Sense Organs

Question 1

Hearing

Answer 1

-mechanical sense
-converts vibrations or air molecules into nerve impulses
-impulses interpreted by brain as sound
-organ of hearing = ear

Question 2

Structures w/in temporal bones of skull

Answer 2

-external ear
-middle ear
-inner ear

Question 3

Pinna

Answer 3

funnels sound waves

Question 4

L-shaped external ear

Answer 4

external auditory canal

Question 5

Tympanic membrane

Answer 5

= eardrum
-paper thin c.t.
*stretched tightly across opening b/w: external auditory canal and middle ear cavity
-vibrations strike and cause to vibrate

Question 6

Otitis externa

Answer 6

infection of the external ear canal

Question 7

Otitis media

Answer 7

infection of the middle ear

Question 8

Middle ear

Answer 8

-hollowed out area in temporal bone
-filled with air
- 3 ossicles: hammer, anvil, stirrup
-opening of the eustachian tube

Question 9

Ossicles

Answer 9

-function to transmit vibrations
-act as system of levers that transmit sound wave vibrations from tympanic membrane to cochlea
-vibrations are decreased in size and increased in force

Question 10

Malleus

Answer 10

outermost bone, attached to tympanic membrane

Question 11

Incus

Answer 11

middle bone

Question 12

Stapes

Answer 12

attached to membrane covering oval window of cochlea

Question 13

Eustachian tube

Answer 13

auditory tube
-connects middle ear cavity with pharynx
-equalizes air pressure on two sides of tympanic membrane

Question 14

Inner ear

Answer 14

-structures contribute to hearing and equilibrium
-includes: cochlea, organ of corti, vestibule, semicircular canals

Question 15

Cochlea

Answer 15

-snail shaped spiral cavity
- contains hearing portion of inner ear

Question 16

Organ of Corti

Answer 16

• w/in cochlea
  -fluid filled portion (endolymph) that makes up receptor organ of hearing
• contains HAIR CELLS (hearing receptors)

Question 17

Process of Hearing

Answer 17

• sound wave vibrations cause tympanic membrane and ossicles in middle ear to vibrate
  -vibration goes to the cochlea which houses the organ of corti
  -preilymph vibrates causing distortion of hair cells
  -nerves impulses are generated (Vestibulocochlear nerve)
  -impulses travel to brain and are interpreted as sound

Question 18

Vestibulocochlear nerve

Answer 18

CN 8
convey sensory for hearing and balance

Question 19

Equilibrium- Inner ear

Answer 19

-mechanical sense
-helps animal maintain balance by keeping track of head’s position and movements

Question 20

Equilibrium receptors in inner ear

Answer 20

vestibule = linear motion
semicircular canals = rotary motion

Question 21

Vestibulocochlear nerve

Answer 21

sends info which is integrated in the brain

Question 22

Vestibular disease

Answer 22

can be caused by central or peripheral vestibular system, idiopathic vestibular disease
-head tilt, loss of balance
-inner ear disease or vestibulocochlear nerve lesion

Question 23

Eye components

Answer 23

-function to help form an accurate visual image
-not to detect the image

Question 24

Photoreceptors

Answer 24

-located in single layer of cells in retina
-function is to detect the image
-generate visual nerve impulses

Question 25

Outer fibrous layer of eyeball

Answer 25

cornea, sclera

Question 26

Middle vascular layer of eyeball

Answer 26

choroid, iris, ciliary body

Question 27

Inner nervous layer of eyeball

Answer 27

retina

Question 28

Cornea

Answer 28

-transparent; admits light to interior of eye -orderly arrangement of collagen fibers -no blood vessels; many pain receptors

Question 29

Sclera

Answer 29

white of the eye

Question 30

limbus

Answer 30

junction of the cornea and sclera

Question 31

Uvea

Answer 31

Middle vascular layer of eye -choroid -iris -ciliary body

Question 32

Choroid

Answer 32

-lies b/w sclera and retina -consists mainly of pigment and blood vessels *tapetum lucidum = highly reflective area in rear of eye (not present in humans and swine)

Question 33

Iris

Answer 33

-pigmented muscular diaphragm -controls amount of light that enters the posterior part of eye *pupil = opening in center of iris

Question 34

Ciliary body

Answer 34

-ring shaped behind iris -contains tiny muscles that adjust shape of the lens to allow near and far vision

Question 35

Retina

Answer 35

-lines back of eye -component of fundus -contains rods and cones, sensory receptors for vision

Question 36

Aqueous compartment of eye

Answer 36

-located in front of lens -subdivided by iris: anterior and posterior chamber -contains clear watery fluid = aqueous humor

Question 37

Where is aqueous humor produced?

Answer 37

posterior chamber by cells of ciliary body

Question 38

Vitreous compartment/ chamber

Answer 38

-clear gelatinous fluid = vitreous humor -fills whole back of eyeball behind lens and ciliary body

Question 39

Lens

Answer 39

-elastic and biconvex -helps focus clear image on the retina through accommodation process

Question 40

Nuclear sclerosis

Answer 40

aka lenticular sclerosis -normal age related change -can still see the back of the eye -compression makes lens less elastic and visible

Question 41

Optic disc

Answer 41

"blind spot" of eye -site where nerve fibers on inside of retina converge and leave the eye to form optic nerve

Question 42

Photoreceptor cells

Answer 42

-neurons with dendrites modified into sensory receptors for light rod= more sensitive to light cones = more sensitive to color and detail

Question 43

4 refractive media

Answer 43

cornea, aqueous humor, lens, vitreous humor

Question 44

Nerve fibers leave the eye and form

Answer 44

the optic nerve (CN II)

Question 45

Conjunctiva

Answer 45

thin moist transparent membrane covers front portion of eyeball

Question 46

Bulbar conjunctiva

Answer 46

covers front portion of eyeball

Question 47

Palpebral conjunctiva

Answer 47

lines interior surfaces of eyelids

Question 48

Conjunctival sac

Answer 48

space b/w bulbar and palpebral portions of conjunctiva

Question 49

Tear drainage system

Answer 49

-lacrimal puncta -lacrimal sacs -nasolacrimal duct

Question 50

3 main layers of tears

Answer 50

1. inner mucous layer - from cells in conjunctiva 2. middle tear layer - from lacrimal glands and accessory lacrimal glands of third eyelid 3. outer oily layer -from tarsal or meibomian glands

Question 51

Not enough tears

Answer 51

KCS- keratoconjunctivitis sicca