Metabolism

The briefest and simplest medical definition of metabolism is:

"The sum of all the chemical and physical changes that take place within the body and enable its continued growth and functioning"

Further to this, metabolism can be defined in two parts:

Anabolism - the building up of complex substances from simple ones to form materials for tissues and organs.

...and...

Catabolism - the breaking down of complex constituents of the body which liberates energy and raw materials required for other processes (anabolism) or wastes to be excreted.

As the image shows, these definitions provide a much simplified picture of a cycle of creation and destruction running continuously throughout the body. Metabolic disturbance may be the cause of a wide range of illnesses and is frequently what herbal medicine attempts to address.

image: Zephyris

System: Lymphatic (part 1)

The lymphatic system is central to the body's defense and immunity. A network of lymphatic vessels run throughout the body and collect the watery lymph fluid which drains from blood and from between cells (interstitial fluid).

Lymphatic vessels have larger pores than capillaries so that they can exchange large molecules such as proteins, fragments of damaged tissue and micro-organisms.

Lymph nodes, which contain certain leukocytes, are found throughout the lymphatic system and serve to filter lymph of waste materials and dangerous substances before the fluid is returned to the blood stream.

Lymphocytes, a type of leukocyte, are formed within the lymphatic system.

System: Cardiovascular (part 1)

Blood is pumped through the vessels of the cardiovascular system by the heart.


Arteries transport blood away from the heart towards either the lungs or the rest of the body. Blood returns to the heart via the veins. Networks of capillaries throughout the body connect arteries and veins and provide sites for the exchange of substances because of their very thin walls.

Blood is continuously circulated from the heart to the lungs (for absorption of oxygen and excretion of carbon dioxide), back to the heart and around the entire body (for two-way transport of oxygen and other substances) before returning to the heart again. The circulation of blood to the lungs is called the pulmonary circulation whilst circulation around the rest of the body is called systemic or general circulation.