2.80: Understand How Organisms are Able to Respond to Changes in their Environment

SENSITIVITY IN ORGANISMS:

• All living organisms need to respond to changes in environment for survival
• Nervous system coordinated by the Brain allows body to respond to changes in environment
• Organisms additionally have reflexes for fast involuntary actions that protect body from damage

FACTORS NEEDED TO RESPOND TO ENVIRONMENT:

FACTOR	EXPLANATION
STIMULI	Change in environment
RECEPTOR	Specialised cells that detect changes in environment E.g, Sensory Neurones in the finger detect heat
EFFECTOR	Part of body that carries out response to Stimuli E.g Muscles in finger that contract to pull finger away from heat