Senses Flashcards
Chemoreceptors:
change in chemical [bonds]
Nociceptors (pain):
tissue damage
Thermoreceptors:
changes in temperature
Mechanoreceptors:
changes in pressure and movement (tension)
Photoreceptors:
changes in light
There are no photoreceptor cells in the optic disc/ blind spot
general senses of touch
Temperature
Pressure
Pain
Special senses
Smell Taste Sight Hearing Equilibrium
Emmetropic-
normal vision
Myopic-
nearsightedness; inability to see faraway objects
Hyperopic
inability to focus well on close objects; farsightedness
Layers forming the wall of the eye
Fibrous layer - outside layer Vascular layer - middle layer Sensory layer - Inside layer
Sclera-
White connective tissue layer
Seen anteriorly as the “ white of the eye”
Cornea-
Transparent, central anterior portion
Allows for light to pass through
Repairs itself easily
The only human tissue that can be transplanted without fear of rejection
Rods-
Most are found towards the edges of the retina
Allow dim light vision and peripheral vision
All perception is in gray tones
Cones-
Allow for detailed color vision
Densest in the center of the retina
Fovea centralis-
area of the retina with only cones
5 Types of Receptors
Chemoreceptors: Nociceptors (pain): Thermoreceptors: Mechanoreceptors: Photoreceptors:
The eye and vision
70% of all sensory receptors are in the eyes
Each eye has over a million nerve fibers
Protection for the eye
Most of the eye is enclosed in a bony orbit
A cushion of fat surrounds most of the eye
Conjunctiva
Membrane that lines the eyelids
Connects to the surface of the eye
Secretes mucus to lubricate the eye
Ciliary body-
Smooth muscle attached to lens
Iris-
Regulates amount of light entering eye
Pupil-
Rounded opening in the iris
Retina contains two layers
Outer pigmented layer
Inner neural layer
- contains receptor cells
- rods
- cones
Two segments or chambers of the eye
Anterior (aqueous) segment
- anterior to the lens
- contains aqueous humor
Posterior (vitreous) segment
- posterior to the lens
- contains vitreous humor
Aqueous humor
Watery fluid found between lens and cornea
Helps maintain intraocular pressure
Provides nutrients for the lens and cornea
Vitreous humor
Gel-like substance posterior to the lens
Prevents the eye from collapsing
Helps maintain intraocular
Ophthalmoscope
Instrument used to illuminate the interior of the eyeball
Can detect diabetes, arteriosclerosis, degeneration of the optic nerve and retina
Accommodation-
the lens must change shape to focus on closer objects (less than 20 feet away)
Pathway of the light through the eye
Image formed on the retina
Real images are
- reversed from left to right
- upside down
- smaller than the object
Which homeostatic imbalance is best characterized by light rays converging in front of the retina?
Myopia
Which of the following statements are TRUE about your optic disc?
It is also known as the blind spot.
It is where the optic nerve leaves the back of the eye.
You should have tested for it in Mr. Prey’s Lab: Visual Tests & Demonstrations.
What was the jelly-like substance that came out of the eye during the dissection?
Vitreous humor
3 layers of the eyeball
Fibrous layer (no blood, dense CT)
vascular layer (pigmented)
inner layer (retina)
Three layers of the retina
I. Photoreceptorlaver- generatesaction potential; made of rods and cones 2. Bipolar laver- transmits impulse 3. Ganglion cells- relays message to optic nerve and then to occipital lobe
Cataracts
hardening of lens with age, causing hazy vision
Glaucoma
drainage of the aqueous humor is blocked, causing pain and possibly blindness
Night Blindness
rod function interferences/vitamin A deficiency, causing impaired night vision
Colorblindness
missing some or all types of cones, causing the inability to distinguish certain colors
astigmatism
Images are blurry
Results from light focusing as lines, not points, on the retina due to unequal curvatures of the cornea or lens
Hemianopia—
loss of the same side of the visual field of both eyes; results from damage to the visual cortex on one side only
The Ear
Houses two senses
-Hearing
- Equilibrium (balance)
- Receptors are mechanoreceptors
- Different organs house receptors for each sense
Anatomy of the Ear
The ear is divided into three areas
External (outer) ear Middle ear (tympanic cavity) Inner ear (bony labyrinth)
The External Ear
Involved in hearing only
Structures of the external ear
Auricle (pinna)
External acoustic meatus (auditory canal)
Bones of the Middle Ear (Tympanic Cavity)
Three bones (ossicles) span the cavity
Malleus (hammer)
Incus (anvil)
Stapes (stirrip)
Function of the Middle Ear Bones
Vibrations from eardrum move the hammer -> anvil -> stirrup -> inner ear
Inner Ear or Bony Labyrinth
Includes sense organs for hearing and balance
Filled with perilymph
A maze of bony chambers within the temporal bone
Organ of Corti
Located within the cochlea
Receptors = hair cells on the basilar membrane
Gel-like tectorial membrane is capable of bending hair cells
Cochlear nerve attached to hair cells transmits nerve impulses to auditory cortex on temporal lobe
Mechanism of Hearing
Vibrations from sound waves move tectorial membrane
Hair cells are bent by the membrane
An action potential starts in the cochlear nerve
Continued stimulation can lead to adaptation
Deafness
earwax build-up, ruptured eardrum, middle ear infections, otosclerosis; damage to Organ of Corti (cochlea)
Tinnitus –
constant ringing in ears
Meniere’s Syndrome
fluid problems lead to vertigo, nausea
