the senses

touch

Touch is the ability to sense pain, pressure, or temperature. Nerve cells that sense touch are found mainly in the skin. The skin on the palms, soles, face, and lips has the most neurons. Neurons that sense pain are also found inside the body inside the body in the tongue, joints, muscles, and other organs. Suppose you wanted to test the temperature of bath water before getting into the tub. You might stick one toe in the water. Neurons in the skin on your toe would sense the temperature of the water and send a message about it to the brain through the spinal cord. The brain would process the information. It might decide that the water is too hot and send a message to your muscles to pull your toe out of the water.

hearing and balance

What do listening to music and riding a bike have in common? Both activities depend on the ears. The ears are organs that sense sound. They also sense the position of the body and help maintain balance. Hearing is the ability to sense sound. Sound travels through the air in waves. Suppose a car horn blows in the distance. Sound waves spread through the air from the horn. Some of the sound waves enter your ears and cause vibrations. The vibrations trigger nerve impulses that travel to the brain through the auditory nerve. You can learn how this happens in Figure 20.15. The brain then interprets the impulses and tells you what you are hearing. To find out how the brain determines where a sound is coming from, watch this amusing video: MEDIA Click image to the left or use the URL below. URL: The parts of the ears involved in balance are the semicircular canals. These are the curved structures above the cochlea in the inner ear in Figure 20.15. Like the cochlea, the semicircular canals contain liquid and are lined with tiny hair cells. As the head changes position, the liquid moves. This causes the hair cells to bend. The bending of the hair cells triggers nerve impulses that travel to the cerebellum in the brain. The cerebellum uses the information to maintain balance.

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taste and smell

The sense of taste is controlled by sensory neurons on the tongue. They are grouped in bundles called taste buds. You can see taste buds on the tongue in Figure 20.16. Taste neurons sense chemicals in food. They can detect five different tastes: sweet, salty, sour, bitter, and umami, which is a meaty taste. When taste neurons sense chemicals, they send messages to the brain about them. The brain then decides what you are tasting. The sense of smell also involves sensory neurons that sense chemicals. These neurons are found in the nose, and they sense chemicals in the air. Unlike taste neurons, smell neurons can detect thousands of different odors. Your sense of smell plays a big role in your sense of taste. You can use your sense of taste alone to learn that a food is sweet. However, you have to use your sense of smell as well to learn that the food tastes like apple pie.

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how the eye works

The function of the eye is to focus light and form images. We see some objects, such as stars and light bulbs, because they give off their own light. However, we see most objects because they reflect light from another source such as the sun. We form images of the objects when some of the reflected light enters our eyes. Look at the parts of the eye in Figure 20.12. Follow the path of light through the eye as you read about it below. 1. Light from an object passes first through the cornea. This is a clear, protective covering on the outside of the eye. 2. Then light passes through the pupil, an opening in the center of the eye. The pupil, which looks black, is surrounded by the colored part of the eye, called the iris. 3. Light entering through the pupil next passes through the lens. The lens is a clear, curved structure, like the lens of a magnifying glass. Along with the cornea, the lens focuses the light on the back of the eye. 4. The back of the eye is covered by a thin layer called the retina. This is where the image of the object normally forms. The retina consists of special light-sensing cells called rods and cones. Rods sense dim light. Cones sense different colors of light. 5. Nerve impulses from rods and cones travel to the optic nerve. It carries the nerve impulses to the brain.

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human vision

The ability to see is called vision. It depends on both the eyes and the brain. The eyes sense light and form images. The brain interprets the images formed by the eyes and tells us what we are seeing. For a fascinating account of how the brain helps us see, watch this short video: . MEDIA Click image to the left or use the URL below. URL:

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other human senses

Vision is just one of several human senses. Other human senses include hearing, touch, taste, and smell. Imagine shopping at the fruit market in Figure 20.14. It would stimulate all of these senses. You would hear the noisy bustle of the market. You could feel the smooth skin of the fruit. If you tried a sample, you could smell the fruity aroma and taste its sweet flavor.

