Senses (Not in your Textbook)

" Is that really the strongest muscle in the body ? "

Illusions webpage - or tricks for your brain  Look !

Sensory adaptation - Getting used to a stimulus. Like hot bath or Nasal fatigue or clothes against your skin.

Pheromones - Trigger a social response (alarm or sexual). Odorless chemicals secreted by 1 sex and act on the opposite sex.

*Smell - Chemoreceptors - Stimulated by dissolved molecules (taste) or airborne molecules that become dissolved (smell).

          Olfactory cell - Can recognize 7 distinct odors and with combinations of these 7 we can identify hundreds of smells.

*Taste - Chemoreceptors - The molecules have to be dissolved in something like saliva before the taste buds can detect it.

          Taste buds - Once it is dissolved they can recognize sweet, salty, bitter, and sour and umami. Flavor is really a combination of taste, temperature, texture, and smell.

                    Umami - detects MSG - Is a meat-like flavor. Put in snack foods to make you want more.

*Temperature - Thermoreceptors - Are stimulated by temperature.

          Warm receptors - Increase firing when warmed.

          Cold receptors - Increase firing when cooled.

*Vision - Photoreceptors - Are stimulated by light.

          Cornea - Outer part of the eye.

          Iris and Pupil - A hole which is surrounded by the iris - colored part.

          Lens - Focuses the image onto the retina.

          Retina - The layer of the eye with the photoreceptor cells and lies on top of the optic nerve.

Vitreous humor - The clear jelly that fills the inside of the eye.

Optic nerve - Photoreceptors send the message to the optic nerve (axons) that leaves the eye and goes to the occipital lobe of the brain.

          Rods - Used for Coarse vision - Used for dim light vision and only see in black and white.

          Cones - Used for Sharp color vision - Used in bright light for color vision. There are 3 kinds of cones red, green, and blue.

                   Fovea - A depression in the center of the retina that is packed with cones where the lens focuses the image onto.

*Ears - Mechanoreceptors - They are mechanically stimulated.

          Hair cell - A common type of Mechanoreceptor. They are used for touch, hearing, balance, and pressure.

*Balance - Mechanoreceptors - Located in the inner ear.

          Vestibular apparatus - Contains the mechanoreceptors for balance.

                    3 Semicircular canals - These are the main part of the vestibular apparatus and they contain fluid and tiny rocks.

*Hearing - Mechanoreceptors - They are found in the inner ear (cochlea).

          Pinna - Funnels sound down into the ear canal.

          Ear Canal - In the outer ear to cary sound to the tympanum.

          Tympanum (Ear drum) - Vibrates when sound strikes it.

          Middle ear - Between the tympanum and the cochlea.

                    Ossicles - 3 tiny bones that send the sound vibrations to the cochlea.

          Inner ear - Contains the vestibular apparatus (balance) and the hearing mechanism (cochlea).

                    Cochlea - the coiled tubular structure containing the hair cells for hearing.


Cornea --> Pupil --> Lens --> Retina --> Optic nerve --> Brain (occipital lobe)


Pinna --> Ear Canal --> Tympanum --> Ossicles --> Cochlea

Return to Greg Sievert's GB 100 Syllabus
Last updated on 2 January 2018