5.1.1-2(Homeostasis)

Define the term homeostasis

• The maintenance of the internal environment in a constant state despite changes in the internal and external environment

What are the main factors which need to be maintained

• Blood glucose

• Water potential

• Body Temperature

• blood pressure

• Blood salt concentration

• CO2 concentration

Describe how negative feedback works

• A negative feedback mechanism responds when conditions change from the ideal or set point and returns conditions to this set point

Describe how positive feedback works

• Process that increases any change detected by receptors and does not bring it back to normal levels

Describe the features of a good communication system

• Cover the whole body

• Enable cells to communicate with each other

• Enable specific communication

• Enable rapid communication

• Enable both short-term and long-term responses

Name the 2 major communication signals

• Neuronal system

• Hormonal system

Describe the differences between the 2 communication systems

• Neuronal:

  • Fast

  • Short term effect

  • Localised effect

  • Uses nerve fibres to transport signal

  • Electrical impulses

• Hormonal:

  • Slow

  • Long term effect

  • Widespread effect

  • Uses blood plasma to transport signal

  • Chemical

Define what sensory receptors are

• cell nerve endings that respond to a stimulus in the internal or external environments of an organism and can create actions potentials

Define what effectors are

• Cells which bring about a response to the stimulus

What is the mechanism which homeostasis follows

• Stimulus → Receptor → Coordination → Effector → Response