Blood pressure is kept between 60 and 80 diastolic and 90 and 120 mm Hg systolic. Heart rate at rest is between 60 and 100 beats per minute. The potassium concentration ranges between 3.5 and 5.0 mEq/l. One can go on, listing each aspect and area that the body is keeping afloat. Should these measurements stray much outside of these parameters, the body is in trouble, and unless corrected, sickness or death will soon follow.
This monitoring and regulating process is called homeostasis. Its concept was first described by French physiologist Claude Bernard in 1865, and the word was coined by Walter Bradford Cannon in 1926. Homeostasis is a 24/7 365 process managed by the body’s 78 organs. (It actually may be 79. In November of last year, Professor J Calvin Coffey, of Limerick, Ireland, postulated strongly in the Lancet that the mesentery, a two walled membrane lining the abdomen, may be a fully independent body organ).
An organ is body tissues grouped together and joining each other to perform the duties and functions assigned by the body’s DNA. The organ’s main tissue is designed to do the specific function – for example the pancreas’s main tissue is designed to produce insulin—and the organ’s sporadic tissue is its blood and nerve supply, as well as the connective tissue that holds the organ together.
Our organs are arranged in systems, which are all closely connected and related. In total there are eleven organ systems in our body. I will list them in alphabetical order as there is not one of them that is not integral to homeostasis and life. They are the:
- Cardiovascular system. This system helps with the pumping and channeling blood to and from the body and lungs; by means of the heart, blood and blood vessels.
- Digestive system. This system helps with the digestionand processing of food. It does so by means of its salivary glands, its esophagus, its stomach, its intestines, its colon, rectum and anus, as well as its liver, gallbladder and pancreas.
- Endocrine system. This system is a communicator within the body by means of messengers calledhormones. Hormones are made by endocrine glands. These are the hypothalamus, pineal gland, pituitary gland, thyroid, parathyroid, thymus and adrenal gland. (The pancreas, ovaries and testes are also endocrine glands, but they are classified under the digestive system in the case of the pancreas and the reproductive system in the case of the latter two).
- Excretory system. This system helps with the accomplishment of fluid balance, electrolyte balance and the excretion of urine. The body manages that by means of the kidneys, the ureters, the bladder and the urethra.
- Lymphatic system. This system helps with transporting lymph between the tissues and the blood stream. (Lymph is the fluid that occupies the space between cells, the fluid in which they “float”, and as such the lymph collects some of the toxins and waste products of our cells). The lymphatic system does so by the lymph nodes and lymph vessels, and it includes the immune system with its white blood cells, the tonsils, the adenoids, the thymus and the spleen.
- Integumentary system. This system protects the body from all sorts of damage, such as wounds, getting knocked about, or losing water. It does so by way of the skin, the hair and the nails.
- Muscular system. This system helps us move about, move things around and speak. It does so with the between 640 and 850 muscles in our body (depending on what counts as a muscle!).
- Nervous system. Any reader of mine will know that I am besotted with this system that helps with the collection, transfer and processing of information about what is going on outside and inside the body. It does this with the brain,spinal cord and nerves.
- Reproductive system. This is the system that helps with continuing the species. It does so by means of (in females) theovaries, the fallopian tubes, the uterus and the vagina, and by means of (in males) the testes, the vas deferens, the seminal vesicles, the prostate and the penis.
- Respiratory system. This is the system the body uses for breathing , and it does so by means of thepharynx, the larynx, the trachea, the bronchi, the lungs and the diaphragm.
- Skeletal system. This is the system that keeps the body together by providing structural support and by keeping the body protected. It does so by means of 206 bones (in the human adult), the cartilage, the ligaments and the tendons.
For the rest of the year, I will look more closely at each organ system every month; discuss what it does; and what we can do to help do that best. There has been an information explosion over the past thirty years as we came to understand better how the body works. This helps us to attend to, and maintain the spectacular body machine; for it to run younger and healthier over the years of our life.
