Sensory receptor Transducers

Mechano R. Thermo R. Nociceptors Electromagnetic R. Chemo R. Types of receptors (R.) Mechano R. Thermo R. Nociceptors Electromagnetic R. Chemo R.

The Pacinian Corpuscle

It is that particular form of energy to which a R. is most sensitive. The adequate stimulus It is that particular form of energy to which a R. is most sensitive.

Labeled line Principle The modality of sensation felt when a nerve fiber is stimulated throughout its pathway, is determined by the point in the brain to which the nerve fiber ultimately activates.

Law of Projection No matter where a sensory pathway is stimulated along its course to the cortex, the conscious sensation produced is referred to the location of the R. e.g. Phantom limb

The Receptor Potential & The Action Potential

The frequency of AP is proportional to the magnitude of the applied stimulus.

Relation between amplitude of receptor potential to strength of mechanical stimulus applied to a pacinian corpuscle

Adaptation of R. Phasic R. Tonic R.

Mechanism of adaptation 1. Lamella slips back to its original place after a short period away from the nerve terminal 2. Accommodation of the nerve fiber

Synesthesia Synesthesia: is a neurologically based condition in which stimulation of one sensory or cognitive pathway leads to automatic, involuntary experiences in a second sensory or cognitive pathway

Grapheme test

2 Classification Schemes for Peripheral Fibers Fiber size: I, II, III, IV Conduction velocity: A, B, C Major afferent Major efferent Nolte 9-21

Susceptibility of Different Types of Fibers to Conduction Block by Various Agents Effect Most susceptible Intermediate Least susceptible Block by hypoxia B A C Block by pressure Block by local anesthetics

Classification of Peripheral Nerve Fibers