University:
Kentucky State University
Course:
BIO 303 | Human Physiology
Academic year:

2024
Views:

180

Pages:

23
Author:

garciavelascogr13

Physiology of the sensory system Sensory Types of Sensory Receptors • Mechanoreceptors – detect deformation • Thermoreceptors – detect change in temperature • Nociceptors – detect damage (pain receptors) • Electromagnetic – detect light • Chemoreceptors – taste, smell Receptor Excitation Figure 46-03 Receptor Potential • the membrane potential of the receptor. – excitation of the receptor results from a change in this potential. – when the receptor potential rises above the threshold, action potentials appear and the receptor is active. – the greater the intensity of the stimulus, the greater the receptor potential, and the greater the rate of action potential generation. Relationship between receptor potential and action potentials Figure 46-2 Adaptation of Receptors • when a continuous stimulus is applied, receptors respond rapidly at first, but response declines until all receptors stop firing. Adaptation of Receptors • when a continuous stimulus is applied, receptors respond rapidly at first, but response declines until all receptors stop firing. Figure 46-5 Sensations receptors Tactile Receptors • Merkel’s discs. – respond rapidly at first and then slowly adapt, detect the “steady state” – found on hairy as well a glabrous skin. Tactile Receptors • Merkel’s discs. – respond rapidly at first and then slowly adapt, detect the “steady state” – found on hairy as well a glabrous skin. Tactile Receptors • Merkel’s discs. – respond rapidly at first and then slowly adapt, detect the “steady state” – found on hairy as well a glabrous skin. • Ruffini’s end organ. – slowly adapting and respond to continual deformation of the skin and joint rotation. ALS Pathway Relationship Between Receptive Fields and Cortical Representation Text Fig. 17-3 Text Fig. 17-12 Smaller the receptive fields, greater the density of receptors. This relationship allows for greater discrimination in sensory inputs. Inverse relationship in the cortex. Smaller the receptive fields larger the cortical area Larger the receptive fields smaller the cortical area Conduction speed v Number of synapses Conduction speed v Number of synapses v Myelination Conduction speed v Number of synapses v Myelination v Nerve axon size