Chp 15: Special Senses

Question 1

What are the 5 special senses that aid humans in interpreting their environment?

Answer 1

Gustatory, olfactory, vision, auditory, equilibrium

Question 2

How do special senses differ from general senses?

Answer 2

Special senses: more complex neuron structure, greater area of cerebral cortex, organs are located in the head, involve mainly cranial nerves

Question 3

Taste bud location

Answer 3

Mostly in papillae (peglike projections of tongue mucosa) but some scattered on soft palate, inner surface of cheeks, pharynx, and epiglottis

Question 4

Gustatory epithelial cells

Answer 4

Receptor cells for taste
Long microvilli (gustatory hairs) project from tips of all gustatory epithelial cells and extend through taste pore to surface of epithelium where they are bathed in saliva

Question 5

Basal epithelial cells

Answer 5

Act as stem cells, dividing and differentiating into new gustatory epithelial cells

Question 6

Fungiform papillae

Answer 6

Scattered over tongue surface, taste buds aree located mainly on tops of these mushroom-shaped fungiform papillae

Question 7

Foliate papillae

Answer 7

Taste buds are found in the side walls of the foliate papillae

Question 8

Vallate papillae

Answer 8

Largest, least numerous papillae

Inverted V shape at back of tongue

Question 9

5 Primary Tastes (and mechanism of taste differentiation)

Answer 9

Sweet: OH+
Sour: H+
Salty: ions
Bitter: alkaloids
Umami: glutamate and aspartate

Question 10

The gustatory pathway

Answer 10

Branch of the facial nerve (VII) transmits impulses from taste receptors in the anterior two-thirds of the tongue
Lingual branch of glossopharyngeal nerve (IX) serves the posterior third and the pharynx
Taste impulses from the few taste buds in the epiglottis and the lower pharynx are conducted by the vagus nerve (X)
These afferent fibers synapse in the solitary nucleus of the medulla, steam to thalamus, then to gustatory cortex in the insula.

Question 11

Olfactory apparatus

Answer 11

Olfactory epithelium: located in roof of nasal cavity
Olfactory sensory neurons are cushioned by supporting cells
Olfactory stem cells lie at base of epithelium
Olfactory cilia increase receptive surface area

Question 12

Role of thin mucus lining of olfactory epithelium

Answer 12

Solvent that captures and dissolves airborne odorants

Question 13

Olfactory pathway

Answer 13

Olfactory sense neurons form olfactory nerves that synapse in overlying olfactory bulbs
Filaments of olfactory nerves synapse with mitral cells in glomeruli
When mitral cells are activated, impulses flow from olfactory bulbs via olfactory tracts to piriform lobe of the olfactory cortex

Question 14

Accessory eye structures

Answer 14

Eyebrows: shade eyes from sunlight, prevent perspiration from reaching eyes
Eyelids
Eyelashes
Conjunctiva
Lacrimal apparatus
Extrinsic eye muscles

Question 15

Blood shot eyes are

Answer 15

Dilation of blood vessels in conjunctiva

Question 16

Lacrimal apparatus

Answer 16

Lacrimal gland lies in orbit above lateral end of eye, releases tears
Blinking spreads tears downward, across eyeball, to lacrimal canliculi
Drain into lacrimal sac then into nasolacrimal duct, which empties into nasal cavity

Question 17

Sclera

Answer 17

Forms posterior portion of fibrous layer, protects and shapes eyeball, provides anchoring site for extrinsic eye muscles

Question 18

Cornea

Answer 18

Anterior portion of fibrous layer

Clear, forms window that lets light into eye

Question 19

Choroid

Answer 19

part of vascular layer (middle of the eyeball)

Blood vessel rich, dark brown membrane, its blood vessels nourish all eye layers

Question 20

Ciliary body

Answer 20

Anterior part of choroid
Part of vascular layer
Thickened ring of tissue that encircles the lens , controls lens shape

Question 21

Extrinsic eye muscles

Answer 21

Straplike muscles, 4 rectus, 2 oblique

Control movements of each eyeball

Question 22

Lateral rectus

Answer 22

moves eye laterally

VI

Question 23

Medial rectus

Answer 23

moves eye medially

III

Question 24

Superior rectus

Answer 24

Elevates eye and turns it medially

III

Question 25

Inferior rectus

Answer 25

Depresses eye and turns it medially | III

Question 26

Inferior oblique

Answer 26

Elevates eye and turns it laterally | III

Question 27

Superior oblique

Answer 27

Depresses eye and turns it laterally | IV

Question 28

Retina

Answer 28

Innermost layer of eyeball | Contains millions of photoreceptors that transduce (convert) light energy

Question 29

Rods

Answer 29

Dim light and peripheral vision receptors | More numerous and more sensitive to light than cones

Question 30

Cones

Answer 30

Vision receptors for bright light and color vision

Question 31

Fovea centralis

Answer 31

Pit in center of macula lutea, lateral to blind spot | Contains only cones

Question 32

Visual pathway to brain

Answer 32

Axons of retinal ganglion cells exit eye in optic nerves At optic chiasma, fibers cross over to opposite side and continue via optic tracts which send most of their axons to synapse with neurons in the thalamus, fibers project to the primary visual cortex in the occipital lobes

Question 33

Cataract

Answer 33

"waterfall" clouding of the lens

Question 34

Glaucoma

Answer 34

Damage to the retina and optic nerve due to increased pressure within eye (if drainage of aqueous humor is blocked)

Question 35

Ear gross anatomy

Answer 35

External: auricle/pinna funnels sound waves into the external acoustic meatus Middle: tympanic cavity; small air-filled, mucosa-lined cavity, contains auditory ossicles Internal: "labyrinth" bony and membranous portions, provides secure site for delicate receptor machinery

Question 36

Tympanic membrane

Answer 36

eardrum, boundary btwn outer and middle ears | Sound waves make the eardrum vibrate, transfers sound energy to tiny bones of middle ear and makes them vibrate

Question 37

Pharyngotympanic/Auditory/Eustachian Tube

Answer 37

Links middle ear cavity with nasopharynx Usually flat and closed but can be opened briefly to equalize pressure Mucus drainage

Question 38

Semicircular canals

Answer 38

Region of bony labyrinth Lie posterior and lateral to the vestibule Anterior, posterior, and lateral semicircular canals in each internal ear

Question 39

Vestibule

Answer 39

Central egg-shaped cavity of bony labyrinth

Question 40

Cochlea

Answer 40

Spiral, conical, bony chamber of the bony labyrinth

Question 41

Organ of Corti

Answer 41

aka spiral organ, the receptor organ of hearing | Housed in cochlear duct

Question 42

Auditory pathway

Answer 42

Sound vibrations are collected by outer ear, travel into ear canal, ear drum vibrates and moves auditory ossicles in middle ear, which carry the vibrations the cochlea in the inner ear Fluid vibrates cilia, which are attached to auditory nerves, send signals to brain

Question 43

Sensorineural deafness

Answer 43

Results from damage to neural structures (including hair cells) Single explosively loud noise or prolonged exposure to high-intensity sounds, degeneration of cochlear nerve, strokes, tumors in auditory cortex

Question 44

Conduction deafness

Answer 44

Occurs when something hampers sound conduction to the fluids of the internal ear ex// compacted earwax, ruptured eardrum, middle ear inflammations