The fibrous tunic is composed of the sclera and the cornea. The sclera covers nearly the entire surface of the eyeball. With its external surface being white-coloured, it is commonly known as the “white of the eye”.

What is the sensory tunic?

The innermost layer of the eye is the neural tunic, or retina, which contains the nervous tissue responsible for photoreception. The eye is also divided into two cavities: the anterior cavity and the posterior cavity. The anterior cavity is the space between the cornea and lens, including the iris and ciliary body.

What are the two parts of the nervous tunic?

• Retinal pigment epithelium (RPE)
• Photoreceptor outer segments – Rods and Cones.
• Outer limiting membrane.
• Outer nuclear layer.
• Outer plexiform layer.
• Inner nuclear layer.
• Inner plexiform layer.
• Ganglion cell layer.

Which structures are part of each tunic?

The vascular tunic is comprised of three distinct regions, (1) the iris, (2) the ciliary body, and (3) the choroid. The vascular tunic is mesodermal in origin and is situated between the outer fibrous tunic and the inner nervous tunic. The vascular tunic is also refered to as the uvea.

What does a tunicate look like?

Tunicates are also known as sea squirts. … In the larval stage, tunicates look like little tadpoles. They can swim and have all of the characteristics of chordates – a notochord, a dorsal nerve cord, pharyngeal slits, and a post-anal tail.

What tunic is the cornea in?

The sclera and cornea form the fibrous tunic of the bulb of the eye; the sclera is opaque, and constitutes the posterior five-sixths of the tunic; the cornea is transparent, and forms the anterior sixth.

What produces conjunctiva?

The conjunctiva helps lubricate the eye by producing mucus and tears, although a smaller volume of tears than the lacrimal gland. It also contributes to immune surveillance and helps to prevent the entrance of microbes into the eye.

What causes aqueous humor?

The aqueous humour is a thin, transparent fluid similar to plasma. It’s made up of 99.9% water – the other 0.1% consists of sugars, vitamins, proteins and other nutrients. This fluid nourishes the cornea and the lens, and gives the eye its shape.

What provides nutrients to the lens and cornea?

Aqueous Body: the thin, clear fluid between the cornea and the iris. This fluid provides nutrients to the cornea and the lens.

What part of the retina tunic is responsible for central visual acuity?

Structure and Function The fovea centralis is located in the center of the macula lutea, a small, flat spot located exactly in the center of the posterior portion of the retina. As the fovea is responsible for high-acuity vision it is densely saturated with cone photoreceptors.

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Which of the structures listed below is part of the vascular tunic?

The vascular tunic of the eye wall has the a. choroid, ciliary body, and iris. The vascular tunic is also known as the middle coat. The cornea, sclera, and limbus are components of the fibrous tunic, or outer coat.

What does the anterior chamber do?

Anterior chamber: The anterior chamber is the front part of the eye between the cornea and the iris. The iris controls the amount of light that enters the eye by opening and closing the pupil. The iris uses muscles to change the size of the pupil.

What drains the aqueous humor?

Aqueous humour drains out of the eye through the trabecular meshwork. The trabecular meshwork is a spongy mass of tiny canals located in the drainage angle. The drainage angle is located between the iris and the clear covering of the eye (cornea), where the iris meets the white outer covering (sclera) of the eye.

Which component of the fibrous tunic lacks blood vessels or nerves?

The cornea is transparent because it contains few cells and no blood vessels.

What makes a tunicate an animal?

A tunicate is a marine invertebrate animal, a member of the subphylum Tunicata /tjuːnɪˈkeɪtə/. It is part of the Chordata, a phylum which includes all animals with dorsal nerve cords and notochords (including vertebrates).

Are larval tunicates vertebrates?

Although tunicates are invertebrates (animals without backbones) found in the subphylum Tunicata (sometimes called Urochordata), they are part of the Phylum Chordata, which also includes animals with backbones, like us.

Why are tunicates called tunicates?

The name, “tunicate” comes from the firm, but flexible body covering, called a tunic. Most tunicates live with the posterior, or lower end of the barrel attached firmly to a fixed object, and have two openings, or siphons, projecting from the other. Tunicates are plankton feeders.

How does metamorphosis occur in tunicates?

With rare exceptions, tunicates are hermaphrodites, but reproduction may be by sexual or asexual (budding) means. … Free-swimming tunicates metamorphose without attachment. Colonies are formed by asexual reproduction, with zooids usually being formed by budding.

What makes tunicates different from all other chordates?

However, tunicate larvae, such as the one shown in Figure below, possess all four of the major distinguishing characteristics of chordates: a post-anal tail, a notochord, a dorsal nerve cord, and pharyngeal slits. The larva of a tunicate species.

What is difference between conjunctiva and sclera?

The conjunctiva contributes to the tear film and protects the eye from foreign objects and infection. The sclera is the thick white sphere of dense connective tissue that encloses the eye and maintains its shape.

What is palpebral conjunctiva?

Palpebral conjunctiva: The part of the conjunctiva, a clear membrane, that coats the inside of the eyelids. The palpebral conjunctiva is as opposed to the ocular (or bulbar) conjunctiva, the part of the conjunctiva that covers the outer surface of the eye.

What is conjunctiva?

The conjunctiva is the thin clear tissue that lies over the white part of the eye and lines the inside of the eyelid. Children get it a lot. It can be highly contagious (it spreads rapidly in schools and day-care centers), but it’s rarely serious.

What are the three tunics of the eye and their functions?

• Fibrous tunic : It forms an outer layer that consists of the sclera and the cornea. …
• Vascular tunic : It forms a middle layer that consists of the iris,the ciliary body and the choroid. …
• Nervous tunic : It forms an inner layer that consists of the retina.

Where is the uveal tract located?

The middle layer of the wall of the eye.

What are the neural components of the eye?

Neural components: Include the retina and the optic nerve: Retina – cup-shaped outgrowth of the brain which forms the inner layer of the eyeball. Optic nerve – CNII responsible for vision.

What attaches to the lens?

The lens is suspended in place by the suspensory ligament of the lens, a ring of fibrous tissue that attaches to the lens at its equator and connects it to the ciliary body. Posterior to the lens is the vitreous body, which, along with the aqueous humor on the anterior surface, bathes the lens.

What is the nutritive tunic of the eye?

The eye is made up of three layers: the outer layer called the fibrous tunic, which consists of the sclera and the cornea; the middle layer responsible for nourishment, called the vascular tunic, which consists of the iris, the choroid, and the ciliary body; and the inner layer of photoreceptors and neurons called the …

What is the sensory layer of the eye?

The retina consists of two layers: the sensory retina, which contains nerve cells that process visual information and send it to the brain; and the retinal pigment epithelium (RPE), which lies between the sensory retina and the wall of the eye.

What contains aqueous humor?

aqueous humour, optically clear, slightly alkaline liquid that occupies the anterior and posterior chambers of the eye (the space in front of the iris and lens and the ringlike space encircling the lens).

What secretes the aqueous humor quizlet?

Functions: change shape of lens (ciliary muscle), epithelium produces aqueous humor (secretes into posterior chamber). Ciliary muscle occupies most of the region.

Which enzymes are involved in aqueous humor formation?

The ciliary epithelium contains enzyme systems that function in the production of aqueous humour. The enzymes sodium-potassium-activated adenosine triphosphatase [(Na+:K+)ATPase] and carbonic anhydrase participate in the active transport across this epithelium.