Sensory Biology INE BIOSYNTHESIS (ASSIGNMENT 2 ANSWER)●Norepinephrine (NE) is synthesized in axonterminals of preganglionic neurons●NE levels regulated○Monoamine oxidase (MAO) catalyzesbreakdown○Cocaine inhibits reuptake of NE anddopamine - This causes NTs to bedumped into the synapse whichcauses signals to be sentcontinuously●How do we counteract the effect of cocaine?○Introduce something that willoutcompete the receptor○Antagonise the adrenergic receptor so there’s no uptake○Could take away the whole receptor (causes other issues)○The channels that are retaking the NE could be upregulated○Don’t take cocaine to begin withEVOLUTION OF SENSORY PHYSIOLOGY●Example given with two different bat species; Natterer’s bat (Myotis natterei), whichhunts by echolocation, and Bechstein’s bat (Myotis bechsteinii), which hunts only bysound. These two bats live in the same environment but do not compete with oneanother.○The hypothesis for such is that sensory access to prey leads to resourcepartitioning○A specific example of this, there is a bug known as a katydid (Copiphoragorgonesis) that has developed a mechanism in its leg which allows it to detectecholocation, thus making it less likely to be captured by bats who only useecholocation; however, it can still be eaten by the bad that hunts purely by soundreception.INTRODUCTION TO SENSORY PHYSIOLOGY●The study of how sensory stimuli are transduced by sensory receptors and processed bythe nervous systemSENSORY SYSTEM ORGANIZATION●Sensory system: Sense organ + afferent sensory neuron + area of the brain to whichthese neurons project
○Ex. Visual system: Eyes, optic nerve, brain areas concerned with processingvisual information●Sense organ: Receptor cells + Accessory non-neural tissues○Ex. Eye●Sensory receptors: Cell that is specialized to detect incoming sensory stimuli○Ex. Rods and cones●Receptor proteins: Proteins on membranes of sensory receptors (cell) specialized todetect incoming sensory signals○Ex. Opsin○This is the part that conformationally changes due to a stimuli○With regards to opsin, when light is present it changes shape > The cell thendepolarizes > A signal is sent to the integrating signal > That center knows wherethe light is coming fromCLASSIFICATION OF SENSORY RECEPTORS●Human-centered classification of senses that we consciously use○First developed by Aristotle over 2000 years ago○Seeing, hearing smelling, tasting and feeling●Classification is based on location○Exteroceptors: Detect stimuli occurring on the outside of the body■Ex. Pressure, temperature, etc○Interoceptors: Detect stimuli occurring inside the body■Ex. Blood pressure, blood oxygen●Stimulus: Form of external energy to which a receptor responds
SENSORY RECEPTORS●Most receptors have a preferred stimulus modality○Require adequate stimulus■Ex. Photoreceptors in eyes are the most sensitive to light●Enough stimulus energy can overcome this specialisation○
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