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vision problems

You probably know people who need eyeglasses or contact lenses to see clearly. Maybe you need them yourself. Lenses are used to correct vision problems. Two of the most common vision problems in young people are myopia and hyperopia. You can compare myopia and hyperopia in Figure 20.13. To learn about astigmatism, another common vision problem, watch this very short video: . MEDIA Click image to the left or use the URL below. URL: Myopia is commonly called nearsightedness. People with myopia can see nearby objects clearly, but distant objects appear blurry. Myopia occurs when images focus in front of the retina because the eyeball is too long. This vision problem can be corrected with concave lenses, which curve inward. The lenses focus images correctly on the retina. Hyperopia is commonly called farsightedness. People with hyperopia can see distant objects clearly, but nearby objects appear blurry. Hyperopia occurs when images focus in back of the retina because the eyeball is too short. This vision problem can be corrected with convex lenses, which curve outward. The lenses focus images correctly on the retina.

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seeing in 3d and color

Did you ever use 3-D glasses to watch a movie, like the teens in Figure 20.11? If you did, then you know that the glasses make images on the flat screen seem more realistic by giving them depth. The images seem to jump right out of the screen toward you. Unlike many other animals, human beings and other primates normally see the world around them in three dimen- sions. Thats because we have two eyes that face the same direction but are a few inches apart. Both eyes focus on the same object at the same time but from slightly different angles. The brain uses the different images from the two eyes to determine the distance to the object. Human beings and other primates also have the ability to see in color. We have special cells inside our eyes that can distinguish different wavelengths of visible light. Visible light is light in the range of wavelengths that the human eye can sense. The exact wavelength of visible light determines its color.

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instructional diagrams

description_image

Below is a diagram of the ear. The ear is made up of several parts, as shown in the diagram. Sound waves travel through the ear. Sound waves enter the auditory canal. Then they travel to the ear drum where it sends the vibrations from the sound waves to the inner ear. The sound waves then liquify and go into the cochlea. They then travel through the ear nerves, and is sent to the brain.

description_image

This diagram shows the anatomy of the human ear. The human ear is divided into the outer ear which contains the auricle and the earlobe. The outer ear is followed by the middle ear that contains eardrum and tympanic cavity and the ossicles. Lastly, the inner ear followed the middle ear and it contains the semicircular canals, vestibule, cochlea portions. The auditory canonical connects the outer ear to the middle ear. The eardrum and the tympanic cavity are at the end of the auditory canal. The vestibular nerve, semicircular ducts and cochlea are after the tympanic cavity. Ossicles are tiny bones in the middle ear that transmit sound from the eardrum to the cochlea. Sound waves travel through the outer ear, are modulated by the middle ear, and are transmitted to the inner ear.

questions

In the eye, light is focused by the

a. retin

b. cornea.

c. lens.

-->  d. two of the above

We see most objects because they reflect light from another source.

-->  a. true

b. false

The colored part of the eye is called the iris.

-->  a. true

b. false

Which statement about hyperopia is true?

-->  a. It can be corrected with convex lenses.

b. It happens because the eyeball is too long.

c. It occurs when images focus in front of the retina.

d. two of the above

Nerve impulses travel from the ears to the brain through the

a. optic nerve.

b. spinal cord.

-->  c. auditory nerve.

d. Eustachian tube.

Hyperopia can be corrected with concave lenses.

a. true

-->  b. false

The only function of the ears is to sense sound.

a. true

-->  b. false

How many different tastes can taste buds detect?

-->  a. 5

b. 10

c. 15

d. 1,000

Taste neurons on the tongue can detect thousands of different tastes.

a. true

-->  b. false

What happens when sound waves strike the eardrum?

-->  a. It vibrates.

b. It sounds like a drum.

c. It sends nerve impulses to the brain.

d. none of the above

Sensory neurons in the nose sense chemicals in the air.

-->  a. true

b. false

The sense of smell plays an important role in the sense of taste.

