Homeostasis Flashcards
What is meant by negative feedback?
Bringing back monitored variables within a set range
What is the overall goal of homeostasis?
To allow maintenance of an optimum internal environment
What is defined as feed forward systems?
When the body anticipates and responds to changes in the environment before they have an effect.
Give two examples of feed forward mechanisms?
Salivating before eating
Skin activates response to temperature before internal body temperature change arises
What is positive feedback?
An initial disturbance sets off a train of events that leads to an even greater disturbance.
eg - action potential
How does daily input and output of water compare on a daily basis?
It is the same
What fraction of body water is ICF?
Two thirds
How much of ECF is plasma?
20%
Why do women and old people have lower water content?
Women have a higher proportion of body fat
Old people have less muscle
What is the only difference in composition between ISF and plasma?
Plasma contains plasma proteins
Concentration =
Mass/volume
What is the only region who’s water content can be directly measured?
Plasms
Give examples of substances that can be used to measure the ECF?
Sucrose
Na+
Cl-
(Substances that can not pass over the plasma membrane)
What is used to measure the water content of the plasma?
Radioactively labelled or dyed proteins
How do you measure total body water?
Using a radioactive water (deuterium oxide)
