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Responding to Stimuli What are Stimuli? How do we sense them? How do we respond to them?

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Presentation on theme: "Responding to Stimuli What are Stimuli? How do we sense them? How do we respond to them?"— Presentation transcript:

1 Responding to Stimuli What are Stimuli? How do we sense them? How do we respond to them?

2 Figure 46-00

3 Responses to Stimuli Tactile Senses

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5 Copyright Norton Presentation Manager

6 sensory motor Pictogram of Brain Sensitivity and Responsiveness Copyright Norton Presentation Manager

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8 Responses to Stimuli Tactile Senses Chemical Senses

9 Figure Brain Nasal cavity Odor molecules Glomeruli Action potentials Olfactory bulb of brain Bone Olfactory receptor neuron Mucus

10 Copyright Norton Presentation Manager

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12 Mammalian Tongue Copyright Norton Presentation Manager

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14 Figure Taste bud Pore Taste cells (salt, acid, sweet, bitter, meaty, etc.) Afferent neuron (to brain) (umami) mmons/d/db/Monosodium_glutamate.svg

15 sucrose sucralose saccharin sodium cyclamate lead acetate mannitol sorbitol xylitol (alitame) truvia/purevia

16 A Bogus Tongue Map bitter sweet salt sour salt sour All sensors are broadly distributed

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19 Responses to Stimuli Tactile Senses Chemical Senses Wave Senses

20 Sound Perception Do the wave application here! ~imaging/ /19537/ Do the wave beats (tuning) application here!

21 Loudness in Decibels

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23 Figure 46-4 Outer ear Middle ear Inner ear Auditory neurons (to brain) Cochlea Ear ossicles Ear canal Sound waves (in air) Tympanic membrane (eardrum) Middle ear cavity Cochlea stapes Sound waves (in fluid) Oval window malleus incus

24 Figure 46-5 Cochlea Auditory nerve Neurons (to auditory nerve) Three fluid- filled chambers Tectorial membrane Hair cells Tectorial membrane Stereocilia Outer hair cells Axons of sensory neurons Inner hair cells Basilar membrane The middle chamber of the fluid-filled cochlea contains hair cells. Hair cells are sandwiched between membranes.

25 Figure 46-3 Hair cells have many stereocilia and one kinocilium. WHEN STEREOCILIA BEND, A SEQUENCE OF EVENTS RESULTS IN THE RELEASE OF NEUROTRANSMITTER. Kinocilium Stereocilia Potassium channels joined by threads Nucleus Hair cell Afferent sensory neuron Efferent sensory neuron Pressure wave K+K+ K+K+ Depolarization Synaptic vesicle Calcium channel Neurotransmitter released into synapse Afferent neuron (to brain) Ca Arrival of pressure wave bends stereocilia. 2. Potassium channels open in response to bending. 3. Membrane depolar- izes due to influx of K Depolarization triggers inflow of calcium ions. 5. Ca 2+ causes synaptic vesicles to fuse with plasma membrane. 6. Neurotransmitter is released and diffuses to afferent neuron.

26 Figure 46-2 Sound stimulus Depolarized Louder sound Softer sound Highest response occurs at a characteristic frequency Sound-receptor cells depolarize in response to sound. Sound-receptor cells respond more strongly to louder sounds.

27 Figure 46-6 Cochlea Oval window Base of cochlea (near oval window) Wide part of basilar membrane is flexible vibrates in response to low frequencies Narrow part of basilar membrane is stiff vibrates in response to high frequencies 500 Hz 1 kHz 2 kHz 4 kHz 16 kHz Uncoiled cochlea (to show basilar membrane) Basilar membrane) Human Hearing ranges from 20 Hz to 20 kHz Semicircular canals

28 Copyright Norton Presentation Manager

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30 Responses to Stimuli Tactile Senses Chemical Senses Wave Senses Vestibular Senses

31 Figure 46-5a Cochlea Auditory nerve Neurons (to auditory nerve) Three fluid- filled chambers Tectorial membrane Hair cells The middle chamber of the fluid-filled cochlea contains hair cells. Semicircular canals

32 Semicircular Canals Contain Statoliths (Otoliths) Copyright Norton Presentation Manager

33 SemiCircular Canals Copyright Norton Presentation Manager

34 Responses to Stimuli Tactile Senses Chemical Senses Wave Senses

35 Light: An Energy Waveform With Particle Properties Too wavelength (nm) meter meter! nm wavelength violetbluegreenyelloworangered

36 Light: An Energy Waveform With Particle Properties Too wavelength (nm) meter meter! nm wavelength visible spectrum

37 White light: all the colors humans can see at once

38 et/websmurfclub/images/pinsmur foncloudrainbow.jpg site/images/introduction/apple_logo. gif Which side of our brains are we using?

