Special Senses

Question 1

special sensory receptors

Answer 1

localized: confined to the head region
receptors are not free endings of sensory neurons
special receptor cells: neuron-like epithelial cells or small peripheral neurons

Question 2

taste

Answer 2

receptors are classified as chemoreceptors that respond to food dissolved in saliva fluids

Question 3

the superior surface of the tongue

Answer 3

stratified squamous epithelium
filiform, fungiform, foliate, vallate papillae
sulcus terminalis: marks border between mouth and pharynx
lingual tonsil: covers posterior 1/3 of tongue that lies in oropharynx

Question 4

sulcus terminalis

Answer 4

marks border between mouth and pharynx

Question 5

lingual tonsil

Answer 5

covers posterior third of tongue that lies in oropharynx

Question 6

filiform papillae on tongue

Answer 6

the most numerous papillae on the tongue
small and conical pointed in shape
line up in parallel rows which enable tongue to grasp and manipulate food
do NOT contain taste buds

Question 7

taste buds

Answer 7

present on fungiform, foliate, and vallate papillae
contain taste of receptors
two major cell types: gustatory epithelial cells and basal epithelial cells
long microvilli (gustatory hairs): project from gustatory epithelial cells and extend through a taste pore to the surface of the stratified squamous epithelium
cells in taste buds replaced in every 7-10 days

Question 8

taste: two major cell types

Answer 8

gustatory epithelial cells

basal epithelial cells

Question 9

long microvilli (gustatory hairs)

Answer 9

project from gustatory epithelial cells
extend through a taste pore to the surface of the stratified squamous epithelium
microvilli are bathed in saliva containing dissolved food molecules
triggers gustatory epithelial impulses in the sensory nerve fibers

Question 10

gustatory pathway

Answer 10

taste information reaches the cerebral cortex primarily through the facial (CN VII), glossopharyngeal (CN IX), and vagus nerve (CN X)

Question 11

smell

Answer 11

olfactor

classified as chemoreceptors which responds to airborne chemicals that dissolve in fluids of the nasal mucosa

Question 12

olfactory epithelium

Answer 12

pseudostratified columnar epithelium

3 main cell types

Question 13

3 main cell types of olfactory epithelium

Answer 13

olfactory sensory neurons (bipolar)
supporting epithelial cells
basal epithelial cells

Question 14

olfactory cilia

Answer 14

act as receptive sites for smell

Question 15

mucus and olfaction

Answer 15

mucus captures and dissolves odor molecules

Question 16

smell: cell body to brain

Answer 16

passes through cribriform plate of ethmoid bone
enters into olfactory bulbs and synapses with mitral cells
1. limbic system
2. piriform lobe of cerebral cortex (primary olfactory cortex)

Question 17

anosmia

Answer 17

absence of the sense of smell

due to injury, colds, allergies, zinc deficiency

Question 18

uncinate fit

Answer 18

distortion of smells or olfactory hallucinations (phantosmia)
often result from irritation of olfactory pathways from brain surgery or head trauma
cacosmia = phantom bad smells

Question 19

accessory structures of the ey

Answer 19

eyebrows
eyelid
levator palpebrae superioris muscle
conjunctiva - transparent mucous membrane
lacrimal apparatus - keeps surface of the eye moist

Question 20

eyelid

Answer 20

lacrimal caruncle - reddish elevation at medial canthus
tarsal plates - connective tissue within the eyelids
tarsal glands - modified sebaceous glands

Question 21

types of tears

Answer 21

continuous (basal) tears - produced for basic eye function, such as lubrication
reflex (irritant) tears - occur when the eye is exposed to excessive light, wind, cold, foreign body, gas
psychogenic tears - shed for emotional reasons

Question 22

extraocular eye muscles

Answer 22

lateral rectus: CN VI (abducens), moves eye medially
medial rectus: CN III (oculomotor), moves eye medially
superior rectus: CN III, elevates eye and turns it medially
inferior rectus: CN III, depresses eye and turns it medially
inferior oblique: CN III, elevates eye and turns it laterally
superior oblique: CN IV (trochlear), depresses eye and turns it laterally

Question 23

posterior segment of the eye

Answer 23

filled with vitreous humor
clear, jelly-like substance
transmits light into the eye
supports the posterior surface of the lens
helps maintain intraocular pressure

Question 24

anterior segment of the eye

Answer 24

anterior and posterior chambers separated by the iris
aqueous humor -
formed from a filtrate of the capillaries in the ciliary process
reabsorbed into the venous blood by scleral venous sinus
provides nutrients to lens and cornea

Question 25

glaucoma

Answer 25

increased intraocular pressure in the anterior segment of the eye occurs when aqueous humor drains more slowly than it forms causes compression of the retina and optic nerve (blindness)

Question 26

the lens

Answer 26

thick, transparent, biconvex disc held in place by its ciliary zonule lens epithelium covers anterior surface of the lens

Question 27

3 layers of the wall of the eye

Answer 27

``` fibrous layers (sclera and cornea) vascular layer (choroid, ciliary body, and iris) sensory layer (pigmented layer, neural layer) ```

Question 28

cornea

Answer 28

thick layer of dense collagen-rich connective tissue endothelium (inner layer) cornea is avascular, but gets O2 from air in front and nutrients from aqueous humor behind richly supplied with nerve endings, most of which are pain receptors

Question 29

choroid

Answer 29

vascular darkly pigmented membrane - brown color from melanocytes prevents scattering of light rays within the eye choroid corresponds to the arachnoid and pia maters

Question 30

ciliary body

Answer 30

thickened ring of tissue, which encircles the lens | ciliary body consists chiefly of smooth muscle called the ciliary muscle which acts to focus the lens

Question 31

the iris

Answer 31

attached to the ciliary body and positioned anterior to the ciliary body composed of smooth muscle pupil is the round, central opening

Question 32

photoreceptors

Answer 32

rods and cones have an inner and outer segment outer segments are receptor regions that contain light absorbing pigments light particles modify the visual pigment and generate a nerve impulse

Question 33

visual pathways that branch to the hypothalamus

Answer 33

branch to the suprachiasmatic nucleus of hypothalamus which processes visual input to help synchronize daily biorhythms with the daylight-darkness cycle

Question 34

visual pathways that branch to the midbrain

Answer 34

superior colliculi: control extrinsic eye muscles and visual reflexes pretectal nuclei: mediate pupillary eye reflexes (subcortical visual system)

Question 35

the outer ear

Answer 35

``` the auricle (pinna): helps direct sounds external ear/auditory canal: lined with skin, hairs, sebaceous glands tympanic membrane: forms the boundary between external and middle ear ```

Question 36

the middle ear

Answer 36

tympanic cavity small, air-filled space located within the petrous portion of the temporal bone ear ossicles: malleus, incus, stapes

Question 37

the inner ear: bony labyrinth

Answer 37

semicircular canals, vestibule, cochlea | filled with perilymph

Question 38

the inner ear: membranous labyrinth

Answer 38

semicircular ducts, utricle/saccule, cochlear duct | filled with clear fluid endolymph

Question 39

the cochlea

Answer 39

spiraling chamber in the bony labyrinth of the inner ear from its attachment on the vestibule it coils around a pillar of bone - the modiolus osseous spiral lamina - a spiral of bone in the modiolus cochlear nerve - runs through the core of modiolus

Question 40

spiral organ of Corti

Answer 40

stereocilia are embedded in the gel-like tectorial membrane which does not move basilar membrane vibrations cause stereocilia to move