Special Senses (Part 1)
What are the 5 senses?
What is the point of the accessory structures?
Defend and support
What pathway does a tear follow starting at the gland?
surface of eye
What is the point of blinking?
keeps eye surface lubricated, and free of disease
What's another name for eyelids?
What is the function of eyelashes?
prevent forging matter from reaching the eye
This is a modified sebaceous gland on inner eyelid margin.
Whats another name for tarsal gland?
The tarsal glands secrete a lipid-rich product that helps do what?
prevents eyelids from sticking together
A cyst resulting from an infected tarsal gland is known as what?
An inflammation of conjunctiva due to infection, physical, allergic, or chemical irritation is known as what?
The transparent portion of outer fibrous layers that is covered by 5-7 layers of delicate squamous epithelium is known as what?
Tears are formed in what gland?
Tears contain an antibacterial known as what?
The large posterior cavity of the eye contains what kind of jelly-like substance?
The small anterior cavity contains what kind of water substance?
The anterior portion of the eye is further separated into two chambers. Where is the anterior chamber located?
Between cornea and iris
The anterior portion of the eye is further separated into two chambers. Where is the posterior chamber located?
between the iris and the lens
What divides the two many anterior and posterior chambers of the eye?
The ciliary body and the lens
What is the point of Aqueous humor?
provides an important route for nutrient and waste transport
What, in the aqueous humor, helps to retain eye shape?
This is the result of inadequate drainage of aqueous humor.
What are the three layers of the eye wall from outer to deep?
fibrous layer (sclera)
vascular layer (uvea)
inner layer (retina)
The Sclera is made up of what?
Dense connective tissue (collegen and elastin)
This provides a route for blood vessels and lymphatics that supply the eye tissue, regulates amount of light entering eye, secretes and reabsorbs aqueous humor, and controls the shape of the lense.
Vascular layer (Uvea)
The Iris is contained in this layer, it has blood vessels and lymphatics, pigment cells, and papillary muscles. It changes the diameter of the pupil and attaches to ciliarly body posteriorly.
Vascular layer (uvea)
This muscle extends radially away from the edge of the pupil. contraction of these muscles enlarges the pupil.
These muscles form a series of concentric circles around the pupil, when these sphincter muscles contract, the diameter of the pupil decreases.
The pupillary constrictors
The ciliary body attaches to what?
What are the two kinds of photoreceptors?
Rods and Cones
These photoreceptors only see in black, gray, and white, are highly sensitive to light, and enable us to see in dimly lit rooms.
These photoreceptors provide color vision, require more light, and densely cluster in fovea at the center of macula.
These cells extend across the neural layer of the retina at the level of synapses between bipolar cells and photoreceptors.
These cells are comparable to the horizontal cells and occur where bipolar cells synapses with ganglion cells.
These cells facilitate or inhibit communication between photoreceptors and ganglion cells by altering the sensitivity of the retina.
Horizontal and Amacrine Cells
The lens is held in place by what?
suspensory ligaments of the ciliary body
The primary function of this is to focus the visual image on photoreceptors.
The lens is filled with transparent proteins called what?
In this condition, the lens has lost its transparency and can occur due to age but can also result from injuries, drugs, and radiation.
This is the bending of light when I passes from one medium to another. I.E., cornea to aqueous humor to lens.
When light is refracted to a specific point of intersection on the retina, it is known as what?
The distance between the center of the lens and the focal point is known as what?
The focal distance is affected by what two things?
the distance of an object from a lens
shape of the lense
The automatic adjustment of the eye to give us clear vision is called what?
This is a condition where light passing through the cornea and lens is not refracted properly due to degree of the curvature from one axis to another.
As light from an image is focused onto the retina, a miniature image of the original results, but arrives upside down and reversed. This is known as what?f
This is defined as the level of detail seen at a distance of 20 feet by an individual with normal vision.
If the resting curvature of the lens is too great, this is known as what?
If the lens is too flat, this is known as?
The basic unit of light, detected by photoreceptors, is known as what?
Concerning the anatomy of rods and cones, what segment contains visual pigment?
The outer segment
Concerning the anatomy of rods and cones, what segment contains the cells organelles and is responsible for all cell functions other than photoreception?
Concerning the anatomy of rods and cones, where does light absorption occur?
in the visual pigments
Concerning cones, this determines the wavelength of light that can be absorbed by the retinal.
The inability to detect certain colors is known as what?
The plasma membrane in the outer segment of a photoreceptor contains what kind of gate?
Chemically gated Na+ channel
In darkness, are the chemically gated Na+ channels open or closed in the photoreceptors?
When the chemically gated Na+ channels remain open, this is continuously released across the synapse at the inner segment.
What activates rhodopsin?
What does rhodopsin activate?
What causes cGMP to decline and closes Na+ channels causeing hyperpolarization?
When Na+ channels close, the membrane plasma hyperpolarizes and the rate of NT does what?
When this happens, rhodopsin molecule breaks down into retinal and opsin and can contribute to lingering visual impressions after seeing a cameras flash.
Where does the visual pathways begin and end?
Begin at photoreceptors and end at visual cortex of cerebral hemispheres`