The Basic Functions of Life

     Galen was a brilliant physician and anatomist who contributed much to Greek Medicine's understanding of the organs and systems of the human body and how they function.  His chief contribution in this area was his doctrine of the Four Faculties.
     According to Galen, the human body and all living organisms have to be able to do four basic things for themselves in order to live and survive:
     1)  They have to be able to vitalize themselves with the basic Life Energy necessary to function.
     2)  They have to be able to feed themselves and nourish, grow and regenerate their physical structure.
     3)  They must have consciousness and cognition, perception and awareness to be able to respond to their environment in an intelligent and timely manner in the interest of self preservation.
     4)  They must be able to reproduce themselves to further the continuity of Life and the propagation of their species.
     These four seminal ideas became the basis for his doctrine of the Four Faculties of the organism, which perform these four basic functions.  Each of these faculties has a principal organ, which is its central control or processing unit, which in turn is served by subsidiary organs and vessels of the faculty. 
the_four_faculties     The Four Faculties of the organism, and their principal functions and organs, are as follows:
     Vital Faculty - Vitalizes the organism, enabling it to function; coordinates whole body responses.  Governs respiration, circulation, cellular metabolism and the immune response.
Principal Organ - Heart
     Natural Faculty - Feeds the organism, enabling it to grow and regenerate its physical structure.  Governs digestion, metabolism, nutrition and growth.
Principal Organ - Liver
     Psychic Faculty - Intelligence, awareness, perception.  Stimulus and response.  Enables the organism to respond to its environment in the interests of self preservation.
Principal Organ - Brain
     Generative Faculty - Reproduction, procreation.  Propagates the species in service of the continuance of Life.
Principal Organ - Gonads
     The first three faculties are primary, because they're needed on a daily basis.  The fourth faculty, the Generative Faculty, serves the purpose of procreation, which is not needed on a daily basis.
     To demonstrate the importance of the three primary faculties, let's consider a limb of the body, like a leg, for example:
     The Vital Faculty vitalizes that leg, giving it life.  Without the Vital Faculty and its lifegiving blood supply, that leg would necrose and die within minutes. 
     The Natural Faculty feeds that leg, nourishing it and regenerating its structure.  Without the humors and nutrients it supplies, that leg would gradually atrophy and wither away over a period of days, weeks or months.
     The Psychic Faculty enables that leg to perform specialized movements like kicking and walking, and take us where we want to go.  Through the Psychic Faculty, that leg becomes a useful instrument for the indwelling soul, or psyche.


Principal Organs and Attendant Vessels

     The principal organs are the master organs, the central control and processing units, which are served by various subsidiary organs and attendant vessels.  Those which come before the principal organ in functional order are called afferent vessels, whereas those that come after it are called efferent vessels.
     A chart of the Four Faculties, their principal organs, and the afferent and efferent vessels to them, would be as follows:


Vital Faculty
Principal Organ Heart
Afferent Vessels Lungs and respiratory tract; diaphragm
Veins and pulmonary vessels; lymphatics
Efferent Vessels Arteries and capillaries


Natural Faculty
Principal Organ Liver
Afferent Vessels Stomach and digestive tract
Veins of hepatic portal system
Efferent Vessels Inferior vena cava, gall bladder, spleen


Psychic Faculty
Principal Organ Brain
Afferent Vessels Sense organs, sensory nerves
Efferent Vessels Motor nerves, effector organs and muscles


Generative Faculty
Principal Organ Gonads - testes (male)  ovaries (female)
Afferent Vessels male - epididymus, vas deferens, seminal vesicles, prostate, urethra, penis
female - fallopian tubes, uterus, cervix, vagina, vulvae
Efferent Vessels Arteries and capillaries



The Noble Organs

     Besides the principal organs of the Four Faculties, there are other important organs, which are also served by their subsidiary organs and vessels; these are called the Noble Organs.  Some of the Noble Organs clearly pertain to one faculty, whereas others interface between multiple faculties. 
     The main Noble Organs, the faculties they serve, and the organs and vessels that serve them, are as follows:


Vital Faculty
Lungs - served by the ribs, diaphragm and upper respiratory tract.
Thymus Gland - served by the lymphatic system and lymphocytes.


Natural Faculty
Spleen - served by the stomach, colon, lymphatic and circulatory systems.
Pancreas - served by the circulatory system, digestive tract.
Kidneys - served by bladder, lower urinary tract; also interfaces with Vital Faculty.


Psychic Faculty
Sense Organs - eyes, ears, nose, tongue, skin - served by their sensory nerves.


Generative Faculty
Uterus - served by all the other organs and vessels of the female reproductive system; grows the foetus into the newborn.
Breasts - The female breasts produce milk.

     The endocrine glands, which produce important hormones that regulate and govern important whole body responses, are also noble organs; most of them interface between multiple faculties and systems.  Every organ, vessel or gland in the human body serves at least one of the Four Faculties.