18/04/2022
Which is the most important internal organ in the body?
All organs/systems are interdependent and in the long-term (matter of a few minutes) all other internal organs/systems cannot function when one organ/system fails. For example, the nervous system (NS) composed of brain, spinal cord and nerves which connect them to sensory receptors and effectors, cannot function without O2 and fuels (FFAs and glucose) whose availability to cells of NS depends on three systems including the cardiovascular system (CVS), Respiratory system (lungs) and the gastrointestinal system or GIT (alimentary canal, liver, gall bladder and pancrease). The CVS supplies the NS and other organs with O2 and fuels, and moves metabolic waste from tissues to excretory organs like the kidneys. The Lungs adds O2 to the blood, removes CO2 and helps in long-term regulation of blood pressure and blood pH. The GIT adds nutrients (fuels) to the blood (through processes of digestion and absorption) and excretes excess cholesterol. However all the three system’s (GIT, CVS, Resp) functions are integrated and regulated by the NS.
For systems to respond appropriately to each other’s needs, the cells and tissues making up these systems or organs must communicate effectively. Cells communicate using chemical messengers or signaling molecules. Signaling molecules occur in many different forms and include peptides like insulin, ions like calcium, amines like epinephrine, steroids like cortisol or gases like nitric oxide or carbon monoxide. Cells that are communicated to are called target cells and respond to signaling molecules because they have protein receptors in their membranes, cytoplasm or nucleus which bind the signaling molecules. When a signaling molecule binds to its appropriate receptor, it induces the target cell to respond in a specific way (e.g., contraction of muscle, secretion an enzyme, etc.). Specific forms of intercellular communication include cell-to-cell (via gap junction or contact dependent signaling), autocrine and paracrine signaling, nervous/synaptic signaling, endocrine signaling and neuroendocrine signaling.
In the first paragraph I have stated that systems need each other for survival. However, you may be wondering that you can do just fine with a dysfunctional or non-functioning reproductive system and certainly you can do without certain movements, sense of vision, sense of smell (olfaction) and sense of hearing. But imagine the quality of life. Simply put, the reproductive system is not essential for your survival (although it is essential for your happiness….according to one Col CM Zaza). Without movement, vision, olfaction, smell and taste, independent and prolonged survival will be difficult because an individual will have to depend on others to avoid danger and to feed. What do you think? Are all your body parts essential?
