Sensory System

How much information about a person's surroundings reaches the brain through the eyes?

90%

The cells that sense color and are mainly used for vision in bright light are _______.

Cones

What is the name of the mucous membrane that lines the eyelids and covers the front of the eye?

Conjunctiva

The pathway of light goes through these parts of the eye in order:

Cornea Aqueous humor Pupil Lens Vitreous humor

What part of the ear allows air to enter to help equalize pressure on both sides of the tympanic membrane?

Eustachian tube

Diseases and Disorders of the Sensory System

Eye Conjunctivitis Cataract Ear Hearing Loss Otitis Media Nose Common Cold

Each general sense receptor is capable of perceiving many types of feelings. (T or F)

False

The sense of taste is more sensitive than the sense of smell. (T or F)

False

Vision, hearing, smell, taste, and touch are part of the integumentary system. (True or false)

False

Hearing

Hearing is one of the five special senses.

Otitis Media Treatment involves

If left untreated, otitus media may lead to hearing loss. Treatment involves antibiotics and possibly inserting tubes to relieve the pressure and fluid in the ear.

What part of the ear is the most complex?

Inner Ear

Protection of the Eye

It is partly enclosed in a bony socket in the skull. Tears produced in the lacrimal glands constantly clean the eye and keep it moist. The tears flow across the eye and drain through the lacrimal duct into the nasal cavity. Eyelids and eyelashes help keep out foreign materials. Conjunctiva, a mucous membrane, lines the eyelids and covers the front of the eye to provide added protection and moisture.

Which of these parts of the eye help to refract light rays to focus them on the retina?

Lens Aqueous humor Vitreous humor (All of the above)

Hearing and the Ear

Like all special senses, it receives stimuli and sends the impulses to the brain to be interpreted. After receiving sound waves, the ear carries the information to the brain where it is translated into hearing.

ossicles

Middle Ear It contains three small bones. They receive sound from the vibrations of the tympanic membrane and in turn transmit the sound waves to the inner ear.

The nerve cells that receive stimuli for the sense of smell are _______ receptors.

Olfactory

What is the name of the visible part of the outer ear?

Pinna

What is the function of the sensory system?

Receive stimuli to allow the body to react to changes

The cells that are used for vision in the dark or dim light are _______.

Rods

What part of the ear helps to maintain balance?

Semicircular canals in the inner ear

Which type of hearing loss results from damage to the inner ear or auditory nerve and usually cannot be corrected?

Sensory hearing loss

Sense of Smell

Smell is one of the five special senses. The nose is the organ that controls this sense.

What is the treatment for cataracts?

Surgical replacement of the lens of the eye

The four basic tastes and their regions of the tongue are:

Sweet tastes at the tip. Salty tastes near the tip. Sour tastes at the sides. Bitter tastes at the back. The sense of smell also influences taste.

Taste and the Tongue

Taste is one of the five special senses. The tongue is the organ that controls this sense. It is a mass of muscle tissue that contains projections called papillae, which contain "taste buds." When food is moistened in fluid or saliva, taste buds are activated. The receptors in the taste buds send a signal to the brain to detect the flavor of the food.

Ear

The ear is the organ that controls this sense as well as the sense of balance.

Inner Ear

The inner ear is the most complex section of the ear.

Middle Ear

The middle ear is a small chamber in the temporal bone.

Common Cold

There is no cure for a cold. Treatment involves rest and medications to relieve symptoms.

Common Cold Treatment involves

There is no cure for a cold. Treatment involves rest and medications to relieve symptoms.

cilia

They are nerve cells covered with tiny hairs. These cells receive stimuli from gases in the air. Then the impulses are carried by the olfactory nerve to the brain, where they are translated into smell.

Three semicircular canals are also part of the inner ear

They contain fluid and delicate, hair-like cells that bend when the liquid moves with head and body movements. These impulses are sent to the cerebellum to help maintain balance.

auditory canal, external auditory meatus

This canal contains special glands that secrete wax to protect the ear. Sound waves are collected and channeled through the canal to the tympanic membrane, or eardrum.

tympanic membrane, or eardrum

This membrane vibrates when sound waves hit it, and it separates the outer ear from the middle ear.

