What is it?
Maintenance of a relatively constant internal environment
The human body is constantly responding to internal and external factors in order to maintain relative stability within the body Homeostasis is vital to the body as a whole, right down to each individual cell. If homeostasis is not maintained at the cellular level this will affect the body as a whole. History
Claude Bernard (1813-1878): consistency of internal environment is the condition for free life. Internal environment: Immediate surroundings of cells—Intracellular fluid and interstitial fluid provide the medium which baths the cells. Appropriate cellular functioning depends on constancy of this environment. Cellular Homeostasis
Cells must maintain a constant internal environment and must be able to reproduce themselves when needed by the body. Cells need ions, nutrients and various other substances to perform cellular activities. The presence of ionic gradient is essential, check and control are also very important. Nervous systems are dependent on the generation of ionic gradient Intracellular and Extracellular fluids play a key role in homeostasis Formation of tissue fluid: caused by the pressure of blood flowing into capillaries which pushes certain components in blood to pass through capillary wall (e.g. water, oxygen, glucose etc) and bathe the cells. ‘waste products’ also diffuse back into veins to be taken out by another system Tissue fluids can also go to lymphatic vessels/lymphatic systems Intracellular fluid (cytosol)
Liquid inside cells
Further separated by organelles
E.g. golgi, mitochondria are all sitting in the intracellular fluid Ion concentrations are different to (ECF)-concentration gradients Other components: contains enzymes, calcium and proteins (enzyme will not function if not kept in homeostatic condition). Homeostasis maintains
Temperature at 37.2 -37.6oC
CO2 and O2
Waste products e.g Urea
Hormones - thyroid hormone...
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