Psych Part 7 Flashcards
Mechanoreceptors
Pacinian Corpuscle - pressure sensor
Auditory hair cell - cochlea of inner ear
Vestibular hair cell - in semi-circular canals of the inner ear, detect relative position to gravity + acceleration
Chemoreceptors
Olfactory receptors
Gustatory receptors
Nociceptors
Simplest receptor, autonomic or somatic.
Note that nociceptors do not adapt, so we have to do something about pain.
Thermoreceptors
Detects changes in temperature. Autonomic and somatic examples.
Peripheral types: cold-sensitive; warm-sensitive; thermal nociceptors
Electromagnetic receptors
Only example in humans are photoreceptors
Encoding sensory stimuli
Modality
Location
Intensity
Duration (phasic, tonic, sustained)
Proprioception
Muscle Spindles (mechanoreceptor) - detect muscle stretch
Golgi tendon organs - detect stretch in tendons
Joint capsule receptors - detect pressure/tension/movement in joints
Gustation
Can only detect 5 flavours with 5 types of taste buds responding most strongly to a specific one.
Tate buds - composed of multiple epithelial cells with a taste pore at the centre with taste hairs that detect food chemicals.
Information from taste buds is moved from cranial nerves to temporal lobe.
Olfaction
Olfactory receptors located in the nasopharynx.
Chemicals dissolve into mucus of the nasal membrane. Neurons project to the olfactory bulb in the temporal lobe.
Note: there are no inherently noxious odours, this is entirely learned.
Auditory/Vestibular system composition
Outer Ear
Middle Ear
Oval Windom
Inner Ear
Outer Ear
Auricle
Pinna
Auditory canal
Middle Ear
Tympanic membrane
Ossicles: Malleus (hammer), Incus (anvel), Stapes (stirrup)
Inner Ear
Cochlea
Other components relevant to balance:
Semicircular canals
Utricle
Saccule
Eustachian Tube
Auditory Tube
Equalizes pressure on both sides of the tympanic membrane.
Connects to the back of the throat.
Mechanism of Hearing
Sound waves > ear drum > malleus receives vibration > incus > stapes vibrates oval window > Creates vibrations in the perilymph and endolymph in cochlea > Vibration in basilar membrane covered in hair cells that contact TECTROIAL MEMBRANE > hair cell displacement opens ion channels activating bipolar auditory afferents.
Organ of corti
Includes bipolar auditory afferents and the tectorial membrane.
Pitch and Intensity determination
Pitch - determined by region of basilar membrane vibration. Low frequencies are at the apex and higher frequencies are closer to the oval window.
Intensity - amplitude of vibration.
Vestibular Complex
Formed by 3 semi-circular canals:
Utricle
Saccule
Ampullae
All three are filled with endolymph and covered in hair cells that detect motion (rotational acceleration to be specific).
Vision structures and mechanism
Light > Cornea (refracts light) > Anterior chamber with aqueous humour > Iris with pupil opening (iris muscles dilate pupil) > posterior chamber with aqueous humour > Lens (tunes incident light and altered by ciliary muscles) > Vitreous chamber with vitreous humour .
Note that the cornea is continuous with the sclera and beneath the sclera is the choroid, which is the dark pigmented surface.
Special regions of the retina
Optical Disc - blind spot where ganglion cell axons form optic nerve.
Macular - in the centre is the fovea centralis, only cone cells here and high visual accuity.
Photoreceptors
Opsins respond to light.
Retinol when cis-bound; Na channels remain open (depolarized) when all trans form hyperpolarizes cell by closing Na+ channels.
Glutamate effect on bipolar cells
Inhibitory when released from photoreceptors, as only when photoreceptors hyperpolarize is an ON-bipolar cell activated.
Emmetropia
Normal Vision
Myopia
Nearsightedness - light is bent too much. Can be corrected with a concave lens.
Hyperopia
Farsightedness (light is bent too little and focuses behind the retina). Corrected with a convex lens.
Presbyopia
Inability to focus (accommodate) results from a lack of flexibility in the lens and usually occurs with aging.