Internal and external stimuli
- Created by: tash_c1ark
- Created on: 25-01-22 10:21
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- Internal and External Stimuli
- Receptors
- Pacinian corpuscle
- stretch-mediated sodium channels are deformed when pressure is applied
- influx of sodium ions depolarises the membrane of the neurone
- converts mechanical energy into a generator potential
- Specific to detecting mechanical pressure
- layers of connective tissue surrounding a neurone ending
- stretch-mediated sodium channels are deformed when pressure is applied
- Rods and cones in retina
- visual acuity
- different light sensitivities
- retinal convergence with rods
- distribution in retina (periphery and fovea)
- Pacinian corpuscle
- Heart rate
- chemoreceptors and baroreceptors
- CO2, pH and pressure changes
- autonomic nervous system
- sympathetic - increases heart rate
- parasympathetic - decreases heart rate
- autonomic nervous system
- sympathetic - increases heart rate
- parasympathetic - decreases heart rate
- Myogenic - contraction is initiated from within heart itself
- Sino-atrial node
- electrical wave is transmitted throughout heart
- Sino-atrial node
- chemoreceptors and baroreceptors
- External stimuli
- Responses
- increases chance of survival
- Reflex arc
- stimulus - receptors - sensory neurone - relay neurone - motor neurone - effector - response
- motile organisms
- kinesis
- change in speed of movement or rate of turning
- Taxis
- movement (not growth) of an organism in response to a stimulus
- kinesis
- Stimulus - a change that is detected and leads to a response
- Plants
- IAA, an auxin, controls plant cell elongation
- Gravitropism
- Negative gravitropism in shoots - grow away from force of gravity
- Positive gravitropism in roots
- IAA is produced in tip of root and moves to the lower side of the root
- IAA inhibits cell elongation in roots
- IAA is produced in tip of root and moves to the lower side of the root
- Phototropism
- Negative phototropism in roots
- IAA synthesised in the tip moves down to the shaded side of the shoot
- Shoots grow and ben towards light - positive
- Gravitropism
- IAA, an auxin, controls plant cell elongation
- Responses
- Receptors
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