The main condition for the existence of any living organism is to maintain a certain constancy of the internal environment. What is surprising is tha

Maintaining homeostasis with neural and humoral control

The main condition for the existence of any living organism is to maintain a certain constancy of the internal environment. What is surprising is that a man can live in very different conditions: at temperatures from +50 to -70°C (120 degrees difference), to withstand prolonged fasting or taking part in the gluttons competition, live in the mountains or below sea level, to be in space, under water. All this would be impossible without mechanisms that provide consistency of internal environment of body.

Homeostatic balance in a healthy body has a wide range of endurance. However, each person has different one depending on the state of his health, tempering, fitness, age.

The relative constancy of the internal environment at any level — the molecular, cellular, tissue, organ, and system is called homeostasis (from Greek “with the same state, property”).

First of all, it manifests with the constancy of the chemical compound of the blood. There are two systems that control functions of organs and systems, ensuring the maintenance of homeostasis — the neural (nervous) and humoral.

Neural control

Neural control is ensured by bilateral relations between the nervous and other systems and organs. The nerve centers, which are located in the brain and spinal cord, instantly receive information in the form of nerve impulses from all parts of the body. They process it quickly and send “orders”: excitatory or inhibitory impulses to the working organs and systems, changing the intensity of their work. Taken from http://worldofschool.org

Humoral control

Humoral control of body functions occurs through the blood and other body fluids (lymph, intercellular fluid) using biologically active substances which secrete certain cells. They are products of the metabolism of cells, mediators, decomposition products of proteins, carbohydrates, carbon dioxide, and hormones. Biologically active substances act as irritants to the membrane and structural components of cells, causing changes in their biochemical and physiological state.

Humoral control is, certainly, slower method of controlling the functions of organs and systems than with a nervous system, but this effect can be long-lasting. For example, a growth hormone, secreting for years, provides child growth. Humoral control submits to neural, and together they carry out neurohumoral regulation of all body functions.

Categories:
Questions:
  • Explain the biological significance of the homeostasis phenomenon.

  • Describe the mechanism of neural control.

  • Explain the mechanism of humoral control.