Special Senses Flashcards
Special Senses
Taste, Smell, Sight, Hearing
Olfaction
Sensation of Smell
Olfactory Fibers
The reason why it’s the bulb, because it has cell bodies.
It is like Olfactory Ganglia
Cribiform Plate is on either side of the crista galli
Cells will be the olfactory cells, then support cells are in between
Part of the mucus membrane or epithelial of the nasal cavity, so you will pick up different chemicals that will be registered as smell
How is sense of smell determined?
Axons pass through the cribiform plate, synapse at the cell body of the olfactory bulb ending at the olfactory areas of the brain
True or False? Each olfactory bulb will pick up the different or specific chemicals that are perceived as smell
True
Gustation
Sense of Taste
Are taste and smell closely related?
Yes
Where is sensation of taste picked up?
On taste buds on the sides of the papilla
6 Senses of taste
Sweet
Sour
Salt
Bitter
Umami
pH
Umami
More of the savory sensation, picks up different amino acids
pH sense of taste
Spicy foods
Tongue
Throat and Soft Pallet
Throat and Soft Pallet
Have taste buds, areas inside of the mouth
Papillae
Projections of the tongue
Epithelial projections on the surface of the tongue that contain the actual taste bud
Three parts of the Papillae
Circumvallate Papillae
Fungiform Papillae
Filliform Papillae
Circumvallate Papillae
relatively large. 20 of these. Inverted V pattern on back of the tongue
Bitter is found back here. Protective taste because most people don’t like the sensation of bitter.
Fungiform Plate
Mushroom shaped. They’re knob like elevations, comes from fungi.
Little bumps on the surface of the tongue. Most of them will be fungiform papillae
Filliform Papillae
More pointy and tall.
Anteriorly covers 2/3 of the tongue
Filliform means threadlike, or thread shaped
Can elongate with deficiency in nutrition(hairy tongue)
Taste Buds
Are circular structures; They are neurologic receptors for taste on the sides of the papilla.
Gustatory Cells
Connected to nerves, supporting cells.
Opening is the taste pore, taste hairs are sticking up to pick up sensations, microvilli, chemicals picked up.
Why are taste receptors located on the sides and not the top?
- Because you get the moisture from the saliva in the nooks and crannies mixing with the taste sensation to more easily diffuse those chemicals. So chemical diffusion is one reason it’s on the side. If it’s on top, there’s less moisture and less diffusion. It will take longer to diffuse the chemicals we perceive as taste
- By setting on the sides, they are protected from abrasions. To keep from damaging them
Gustatory Pathway
Cranial Nerves 7, 9, 10. Picking up sensation of taste
Eyeball
2.5 cm in diameter
Three layers of the eyeball
Anterior 1/6 of eyeball is exposed
Fibrous Tunic (Outer Tunic)
fibrous coat
Has 2 parts:
Sclera
Cornea
Sclera
the white of the eye.
Posterior part
Gives shape to the eye
Posteriorly pierced by the optic nerve
Cornea
Fibrous Tunic
Transparent nervous tissue
Anterior part
Nonvascular transparent nervous tissue
Covered by a continuous epithelial layer called the conjunctiva
Physiology of Cornea
Light is bend and refracted to be placed on the back of the retina.
Light rays pass through the lens, they are bent or refracted to be placed on the back of the retina. Cornea bends the light rays more than any structure inside the eye.
Important because we place that image on the back of the retina.
Function of Lens
Allows for adjusting so we can see things.
It can bulge and flatten to help place that image on the back of the retina
Limbus
Junction in between the cornea and sclera
Vascular Tunic
Tunic means coat. It has a lot of vessels in it. Commonly known as Uvea
Three parts of the Uvea
Choroid
Ciliary Body
Iris
Choroid
Posterior 2/3 of the eye.
Deep in the sclera
Highly vascular, lots of capillaries, serves as the blood for the retina
Also pigmented, thin brown membrane
Optic nerve pierces this layer too
As it moves forward, it transitions into the Ciliary Body
The reason for pigmentation?