-->  a. true

b. false

__structure in the inner ear that responds to vibrations by sending nerve impulses to the auditory nerve

a. retina

b. hyperopia

c. pupil

d. semicircular canal

e. taste bud

-->  f. cochlea

g. myopia

__opening in the center of the eye that lets light pass through

a. retina

b. hyperopia

-->  c. pupil

d. semicircular canal

e. taste bud

f. cochlea

g. myopia

__vision problem in which distant objects can be seen clearly but nearby objects appear blurry

a. retina

-->  b. hyperopia

c. pupil

d. semicircular canal

e. taste bud

f. cochlea

g. myopia

__layer of cells at the back of the eye where images normally form

-->  a. retina

b. hyperopia

c. pupil

d. semicircular canal

e. taste bud

f. cochlea

g. myopia

If you lost vision in one eye, you could still see in three dimensions.

a. true

-->  b. false

When light reaches the eye, it passes first through the iris.

a. true

-->  b. false

__vision problem in which nearby objects can be seen clearly but distant objects appear blurry

a. retina

b. hyperopia

c. pupil

d. semicircular canal

e. taste bud

f. cochlea

-->  g. myopia

The middle ear contains the cochlea and semicircular canals.

a. true

-->  b. false

__structure in the inner ear involved in maintaining balance

a. retina

b. hyperopia

c. pupil

-->  d. semicircular canal

e. taste bud

f. cochlea

g. myopia

__bundle of sensory neurons on the tongue that sense chemicals in food

a. retina

b. hyperopia

c. pupil

d. semicircular canal

-->  e. taste bud

f. cochlea

g. myopia

Nerve cells that sense touch are most numerous in the skin.

-->  a. true

b. false

Rods are light-sensing cells in the eye that can sense dim light.

-->  a. true

b. false

Why are human beings able to see in three dimensions?

a. We have two eyes that face the same direction but are a few inches apart.

b. Both of our eyes focus on the same object but from slightly different angles.

c. The brain uses images from the two eyes to determine the distance to the object.

-->  d. all of the above

When light from an object reaches the human eye, it passes first through the

a. pupil.

-->  b. cornea.

c. lens.

d. iris.

Which statement about rods and cones in the human eye is false?

-->  a. Rods and cones are special light-sensing cells in the lens.

b. Rods and cones send nerve impulses to the optic nerve.

c. Cones sense different colors of light and rods sense dim light.

d. none of the above

Myopia

-->  a. occurs when images focus in front of the retin

b. results when the eyeball is too short.

c. can be corrected with convex lenses.

d. all of the above

The middle ear

a. contains three tiny bones called ossicles.

b. passes vibrations from the eardrum to the inner ear.

c. amplifies vibrations as they pass through.

-->  d. all of the above

The human eye senses differences in the wavelengths of visible light as different

a. brightnesses.

b. intensities.

c. shapes.

-->  d. colors.

Nerve cells that sense touch are found mainly in the

a. joints.

b. muscles.

c. heart.

-->  d. skin.

diagram questions

question_image

Identify the cochlea.

a. N

b. X

c. L

-->  d. D

question_image

What is the name of the part of the ear that connects parts L and R?

a. EUSTACHIAN TUBE

-->  b. EARDRUM

c. PINNA

d. COCHLEAR

question_image

Which letter corresponds to the part that connects the lobe to the eardrum?

-->  a. R

b. D

c. X

d. L

question_image

Which label refers to the cochlea?

-->  a. T

b. D

c. E

d. H

question_image

Which label refers to the incus?

-->  a. C

b. H

c. X

d. J

question_image

If the auditory nerve was affected, which structure would not function properly?

a. E

-->  b. T

c. A

d. C

question_image

Which letter represents the cochlea?

a. H

b. L

-->  c. T

d. X

question_image

Which label identifies the tympan?

a. F

-->  b. C

c. T

d. W

question_image

Which label represents the Incus (or Anvil)?

a. K

-->  b. X

c. W

d. A

question_image

Identify the part of the ear that passes vibrations through tiny bones called ossicles.

a. W

b. X

-->  c. C

d. E

question_image

If you find yourself dizzy, what structure can be affected?

a. W

b. A

-->  c. F

d. K

question_image

Which part is the outer ear?

