receptor physiology Flashcards
ecteroreceptor
info from the external world
proprioceptor
info from the musculoskeletal system (deep sensation from muscle and tendons and joints)
interoreceptors
info from internal organs
PNS is link bw what
periphery and CNS
PNS consists of what and what are the divisions
nerve fibres that carry info bw CNS and other parts of body
afferent division: info from receptors about internal and ectermal enviroment to CNS- sensory- somatosensory, visceral sensory
efferent division- response that controls the effectors (skeletal muscles, tissues, organs- motor, somatic motor, visceral motor
where does sensory info go
either to spinal chord or travel directly to higher levels in brainstem and thalamus to the primary sensory cortex
first order sensory neuron
afferent neuron with its peripheral receptor that first detects stimulus
second order sensory neuron
either spinal chord or medulla and synapsys with third order neuron
third order sensory neuron
located in thalamus
somatic sensory information
body sense- temp, pain, tactile, proprioceptive from skin, muscles, joints, and inner ear
visceral sensory information
internal organs- pain temp, stretch, chemica, osmotic
special sense sensory info
vision, hearing, balance, taste, smell
where are sensory receptors located
at peripheral endings of afferent neurons
what detects stimuli
sensory stimuli or receptor cells
sensory transduction
conversion of different forms of energy into electrical signals- action potentials-
modality
different types of sensation such as sound, light, taste, pain, touch
photoreceptors
visible wavelengths of lighty
photoreceptors
visible wavelengths of light
mechanoreceptors
mechanical energy
thermoreceptors
heat and cold
nocioceptors
pain
chemoreceptors
specific chemicals
receptors for smell, taste, o2 and co2 conc in blood and chemical content of digestive tract
osmoreceptors
osmotic pressure
adequate stimulus
least amount of energy to activate particular receptor. form of energy that receptor is most responsve
law of specific nerve energies
sensation characteristic of each sensory neuron produced by its adequate stimulus
categories of sensory receptors
free nerve endings- nociceptors
specialized endings of sensory neurons- encapsulated receptors- pacinian corpuscle, meissners corpuscles
specialized structures that have synaptic connections with sensory axons- taste buds, hair cells
what does a stimulus do to a receptor
alters its permeability causing nonselective opening of all small ion channels leading to influx of na ions depolarizing membrane. graded local potential known as RECEPTOR POTENTIAL
receptor potential
graded potential for one separate receptor- amp and duration can vary
generator potential
graded potential in the case of the specialized ending of a nerve fibre- amp and duration can vary
do receptor potential have a refractory period
no
can receptor potentials haev summation
yes with rapidly successive stimuli
tonic receptors
do not adapt or adapt slowly to sustained stimulation. muscle stretch receptors, joint proprioceptors
constant rate of depolarization
phasic receptors
rapidly adapting receptors or sustained stimuli. tactile receptors in skin
burst of activity when stimulus is first applied then quicly decrease firing rate. exhibit off response
somatosensory
1:1 association of receptor with a sensation- labelled line coding
pathway for a detected modality
modality detected by a specialized receptor is sent over to a specific afferent and ascending pathway to excite a defined area in the somatosensory cortex. sensory info is mapped along specific pathways
synesthesia
one sensation triggers another sensation
receptive field
region of skin surface that the somatosensory neuron responds to
acuity
the smaller the receptive field the greater the acuity- discriminative ability
lateral inhibition
influences acuity
sensory humonculus
represents a map of brain areas dedictaed to sensory processing for diff anatomical divisions of the body
where is the primary sensory cortex located
postcentral gyrus
what does the primary sensory cortex do
handles signals coming from the thalamus
does a stronger receptor potential produce a larger action potential
no. it can induce a higher frequency firing of AP
adaptation
reduction in receptor potentials despite sustained stimulation of the same magnitude. can be reduction in number of APs. helps prevent overload