So light rays absorb and don’t bounce around in the eye. Because it will decrease visual acuity.
Astigmatism
Irregularities of the surface of the cornea.
Ciliary Body
thick anterior part of the choroid
Has ciliary muscles
Suspensory Ligaments
Contraction of the ciliary muscles relaxes the suspensory ligaments allowing the lens to bulge
Because of the orientation of the muscle fibers, it allows this to happen
Fibers are pulling the ciliary muscles causing it to bulge
Suspensory Ligaments
Like a trampoline, the tramp would be the lens and the springs would be the suspensory ligaments radiating from the tramp, they will either loosen or tighten the shape of the lens or eyeball
Lens can either bulge out or flatten
Iris
Smooth muscle fibers responsible for constriction and dilation of the pupil (inner opening)
Pupil
Inner opening of the iris
Iris Muscle fibers
arranged in the shape of a doughnut
Has two sets:
Circular
Radial
Circular Fibers
Sphincter, like the orbicular oris, orbicular oculeye
When we contract the circular fibers the size of the pupil will shrink, causing pupillary constriction.
Cranial nerve 3 runs through the ciliary ganglion causing pupillary constriction
Radial Fibers
Radiate out from the pupil
Bound to the edge of the iris. So when these contract, it causes the pupil to open up or causes pupillary dilation
Smooth muscles, ciliary ganglion causes or creates the pupils to dilate
Optic nerve brings light in and sends it back out
Retina
Inner coat of the eye
Contains visual receptors for sight
Covers only posterior part of the eye
Nervous Tissue Layer of Retina
2nd layer
Photoreceptors are located here
Most superficial layer to light
Layer meaning light ray prospective tissue
Pigmented Layer of Retina
Deepest tissue
Assist the choroid in absorbing scattering photons of light
Increase visual acuity
4 Layers of the Eye
Nervous Layer
Pigmented Layer
Choroid Layer
Scelera Layer
Structures Associated with the Retina
Optic Disc
Macula Lutea
Central Fovea
Optic Disc
Located inferiorly and medially on the back of the retina.
Blind spot, region where optic nerve pierces the back where it enters the eye
Macula Lutea
means yellow spot in the exact center of the retina
Areas where we have extremely sharp vision because of the high density of cones
Lateral and Superior to the Optic Disc
Physiology of Macula Lutea
When it is bright in the room, we can see all the different colors. But as light diminishes or decreases we start to lose color, we start to see variations of gray. In bright light, we’ve got these cones that are found in the center of our visual field, if we want to see something we’re gonna look directly at that individual and place that image on the back of the retina.
Central Fovea
Contains only cones and nothing else
Where we place the specific image we’re looking at.
In the direct center of the macula lutea. Avascular, no capillaries in here. No blood vessels
Chambers and Cavities of the Eye
Anterior Cavity
Posterior Cavity
Anterior Cavity
From the lens forward. Two Parts:
Anterior Chamber
Posterior Chamber
Anterior Chamber of Anterior Cavity
From the Iris to the cornea
Posterior Chamber of Anterior Cavity
From the Iris to the lens
Posterior Cavity
One part, aka Vitreous Body
Behind lens to retina
Slow turnover rate of the gelatinous, replenished over period of 13-20 years
Flow of Aqueous Humor
Fluid in the front
Found in the anterior cavity.
Replenished all the time
Ciliary body produces the flow of aqueous humor
It then flows to posterior chamber up through the iris (pupil) into the anterior chamber, picked up by venous vessel or to Canal of Schlemm, drained by canal of schlemm, and return it to the venous blood.
If it gets blocked leads to glaucoma, which glaucoma can cause blindness
Closed Angle Glaucoma
Fluid can’t get drained out
Opened Angle Glaucoma
Fluid gets blocked, prevents fluid from re-absorbing
Tonometers
Measures the air pressure back from the eye ball.
Decreased blood flow to the back of the eye, retina
Functions of Posterior Cavity
Stabilizes the eyeball
Holds the Retina against the back of the eye
It’s transparent so it allows light rays to pass through it so it can go to the posterior aspect of the eye.