The Need For Communication:
Homeostasis is the maintenance of the internal environment in
a constant state despite external changes.
A stimulus is any change in the environment that causes a
response.
A response is a change in behaviour as a result of a change in
the environment.
All chemical reactions in the body are controlled by enzymes –
if the enzymes don’t work, the organism dies.
To keep enzymes working efficiently, cells need to maintain
conditions at (or close to) the optimum of those enzymes.
Conditions include temperature, pH, an aqueous environment
that keeps substrates & products in solution, & freedom from
toxins & excess inhibitors.
Organisms have to cope with changing external conditions
which can place stress on an organism.
If an organism is to survive, changes in the external
environment must be monitored & the organism must be able
to respond to reduce or eliminate the stress.
The response can be behavioural, physiological or both.
Responding to internal stimuli:
o Most cells in a multicellular organism don’t come into
contact with the external environment.
o The internal environment of an organism is altered
through the metabolic processes of its cells – these
alterations may disrupt the cells’ processes.
Homeostasis is the maintenance of the internal environment in
a constant state despite external changes.
A stimulus is any change in the environment that causes a
response.
A response is a change in behaviour as a result of a change in
the environment.
All chemical reactions in the body are controlled by enzymes –
if the enzymes don’t work, the organism dies.
To keep enzymes working efficiently, cells need to maintain
conditions at (or close to) the optimum of those enzymes.
Conditions include temperature, pH, an aqueous environment
that keeps substrates & products in solution, & freedom from
toxins & excess inhibitors.
Organisms have to cope with changing external conditions
which can place stress on an organism.
If an organism is to survive, changes in the external
environment must be monitored & the organism must be able
to respond to reduce or eliminate the stress.
The response can be behavioural, physiological or both.
Responding to internal stimuli:
o Most cells in a multicellular organism don’t come into
contact with the external environment.
o The internal environment of an organism is altered
through the metabolic processes of its cells – these
alterations may disrupt the cells’ processes.
