These are SENSORY! Based on sensory neurons.

Smell
Taste
Sight
Hearing (auditory)
Balance (equlibrium)
          Are all SPECIAL, because the sensory nerve endings are located in a SPECIAL place. 
            Sight - in the eyes, ... And the sensation is 'special'  (sight is unlike smell or taste, etc)
            Where are the others located?

Touch - GENERAL - the TACTILE receptors-
       Sensory receptors are located all over the body. Fingers, toes,
       hands, elbows, hips, stomach, everywhere.

What is the difference between the sense of touch and the Special Senses?
   LOCATION  of sensory nerve endings

List the 6 cutaneous and other general sensory nerve endings and the sensations.
  Pacinnian corpuscles, etc
  Mechanoreceptors, etc
  Proprioceptors, etc.
What are the sensations that these cutaneous nerve endings 'sense'?
  List these GENERAL sensations.

Review the previous chapter's information about Sensations, the sensory pathway, the types of sensory nerve endings and the sensations each responds to.
  Be sure to include the cutaneous sensory nerve endings, the interoceptors (chemo, baro and proprio -ceptors), the exteroceptors (noci, thermoreceptors, and special senses, etc)

Describe the 3 types of Pain. (see the previous chapter's discussion of Pain)
What is the name of the 'pain' sensor?

Make a TABLE.  5 or 6 columns. 6 or so rows.
Across the top put:
    Characteristic | Olfactory | Gustatory | Sight | Hearing | Equilibrium.

Under characteristic put:                    Ex: Olfactory
    Location of sensory structure,               Top of Nasal Cavity
    Name of sensory structure,                     olfactory epithelium
    Name of sensory NE,                                olfactory sensory nerve endings
    Type of receptor                                        chemoreceptor

    

Olfactory

– sense of smell. Receptors are chemoreceptors in the Olfactory epithelium in the top of the nasal cavity. This mucous membrane contains the sensory nerve endings for the sense of smell. Chemoreceptors – respond to airborne chemicals that dissolve into the mucous of the nose and send sensory signals to the CNS about molecules in the air.

7 basic smells:

peppermint,
ether,
floral,
pungent,
putrid,
camphor, and
musk.

Gustatory

– sense of taste. Gustatory Sensory NEs are chemoreceptors in the Taste buds on the sides of the lingual papilla. Chemoreceptors – respond to food molecules that dissolve into the saliva and send sensory signals to the CNS about the molecules in the oral cavity.

4 basic tastes:

sweet,
sour,
salty,
bitter.

Why are the Olfactory and Gustatory Senses tightly connected?

Taste and smell are very tightly interconnected. The sense of smell greatly enhances the sense of taste.
    - The nasal cavity and oral cavity share common openings.
    - Anything that enters the mouth has to pass close to the nose.
    - Molecules that dissolve into the saliva of the mouth can diffuse to the olfactory epithelium.

Sight – Vision –

receptors are chemoreceptors called Rods and Cones on the retina – chemoreceptors respond to a chemical produced in the retina by light energy. The chemical stimulates the rods and cones, which transmit a sensory signal to the CNS about light conditions.

Rods – black and white, used most at night or in low light conditions.
Cones – sense color, used most in daylight when there is plenty of light.

External muscles:

Superior rectus,
Medial rectus,
Inferior rectus
Lateral rectus,
Superior oblique
Inferior oblique

Eyelids 
Eyelashes
Tear glands
Lacrimal duct
Conjunctiva – the clear cover over the front of the eye, connects to the eyelid.
Cornea – the clear front portion of the sclera.
Sclera – a capsule the white of the eye. Made of thick ropelike collagen fibers.
      The Sclera encloses the following structures:

Iris – the smooth muscle with the pupil (hole in middle of iris) that controls the amount of light
       that enters the eye.
Lens – the structure that focuses the entering light waves on the retina for vision.
Retina – the neural cover on the back of the eye that contains the rods and cones.
Choroid – the vascular layer posterior to the retina that contains the capillaries that
      support the retina.
Anterior Cavity – the cavity between the cornea and the lens. It is filled with
      Aqueous Humor – a watery fluid that can increase in pressure, causing Glaucoma.
Posterior Cavity – the cavity posterior to the lens, filled with the Vitreous Humor -a
      viscous, jelly like fluid that holds the retina in place.

