The upper eyelid elevator muscle helps the eyelid move. The human eyelid has a row of eyelashes along the edge of the eyelid that help protect the eye from dust and foreign objects. The primary function of the eyelid is to keep the cornea moist and clean.
How is the eye protected from mechanical injury?
Our eyes naturally protect us from a wide range of hazards. Innate defenses include the eyelid, eyelash, and blink reflexes. This reflex provides a mechanical barrier and includes the iris’ ability to contract in response to bright visible light.
How does the structure of the eye support its function?
The cornea is a transparent window in front of the eye that covers the iris and pupil. The transparent lens behind the pupil functions like a camera lens by focusing light onto the retina at the back of the eye. The retina is the light sensitive inner lining behind the eye.
Which accessory glands or structures help lubricate the eye?
Lacrimal apparatus The lacrimal gland is a serous compound tubular gland similar to its parotid gland. It secretes lachrymal fluid (tears) through a duct that opens into the conjunctival sac in the outer portion of the superior border fornix. Tears are composed of water and lysozyme, an antibacterial agent.
What are the accessory structures of the eye quizlet?
What are the accessory structures of the eye? Eyebrows, eyelids, eyelashes, conjunctiva, lacrimal apparatus, and extrinsic eye muscles.
What is the protective layer of the eye?
The sclera (pronounced Sleer-UH) is the protective layer. This tough, fibrous tissue surrounds the eye and attaches to the cornea. This is the transparent front surface of the eye. What we see as the white of the eye is the sclera.
What type of PPE has built in eye protection?
There are four main types of safety goggles, each with its own limitations: general safety glasses, laser safety glasses, chemical splash goggles, and impact goggles. Wearing a face shield provides complete facial protection. Side shields, or one-piece lenses that wrap around the temple, are required.
Which eye structure supports the retina to keep it Flushing behind the eye?
What is the function of vitreous humor? The primary function of vitreous humor is to maintain the round shape of the eye. The size and shape of the vitreous humor also ensures that it remains attached to the retina, the light-sensitive back layer of the eye.
What structure in the eye is responsible for controlling the pupils size?
The iris controls the amount of light entering the eye by regulating the size of the pupil.
Which four accessory glands or structures help lubricate the eye quizlet?
The tarsal, ciliary, conjunctival, and lacrimal glands all contribute to the lubrication of the eye, although their secretions differ.
Which of the following structures is considered to be an accessory structure of the eye?
The accessory structures of the eye include the eyelids, eyebrows, eye muscles, fascia, tear ducts, and conjunctiva. The conjunctiva is a mucous membrane that lines the inner surface of the eyelid and part of the front surface of the eye (sclera) and helps lubricate the eye.
What part of the eyes prevent the sweat from entering eyes?
When closed, the eyelids trap moisture on the surface of the eye. Small glands at the edges of the upper and lower lids contribute to the tear film and secrete an oily substance that keeps tears from evaporating. Tears moisten the surface of the eye.
Which structure secretes a fluid that helps keep the eyelids from adhering to each other?
Large sebaceous glands. Secreted fluid that prevents the eyelids from sticking together.
Does the cornea protect the eye?
The cornea is a transparent vascular tissue that acts as a structural barrier and protects the eye from infection. [1] Together with the tear film, it provides the proper anterior refractive surface to the eye. The cornea contributes two-thirds of the refractive power of the eye.
Do eyebrows protect your eyes?
Many people believe that the eyebrows do not serve many functions. However, even though they are farther away from the eye than eyelashes, they still play an important role in protecting the eye. Eyebrows ensure that liquids, whether sweat or rain, do not run into the eyes.
What are 5 eye protection types?
In this manual, they are grouped into seven classifications based on CSA Standard Z94 3-15: Eye and Face Protectors. Class 1 – Glasses Class 2 – Goggles Class 3 – Welding helmets Class 4 – Welding hand shields Class 5 – Hoods Class 6 Face Shield Class 7 – Respirator Facepiece.
Which is the most common types of eye protection?
Safety Glasses These are the most common form of protective eyewear. They look similar to regular glasses, but are industrial in design and made of more durable materials. They are designed to protect the eyes from impact from small objects in accordance with ANSI standards.
Which structure maintains the shape of the eye and protects the delicate layers of tissue?
Sclera. The outermost layer of the eye consists of the sclera, also known as the white part of the eye. The sclera is composed of tough fibrous tissue that rounds the eye and protects the internal structures of the eye.
What controls the shape of the lens?
The lens is flexible and its curvature is controlled by the ciliary muscle via the obicularis oculus. By changing the curvature of the lens, the eye can adjust to objects at a distance away from the lens. This process is called accommodation.
Which structure of the eye is responsible for color vision?
There are two main types of photoreceptors: cones and rods. The cones are responsible for clear, detailed central vision and color vision and are primarily clustered in the macula. The rods are responsible for night and peripheral (lateral) vision.
What structure is attached to the lens and wants to come out with the lens?
The lens is a transparent, flexible structure located just behind the iris and pupil. A ring of muscle tissue called the ciliary body surrounds the lens and is connected to it by thin fibers called the ciliary body.
How does iris control the size of pupil?
The iris is composed of two smooth muscles that have opposing actions: dilatation (expansion) and contraction (contraction). These muscles control the size of the pupil and determine the amount of light reaching the sensory tissues of the retina.
How does the pupil control the amount of light?
The iris is a ring of pigmented tissue that surrounds the pupil and varies in color from person to person. It contracts and dilates to control the amount of light entering the eye through the pupil.
Which accessory structure of the eye does pink eye affect?
