lecture 24 Flashcards
four sensory receptor types
nociceptors, thermoreceptors, mechanoreceptors and chemoreceptors
what are the three sub classes of mechanorecpetor
proprioceptors, baroreceptors, tactile receptors
what do nociceptors do
– typically responding to signals
generated by tissue damage – trigger perception of
pain, very widespread
what is the only body part with no nociceptors
the brain
what are thermoreceptors
temperature sensors that adapt quickly.
They are free nerve endings located in the dermis, skeletal muscles, liver and hypothalamus.
what are mechanoreceptors
these are sensitive to stimuli that distort their plasma membranes. These membranes contain mechanically gated ion channels, the channels of which opening or closing in response to distortion of the membrane.
what do barorecptors, tactile receptors and proprioceptors do
Proprioceptors: monitor the positions of muscles and joints through space and time.
Baroreceptors: detect pressure changes in the walls of blood vessels and in portions of the digestive, respiratory and urinary tracts.
Tactile receptors: provide sensations of touch pressure and vibration. Touch sensations provide information about shape or texture, whereas pressure sensations indicate the degree and frequency of mechanical distortion.
what are chemoreceptors
Chemoreceptors: respond to water soluble and lipid soluble substances that are dissolved in body fluids.
what are encapsulated nerve enedings and why
As they are encapsulated by some sort of membranous structure that increases their sensitivity to the stimulus they receive.
Tactile Corpuscles, Lamellar Corpuscles, Bulbous Corpuscles and Tactile Discs
what do tactile corpuscles do
Tactile Corpuscles: provide sensation of fine touch and pressure, and low frequency vibrations
what do lamellar corpuscles do
Lamellar corpuslces: sensitive to deep pressures and heavier touches.
what do bulbous corpuscles do
Bulbous Corpuscle: are sensitive to pressure and distortion of more deep layers of the skin, when the skin is stretched.
what do tactile disks do
Tactile disks: fine touch and pressure receptors. Very small receptive fields.
what are hair units
On hairy skin, we have nerve endings asociated with roots of each hair, so that we can sense moevemnts that happen to the hairs. These are called Hair Units.
what are free nerve endings and where are they common
Free nerve endings: look like branches of axons at the top skin layer. Prevalent in skin that is sensitive to pain and temperature.
what stimuli do nociceptors respond to
chemo, thermo and mechanical
what is signal transduction
The
process of converting a stimulus of
one form (eg touch, pressure) into a different form (change in membrane
potential) is called signal transduction.
whats a phasic receptor
Phasic receptors, fast adapting receptors, are normally inactive but become active for a short time due to a change in the conditions which they are monitoring.
what are tonic receptors
Tonic receptors, slow adapting receptors, are always active and generate action potentials at a frequency that reflects the background level of stimulation. When the stimulus increases or decreases the rate of action potential generation changes accordingly.
Muscle spindles are an example of tonic receptors as this reception type allows them to detect muscle contraction and extension
what are the 4 types of information about a stim that are encoded by sensory systems
modality, intensity, duration, location
what is modality
- Modality- type of receptor activated that carries the given info.
what is intensity
- Intensity- stimulus strength, encoded by frequency of action potential firing in afferent neurons
what is duration
- Duration= time period over which stimulus exists
what is location
- Location- place in body where receptor are activated, “mapped” in brain.
