BSCI207 Neural integration and senses Cnidarians first to develop CNS Bilaterians developed head and tails Head brain massive integration center Cephalization High density of neurons Integrates and sends signals out to rest of body Brain coordinates response electrical nervous system Chemical endocrine system Both Sensory Organs different sensory receptor cells specialized Sensory membrane contains receptor molecule More membrane more receptors increased sensitivity larger response Responds by Opening closing ion channels May may not generate action potentials Amount of neurotransmitter released Two Types of Sensory Neuron Receptors 1 Receptor is ion channel 2 Separate from ion channel G protein coupled receptor Receptor activated G protein G protein activates effector molecule change in conformation of 2nd messenger ex cAMP change in ion gates Do all receptors put out action potentials Olfaction taste touch Hearing and vision DO NOT All depolarize When depolarizing neurotransmitter released When hyperpolarizing neurotransmitters released decreased Sound and Hearing Sensory Mechanisms Sound is a pressure wave 5 ways to produce vibrations 1 Muscular vibration of membrane sac Fish humming 2 Stridulation rub one part against another Crickets 3 Forced flow of medium through small orifice 4 Muscular vibration of appendages Rattle snake 5 Percussion on a substrate Spider Sound detection 1 Particle 2 Pressure Hair with sensory neurons that detect deflection mechanical movement insects membrane detects pressure bends away from higher pressure activate sensory cell Human Ear Amplification factors 1 Pinna gathers sound pressure from large area to focus down to ear canal 2 Ear canal focuses wavelength to tympanum 3 Sound transferred to ossicles and oval window concentrated by factor of 15 4 Middle ears act as lever Another 1 5 amplification 5 Cochlea is then stimulated by sound Fluid moves Pushes on hair cells Inner Ear The inner hair cells are the most sensitive to sound Outer hair cells help decrease amount of sound absorbed by inner hair cells to prevent them from being overwhelmed Hair cells are surrounded by high concentration K s Hair Cells Between Two Membranes Basilar membrane and Stereocilia Steriocilia then bend towards kinocilium from pressure of wave Potassium channels open depolarization influx of calcium synaptic vesicles fuse to membrane release of neurotransmitter no action potential POTASSIUM IS LET IN If stereocilia were to bend in the opposite way hyperpolarize Less neurotransmitters would be released 1 Basilar Membrane Detecting intensity of sound Wide part flexible responds to low frequencies Farther from oval window Narrow part stiff responds to high frequencies Closer to oval window 2 Directionality 3 Arrival Times which side hears first Other Receptors Water strider detects substrate water vibrations with receptor in legs Johnston s Organ drosophila in antenna to sense vibrations Insects tympanum membranes in legs Fish otoliths in 3 chambers which stimulate hair cells in response to low frequency vibrations Echolocation use sound to probe objects around them and retrieve sound Swim bladder used to detect sound Vision The color than an object is corresponds to the color that is transmitted reflected not absorbed Different forms of light have different distributions Light is absorbed while the remaining is reflected the color we see Eye Structure Light focused by cornea 80 and lens 20 goes to retina Eye is backwards Photoreceptors at back of retina Light passes through ganglion cells and neurons before reaching photoreceptor cells Blind spot ganglion axon cells without photoreceptors present Photoreceptors Rods low light detection Middle of spectrum Presence or absence of light At night Cones Sensitive to different parts of spectrum Day time Photoreceptor Visual Pigments Short blue Medium green Long red Opsin protein combine to form visual pigment that sees light Visual pigment with 11 cis retinal creates visual pigment that absorbs light Retinal molecule absorbs light photon Opsin modifies absorption With absorption of light by retinal isomerization of cis to trans now activated Opsin G protein coupled to opsin sends signal connects to ion channel to hyperpolarize cell Opsin molecule absorbs photon isomerization occurs 11 cis to 11 trans changes configuration of opsin protein enabling it to couple to g protein G protein is connected to phosphodiesterase chews up cGMP Ion channel is gated by cGMP Thus ion channel closes Ion channel in dark no signals ion channels open Depolarize More neurotransmitter released Detection of light more negative inside Hyperpolarize Less neurotransmitter released No action potentials in photoreceptors Color Cone Long wavelengths red Short wavelenths blue Medium wavelengths green rods evolved from cones cones evolved first rods later bright light cones Brain reviews ratio of pigments stimulated to devise what color is being seen across all vertebrates different pigments always absorb light in the same places transmission properties of the ocean water determine the general range of the wavelengths of light received by animals Dichromats color blind one short wavelength one long wavelength Cichlids use color to differentiate between species Helps females to find proper mate Motility Prokaryotic motility 1 swimming 2 corkscrewing 3 gliding Prokayotic flagella Proton powered rotary motor 1000 protons per single rotation Eukaryotic motility 1 structural protein actin or tubulin 2 motor protein myosin or kinesin phosphorylated intermediate 2 Mechanisms 1 motor is stationary while structural protein moves 2 structure is stationary while motor protein moves Actin two helical strands Anchored to cell membrane Bind to portion of motor protein usually myosin Cell crawling cell division pinch membrane move cytoplasm around cell Tubulin alpha beta dimers forming hollow tube microtubules Motor protein walks along tube Bigger than actin filament Treadmilling subunits added to positive end and subtracted from negative end Regulated by calcium and GTP Found in centrioles Keratin intermediate Transport in Axons Dissect System stops when ATP is removed KINESIN protein required 2 subunits motor heads Cilia and Flagella Composed of TUBULIN axoneme built from microtubules 9 2 rule 2 central microtubules 9 pairs of tubules around outside Connected to each other by spokes and dynein arms Connected to central pair with spokes Skeletons To pull on it to move
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