106 - unit 5 lesson 5

special senses

3 types of cells found in the olfactory epithelium

olfactory sensory neurons, supporting cells, regenerative basal epithelial cels

what is unique about the dendrites of olfactory sensory receptors?

projects outside epithelial cells and is exposed to the outside environment

what is unique about the regenerative basal epithelial cells

only neuronal replacement, theyre precursor cells replaced every 2 months

molecules that stimulate olfactory receptors

odorants

olfactory stimulation is the only type of sensory information that

reaches the cerebral cortex directly (skips thalamus)

why does our sense of smell change when we age

neurons decline with age and get less sensitive

4 functions of gustatory system

protection, saliva production, msgs to increase gastric motility and production of digestive enzymes, start insulin release

where are the taste buds located

vallate papill

term for molecules that stimulate gustatory receptors

tastants

whats a taste pore

openings on taste buds that food particles come in contact with taste receptors

pathway of taste sensation to cns

taste buds, then taste receptors to the solitary nucleus of medulla, joins with axons to the thalamus, synapses then sent to gustatory cortex

wheres the gustatory area of the cerebral cortex located

insula (grey matter) lies deep to lateral brain surface deep fold

5 categories of taste

bitter, sweet, sour, salty, unami

layers of eye from outer to inner and their accompanists

sclera (with cornea), choroid (ciliary body, iris) and retina

sclera

outer layer of eye - the white part

cornea

anterior transparant outer layer

choroid

blood vessels nourishing retina

ciliary body 

produces aqueous humour

iris

muscle controlling amount of light entering eye

retina

holds photoreceptors (rods and cones)

muscles in the iris

circular (constrictor) radial (dilate)

fluid to carry nutrients to lens and cornea

aqueous humour

fluid to carry nutrients to lens and cornea

vitreous humour

jelly maintaining spherical shape

what nerve innervates the constriction and dilation of the pupil

nerve 3

accommodation 

myopia/hyperopia

myopia

light focused in front of retina - long eye

hyperopia

objects focused behind retina - short eye

term for gradual loss of visual activity that occurs with age 

presbyopia

rods vs cones

rods - black and white, cones - colour

visual field 

what you can see with each eye

optic chiasm

where nerve fibers from medial nerves cross over

structures of middle ear

tympanic cavity, auditory tube and ossicles

structures of inner ear

cochlea and vestibular apparatus

auditory tube and ossicles function

pressure, protection, drainage

cochlea function

converts sound to nerve impulse

vestibular apparatus function

balance

why do kids get ear infections more

smaller auditory tube/less of an angle

sound from external to cns pathway

sound at eardrum, moves auditory ossicles to oval window to cochlea, motion in basalar membrane/bending hair, relayed to cns

auditory reflex

loud noise, muscles stiffen to protect

primary structures of the vestibular apparatus and their function

semicircular canals - moving head around

otolith organs - utricle and saccule - body motions 

conductive vs sensorinueral hearing loss

conductive - issues with sound waves making it to inner ear 

sensorineural - issue with inner ear itself