Sensory Terminology

Sensation

Detection of change in environment

Perception

Conscious awareness of stimuli

Adaptation

Sensory neuron stops producing action potential

Habituation

Thalamus stops relaying information

Non-encapsulated receptors

Most abundant, C-fiber axon, pain and temperature

Two pain pathways

Reflexive protective, conscious sensation

Sharp pain

Travels on myelinated, wide A-Delta fiber

Dull pain

Travels on nonmyelinated, narrow C fiber

Encapsulated receptors

Nerve ending surrounded by connective tissue, mainly mechanoreceptors

Non-encapsulated receptor examples

Free nerve endings, merkel disks, hair follicle receptors

Encapsulated receptor examples

Tactile corpuscles, lamellar corpuscles, bulbous corpuscles, muscle spindles, tendon organs

Lacrimal apparatus

Tear system

Parts of lacrimal apparatus

Lacrimal gland, punctum, canaliculus, nasolacrimal duct, inferior meatus of nasal cavity

Sphincter pupillae

Constricts pupil

Dilator pupillae

Dilates pupil

Retina layers

Neural and pigmented

Visual pigments

Opsin and retinal

Types of opsin

Rhodopsin, blue, green, red

Suprachiasmatic Nucleus

Controls circadian rhythm

Pretectal nucleus

Pupil diameter, eye movements, focus

Superior colliculus

Controls some eye movement

Inner hair cells

Main auditory sensory cell

Outer hair cells

Magnify and refine signal

Cochlear nuclei

Auditory relay center in pons/medulla

Inferior colliculus

Auditory relay center in midbrain

Medial geniculate nucleus

Thalamic auditory relay center

Conductive hearing loss

No sound transmission through external/middle ear

Central hearing loss

Damage to neural pathways

Sensorineural hearing loss

Most common, damage to inner ear

Utricle

Detects horizontal acceleration and head tilt

Saccule

Detects vertical acceleration and head tilt

Maculae

located on utricle and saccule detecting acceleration and head tilt

Otoliths

Crystals suspended in gelatinous fluid that move with acceleration and head tilt stimulating hair cells on maculae

Semicircular ducts

Where rotational acceleration is detected

Anterior duct

Detect flexion and extension of neck

Lateral ducts

Detect rotation of neck

Posterior ducts

Detects lateral flexion of neck

Crista ampullares

Enlargements at end of semicircular ducts containing cupula

Cupula

Flow due to inertia bends these to stimulate hair cells for rotational acceleration detection

Mitral cell

Cell in olfactory bulb that olfactory receptors synapse on taking information to olfactory cortex

Sweet molecules

Nutritious organic molecules

Umami molecules

Glutamate and aspartate

Bitter molecules

Toxic organic molecules

Sour molecules

Excess H+

Salty molecules

Inorganic salts

Papillae

Bumps on tongue

Taste bud

50-100 gustatory epithelial cells

Type I Gustatory Cell

Salt detecting?

Type II Gustatory Cell

Bitter, umami, sweet; uses ATP as neurotransmitter

Type III Gustatory Cell

Sour; uses serotonin and neurotransmitter

Taste involved cranial nerves

CN VII, IX, X

Vestibular involved cranial nerves

CN III, IV, VI, XI

Helicotremma

apex of cochlea

Palpebrae

eye lids