Special Senses Physiology Flashcards
Somatosensory system
part of sensory system concerned with the conscious perception of touch, pressure, pain, temperature, position, movement, vibration
Somatic sensation
sensation from skin, muscles, bones, tendons, joints which is initiated by somatic receptors
Stimulus modality
one aspect of stimulus or what we perceive after a stimulus
light, sound, temperature, taste, pressure, smell
Proprioception/kinesthesia
sense of posture and movement
sensation of the position of your different body parts and muscle contraction in space
Graded potentials
not action potential
small depolarizations that act like EPSPs
Photoreceptors
respond to light
Mechanoreceptors
response to pressure
Thermoreceptors
response to temperature
Auditory receptors
response to sound
Meissner’s corpuscles
rapidly adapting mechanoreceptors that respond to touch and pressure
Merkel’s corpuscles
slowly adapting mechanoreceptors that response to touch and pressure
Free neuron ending
close to skin surface
nociceptors, thermoreceptors, slowly adapting mechanoreceptors
Pacinian corpuscles
rapidly adapting mechanoreceptors that respond to vibration and deep pressure
Ruffini corpuscles
slowly adapting mechanoreceptors that response to skin stretch
As stimulus intensity _____, more action potentials are generated at axon terminal of the afferent neuron
increases
Merkel’s corpuscle stimulation
remains on during the entire time that the stimulus or arm poke is occurring
the frequency of the action potentials decreases over time, but the action potentials are still generated the entire time that the stimulus is on
Meissner’s corpuscle stimulation
it immediately generates a receptor potential with the initial stimulus but quickly decays back to baseline
another receptor potential is generated when the stimulus turns off
Why do we have slowly adapting receptors?
filter unimportant info out
they tell you when you put a shirt on and when you take it off, but do not continually provide information all day that you are wearing a shirt
3 factors of stimulus localization
- receptive field size is the extent of the body which senses the poke
- density of innervations refers to the number of sensory receptors within a certain area of the skin, in the case of touch
- multiple receptive fields exist, and these receptive fields overlap with one another
Lateral inhibition
amplifies the signal from the neuron which is being directly stimulated
adjacent neurons on the edge of stimulus is strongly inhibited compared to central neuron
enhances the contrast between center and periphery regions to localize sensory input
B inhibits A and C strongly
A and C inhibit C weakly
Anterolateral system
pathway which carries pain, hot/cold temp up the somatosensory cortex
Dorsal column system
pathway which carries information on fine touch mechanoreception to somatosensory cortex
Anterolateral tract
- painful stimulus on right arm
- free nerve ending activate action potential
- first synapse happens in the dorsal horn in spinal cord on the same side of body
- second synapse crosses the spinal cord to left side of body
- synapses the thalamus that takes info to cortex
Dorsal column tract
- tap on the right shoulder
- mechanoreceptors activate action potential
- first synapse happens in the brainstem on the same side of the body
- second synapse crosses the brainstem to left side of body
- synapses the thalamus that takes info to cortex
Somatosensory cortex
- sensory info goes from the thalamus to somatosensory cortex
- located behind the motor cortex and central sulcus
- activates motor cortex neurons
- different regions of body represent different regions in cortex
- amount of room taken up in cortex is how densely innervated the sensory receptors
Photoreceptors are _____ at rest
depolarized
Photoreceptors are _____ when activated
hyperpolarized
Optical component
focusing the visual image on receptor cells
front part of eye
Neural component
back part of eye
photoreceptors transform image into patten of graded potentials
Visible light
we are seeing the light that is reflected off the object and it is hitting the photoreceptors
Sclera
white part of eye
membrane surrounding the eyeball
Extraocular muscle
attached to sclera
responsible for eye movements
Cornea
where sclera becomes clear at very front
responsible for refracting light waves
static
