Chapter 14 Seeing and Hearing - PowerPoint Presentation

Slide1

Chapter 14

Seeing and Hearing

Slide2

Senses –General and Special

General

Visceral sensations

Hunger, thirst

Touch

Touch / tactile, pressure

Temperature

Hot/cold

Pain

Receptors inside and surface of body

Proprioception

Sense of body movement and position

Slide3

Special Senses

(Touch)

Smell

Taste

Vision

Hearing

Equilibrium

More complex than General senses,

Sensory structures located in the head

Slide4

1. Smell

Olfactory Sense

“chemical” sense

Dogs

Average of

220 million receptors

Humans: 5 million

Slide5

How do they smell

Two patches of olfactory epithelial cells

Located up high in both nasal passages

Odor molecules dissolve in the mucus

nerve impulses are generated that travel to

the brain

Cranial Nerve I: called Olfactory nerve

Slide6

Slide7

Best Smellers

Pointers

Coonhounds

English Springer Spaniel

Belgian

Malinois

Labrador

Retreivers

German Shepherd – 225 million scent receptors

Beagle

Basset Hound

Blood Hound – 300 million scent receptors!

Slide8

2. Taste

Gustatory Sense

“chemical” sense

Taste sensations vary from species to

species

Humans taste: sweet sour salty and bitter

Cats do not “taste” sweet

(“

tasting” refers to responding to a particular taste sensation)

Slide9

Taste Buds

Tiny rounded structures made

up of gustatory sensory cells

sensory receptors (modified dendrites of neurons)

Found in elevated papillae around the tongue

Substance dissolve in saliva, nerve impulses are

generated that travel to the brain

Cranial Nerve IX (

glossopharyngeal

nerve)

Slide10

3. Equilibrium

Mechanical sense

Balance

Equilibrium works by keeping track of the

position and movement of the head

Equilibrium receptors are located in portions

of the inner ear

(vestibule and semicircular canals)

Slide11

4. Hearing

Auditory Sense

“mechanical” sense

Vibrations of air molecules are converted into

nerve impulses that are interpreted by the brain

External Ear

Middle Ear

Inner Ear

Slide12

Functions of the Ear

The ear is the sensory organ that enables hearing and helps to maintain balance

.

The combining forms for ear are

audit/o

,

aud

/

i

, and

ot

/o

.

Slide13

Outer Ear Structures

Pinna

catches and then transmits sound waves

Pinn/i

is the combining form.

Aur/i

and

aur/o

also mean external ear.

External auditory canal

tube that transmits sound from the pinna to the tympanic membrane

Glands secrete cerumen here.

Slide14

Middle

Ear Structures

Auditory

ossicles

malleus

,

incus

, and stapes

Slide15

Middle Ear Structures

Tympanic membrane

“eardrum”

Transmits sound waves to the ossicles

Tympan/o

and

myring/o

mean eardrum.

Slide16

Middle Ear Structures

Eustachian

tube

equalizes air and middle ear pressure

Tympanic

bulla

osseous chamber that houses the middle ear

Slide17

Inner Ear Structures

Bony labyrinth

vestibule

balance and equilibrium

semicircular canals

three canals that regulate equilibrium

cochlea

organ of hearing

Slide18

Pathological conditions

Vestibular Disease / Old Dog Vestibular Syndrome

Equilibrium

Vestibular Cranial Nerve

Possible inner ear infection

Ideopathic

Slide19

Deafness and “white” hair

Vibrations occur and the hair cells in the Cochlea move.

The mechanical energy is converted by the hair cells of the

cochlea into electrical impulses through the cochlear nerve

to the brain. In order for the hair to convert the mechanical

energy the cell must contain pigment. Lack of pigment in

the inner ear is difficult to predict…but too much white in

Certain dogs seems to be correlated to the amount of white

found in the hair cells.

Slide20

Functions of the Eye

The ocular system is responsible for vision.

The combining forms for the eye or sight are

opt/i

,

opt/o

,

optic/o, ocul/o

, and

ophthalm/o

.