39 White Light Leaf Pigments Absorb Most Colors Green is reflected!

40 Light: An Energy Waveform With Particle Properties Too amplitude brightness intensity Many metric units for different purposes We will use an easy-to-remember English unit: foot-candle 0 fc = darkness 100 fc = living room 1,000 fc = CT winter day 10,000 fc = June 21, noon, equator, 0 humidity

41 Light wavelength demonstration:

42 Figure 46-7 Ommatidia are the functional units of insect eyes. Ommatidia contain receptor cells that send axons to the CNS. Lens Receptor cells Ommatidia Axons

43 Human vs Insect Vision Copyright Norton Presentation Manager

44 Vertebrate Eye blind spot Copyright Norton Presentation Manager

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52 Normal Cornea Astigmatic Cornea

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54 blind spot

55 Figure 46-8 The structure of the vertebrate eye.In the retina, cells are arranged in layers. Ganglion cellsConnecting neuronsPhotoreceptor cells Pigmented epithelium Retina Direction of light Fovea Optic nerve (to brain) Sclera Iris Pupil Cornea Lens Axons to optic nerve

56 Figure 46-9 CorneaLens Retina (photoreceptors are on the inside surface) Sensory nerves to brain The Cephalopod Eye This design is more intelligent than that of mammals (humans) because it lacks the blind spot and maximizes light exposure to receptors

57 Eye Evolution

58 Vertebrate Retina cone rod light

59 Figure Rods and cones contain stacks of membranes. Rhodopsin is a transmembrane protein complex. Cone Rod Light Rhodopsin Retinal (pigment) Opsin (protein component) The retinal molecule inside rhodopsin changes shape when retinal absorbs light. Light trans conformation (activated) Opsin cis conformation (inactive) 0.5 µm Opsin

60 Figure The disk of a photoreceptor cell (a rod) before stimulation The same disk after stimulation (light) Rhodopsin GDP Transducin (inactive) cGMP-gated sodium channel (open) Phosphodiesterase cGMP Plasma membrane of rod Disk membrane cGMP-gated sodium channel (closed) Rhodopsin (activated) GTP Transducin (activated) Light Lack of Na + current hyperpolarizes membrane trans cis

61 Figure Visible spectrum S opsin 420 M opsin 530 L opsin 560

62 Figure No color deficiencyRed-green color deficiency

63 The Eye-Brain Connection Copyright Norton Presentation Manager

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65 Responses to Stimuli Tactile Senses Chemical Senses Wave Senses Vestibular Senses Positional Senses

66 Figure Ball-and-socket joints swivel Hinge joints hinge

67 Figure 46-18a Endoskeleton Flexor (hamstring) contracts Extensor (quadriceps) contracts

68 Figure Sarcomere Myofibril Dark bandLight band Relaxed Contracted Muscle tissue Bundle of muscle fibers (many cells) Muscles Muscle fiber (one cell) contains many myofibrils

69 Figure Myofibril Relaxed Contracted Thin filament (actin)Thick filament (myosin) Z disk A A C C D D B B

70 Figure Myosin head Actin binding site ATP binding site Colors indicate protein subunits

71 Figure CHANGES IN THE CONFORMATION OF THE MYOSIN HEAD PRODUCE MOVEMENT. 1. ATP bound to myosin head. Head releases from thin filament. 2. ATP hydrolized. Head pivots, binds to new actin subunit. 3. P i released. Head pivots, moves filament (power stroke). 4. ADP released. Cycle is ready to repeat. Myosin head of thick filament Actin in thin filament

72 Figure HOW DO ACTION POTENTIALS TRIGGER MUSCLE CONTRACTION? Motor neuron Muscle cell Motor neuron Action potential ACh ACh receptor Action potentials Thick filaments (myosin) Thin filaments (actin) Ca 2+ ions 1. Action potential arrives; acetylcholine (Ach) is released. 2. ACh binds to ACh receptors on the muscle cell, triggering depolari- zation that leads to action potential. 3. Action potentials propagate across muscle cells plasma membrane and into interior of cell via T tubules. 4. Proteins in T tubules open Ca 2+ channels in sarcoplasmic reticulum. 5. Ca 2+ is released from sarcoplasmic reticulum. Sarcomeres contract when troponin and tropomyosin move in response to Ca 2+ and expose actin binding sites in the thin filaments (see Figure 46.23).


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