Sensory Receptors Flashcards
sensory receptors
nerve endings with specializes non-neural structures
transducers that convert different forms of energy into frequency of Action potentials (APs)
sensory modality
type of stimulus activating a particular receptor
pain temperature light touch pressure
mechanoreceptors
stimulated by mechanical stimuli
proprioceptors
mechanoreceptors in joints
signal information related to body or limb position
nociceptors
respond to pain
chemoreceptors
chemical changes
transduction in ALL sensory receptors involves opening and closing of
ion channels
graded membrane potential change is also called a
receptor potential
stimulus in mechanoreceptors and proprioceptors is
membrane deformation
activated stretch sensitive ion channels causing ion flow across the membrane e
A stimulus causes local current to flow to the part of the membrane with
voltage-gated ion channels
the larger the stimulus the higher the frequency of
action potentials
stimulus is enough to cause an above..
threshold generator potential
which triggers APs
mechanoreceptors only signal the
ONSET of stimulus
respond to a change or a novel event
mechanoreceptors
receptors that DO NOT ADAPT
nocireceptors
pacinian corpuscle
most understood mechanoreceptor
how does the pacinian corpuscle respond?
- mechanical stimulus DEFORMS capsule and nerve ending
- this stretches the nerve ending and opens ion channels
- Na+ influx - depolarisation
- APs are fired at myelinated nerve
receptive field
somatic sensory neuron is activated by stimuli in a specific area
our ability to tell 2 points on the skin apart depends on….
receptive field size
neuronal convergence
multiple presynaptic neurons input on a smaller number of post-synaptic neurons
convergence
Acuity
the ability to locate a stimulus on the skin and differentiate it with another close by
proprioceptors include…
muscle spindles
Golgi tendon organs
joint receptors
intra and extrafusal muscle fibres form a
muscle spindle
two types of intrafusal fibre
nuclear bag fibre
nuclear chain fibre
muscle stretch stimulates
spindle stretch receptors
during stretch an increase in frequency is proportional to
velocity of stretch
stretching the agonist increases
spindle discharge
shortening the agonist
reduced spindle discharge
alpha motor neurons cause
extrafusal fibre contraction
gamma motor neurons cause
intrafusal fibre ends to contract
gamma motor neurones are activated to maintain
spindle sensitvity
alpha motorneurones are activated causing
contraction
