1. Introduction to Health Science
Special Senses

2. Description of the Special Senses
Smell
Smell occurs when chemicals are detected by specialized cells in the nose resulting in nerve impulses which are sent to the brain for interpretation.

3. Nose
In the upper part of the nasal cavity are specialized nerve cells called olfactory receptor cells. The olfactory receptor cells contain hair called cilia to which the dissolved chemicals attach.
Basic smells include putrid (rotting food), pungent (spicy), floral (flowers), ethereal (medicine smell), and mint. 3

4. Olfaction
Nerve impulses are transmitted from the olfactory receptor cells -> the olfactory bulb, -> the olfactory nerve -> brain where the sense of smell is interpreted.

5. Taste
Taste occurs when chemicals are detected by specialized cells on the tongue resulting in nerve impulses which are sent to the brain for interpretation.

6. Mouth and Tongue
The sense organs that detect dissolved chemicals for the sense of taste are the taste buds. Taste buds are located in the tongue and throughout the mouth.
When the taste buds are stimulated by chemicals, they generate nerve impulses which are sent to the brain for interpretation.
There are five basic tastes, although they are not limited to specific parts of the tongue: sweet (sugars and carbohydrates), sour (acids), salty (salt), bitter (caffeine) and umami (protein and amino acids). 6

8. Taste Buds
Everyone's tastes are different. In fact, your tastes will change as you get older.
When you were a baby, you had taste buds, not only on your tongue, but on the sides and roof of your mouth
As you get older, your taste buds will become even less sensitive, so you will be more likely to eat foods that you thought were too strong as a child.
We have about 10,000 taste buds in our mouths.

9. Touch
Touch is the detection of various amounts of pressure by the skin. Nerve impulses are generated and sent to the brain for interpretation.

10. Skin
The skin contains several different types of nerve receptors in the skin which are sensitive to deep pressure like poking or light touch.
All regions of the skin are sensitive to touch. The greatest number of touch receptors are found in the fingers, toes, and face.
Once the nerve impulses for touch are
generated, they are sent
to the brain for interpretation. 10

11. Receptors Meissner’s Corpuscles- touch Pacinian Corpuscles – pressure
Free nerve endings – pain/heat/cold

12. Hearing
Hearing involves the movement of sound vibrations through the ear until they reach a specialized region in the inner ear where nerve impulses are generated. These nerve impulses travel to the brain where they are interpreted as sound. 12

13. Outer Ear 13

14. Outer Ear Outer Ear (also known as the auricle or pinna)
The outer ear is composed of cartilage covered with skin and hair.
Captures the sound waves from the environment. 14

15. Auditory Canal Tube lined with hair and wax.
Assists in the passage of sound waves to the middle ear.
Provides protection for the ear as particles, debris, and dust are trapped by the hair and the wax.
Part of the outer ear 15

16. Middle Ear 16

17. Tympanic Membrane
Known as the eardrum, it is the first structure of the middle ear.
It vibrates with the sound waves and passes the vibrations to the middle ear bones. 17

18. Middle Ear and Bones Contains the middle ear bones (ossicles).
The middle ear bones continue the passage of sound vibrations. They also amplify the vibrations twenty times.
Incus (anvil), malleus (hammer), stapes (stirrup) 18

19. Inner Ear Semicircular Canals - Balance Cochlea - Hearing
Organ of Corti (inside cochlea) 19

20. A series of membrane-lined fluid-filled canals that continue to pass along the sound vibrations.
The sound vibrations eventually reach a specialized structure of the inner ear called the Organ of Corti where nerve impulses are generated. The impulses are transmitted to the brain where they are interpreted. 20

21. How the Ear Works

22. Vision
The sense organs that respond to light are the eyes. The light waves travel through the eyes until they reach the back of the eye called the retina where nerve impulses begin. The impulses travel to the brain where they are interpreted as visual images and provide much information about the external world. 22

23. 23

24. Eye Eyelid Structures composed of skin, muscles, and lashes
Protect the eye from foreign objects by the blink reflex.
Moves tears along the surface of the eyeball.

26. Conjunctiva
Mucous membrane lining the insides of the eyelids and eyeball.
Reduces friction
during blinking

27. Sclera The white part of the eye.
Provides protection and shape to the eye.

28. Cornea The clear window of the front part of the eye.
Allows light waves to enter the eye.
Helps to bend the light waves on the back of the eye (retina)

29. Iris
The colored portion of the eye which contains two sets of muscles.
Regulates the size of the pupil.

30. Pupil
An opening in the center of the iris.
Passage for light.

31. Lens Transparent structure located behind the iris and pupil.
Focuses light waves on to the retina.

33. Retina Most inner layer of the eyeball. Located under the sclera.
Contains the nerves that when stimulated by light generate nerve impulses which are then sent to the brain for interpretation.

34. How the Human Eye Works

35. Disorders of the Special Senses
Conjunctivitis
Conjunctivitis is the inflammation of the conjunctiva.
Can be caused by viruses, bacteria, fungi, and allergies. The most common cause is viral.
“Pinkeye” is the common term for conjunctivitis.

36. Otitis Media Otitis media is a middle ear infection.
Causes of otitis media include anything that causes the Eustachian (auditory) tubes to become blocked, inflamed or irritated, Examples include colds, sinus infections, allergies, tobacco smoke or other irritants, babies who spend a lot of time drinking on his or her back.

37. Tinnitus
Also known as ringing in the ears. Tinnitus is the term used for any ear noise when there is not outside source for the sounds.
It is common. Most people have experienced it – and it only lasts for a few minutes.
Causes are unknown but may be associated with an ear infection, ear injury, and as a reaction to various drugs including alcohol, caffeine, antibiotics and aspirin.

38. Vertigo
Also known as dizziness, light headedness, or a feeling that the room is spinning or moving.
Occurs when there is not enough blood to the brain, changing the position of the head, a viral infection of the inner ear, or Meniere’s disease (an inner ear disease).

39. Myopia
Nearsightedness; when a person sees near objects clearly and distant objects are blurred.
Occurs when the physical length of the eye is greater than the optical length.
Symptoms include blurred vision of distant objects, squinting, eyestrain, and sometimes headaches.

40. Hyperopia
Farsightedness; when a person sees far objects clearly and near objects are blurred.
Occurs when the physical length of the eyeball is too small or the focusing power of the lens is too weak.
Symptoms include blurred vision of close objects, eye strain, aching eyes, and headaches while reading.

41. Careers Associated With the Special Senses
Speech Language Pathologist
Speech-language pathologists, sometimes called speech therapists, assess, diagnose, treat, and help to prevent speech, language, cognitive-communication, voice, swallowing, fluency, and other related disorders.

42. Audiologist
Audiologists work with people who have hearing, balance, and related ear problems. They examine individuals of all ages and identify those with the symptoms of hearing loss and other auditory, balance, and related sensory and neural problems. They then assess the nature and extent of the problems and help the individuals manage them.

43. Optometrist
Optometrists provide most primary vision care. They examine people’s eyes to diagnose vision problems and eye diseases, and they test patients’ visual acuity, depth and color perception, and ability to focus and coordinate the eyes. Optometrists prescribe eyeglasses and contact lenses and provide vision therapy and low-vision rehabilitation.

44. Ophthalmologist
Ophthalmologists are doctors and can do many things, such as:
Examines patient’s eyes to diagnose and treat diseases and injuries of the eyes
Performs various tests to determine vision loss.
Prescribes and administers medications and can prescribe glasses and contact lenses
Performs eye surgery.
Salary: ~$200,000/yr.