Special Senses Galena Park High School A&P Instructor: Terry E. Jones.

Special Senses

Galena Park High SchoolA&

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Instructor: Terry E. Jones

A. Sensory 1. Provide a continuous flow of data for the brain to interpret 2. Vital in maintaining homeostasis


P I. Function

A. VisionB. HearingC. SmellD. TouchE. TasteF. Balance


P II. The Senses

A. Facts 1. 70%of all sensory receptors are used for vision 2. Nerve tract to the optic center have over a million fibers


P III. Vision

3. Eyes need the most “learning” in their development 4. Eyes can be fooled into seeing things that are not what they appear to be 5. Most humans are visual learners first.


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B. External Structure 1. Eyelids a. Covers eyes to keep objects out b. Keeps moisture in 2. Eyelashes – a. Protects the eye from debris b. Ciliary sweat glands are between the eyelashes


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3. Meibomian glands a. Secrete and oily substance to lubricate the eye b. Located at the edges of the eyelids


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4. Lacrimal Glands a. Secrete slightly salty tears to moisturize and kill bacteria b. Lacrimal canals collect tears and send them to the nasal cavity c. Excess tear production causes tears to flow out of the eys.


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5. External Homeostasis a. Cojnuctivitis –Inflammation of the linings of the eyelids b. Pinkeye – Common bacterial infection of the conjunctivitis. Eye turns pinkish


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C. Internal Structures 1. Eyeball-Hollow sphere a. Filled with fluid called humors b. Has three tunics or layers 1. Outer tunic – Sclera a. The white area of the eye b. Cornea –clear tissue in front


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2. Middle Tunic - Choroid a. Holds the lens and iris in place b. Controls how much light gets in 3. Inner Tunic - Retina a. Contains the photoreceptors b. Rods - most on sides, helps us see gray tones and at night c. Cones – help us see colors


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2. Optic Nerve a. One mass of fibers in each eye b. There are no photoreceptors where they are attached c. Gives a blind spot in each eye, but because they are not in the center our eyes cover in the blank areas.


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3. Homeostasis of the Eye a. Color Blindness 1. Certain color cones are absent 2. Sex linked genetic trait 3. Effects men more than women 4. People learn to compensate


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b. Cataracts 1. Effect the lens 2. Lens gets thick and inflexible 3. Causes a hazy view of things 4. Cure is a lens transplant


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c. Glaucoma 1. Liquid part of the eye does not circulate properly 2. Pressure builds in eye crushing the retina and optic nerve 3. Causes blindness


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d. Macular Degeneration 1. Build up debris or growth of blood

vessels between the choroid tunic and the retina

2. Causes detachment of the retina and blindness 3. Treated with lasers and medicine


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f. Nearsightedness 1. Things close are in focus 2. Far things out of focus because rays of light are focused in front of the retina 3. Correction is a concave lens in glasses


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g. Farsightedness 1. Things far are in focus 2. Close things out of focus because rays of light are focused behind the retina. 3. Correction is a convex lens in glasses


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A. Outer Ear 1. Pinna – a. Ear on outside of head b. Collects sound waves 2. External Auditory Canal a. 1” long and ¼” wide b. Secretes ear wax


PIV. Hearing and Balance

3. Tympanic Membrane a. Also called ear drum b. Sound waves vibrate the ear drum c. Ear drum separates outer and middle ears


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B. Middle Ear a. Also called the auditory cavity b. Connected to back of throat by the auditory tube c. Colds and infections of the throat can effect the ear through the tube


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d. Three bones transmit the sound waves from the membrane to the inner ear 1. Hammer (malleus) 2. Stirrup (stapes) 3. Anvil (incus)


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C. Inner Ear a. Also called the auditory cavity b. Three linked cavities filled with fluid c. The shapes we see in books are the shapes of the cavities not solid structures


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d. The cavities 1. Vestibule 2. Cochlea 3. Semicircular Canals


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e. Basic Hearing 1. Sound waves are amplified by the ossicles 2. Hairs in the cochlea , move differently for different sounds 3. The hairs convert the waves into impulses that travel to brain for interpretation (temporal lobe)


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D. Homeostasis 1. Otitis media a. Inflammation due to throat infection b. Sometimes ear drum is slit so pressure is reduced and the ear can drain – a tube is inserted


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2. Hearing Loss a. The tiny hairs are destroyed or damaged b. Can not be replaced c. Causes are: Exposure to loud noise, ear wax buildup, ear infections


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A. Chemoreceptors – (olfactory) 1. Located on the top of each nasal passage 2. Bathed in a mucus covering 3. Chemicals in air stimulate the receptors


P V. Sense of Smell

4. Receptors join olfactory fibers which become the olfactory nerve (I) 5. Smells are long lasting in our memory


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B. Homeostsais 1. Very few problems with smell. 2. Loss is usually related to a head injury to the olfactory cortex. 3. Lack of zinc in the diet can cause loss of smell, quickly solved when zinc is added to diet


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A. Chemoreceptors – (taste buds) 1. Most located on the tongue 2. Some on roof of the mouth 3. Some on the cheeks


PVI. Sense of Taste

4. Impulses from stimulation travel to the brain via 3 nerves

a. Facial nerve – back of tongue b. Glossopharyngeal nerve c. Vagus Nerve


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5. Taste Sensations a. Sweet b. Sour c. Bitter d. Salty


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A. Somatosensory(Mechanoreceptors) 1. Pain 2. Pressure 3. Temperature 4. Touch


PVI. Sense of Touch

C. Sending the Signal 1. Receptors get the initial stimulus 2. Sensory nerves flow into larger tracts of nerves 3. Messages generally received in the somatosensory area of the parietal lobe of the cerebrum 4. Responses sent out according to required action


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Special Senses Galena Park High School A&P Instructor: Terry E. Jones.

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