General and Special senses

What are sensation?

What are sensation?

conscious awareness of incoming sensory info

What are the two classes of senses?

general senses and special senses

What are the general senses?

temp, pain, touch, stretch and pressure

What are the special senses?

-gustation (taste)
-olfaction (smell)
-vision
-equilibrium (balance)
-audition (hearing)

What are receptors?

monitor both external and internal conditions and conducts info about those stimuli to the CNS, range in complexity

How does receptive field size effect stimulus identification?

- small field = easily determine precise location and sensitivity
- broad field - only detects general region of stimulus

What are tonic receptors?

involved in maintaining our balance to keep head upright

What are phasic receptors?

signal increased pressure on skin (ex: pinching)

What is acclimation in phasic receptors?

reduction in sensitivity to a continually applied stimulus

Where are special senses receptors housed?

within complex organs in the head

Where are general senses receptors distributed?

throughout the skin and organs

What are exteroceptors?

receptors in skin or mucous membranes, open

What are interoceptors?

receptors located within walls of viscera

What are proprioceptors?

receptors in skeletal muscle, tendons and joint capsules

where does gustation occur?

dorsal surface of tongue using receptors housed in specialized taste buds

Where are tastebuds on tongue?

along sides of epithelial papillae, each bud containing 40 cells

what are the 4 types of papillae?

1. Filiform
2. Fungiform
3. Vallate
4. Foliate

What is Filiform papillae?

on anterior 2/3 of tongue, no taste buds, used to move food around

What is fungiform papillae?

primarily on the tip and sides, only few taste buds

What is vallate papillae?

arranged in an inverted V on the posterior, least amount but largest, many tastebuds surrounded by depressions

What is foliate papillae?

extends as ridges on posteriolateral sides, only few taste buds during childhood; not well developed in adults

What are the 5 taste sensations?

salty (metal ions), sweet (organic compounds), sour (acids), bitter (alkaloids), umami (amino acids)

What is the sixth possible taste sensation?

water

What is olfaction?

receptor cells to detect odors, bipolar neurons synapse with olfactory bulbs

What are the supporting cells of olfaction?

sandwich the olfactory nerves and sustain and maintain the receptors

What are basal cells of olfaction?

function as stem cells to replace epithelium components, when damaged

How many primary odors can olfactory system recognize?

50-60 different odors

What is sense of vision?

visual receptors in eyes detect light, color and movement

What are the accessory structures of the eye?

conjunctiva, eyebrows, eyelids, eyelashes, lacrimal glands, extra-ocular muscles

How does conjunctiva help eye?

provides a superficial covering over its anterior exposed surface

What are lacrimal glands of the eye?

keep the exposed surface moist, clean and lubricated

What is the optic disc?

lacks photoreceptors, blinds spot

What is the macula lutea of the eye?

lateral to optic disc, round yellowish region in retina, has fovea centralis

What is the fovea centralis of the eye?

all cones little rods, region with sharpest vision

What are the two cavities of the eye?

anterior cavity - space anterior to lens and posterior to cornea (has aqueous humor)
posterior cavity - area behind lens (has vitreous humor)

What are the two chambers of the eye?

anterior chamber - between iris and cornea
posterior chamber - between lens and iris

What is vitreous humor?

maintain shaped of eye, thick gelatinous material (inside)

What is aqueous humor?

removes waste products, fluid (outside)

What is the visual pathway?

after nerve conducts visual stimulus info, optic nerves cross over and some do not, sending signals to both side of brain, processed by thalamus and interpreted by cerebrum

Where is middle and inner ear located?

petrous portion of the temporal bone

What causes hearing, equilibrium or balance?

movement of the inner ear fluid, converts sound waves into mechanical movement

What is part of the external ear?

external auditory canal, pinna, helix, tragus, tympanic membrane

What is the function of the outer ear?

helps to funnel sounds into canal

What does the middle ear contain of?

air filled tympanic cavity, auditory ossicles

What are the auditory ossicles?

malleus, incus, stapes

What separates middle ear from inner ear?

bony wall of the oval and round window

What is the purpose of the auditory tube?

maintains open connection with atmosphere, allows pressure to equalize on both sides of tympanic membrane

What is the inner ear?

receptors sense hearing and equilibrium; housed in fluid-filled tubes

What is the inner ear composed of?

membranous labyrinth, vestibule, semicircular canals, cochlea, tympanic and vestibular ducts, organ of corti, tectorial membrane

What is equilibrium?

rotation of the head causes endolymph within semicircular canal to push against capula covering hair cells; resulting in bending of hair and the initiation of a nerve impulse