Slide21

Structures of the Eye

The accessory structures of the eye:

Orbit

Bony cavity of the skull that contains the eyeball

eye

muscles

7 major muscles attach to each eye for movement

eyelids or

palpebrae

Palpebral

reflex (result of Trigeminal Nerve and CN VII)

Also depth of anesthesia

https://www.youtube.com/watch?v=4_zdjL51qoU

Belphar

/o

is the combining form.

Slide22

Structures of the Eye

e

yelashes

Hairlike

structures called cilia

Protect the eye from foreign material

conjunctiva

Mucous membrane that lines the underside of the eyelid

Forms protective covering when the eyelids are closed

Nictitating membrane=third eyelid.

lacrimal

apparatus

Lacrim

/o

and

dacry

/o

are the combining forms.

Slide23

Structures of the Eye

lacrimal

apparatus

Lacrim

/o

and

dacry

/o

are the combining forms

.

Lacrimal

glands produce and secrete tears

Lacrimal

canaliculi

or

lacrimal

duct collects tears and drains them into the

lacrimal

sac

Lacrimal

sac collects tears at the upper portion of the tear duct

Nasolacrimal

duct is the passageway that drains tears into the nose.

Slide24

Structures of the Eye

Outer covering of the eyeball:

Sclera

White of the eye

Fibrous outer layer that maintains shape of the eye

Surrounds most of the eyeball

C

ornea

The

transparent anterior portion

of the sclera is

called the cornea

.

Slide25

Sclera and Cornea

Slide26

Structures of the Eye

Middle

Iris

Colored portion of the eye

Pigmented muscular diaphragm controls amount of light

Located right behind the cornea

Pupil

Hole in the center of the iris

through which light passes

Constricts or dilates

L

ens

Layers of connective tissue fibers

Slide27

Choroid

Main portion of the middle layer

Blood vessels

Dark pigmentation (caudal portion of the eye)

Tapetum

Lucidum

Very reflective “mother of pearl” blues and greensAids night vision due to reflective nature

Pigs and humans do not have a

tapetum

lucidum

Slide28

Structures of the Eye

I

nner layer

Retina

Nervous tissue layer that receives images

Converts light rays into nerve impulses

Photoreceptors “rods and cones”

Rods – light

Cones - color and detail

Send messages via the optic nerve

Slide29

Structures of the Eye

Slide30

Eye Chambers

The eye is divided into parts:

Anterior segment contains

watery fluid called aqueous

humor.

anterior chamber

posterior chamber

Vitreous chamber contains vitreous humor

.

Gel like mass

Slide31

Patological

Conditions

Lenticular

sclerosis

Cataracts

Glaucoma

Eye

EnucleationEye

E

ntropion

Tear Production

Scratches on the Cornea

Slide32

Lenticular

Sclerosis

Age associated

Hardening of the lens

Pupil appears cloudy and gray

Very little loss of vision

Slide33

Cataracts

Protein and cellular debris clump together

Old age – gradual

Sudden – diabetes

White

Surgical removal of

lens

https://

www.youtube.com/watch?v=4JFmPU50kZY

Slide34

Glaucoma

Intraocular pressure

Very painful

Irreversible blindness

Different reasons

One reason is breed

predisposition

Slide35

Intracular

pressure should be between

12

and 25 mm

Hg

Can be measured with a

tonometer

or

tonopen

Usually surgically remove the eye

eye

enucleation

Slide36

Eye

Entropion

An inversion (turned inward) of the eyelid

Causes irritation of the cornea and sclera

Slide37

Tear Production

“Dry Eye”

Schirmer

Tear Test

L

ack

of tears allows the normally transparent cornea to become thickened and opaque, leading to blindness.

Corneal

ulcers and bacterial conjunctivitis are other disorders occurring as a result of dry eye

.

Slide38

Corneal Scratches / Ulceration

If superficial “scratch”

1

st

layer

epithelium

Deeper ulceration

2

nd

/ 3

rd

layers

the liquid inside the

eyeball

leaks

out, the eye collapses

and

irreparable damage

occurs.

Slide39

Flourescein

Stain adheres to ulceration

Slide40

Medical Terms for the

Ocular System

Additional terms for ocular system tests, pathology, and procedures can be found in the text.

Review StudyWARE to make sure you understand these terms.