Mind Map by , created over 5 years ago

A Levels Biology (Response to stimuli) Mind Map on Receptors, created by ely3m17 on 02/12/2014.

Created by ely3m17 over 5 years ago
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1 Photoreceptors
1.1 Cone cells
1.1.1 photopigment = iodopsin erythrolabe = red chlorolabe = green cyanolabe = blue depending on proportion stimulated = full spectrum 11 cis-retinal + opsin
1.1.2 concentrated at fovea absent at peripheries
1.1.3 separate bipolar cell cannot combine to reach threshold low sensitivity 1 impulse for every cell stimulated above threshold good visual acuity
1.1.4 fewer in no. than rods
1.2 Rod cells
1.2.1 more numerous than cones
1.2.2 cannot differentiate different wavelengths of light images in black and white
1.2.3 pigment = rhodopsin Retinal + opsin
1.2.4 periphery of retina absent at fovea
1.2.5 retinal convergence greater chance threshold is reached sensitive to low intensity light e.g. night 1 impulse generated for many rod cells low visual acuity
1.3 light focused on macula
1.4 retina is inverted
2 Mechanoreceptors
2.1 Pacinian corpuscle
2.1.1 Distribution fingers soles of feet external genitalia Joints, ligaments, tendons (proprioception)
2.1.2 How it works In resting state stretch-mediated Na+ channel too narrow Neurone has resting potential Pressure is applied (stimulus) Membrane around neurone becomes stretched Na+ channels widen in the membrane NA+ ions diffuse into neurone Influx causes depolarisation Generator potential Action potential CNS
2.1.3 Stretch-mediated Na+ channel Greater pressure = more channels open = greater influx of Na+ ion

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