Coordination and response

Chapter 3 : Coordination and response3.1 Response & coordinationChanges in External & Internal EnvironmentExternal environmentRefers to the physical and chemical conditions outside an organism and how these conditions affect it

Internal environmentRefers to the physical and chemical conditions of the tissue fluid (interstitial fluid) surrounding the tissues of an organism

Changes in External & Internal EnvironmentCHANGES IN THE EXTERNAL ENVIRONMENT Light Taste Pressure Sound Temperature TouchLiving OrganismsCHANGES IN THE INTERNAL ENVIRONMENT

Blood osmotic level Osmotic pressure of blood pH of tissue fluidThe need for an organism to be sensitive to changesWHY?StimuliIrritability ability of a living organism to react to stimulusReceptorNerve impulse:Electrical messages (or signals) which are sent to the integrating centre via afferent nerve (sensory nerve)Integrating centreProcesses sensory information from afferent nerve decide what to do initiate a response by sending nerve impulses via efferent nerve (motor nerve)

Response:Action taken by an effector in response to impulse receive

STIMULUSSENSE ORGAN (RECEPTORS)SENSATIONLight EyeSightSoundEar HearingChemicals in airNoseSmellChemicals in foodTongueTaste (sweet, salty, sour, bitter)TemperatureSkinWarm, hot, cold or coolPressurePressureTouchTexturePainPainPathway of Information Due to External Stimuli StimulusReceptor Integrating centre (Central Nervous System)Effectors (muscle or gland) brings about a responseAppropriate responsesNerve impulse travels along an afferent nerveNerve impulse travels along an efferent nervePathway of Information Due to Internal Stimuli Stimulus (above normal)Corrective mechanism Negative feedbackNORMAL CONDITIONNORMAL CONDITIONStimulus (below normal)Corrective mechanism Negative feedbackActivity : human response to external environment

Plant responses to external environment2 types of plant responses to stimulus from external environment:TropismGrowth movement of a plant organ towards or away from an external stimulusShows slow responses because they result from differential growth of the plantPlant responses to external environmentNastic movementGrowth movement of a plant organ that is not directed towards or away from an external stimulusFast because it result from osmotic changes at the cellular levelThe Meaning of CoordinationCoordination:The act of making parts of something work together in an efficient and organized wayStimulusReceptorsNervous SystemEndocrine systemEffectorsAppropriate responses