Sensory Biology I-III .pdf - Sensory Biology I NE...

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Sensory Biology I NE BIOSYNTHESIS (ASSIGNMENT 2 ANSWER) Norepinephrine (NE) is synthesized in axon terminals of preganglionic neurons NE levels regulated Monoamine oxidase (MAO) catalyzes breakdown Cocaine inhibits reuptake of NE and dopamine - This causes NTs to be dumped into the synapse which causes signals to be sent continuously How do we counteract the effect of cocaine? Introduce something that will outcompete 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 with EVOLUTION OF SENSORY PHYSIOLOGY Example given with two different bat species; Natterer’s bat (Myotis natterei), which hunts by echolocation, and Bechstein’s bat (Myotis bechsteinii), which hunts only by sound. These two bats live in the same environment but do not compete with one another. The hypothesis for such is that sensory access to prey leads to resource partitioning A specific example of this, there is a bug known as a katydid (Copiphora gorgonesis) that has developed a mechanism in its leg which allows it to detect echolocation, thus making it less likely to be captured by bats who only use echolocation; however, it can still be eaten by the bad that hunts purely by sound reception. INTRODUCTION TO SENSORY PHYSIOLOGY The study of how sensory stimuli are transduced by sensory receptors and processed by the nervous system SENSORY SYSTEM ORGANIZATION Sensory system: Sense organ + afferent sensory neuron + area of the brain to which these neurons project
Ex. Visual system: Eyes, optic nerve, brain areas concerned with processing visual 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 to detect 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 then depolarizes > A signal is sent to the integrating signal > That center knows where the light is coming from CLASSIFICATION 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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