U2L1: Homeostasis Flashcards
What is Homeostasis?
The tendency of the body to maintain a relatively constant internal environment.
What is ECF and how does our body measure its changes?
extracellular fluid. The ECF can change in volume, temperature, chemical composition, etc. These changes are constantly monitored (by sensors in our body which ‘communicate’ with the brain) so that a constant level can be maintained.
What is a monitor?
sensors and receptors – detect changes in environment
What is the Control Centre?
mainly the hypothalamus or medulla oblongata - sets a range of values within which variables should be maintained.
What is a Regulator?
effectors - receives signals from control centre.
What does “feedback” mean
Receptors in the body constantly monitoring your internal environment. Once a certain set point is reached, a message is sent to turn on or off pathway [temporarily].
What is a positive feedback?
Strengthens or increases a change in a variable.
What is a negative feedback?
Reverses the change detected in a variable so that the variable is brought back within a normal range.
What is an example of +feedback?
Giving birth:
Monitor - the head of the baby pushes on the cervix
Control Centre - the hypothalamus (in the brain) processes this information, causing the release of oxytocin (hormone)
Effector - Oxytocin targets the uterus to contract more to help push the baby out
Result - the increase of one variable (pressure on the cervix) causes the increase of another variable (release of oxytocin hormone) which causes contractions to increase more
What is an example of -feedback?
Getting cold:
Monitor - thermoreceptors detect a decrease of temperature
Control Centre - the hypothalamus (in the brain) processes this information
Effector - Skeletal muscles contract, shivering generates energy production to increase temperature
Result - the decrease of one variable (external temp) causes the increase of another (body temp)