-->  a. T

b. R

c. E

d. W

question_image

Select the malleus.

a. M

b. H

c. A

-->  d. S

question_image

Which letter represents the Cochlea?

-->  a. H

b. A

c. M

d. R

question_image

If the structure M was affected, which structure would not work properly?

a. S

b. W

c. K

-->  d. H

question_image

What does E represent?

a. INCUS

b. PINNA

-->  c. EAR CANAL

d. COCHLEA

question_image

Where do sound waves enter?

a. S

b. P

c. W

-->  d. E

question_image

By what letter is the petrous bone represented in the diagram?

a. L

b. N

c. V

-->  d. X

question_image

Which label refers to the auricle?

a. F

b. L

-->  c. N

d. V

question_image

Which letter is being used to label the Middle Ear Cavity?

a. U

b. L

c. E

-->  d. F

question_image

Which letter represents the auricle?

-->  a. N

b. V

c. D

d. H

question_image

Which structure is localized between the outer ear and the inner ear?

a. F

b. L

c. E

-->  d. D

question_image

Which of the following is part of the external ear?

a. Eardrum

b. Eustachian Tube

c. Ear Canal

-->  d. Pinna

question_image

What is the name of the part that connects the Pinna to the Eardrum?

a. Inner Ear

b. Middle Ear

c. Eustachian tube

-->  d. Ear Canal

question_image

Which part of the ear is located between the ear canal and middle ear?

a. Pinna

b. Inner Ear

c. Eustachian Tube

-->  d. Eardrum

question_image

How many arrows depicting parts are used in the image?

a. 4

b. 5

c. 7

-->  d. 6

question_image

How many parts of the ear are shown in the diagram below?

a. 7

b. 5

-->  c. 6

d. 3

question_image

How many parts make up the hearing system?

a. 7

-->  b. 12

c. 10

d. 13

question_image

What is the pinna attached to?

-->  a. External ear

b. Cochlear

c. Nerve

d. Incus

question_image

From the diagram, identify the part of the ear that contains the endings of the nerve that carries information about sound to the brain.

a. malleus

-->  b. cochlea

c. tympanic membrane

d. stapes

question_image

Which part receives vibrations from malleus?

a. Stapes

-->  b. Incus

c. Cochlea

d. Canals

question_image

What ear part is in between the malleus and the stapes?

a. cochlea

-->  b. incus

c. eustachian tube

d. tympanic membrane

question_image

What separates the External Auditory Canal from the rest?

a. Mallelus

-->  b. Tympanic Membrane

c. Cochlea

d. Tympanic Cavity

question_image

How many parts of the ear is being identified in the diagram?

a. 13

b. 11

-->  c. 12

d. 10

question_image

What does external auditory canal lead to?

a. Malleus

b. Stapes

c. Incus

-->  d. Tympanic membrane

question_image

What is the malleus connected to?

a. staples

b. semicircular canals

c. cochlea

-->  d. incus

question_image

These are the semicircular canals contain liquid and are lined with tiny hair cells. The hair cells triggers nerve impulses that travel to the cerebellum to maintain balance.

a. Tympanum

-->  b. Organs of Balance

c. Malleus

d. Outer ear

question_image

Where does sound go after passing through the ear canal?

a. organs of balance

-->  b. tympanum

c. Eustachian tube

d. inner ear

question_image

Small bone located in the middle of the Malleus and Stapes

a. Tympanum

-->  b. Incus

c. Pinna

d. Cochlea

question_image

What connects the middle ear with the outer ear?

a. The Organs of Balance

b. The Mallews

-->  c. The ear canal

d. The Pinna

question_image

How many parts of the ear are located in the middle ear?

a. 6

b. 10

c. 12

-->  d. 5

question_image

If the ear canal is removed, what happens?

a. Sound vibrates through the outer ear and into the hammer.

b. Ear wax will double on the outer ear.

-->  c. Sound does not reach the eardrum, and the person is unable to hear.

d. Ear functions as normal.

question_image

Where does sound go after Outer ear

a. Inner Ear

-->  b. Ear canal

c. Middle Ear

d. Pinna

question_image

Which part of the ear is responsible for balance?

