Survey of Anatomy & Physiology

Chapter 11 The Senses: The Sights and Sounds

The Senses

Senses enable us to

experience ALL aspect of our

life

SEE, HEAR,SMELL, TASTE & FEEL

The Senses

Our senses monitor and

detect changes in the environment

and send information

away from the receptor

(afferent) to the brainAFFERENT NEURONS

The Senses

The brain interprets the information

and makes the appropriate

motor (efferent) response

EFFERENT NEURONS

Special Senses &General Senses

Pain

Hot and coldnausea

Hunger and thirstPressure or touch

See, Hear, Smell and Taste

+

Cutaneou

s

Touch

Heat and Cold

Pain

Visceral

Nausea

Hunger/Thirst

Eliminate

Receptors of Skin and Deep Organs

TWO TYPES OF SENSORS

Sense of Sight

THE EYE IS SIMILAR TO A CAMERA:• Light rays pass through small

opening (pupil)• Through transparent lens (lens of

eye)• Rays are focused on

photoreceptive film (retina)• The shutter (iris) must allow just

the right amount of light to enter

EYES

Sense of Sight

THE EYE IS SIMILAR TO A CAMERA:• Camera case is like external

structures that help protect eye from injury

• Lens cleaner for camera is like lacrimal glands secrete tears to clean eye

EYES

External Structures

ORBITAL CAVITY

• Eyeball• Eyelids• Eyelashes• Conjunctiva• Lacrimal apparatus• Lacrimal gland

External Structures

• A one inch sphere. The orbital is a cone shaped cavity padded with fatty tissue that cushions and protects eyeball from injury

• Contains several openings for nerves and blood vessels

EYEBALL

External Structures

• Movable folds of skin which contain eyelashes to help keep large particles from entering and prevent injury

• Contain sebaceous glands to secrete sebum to keep them soft & trap particles

EYELID AND EYELASH

External Structures

Protective membrane

lines the inner eye, covers

eyeball

CONJUNCTIVA

Pink Eye-Infection of Conjunctivitis

Inflammation of conjunctival

membrane caused by bacteria, virus

or allergies/chemical

s

CONJUNCTIVITIS

External Structures

• Produces and stores tears and includes lacrimal gland with its ducts

• Exocrine glands needed for cleansing and lubrication

• Drain in nasal cavity

• Tears are antisepticLACRIMAL GLANDS

Internal Structures

• Aqueous & Vitreous Humors

• Sclera, choroid & retina

• Cornea• Iris • Pupil • Lens• Ciliary muscles

INSIDE THE EYEBALL

HUMORSFluids of the Eye

AQUEOUS & VITREOUS

Eyeball separated into two chambers of fluid that helps to protect the eye:• Aqueous-watery

and fill area in front of eye

• Vitreous is clear, jellylike fluid behind the eye-maintains eye shape and refracts light rays

3 Layers of Eye

SCLERA

• Sclera-outermost layer with tough fibrous tissue. It is the WHITE OF THE EYE

• Transparent cornea is specialized portion and allows light in and bends the rays to focus them on retina.

• Muscles responsible for moving eye are attached to the sclera

3 Layers of Eye

CHOROID

• Middle layer• Highly vascularized

and pigmented• Nourishes the eye• Contains the iris

and the pupil where light passes into the eye

IRIS AS SPHINCTER

CHOROID CONTAINS IRIS

• Iris is colored portion of the eye and controls the size of the pupil

• It is a sphincter that has intrinsic muscles that relax and contract depending on light conditions

3 Layers of Eye

RETINA

• Innermost layer contains nerve endings and receives and interprets rays of light

• The lens is behind the iris and pupil; elastic and disc shaped with biconvex crystalline structure

LENS & CILIARY MUSCLES

LENS & CILIARY MUSCLES

Light is refracted or bent by the

lens with shape

altered by ciliary

muscles

ACCOMODATION

Ciliary muscles can alter the shape of lens

making it thicker and thinner to

change angle of refraction to

focus incoming light

rays on the retinal areaFOCUS ON THE RETINA

Anatomy of Eye

http://www.youtube.com/watch?v=RE1MvRmWg7I

Watch the video “Anatomy of the Eye”

Summarize how the eyes take what we see and carry it to the brain for the interpretation we call vision

PA/Instructor Asks:

The condition in which the lens loses its flexibility and transparency and light cannot easily pass through a

clouded lens is called:

A. GlaucomaB. AmblyopiaC. StrabismusD. Cataract

PA/Instructor Asks:

The condition in which the lens loses its flexibility and transparency and light cannot easily pass through a

clouded lens is called:

A. GlaucomaB. AmblyopiaC. StrabismusD. Cataract

Sense of Hearing

Ears are responsible for hearing and maintaining balance

Sense of Hearing

We hear by receiving sound vibrations via

the air and translating them into sound via

the vestibulocochl

ear nerve

8TH CRANIAL NERVE

External Ear

Middle Ear (tympanic cavity)

Inner ear (labyrinth)

3 Divisions of Ear

External Ear

• Pinna (or auricle) projects out and collects and directs sound into

• Auditory canal (external auditory meatus)

• Canal contains cerumen to lubricate and protect ear

• Eardrum (tympanic membrane) at end

Middle Ear

• Contains 3 smallest bones called

• Ossicles, joined to amplify sound received from tympanic membrane

• Sound waves transmitted to fluid in internal earHAMMER, ANVIL, STIRRUP

Middle Ear

• The stapes (stirrup) connected to membrane called oval window

• Carries amplified vibrations

• Amplified up to 22 times as original level

MALLEUS, INCUS, STAPES

Middle Ear

• Connects the pharynx to the middle ear

• Equalizes pressure on either side of eardrum

• Eardrum then vibrates freely with incoming sound waves

EUSTACHIAN TUBE

PA/Instructor Asks:

Why is it a good idea to chew gum or swallow when you experience sudden pressure change such as flying in an

airplane?

So the inner ear can better sense and adjust to the rapidly changing outside atmosphere

via the eustachian tubes

Inner Ear

Oval window is portal to inner ear with three hollow bony spaces

that form maze of winding and twisting

channels

LABYRINTH

Cochlea

Vestibular Chamber

Semicircular Canals

LABYRINTH-3 PARTS

LABYRINTH-3 PARTS

COCHLEA

• Bony, snail shaped portion containing perilymph to transmit sound to brain via

• ACOUSTIC nerve or VESTIBULOCOCHLEAR NERVE

LABYRINTH-3 PARTS

VESTIBULE CHAMBER

Houses the inner ear

LABYRINTH-3 PARTS

SEMICIRCULAR CANALS

3 canals containing endolymph transmitting

positional changes to tiny

hair like receptors

stimulated and conduct signal

to brain to maintain balance

HEARING

http://www.youtube.com/watch?v=0jyxhozq89g

Watch the video on 3D Human Ear

Vibrations now vibrate auditory ossicles

Hammer Anvil & Stirrup

Sound waves vibrate the ear drumTympanic membrane

Sound waves enter the outer earAuricle

6 STEPS IN HEARING

Signals travel to auditory center via 8th cranialVestibulocochle

arHairlike

receptors

Vibrations travel through the cochlear ductTo the semicircular canals with endolymph

Pressure waves created by stapes transfer to oval window causing

cochlea fluid to vibrateCochlea contains perilymph

6 STEPS IN HEARING

Sense of Taste

The tongue is covered with tiny bumps called papillae

Taste receptors are called taste buds, found on the tongue, soft palate and back of the throat

TONGUE

Sense of Taste

TONGUE

Sweet

Sour

Salty

BitterUmami-glutamate

Sense of Smell

Receptors located in

OLFACTORY region of nasal

cavity

Sense of Smell

Olfactory epithelium has

specialized nerve cell receptors

90% OF TASTE COMES FROM SMELL

Sense of Smell

Inflammation of the mucous membranes that line nasal

passage

RHINITIS

Release of Histamine

Histamine is a molecule released during an immune response

RHINITIS

Senses of Touch

Tactile corpuscles

located in the skin and

concentrated in the

fingertips are the bodies

touch receptorsTOUCH RECEPTORS

Senses of Touch

The body has separate heat

and cold receptors

Adaptation occurs with continued stimulation

TEMPERATURE RECEPTORS

Cold & Heat

Senses of Touch

Pain receptors are branches

of nerve fibers called

nociceptors (free nerve endings)

PAIN RECEPTORS

Types of Pain

Referred pain

originates in an internal organ and

felt in another regionREFERRED PAIN

Sense Your Body

Your body’s orientation sense that

allows you to locate a

body part with your

eye closedPROPRIOCEPTORS

Sense Your Body

Found in muscles, tendons, joints and the inner ear where they help

with equilibriumPROPRIOCEPTORS

PA/Instructor Asks:

Motion sickness, such as sea sickness or car sickness, occurs because of

excessive stimulation of equilibrium centers in what part of the body?

A. EyeB. EarC. NoseD. Stomach