Special Senses Flashcards
Define olfaction
- Sense of smell
Describe the olfactory pathway
- Receptors for smell are the dendrites of the olfactory nerves
- (Cr. N I) located in the superior nasal cavity.
- They pass through those olfactory formina of the ethmoid bone
- synapse at the olfactory bulb.
- The pathway continues on as the olfactory tract which is interpreted in the temporal lobe of the cerebral cortex.
Define gustation. Identify the 4 main taste zones
-Sense of taste. The sweet taste zone is at the tip of the tongue, salt is just posterior to it; sour is on sides of tongue and bitter is at the back of the tongue.
Describe the gustatory pathway
- Taste buds are the receptors and are at the base of the taste pores (that is why substances must be liquified for taste).
- The pathway travels along cranial nerves VII (anterior tongue), IX (middle tongue) and X (back of tongue & throat) to be interpreted in the parietal lobe of the cerebral cortex.
Name and describe the structures included in the 3 layers of the eyeball
- Fibrus Tunic: Outter most
- selera- white of eye- blood vessels, pain nerve endings
- Cornea- clear- no BV, nerve endings (can repair with surrounding BV)
Vascular Tunic: Layer below (uvea)
- Choroid- inside selera, BV nurish the next layer, Pigment colorful
- Ciliary Body- Smooth muscle, focus lens, innovated by the ocularmotor nerve ( NERVE III)
- Iris- Color part of eye, smooth muscle around pupil
- Pupil- hole in iris, light regulation, Regulated by ocularmotor nerve III
Nervous Tunic- Retina and optic nerve
- outer pigmented layer: (deflects light reflection)
- Nervous layer: receptors (cones and rods) are here
- macula and fovea centralis
- optic nerve, optic discs, blindspot
- Lens: attached to ciliary bodies, rounded clear, focuses light of fovea centralis
Describe the function and the tissue make-up of the iris
-he iris is pigmented smooth muscle and regulates the light coming through the pupil. A large pupil lets in a lot of light.
Describe the location and function of the retina
- Located in the nervus tunic, inner layer of the wall of the eyeball
- the location of the receptors for vision, the rods and cones.
What and where is the blind spot
- In the retina, the optic disc, where the optic nerve exits
- there are no rod or cones located here. No receptors
Describe the location and function of the lense, aqueous humor and vitreous humor.
- Lense- In the retina
- Attached to the ciliary bodies
- focus light waves to land on the fovea centralis
- no bv, gets nurisment from anterior and posterior cavities
- cataracts are opic spots on lense
Aqueous humor
-anterior cavity, maintain shape
Vitreous humor
-posterior cavity, thicker fluid (where glucoma occurs)
Describe the location of the palpebral fissure, medial and lateral commisures, caruncle, tarsal plate, conjunctiva, meibomian glands, palpebrae, and sebaceous ciliary glands
-Palpebral fissure-slip between eyes
-Medial lateral commissures- edge of eyes
-caruncle- gland that makes sticky substance to clean eye at night
-tarsal plate- upper and lower, gives eyelid substance (flip eyelids inside out)
-conjunctiva-attaches to eyeball, palpebral to the bulba of the eyeball (what gets infected with pink eye)
-Meibomian glands- releases oil on rims of eyelids so they don’t stick
-palpebrae- eyelids
sebaceous ciliary glands- eyelash oil glands to prevent eyelashes from breaking
Describe the structures that comprise the lacrimal apperatus
- releases antimicrobial substance to protect eye from infection
- tears to lubricate moisten eye and clean from foreign material
- lacrimal gland- superior lateral margin
- lacrimal puncta- hole
- lacrimal cannal into the nasolacrimal duct
Name the photoreceptors and describe their locations
- Rods & cones on the retina.
- Rods tend to be more peripheral and cones more centrally located.
- Black and white and gray- Rods
- color-cones
define refraction as it pertains to vision
- The bending of light rays so that they all converge on one spot called the focal point. If they all converge on one point and that point is on your fovea centralis, you have clear vision.
- the cornia and lense
Describe how images are focused
- The light rays are refracted by the cornea and again by the lens.
- Hanging from the ciliary body are suspensory ligaments attached to the retina so that the lens can be changed in shape.
- A straighter lens does not bend the light rays very much, a more curved lens bends the light rays a lot.
Define emmetropia
-normal vision, all light rays come to focus on the single point behind the lens called the focal point
Define accommodations
- accommodation is the ability to change the shape of your lens to change from far vision where the lens is relatively straight to close vision where the lens is very curved.
- You lose this ability with age.
define near point of vision
-The near point of vision is the closest point that you can still focus. It is very close to the eyes in the young and farther away in older people.
Describe the controls over eyeball movements
- voluntary fixation movement- premotor/ frontal lobe
- involuntary fixation movement- as the image becomes out of the field of view, the occipital lobe, eyes flicker back and forth, cannot hold eye still.