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.