the body by killing the germs with the help of lymphocytes present in the lymph nodes and by making antibodies is the key function of the lymphatic system.

• Blood pressure is the pressure at which the blood is pumped around the body by the It is always expressed in the form of two factors that are called systolic pressure and diastolic pressure.
• The main nitrogenous waste in the human blood is The kidneys remove the urea from the blood and excrete them in the form of a dilute solution called urine.