List the structures through which LIGHT waves must pass in order to 'give' vision.

Light rays that enter the eye must pass through the following substances in this order:

Any damage or problem with any one of these can cause problems with vision.

Astigmatism – a misshapen cornea.
Floaters in the vitreous humor.
Scarred conjunctiva.
Glaucoma of the aqueous humor.
Cataracts of the lens.
Near sighted (myopia) or far sighted (hyperopia)– a misshapen eyeball, or a lens that does not focus the light correctly.

Optic disc or Blind Spot - where the optic nerve, and the blood vessels enter the back of the eye.  Contains NO rods or cones, therefore, there is NO vision.

Macula lutea with Fovea Centralis - this is the 'yellow' spot on the retina with the highest concentration of cones.  Therefore, it is the point of greatest visual acuity. 
The Fovea Centralis is the FOCAL point for perfect vision - with cones, it is a daylight sense.

Be sure that you know the difference between the optic disc and the fovea centralis.

Hearing and Balance (equilibrium)

Hearing – in the cochlea.

Hair cells in the organ of corti – mechanoreceptors respond to moving molecules in the liquid inside the membranous labyrinth of the cochlea.

External ear:

Pinna
External auditory canal
Tympanic membrane – eardrum

Middle ear:

Eustachian tube (AKA auditory tube) – connects the middle ear to the nasal cavity so that
      air pressure can equalize with external air pressure.

3 bones (auditory ossicles)  –
      hammer (malleus),
      anvil (incus),
      stirrup (stapes).
  - Connect to the tympanum and to the oval window on the cochlea.

The function of the tympanum and these three bones is to AMPLIFY sound waves and direct the sound into the cochlea so that the hair cells can be stimulated.

Inner ear:

Cochlea - snail shell shape-spiral.
Vestibule
Oval window - sound waves, amplified by Tympanum and ossicles, enter the cochlea here.
Round window - absorbs sound waves AFTER passing through the cochlea -
         prevents echos.
 

The cochlea is shaped like a snail shell. It is a CAVITY within the temporal bone. It is NOT a bone itself – it is a CAVITY in a bone. It is a series of passages and tunnels in the shape of a snail shell (cochlea), a vestibule, and semicircles (semicircular canals). The cochlea senses sound, the vestibule and semicircular canals sense balance (equilibrium).

Sound waves are picked up by the pinna and funneled into the auditory canal. The sound waves hit the tympanum causing it to ‘flex’ (like a bass speaker on a stereo- put your hand in front of a base speaker and feel the air molecules).

When the tympanum flexes, it moves the auditory ossicles, which amplify the sound waves from the air and transmit the movement into the liquid inside the cochlea. The movement of the molecules of the liquid cause the hair cells of the organ of corti to bend, thereby sending sensory signals to the CNS.

Why is stimulation of the hair cells in the organ of corti important?

Equilibrium: receptors are hair cells in the vestibule and ampullae of the semicircular canals.

Two types

Static –

Hair cells in the vestibule. Sense the direction of gravity. Otoliths in the fluid drift down toward gravity and bend the hair cells thereby sending sensory signals that tell the CNS which way is ‘down’.

Function: Tells you where your HEAD is with respect to Gravity.

Dynamic –

Hair cells in the ampullae of the Semicircular canals. Sense the direction of movement of the head. Note that the semicircular canals are arranged in 3 dimensions – one is in a horizontal plane, one in sagittal plane, and one in a coronal plane. Head movement in any direction causes fluid movement in one or more of these canals – thereby stimulating hair cells and sending sensory signals that tell the CNS the direction and speed of movement.

Function: Tells you which way your HEAD is moving, how far it moves, and how fast
     in 3D.

Together, static and dynamic equilibrium tell you where your head is with respect to the horizon (gravity) and how fast and how far your head is moving. This is the BENCHMARK position for proprioception – allows you to walk, fight, run, tumble, eat, etc. effectively.

What happens to the special senses as an individual grows older?

Remember – all the systems have to work together to maintain homeostasis.

Remember - you MUST have information  about the enviroment in order to RESPOND to the conditions of that environment. 

How does equilibrium affect proprioception?
How does proprioception affect homeostasis?

Pathway of structures and substances light passes through to enter eye – know it order from outside to retina

1. Conjunctiva
2. Cornea
3. Aqueous humor
4. Lens
5. Vitreous humor
6. Retina