Special Senses Flashcards
Coding
Stimulus E into relevant info for CNS
Stimulus characteristics
Intensity, location of body it affects, type of input
Stimulus Modality
Stimulus Type
Examples of stimulus
Heat, cold, pressure, light, sound, there is a specialized receptor for each
Sensory receptors
At ends of afferent neurons
Receptor Potential
Initiate action potentials that travel to CNS
5 major classes of sensory receptors
Mechano, pressure
Thermo, temp
Photo, light
Chemo, taste
Noci, pain
Receptor potential
Changes in ion flow change membrane potential, Stronger the stimulus, the greater the reaction potential
Sensory Adaptation
Repeated stimuli lead to less sensitivity
Lateral Inhibition
Enable localization of a stimulus site for some sensory systems
Higher contrast between center and outside
Lateral inhibition enhances…
Sensory signals are subject to mods
Yup!
From other ascending neurons, pathways from the brain, synapse from afferent neurons, interneurons
Divergence
Convergence
Association cortex
Areas that are more sensitive have…
Factors that affect perecption
Meissners corpuscle
Merle’s corpuscle
Pacinian corpuscle
Ruffini corpuscle
Free neuron ending
Reffered pain
Free neuron ending
Hyperalgesia
Can pain be altered by past experiences/emotion?
Yup! It can also be altered by suggestion and simultaneous activation
Analgesia
Selective suppression of pain without effects of consciousness or other sensations
Pain relief
Stim, las drogas, opioids, acupuncture, TENS
The eyes are composed of two things
Optical (focuses image) and neural (transforms visual image)
Sclera
Pupil
Iris
Lens
Cornea
Ciliary muscle
Lacrimal gland
Retina
Rods
Shades of gray in dim light
Contains (rhodopsin which absorb dim light)
Gray Roblox rod
Cones
Allow us to see bright light
Contain photopsin (absorb bright colored light)
Frequency
Wavelength
Amplitude
Higher frequency light
Shorter wavelengths higher E
Lower freq light
Refraction
Corrective lenses…
Ganglion cells
Bipolar cells
Photoreceptor cells
Pigment epithelium
Visual info to the brain
Light reaches eye
Lens refracts light and projects onto retina
Retina converts to neural signal down optic nerve
Optic nerves from each eye converge to optic chiasma
Optic chiasma sorts info
(left info sent to right side of brain and v.v)
Some visual info goes to occipital lobes, but not all…
Brain stem and cerebellum
Light perceived as white…
Mixture of all wavelengths while black is the absence of all light
The Organ of Corti
Converts sound E to neural impulses using cilia
Why does an object appear the color it does?
It absorbs some light and reflects the color that it is
Audition (hearing)
Based on physics of sound and physiology of the ear, air is the most common media
There is no sound in a vacuum
True
How does the body determine the position of the head?
The cochlea is filled with fluid that moves around
Cochlear nerve fibers synapse with inter neurons in the…
Brain stem
Neural pathway in hearing
Cochlear nerve fibers>brain stem>thalamus>auditory cortex(temporal lobe)
How do we know our position? (Laying down, sitting etc)
Orientation of semicircular canals (vestibular system)
Vestibular information is used…
Control eye movement
Posture and balance
Body position awareness/spatial info
Vestibular Pathway
Vestibular nerve fibers>
Brain stem> thalamus > vestibular centers in parietal lobe
Chemical senses
External chemicals bind to chemoreceptors for taste and smell
Gestation
Tasting by taste buds
Purpose of microvilli
Increase surface area and transducer chemicals into receptor portential
Basal cells
At bottom of taste buds and divide to continuously replace taste cells
To enter taste buds, food..
Is dissolved in liquid, saline or otherwise
Olfactory Epithelium
Location of olfactory receptor neurons in nasal cavity
How long do olfactory nerves live?
2 months
Where do odor molecules bind?
Receptor proteins on cilia
Olfactory nerve
Axons of the neurons from nasal cavity
