The seventh level: environmental context Hendrick Avercamp New York City
And the environment also contains: Yellow fever
Organism and environment The organism is subject to: Climate Microbes Social interaction Air pressure And dependent on the environment for: Oxygen Nutrients Water
Boundaries Question: What seperates the organism from its environment?
‘Milieu intérieur’ and ‘milieu extérieur’ “The fixity of the milieu supposes a perfection of the organism such that the external variations are at each instant compensated for and equilibrated. All of the vital mechanisms, however varied they may be, have always one goal, to maintain the uniformity of the conditions of life in the internal environment. The stability of the internal environment is the condition for the free and independent life.” Claude Bernard, French Physiologist, 1854:
Example: Temperature Question What is the baseline temperature of the human body? Question What happens when the environmental temperature drops?
This is called: Homeostasis Homeostasis: The ability of the body to maintain a relatively constant internal environment, regardless of environmental changes.
How does it work? The mechanism of negative feedback: failure leads to imbalance which means disease.
Concluded There are several levels of structural organization within an organism: from the atom to the organism (living in an environment). All vital systems work together to maintain a stable internal environment, compensating for external variations. The mechanism is negative feedback. This is called homeostasis.