Guyton and Hall, Medical Physiology
Chapter 47 - Sensory Receptors, Neuronal Circuits for Processing Information
Mechanoreceptors detect mechanical compression or stretching
Thermoreceptors detect changes in temperature
Nociceptors (pain receptors) detect physical or chemical damage to the tissue
Electromagnetic receptors detect light on the retina of the eye
Proprioceptors generate information about the position of (parts of) the body (in muscles,
tendons, joints)
Chemoreceptors detect taste in the mouth, smell in the nose, oxygen level in the arterial
blood etc.
Each type of receptor is highly sensitive to one type of stimulus for which it is designed.
The labeled line principle is the specificity of nerve fibers for transmitting only one modality
of sensation (wanneer een pijnreceptor geactiveerd wordt door een
temperatuurverandering voelt de persoon toch pijn).
Ways to cause receptor potentials:
By mechanical deformation, which stretches the receptor membrane and opens ion
channels
By application of a chemical, which opens the ion channels
By change of temperature, which alters the permeability of the membrane
By the effects of electromagnetic radiation, which either directly or indirectly
changes the receptor membrane characteristics and allows ions to flow through the
membrane channels
Maximum receptor potential amplitude is about 100 millivolts.
When the receptor potential rises above the threshold for eliciting action potentials in the
nerve fiber attached to the receptor, then action potentials occur. The more the receptor
potential rises above the threshold level, the greater becomes the action potential.
A receptor has a very wide range, from very weak to very intense responses.
Sensory receptors adapt either partially or completely to any constant stimulus after a period
of time.
Slowly adapting receptors:
Receptors of the muscle spindles and Golgi tendon
Receptors of the macula in the vestibular apparatus
Pain receptors
Baroreceptors of the arterial tree
Chemoreceptors of the carotid and aortic bodies
Receptors that adapt rapidly cannot be used to transmit a continuous signal because they are
stimulated only when the stimulus strength changes. They react strongly when there is a
change. These receptors are called rate receptors, movement receptors or phasic receptors.
Spatial summation is the phenomenon whereby increasing signal strength is transmitted by
using progressively greater number of fibers.
Temporal summation is the phenomenon whereby increasing signal strength is transmitted
by increasing the frequency of nerve impulses in each fiber.
The neuronal area stimulated by each incoming nerve fiber is called its stimulatory field.
Divergence is the phenomenon when weak signals entering a neuronal pool excite far
greater numbers of nerve fibers leaving the pool.
Amplifying divergence means that an input signal spreads to an increasing number
of neurons in its path.
Divergence into multiple tracts means that the signal is transmitted in two
directions from the pool.
Convergence means signals from multiple inputs uniting to excite a single neuron.
1
Chapter 47 - Sensory Receptors, Neuronal Circuits for Processing Information
Mechanoreceptors detect mechanical compression or stretching
Thermoreceptors detect changes in temperature
Nociceptors (pain receptors) detect physical or chemical damage to the tissue
Electromagnetic receptors detect light on the retina of the eye
Proprioceptors generate information about the position of (parts of) the body (in muscles,
tendons, joints)
Chemoreceptors detect taste in the mouth, smell in the nose, oxygen level in the arterial
blood etc.
Each type of receptor is highly sensitive to one type of stimulus for which it is designed.
The labeled line principle is the specificity of nerve fibers for transmitting only one modality
of sensation (wanneer een pijnreceptor geactiveerd wordt door een
temperatuurverandering voelt de persoon toch pijn).
Ways to cause receptor potentials:
By mechanical deformation, which stretches the receptor membrane and opens ion
channels
By application of a chemical, which opens the ion channels
By change of temperature, which alters the permeability of the membrane
By the effects of electromagnetic radiation, which either directly or indirectly
changes the receptor membrane characteristics and allows ions to flow through the
membrane channels
Maximum receptor potential amplitude is about 100 millivolts.
When the receptor potential rises above the threshold for eliciting action potentials in the
nerve fiber attached to the receptor, then action potentials occur. The more the receptor
potential rises above the threshold level, the greater becomes the action potential.
A receptor has a very wide range, from very weak to very intense responses.
Sensory receptors adapt either partially or completely to any constant stimulus after a period
of time.
Slowly adapting receptors:
Receptors of the muscle spindles and Golgi tendon
Receptors of the macula in the vestibular apparatus
Pain receptors
Baroreceptors of the arterial tree
Chemoreceptors of the carotid and aortic bodies
Receptors that adapt rapidly cannot be used to transmit a continuous signal because they are
stimulated only when the stimulus strength changes. They react strongly when there is a
change. These receptors are called rate receptors, movement receptors or phasic receptors.
Spatial summation is the phenomenon whereby increasing signal strength is transmitted by
using progressively greater number of fibers.
Temporal summation is the phenomenon whereby increasing signal strength is transmitted
by increasing the frequency of nerve impulses in each fiber.
The neuronal area stimulated by each incoming nerve fiber is called its stimulatory field.
Divergence is the phenomenon when weak signals entering a neuronal pool excite far
greater numbers of nerve fibers leaving the pool.
Amplifying divergence means that an input signal spreads to an increasing number
of neurons in its path.
Divergence into multiple tracts means that the signal is transmitted in two
directions from the pool.
Convergence means signals from multiple inputs uniting to excite a single neuron.
1