Overview. The conjunctiva is a loose connective tissue that covers the surface of the eye (ocular conjunctiva) and reflects to form the inner layer of the eyelid (eyelid conjunctiva).
What keeps the retina in its proper place against the choroid?
Within the vitreous cavity is the vitreous humor, a clear jelly-like substance that holds the retina against the choroid.
Where are the two humors of the eye and what are their functions?
The aqueous humor also drains excess material and waste from the eye. Vitreous or vitreous humor is a clear, colorless, gelatinous substance. Vitreous humor is located between the retina and the lens.
What is the visual role of the external eye muscles?
These muscles attached to the outer surface of each eye produce the coarse movement of the eye and allow the eye to follow moving objects .
How many different external muscles control your eye?
There are six muscles that attach to the eye to move it. These muscles begin in the orbit (glabella) and are responsible for moving the eye up and down, left and right, and rotating the eye. The superior rectus muscle is an external eye muscle that attaches to the upper part of the eye. It moves the eye upward.
What structures are involved in tear production?
Lacrimal duct and lacrimal gland. Also called the lachrymal duct or lacrimal gland, the structure that produces and distributes the water component of the lachrymal film. Tears consist of a complex, usually clear fluid that diffuses between the eye and the eyelid.
Which part of the eye absorbs excess light?
Choroid: the middle layer of the eye between the retina and sclera. It also contains pigments that absorb excess light, thus preventing blurred vision.
What is the pink part of eye called?
The caruncle of licrimal, or Caruncula licrimalis, is a small, pink, globular nodule located on the inner corner of the eye (medial horn). It is composed of tissue types of adjacent eye structures.
How does the eye protect itself from infection?
The eyes are protected by tears, which moisten them and clean them of dirt, dust, and other irritants that overcome the defenses of the eyelashes and eyelids. Tears also help protect against infection. With each blink, the eyelid spreads a layer of mucus, oil, and tears to cover the front of the cornea.
What is the eyes protective reflex?
The purpose of this reflex is to protect the eye from foreign objects and bright light (the latter known as the light reflex). The blink reflex also occurs when sounds are produced that exceed 40-60 dB.
| Corneal Reflex | |
|---|---|
| Objective. | Examination of the corneal reflex is part of several neurological tests |
What structure in the eye has specialized nerve cells that receive information about light?
The retina is the back part of the eye that contains cells that respond to light. These specialized cells are called photoreceptors.
What covers the lens of the eye?
Cornea. A transparent, dome-shaped surface that covers the front of the eye.
Do eyelashes protect your eyes from the sun?
The eyelashes help to tell the eyelids when they need to close to protect the eye. In addition to the eyebrows and forehead, eyelashes also help protect the eyes from the bright rays of the sun. They are not a substitute for sunglasses, but they do help filter the glorious sunlight into your eyes.
What is the most common form of eye protection?
Safety Glasses These are the most common form of protective eyewear. They look similar to regular glasses, but are industrial in design and made of more durable materials. They are designed to protect the eyes from impact from small objects in accordance with ANSI standards.
What is the uses of eye protection?
They form a protective seal around the eyes, preventing objects and liquids from entering under or around the goggles. This is especially important when working with or around liquids that may splash, spray, or mist.
Which of the following provides best eye protection?
According to the National Institute for Occupational Safety and Health (NIOSH), safety goggles provide the best eye protection from blood, splatter, blood, other bodily fluids, or chemicals.
Which is used to protect the eyes against debris and harmful liquids?
Safety goggles are close eye protection that completely covers the eyes, eye sockets, and facial area around the eyes, providing protection from impact, dust, mist, and splashes. Safety goggles can be worn over prescription lenses.
Which three of the following are classified as accessory organs of the eye?
The appendages of the eye include the eye muscles, fascia, eyebrows, eyelids, conjunctiva, and tear ducts.
Which layer of dense connective tissue serves to protect the inner parts of the eyeball?
The outer layer of the eye is made of dense connective tissue that protects the eye and maintains its shape. It is also known as the fibrous tunic. The fibrous tunic is composed of the sclera and cornea. The sclera covers almost the entire surface of the eye.
Which structure controls the amount of light that enters the eye?
Iris: The iris is the colored part of the eye that surrounds the pupil. It regulates the amount of light entering the eye. Lens: The lens is the distinct part of the eye behind the iris that helps focus light and images onto the retina.
What sends some fluid across the eye to keep it moist?
The watery fluid comes from the lachrymal glands. There are lacrimal glands just above and outside of each eye. The lacrimal glands continually produce a small amount of watery fluid that drains into the upper part of the eye. When they blink, the eyelids spread the tears in front of the eyes.
What holds the eye in place?
Lens suspension ligament – has a series of fibers that tie the ciliary body of the eye to the lens and hold it in place.
Which part of the eye continues to grow throughout life?
It is important to note that in adults, the lens is typically about 10 mm in diameter with an axial length of about 4 mm, but may change in size and shape with perspective adjustment. .
Which four accessory glands or structures help lubricate the eye?
Name the three accessory ocular structures that help lubricate the eye and name their respective secretions . Lacrimal glands: saline and lysozyme. Tarsal and ciliary glands: oily secretions. Conjunctiva: mucus. Internal vestibule.
- Crystals Ampullaris ;
- Macula;
- Macula;
- Crysta ampullaris;
- Crysta ampullaris;
- Macula.
Which part of the body has no blood supply?
The only part of the body not supplied with blood is the cornea of the eye. It takes in oxygen directly from the air.
Are there colors we Cannot see?
Red-green and yellow-blue are the so-called “forbidden” colors. In the human eye they consist of pairs of hues whose light frequencies automatically cancel each other out, making it impossible to see them simultaneously.