Response to Stimuli Summary
Overview of Responses to Stimuli
-Sensory Control
-Nervous Control
-Control of Heart Rate
-Role of Receptors
- Created by: emma louise
- Created on: 01-05-14 21:03
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- Response to Stimuli
- Survival and Response
- Nervous Control
- Simple Reflex Arc
- 1) Stimulus
- 2) Receptor
- 3) Sensory Neurone
- 4) Intermediate Neurone
- 5) Motor Neurone
- 6) Effector
- 7) Response
- Important because...
- Involuntary- Brain not overloaded
- Protect from harmful stimuli
- Fast- important for withdrawal reflexes
- Nervous Organisation
- Peripheral Nervous System
- Sensory Nervous System
- Motor Nervous System
- Voluntary Nervous System (to body muscles; conscious)
- Autonomic Nervous System (to glands, smooth muscle and cardiac muscle; unconscious)
- Central Nervous System
- Brain
- Spinal Cord
- Peripheral Nervous System
- Simple Reflex Arc
- Sensory Control
- Taxes
- Simple response directed by stimulus
- Direct response to stimulus
- Positive taxis = towards stimulus
- Negative taxis = away from stimulus
- Kinesis
- Random movement in response to a stimulus
- The more unpleasant the stimulus, the more rapid the movement
- Tropisms
- Growth movement in response to a stimulus
- In plants
- Positive = towards stimulus
- Negative = Away from stimulus
- Type of response named after stimulus (eg. light = phototropism)
- Taxes
- Nervous Control
- Control of Heart Rate
- Chemoreceptors
- In wall of carotid arteries
- Sensitive to changes in pH
- Increase frequency of nerve impulses
- Via sympathetic nervous system
- Pressure Receptors
- Blood pressure too high
- Impulse via parasympathetic nervous system
- SAN decreases heart rate
- Blood pressure too low
- Impulse via sympathetic nervous system
- SAN increases heart rate
- In wall of carotid arteries and aorta
- Blood pressure too high
- Autonomic Nervous System
- Controls involuntary activities of internal muscles and glands
- Sympathetic- speeds up any activity
- Parasympathetic- slows any activity
- Antagnostic
- Control Method
- Changes in heart rate controlled by medulla oblongata
- Medulla has 2 centres, one linked with sympathetic, one with parasympathetic
- Centres linked to sinoatrial node
- Stimulated by chemical and pressure changes in blood
- Chemoreceptors
- Role of Receptors
- Pacinian corpuscle
- Only responds to mechanical pressure
- Acts as a 'transducer' (converts information from stimulus to something that can be understood)
- Produces a 'generator potential' (nerve impulse that stimuli information is converted to)
- Stimulation of membranes produces deformation of stretch-mediated sodium channels
- Leads to the establishment of a generator potential
- Mammalian Eye
- Rod cells
- Rod shaped
- Mostly around retina
- Give poor visual acuity
- Sensitivity to low light levels
- Cone cells
- Cone shaped
- Mostly around fovea
- Give good visual acuity
- Not sensitive to low light levels
- Rod cells
- Pacinian corpuscle
- Survival and Response
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