HOMEOSTASIS
HomeostasisandControlSystems
Homeostasis:· processbywhichaconstantinternalenvironmentismaintaineddespitechangesintheexternalenvironment
· Pictureanysysteminyourbodyasaroominyourhouse
Having a system of active balance requires constant monitoring and feedback about body conditions.
All homeostatic control systems have three functional components:
1. Monitor
2. Coordinating centre
3. Regulator
Example: ExerciseCO2 levels increase
Stimulates chemical receptors in brain stem
Nerve cells from brain carry impulses to
muscles
Increases the depth and rate of breathing
Increased breathing movements help flush excess CO2
from the body.
Homeostasis is often referred to as a dynamic equilibrium.
Despite fluctuations in blood glucose, body temperature, bloop pressure, and blood pH, the homeostatic mechanism ensures that all body systems function within an acceptable range to sustain life.
Negative Feedback- Negative feedback mechanisms that make adjustments to bring the body back within an acceptable range.
- Think of it as an off switch!Household thermostat
Why negative feedback?
because a change in the variable being monitored triggers the control mechanism to counteract any further change in the same direction.
Negative feedback mechanisms prevent small changes from becoming too large.
Positive Feedback- Positive feedback systems reinforce change.
- less common in the body
Positive feedback systems move the controlled variable even further away from a
steady state.
What is the value of positive feedback within our body?
Thermoregulation:Thermoregula0on:-themaintenanceofbodytemperaturewithinarangethatenablescellstofunc9onefficiently
Ectotherms:Aredependantonexternaltemperaturetoregulate
metabolicrates-includesinvertebrates,mostfish,rep?lesandamphibians
Endotherms:Areabletomaintainaconstantbodytemperature
regardlessofsurroundings-includesmammalsandbirds
Hypothermia- a condition in which our body core temperature falls below the normal range.
- Some people have survived sustained exposure to cold temperatures because of the mammalian diving reflex.
- When a mammal is submerged in cold water, the heart rate slows and blood is diverted to the brain and other vital organs to conserve heat.