Lecture 12 u2013 Animal Phys.docx - Lecture 12 u2013...

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Lecture 12 – Animal PhysWhat are 5 diff taste receptor proteins and how do their transduction mecahnisms differElectroreception in mammals (platypus) Bitter taste – 2 methods to boost immune function1.TRR38 bitter receptors on cilia in cells lining the inside of the nose- Bacteria passing by release acylhomoserine lactones (AHLs), that are detected by T2R38 receptors- Nasal epithelial cells then release nitrous oxide to kill the bacteria- Cilia also beat back and forth brushing bacteria away2.T2Rs(bitter) and T1Rs(sweet) work together-Bacteria passing by release compound detected by T2R bitter receptors causing cells to release Ca2+-Ca2+ signals nearby cells to release defensins that kill bacteria-Sweet substances like glucose increase because they are no longer being eaten by bacteria, and are thus detected by T1R sweet receptors-T1R receptors activate to reduce bitter receptor activity.Mechanoreceptor proteins (2 types)1.ENaCs (epithelial sodium channels)2.TRP (Transient receptor potential channels)Mecahnoreceptors are stretch activated ion channels with 2 different attachment points. One being the extracellular matrix proteins and the other being the intracellular cytoskeleton. This isfacilitated through an intracellular link. -Mechanical forces cause displacement of extracellular anchoring proteins, that are attached to the mecanoreceptor, causing a conformation change. This can be seen inhair cells. If one is bended there are mechnosensory neurons right under the cuticle.In ENaC channels there is an extracellular link that links it to the extracellular anchor. ENaC channels in a C. elegans actually touch the receptor. -Mechanoreceptors don’t have an intracellular cascade. They are just ion channels connected to the cytoskeleton.-The channels are embedded in the membrane of the mechanosensory neuron.-There is a similar sensory transduction in inverts and vertebrates-Location and or peripheral filtering mechanisms determine whether activated by sound, gravity, acceleration, or water currents. Types Touch and pressure-Baroreceptors (vertebrates)-Tactile receptors (verts and inverts)
-Proprioceptors (verts and inverts)Equilibrium and hearing (verts and inverts)-Statocysts-Hair cells-Neuromasts-ElectroreceptorsBaroreceptors(vertebrates)-These detect pressure changes in the walls of blood vessels, parts of the heart and the digestive tract-Carotid sinus baroreceptors – monitor blood pressure to the brain. Occurs in the carotid body. As parasympathetic innervates down cranial nerve 9, the blood vesselsdilate-Baroreceptors are excited by the stretch of blood vessels. Therefore increase in the blood pressure triggers increased AP firing frequency – this in turn provides info to the CNS – in the medulla oblongata. Influences cardiac output.

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