-->  a. Semicircular canal

b. Temporal bone

c. Cochlea

d. Pinna

question_image

Through where does sound enter the ear?

a. Eustachian tube

b. Pinna

c. Temporal bone

-->  d. Ear canal

question_image

What connects the outer ear to the inner ear?

-->  a. Ear canal

b. Incus

c. Temporal bone

d. Cochlea

question_image

How many parts of the ear are shown in this diagram?

a. 10

-->  b. 12

c. 15

d. 11

question_image

What is the curly part of the ear that looks like a snail called?

a. malleus

b. incus

c. ear canal

-->  d. cochlea

question_image

Sound propagates through which organ to the eardrum

a. Pinna

b. Ossicles

-->  c. External canal

d. Vestibular system

question_image

What does the Eardrum do when sound waves hit it?

a. nothing

-->  b. vibrates

c. becomes cold

d. becomes hot

question_image

What part of the ear separates the outer and the inner ear?

a. eustachian tube

b. pinna

-->  c. ear drum

d. ossicles

question_image

How many ossicles are there?

-->  a. 3

b. 2

c. 1

d. 4

question_image

In how many basic parts is the ear divided?

a. 1

b. 4

c. 2

-->  d. 3

question_image

What happens when sound waves enter the outer ear?

a. the eardrum is damaged

b. eardrum explodes

-->  c. it strikes the eardrum making it vibrate

d. eardrum shrinks

question_image

What part connects the outer ear to the middle ear?

a. inner ear

b. eardrum

c. auditory nerve

-->  d. The ear canal

question_image

It acts as a kind of funnel which assists in directing the sound further into the ear.

a. ear drum

-->  b. pinna

c. ear canal

d. auditory nerve

question_image

What connects the outer ear and middle ear?

a. pinna

-->  b. ear canal

c. auditory nerve

d. eardrum

question_image

Which of the following is at the threshold of the inner ear?

-->  a. Eardrum

b. Auditory nerve

c. Ear canal

d. Pinna

question_image

How many ear parts are shown in the diagram?

a. 1

b. 4

c. 2

-->  d. 3

question_image

How many parts of the outer ear is identified in the diagram?

a. 2

b. 4

-->  c. 3

d. 1

question_image

What is between the pinna and the eardrum?

a. auditory nerve

b. malleus

c. pincus

-->  d. ear canal

question_image

Identify which is not a part of the outer ear.

a. Pinna

-->  b. Cochlea

c. Eardrum

d. Auditory Canal

question_image

The name of the outer ear.

a. Auditory Nerve

-->  b. Pinna

c. Stapes

d. Cochlea

question_image

What part of the ear carries the information to the brain?

a. stapes

b. eardrum

c. pinna

-->  d. auditory nerve

question_image

What connects the pinna to the eardrum from the diagram?

a. cochlea

-->  b. auditory canal

c. semicircular canals

d. eustachian tube

question_image

What connects the pinna with the inner ear?

a. Stapes

b. Malleus

-->  c. Auditory canal

d. Cochlea

question_image

According to location, how many sections does the ear have?

a. 5

-->  b. 3

c. 2

d. 4

question_image

How many bones are there in the middle ear?

a. 1

-->  b. 3

c. 4

d. 2

question_image

What is between the pinna and the eardrum?

a. incus

-->  b. auditory canal

c. stapes

d. malleus

question_image

What is the outer part of the ear?

a. auditory tube

b. petrous bone

-->  c. auricle

d. auditory ossicles

question_image

Which part of the ear transmits sound from the air to the ossicles inside the middle ear and then to the cochlea?

a. petrous bone

b. auricle

-->  c. tympanic membrane

d. auditory ossicles

question_image

How many parts of the ear are depicted?

a. 7

-->  b. 8

c. 10

d. 4

question_image

What's in between the middle ear cavity and tympanic membrane?

a. external auditory meatus

-->  b. auditory ossicles

c. auditory tube

d. membranous & osseous labyrinths

question_image

Identify the ear drum

a. R

b. D

-->  c. N

d. L