What is the purpose of the wax secreted by glands in the auditory canal?

To protect the ear

Tears clean the eye and keep it moist. (T or F)

True

Two muscles in the iris control the size of the pupil and how much light enters the eye. (True or False)

True

What part of the ear is also known as the eardrum?

Tympanic membrane

Vision and the Eye

Vision is one of the five special senses. The eye is the organ that controls this sense. Like all special senses, it receives stimuli and sends the impulses to the brain to be interpreted. After receiving light rays, the eye carries the information to the brain where it is translated into vision, or sight. Vision is considered to be the most important sense. About 90% of the information about a person's surroundings reaches the brain through the eyes.

cornea

a clear, circular part at the front of the sclera that allows light rays to enter.

lens

a clear, circular structure located behind the pupil. It refracts, or bends, the light rays so they focus on the retina.

aqueous humor

a clear, watery fluid that fills the space between the cornea and the iris.

Cataract

a condition where the lens of the eye gradually becomes cloudy, which causes blurred or partial vision. The cause is not known. If left untreated, cataracts may lead to blindness.

Conjunctivitis

also called "pink eye." It is an inflammation of the eyelid caused by a bacteria or virus, and it is extremely infectious.

Otitis Media

an infection of the middle ear caused by a bacteria or virus. It is common in young children and often follows a sore throat.

Conjunctivitis Treatment involves

antibiotics.

General Senses

are involved in feeling touch, temperature, pressure, and pain. General sense receptors are located throughout the body in the skin and connective tissue. Each receptor perceives only one type of feeling.

Rods

are used for vision in the dark or dim light.

Olfactory receptors

at the top of the nasal cavity make the sense of smell possible.

eustachian tube

connects the middle ear to the pharynx, or throat. This tube allows air to enter the middle ear and helps equalize pressure on both sides of the tympanic membrane.

choroid coat

contains many blood vessels that nourish the eyes. The ciliary muscles in this layer help to focus the eyes.

retina

contains many layers of nerve cells that transmit the impulses from the light rays to the optic nerve. Two special cells in this layer are cones and rods.

Hearing loss or deafness

has two classifications, conductive or sensory: Conductive hearing loss- occurs when sound waves are not carried to the inner ear. It is caused by a ruptured tympanic membrane or blockage in the ear, such as from wax, a foreign body, or an infection. Treatment involves removing the cause. Sensory hearing loss- occurs when the inner ear or auditory nerve is damaged. Usually this type of hearing loss cannot be corrected.

Common Cold

is a respiratory infection. It may be caused by 1 of more than 200 viruses that are highly contagious.

pupil

is the opening in the center of the iris.

pinna, or auricle

is the visible part of the outer ear.

sclera

made of tough connective tissue and is often referred to as the "white" of the eye. It gives shape to the eye. Muscles attached to the sclera help the eye move.

Otitis Media Symptoms include

pressure or pain in the ear and fever.

Conjunctivitis Symptoms include

reddening of the eyelids and sclera. In addition, pus may form and lead to the closing of the eye.

Sensory System

refers to the special senses associated with vision, hearing, smell, taste, and touch. It consists of receptors in specialized cells and organs. The sensory system receives stimuli and sends the impulses to the brain to be interpreted. It performs the function of recognizing changes in the internal and external environment to allow the body to react.

In which part of the eye are cones and rods located?

retina

Cones

sense color and are mainly used for vision in bright light.

cochlea

shaped like a snail shell. Inside the cochlea, delicate, hair-like cells make up the organ of Corti. The cells pick up sound waves and pass them on to the auditory nerve, which sends the impulse to the brain to be interpreted.

Common Cold Symptoms may include

sneezing, runny nose, sore throat, congestion, and cough. The symptoms typically last for one to two weeks.

Cataract Treatment involves

surgical replacement of the lens.

iris

the colored portion of the eye, located behind the cornea on the front of the choroid coat.

vitreous humor

the jellylike substance that fills the area behind the lens.

The ear is divided into three main sections:

the outer ear, middle ear, and inner ear.

The three main layers of the eye

the sclera (outermost), choroid coat (middle), and retina (innermost).

Two muscles in the iris control:

the size of the pupil and how much light enters the eye.