Homeostasis : What is Homeostasis? Roles of Lungs, Skin and Kidney in Homeostasis

Homeostasis : What is Homeostasis? Roles of Lungs, Skin and Kidney in Homeostasis
 

Homeostasis is the maintenance of a constant internal environment. The cells in the body of multicellular organisms are able to carry out their metabolic functions perfectly. They can, however, do this only when the conditions in their external environmental are kept constant. A change in the external conditions of the cells can greatly affect the proper functioning of the cells. The external environment of the cells is. however, the internal environment of the organism as a whole.

The maintenance of the constancy of this internal environment constitutes homeostasis. It involves the maintenance of constant (or changes kept within very narrow limits) temperature, pH, concentration of hood glucose, carbon [IV] oxide, Oxygen and many other factors.

 Roles of the Skin in Homeostasis

Thermoreceptors in the brain detect low or high temperature in the body. When the body temperature is high, superficial blood capillaries dilate. or vasodilation takes place, to allow heat loss by convection and radiation. Erector muscles relax, hairs lie flat and heat is lost by radiation and convection through the skin. Sweating increases to effect heat loss through evaporation of sweat.

When the body temperature is low, superficial blood capillaries constrict, or vasoconstriction takes place, thereby conserving heat by preventing heat loss by radiation and convection. Erector muscles contract, hairs are raised to stand on end. This traps air around the skin to prevent heat loss by radiation and convection. Spontaneous contraction of muscles, called shivering occurs. This generates heat which raises the body temperature.

Roles of the Kidneys in Homeostasis

The kidneys regulate the water and salt balance in the body. Antidiuretic hormone, ADH, increases the permeability of the walls of the collecting duct. This results in the production of more concentrated or hypertonic urine. in the absence of ADH, the permeability of the walls of the collecting duct decreases. Dilute or more hypotonic urine is, therefore, produced.

When the solute concentration of the blood increases. secretion of ADH increases. This results in the production 0f concentrated or hypertonic urine.

Roles of the Lungs in Homeostasis

The lungs regulate the concentration of carbon (IV) oxide in the body. High concentrations of carbon (IV) oxide in the blood are detected by the chemoreceptors in the wall of the aortic arch.

Through the stimulation of the hypothalamus, the breathing rate or the rate of expiration increases. The lungs remove (excess) carbon (IV) oxide from the body during expiration.

Low concentrations of carbon (IV) oxide in the blood do not stimulate the chemoreceptors in the aortic arch. The rate of expiration therefore remains normal.