Lecture 34 notes

Lecture 34 notes - Lecture 34: Sensory Systems 1087-1105...

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Lecture 34: Sensory Systems 1087-1105 Chapter 50: Sensory and Motor Mechanisms 50.1 Sensory Receptors Transduce Stimulus Energy and Transmit Signals to the CNS -stimuli represent forms of energy -sensation involves converting this energy to a change in the membrane potential of sensory receptor cells and thereby regulating the output of action potentials ot the CNS Sensory Pathways -sensory pathways have four basic functions: sensory reception, transduction, transmission, and perception Sensory Reception and Transduction - sensory reception : detection of a stimulus by sensory cells -most sensory cells are specialized neurons or epithelial cells - sensory receptors : sensory cells and organs, as well as the structures within sensory cells that respond to specific stimuli -many detect stimuli from outside the body such as heat, light, pressure, and chemicals but are also receptors for stimuli from within the body such as blood pressure & body position -in other senory receptors, hannels opne or close when substances outside the cell bind to proteins on the membrane or when pigments in the sensory receptor absorb light and the resulting flow of ions across the plasma membrane changes the membrane potential - sensory transduction : conversion of a physical or chemical stimulus to a change in the membrane potential of a sensory receptor - receptor potential : change in membrane potential -graded potentials (magnitude varies with strength of stimulus -sensory receptors very sensitive Transmission -sensory info transmitted thorugh nervous system in the form of nerve impulses or action potentials -transducing the energy in a stimulus into a receptor potential intiates transmission of action potentials to the CNS -some sensory receptor cells such as the crayfish stretch receptor are nerousns that produce action potentia;sl they have an axon that extends into the CNS -other sensory recepotr cells release neurotransmitters at synapses with sensory neurons -at almost all such ynapses, the receptor releases an excitatory neurotransmitter -magnitude of a receptor potential controls the rate at which action potentials are produced by a sensory receptor…if the receptor is a sensory neuron, a larger receptor potential results in more frequent action potentials -if the receptor is not a sensory neuron, a larger receptor potential causes more neurotransmitter to be released, which usually increases the production of action potentials by the postsynaptic neuron -many syensory neuonrs generate action potentials at a low rate and in these neurons a stimulus does not switch the production of action potentials on or off but it does change how often an action potential is produced. .neruons are also able to alert the cns to changes in stimulus intensity -processing of sensory info can occur before, during and after transmission of action p;otentials to the CNS -the integratin of sensory info begins as soon as the info is received -receptor potentials producd by stimuli delieverd to diff parts of a sensory receptor cell are
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This note was uploaded on 03/03/2010 for the course BIOG 1101 taught by Professor N/a during the Fall '10 term at Cornell.

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Lecture 34 notes - Lecture 34: Sensory Systems 1087-1105...

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