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 makes up the thorax? thorax function.


What is the tunic composed of?

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 are the 3 tunics?

Arteries, arterioles, venules, and veins are composed of three tunics known as the tunica intima, tunica media, and tunica externa.

What are the tunic layers?

With the exception of capillaries and sinusoids, all larger vessels have the same three basic structural elements (tunics). These are the tunica intima (inner or luminal layer), tunica media (middle layer), and tunica adventitia (outer layer).

What are tunics anatomy?

In modern biology in general, tunica occurs as a technical or anatomical term mainly in botany and zoology. It usually refers to membranous structures that line or cover particular organs. … An organ or organism that has a tunic(a) may be said to be tunicate, as in a tunicate bulb.

What are the two parts of the first tunic?

FIG. 869– Horizontal section of the eyeball. From without inward the three tunics are: (1) A fibrous tunic, (Fig. 869) consisting of the sclera behind and the cornea in front; (2) a vascular pigmented tunic, comprising, from behind forward, the choroid, ciliary body, and iris; and (3) a nervous tunic, the retina.

What is the sensory tunic of the eye?

Fibrous tunic of eyeball
Anatomical terminology
What is the tunica Fibrosa?

Tunica fibrosa refers to the outer fibrous layer of the eye. This includes the sclera and the cornea, which are continuous with one another.

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.

Which tunic makes valves?

The tunica intima differs from the inner layer of an artery: many veins, particularly in the arms and legs, have valves to prevent…

What are the causes of vasoconstriction?

  • Prescription medicines or non-prescription medicines like decongestants. These have ingredients that cause blood vessels to narrow to provide relief.
  • Some medical conditions. …
  • Some psychological problems, such as stress. …
  • Smoking. …
  • Being outside in the cold.
Where are Myointimal cells?

Myointimal cells are situated between the internal elastic lamina and endothelial cells. They often have myofilaments and other characteristics of smooth muscle; but they are not normally in contact with circulating blood (Fig.

What is another word for tunic?

  • blouse.
  • coat.
  • jacket.
  • robe.
  • chiton.
  • kirtle.
  • surcoat.
  • toga.
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.

Who made the tunic?

Developer(s)Andrew Shouldice
Platform(s)Mac OS X Microsoft Windows Xbox Series X/S Xbox One
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.

When was the tunic created?

They appeared in the middle of the 14th century and were worn under outer garments.

What structure makes up the nervous tunic layer of the eye?

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 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.

Which of these is part of 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.

Which two structures make up the outermost fibrous tunic of the eye?

The outermost layer of the eye is called the fibrous tunic. The sclera and cornea make up the fibrous tunic.

What structure makes up the posterior portion of the fibrous tunic?

Sclera. The sclera (SKLAIR-uh) is the white part of the eyeball, which makes up the posterior five- sixths of the fibrous tunic.

What are the roles of aqueous humor?

Aqueous humor – the clear, watery fluid between the cornea and the front of the vitreous. The aqueous humor bathes and nourishes the lens and maintains pressure within the eye. Since the lens and cornea have no blood supply, the aqueous humor performs the blood’s job of carrying nutrients to those structures.

What does foveal mean?

pl. fo·ve·ae (-vē-ē′) 1. A small cuplike depression or pit in a bone or organ.

How are sensory receptors related to the blind spot in the eye?

The natural blind spot (scotoma) is due to lack of receptors (rods or cones) where the optic nerve and blood vessels leave the eye. There can also be artificial blind spots when something blocks light from reaching the photoreceptors, or when there is local adaptation of the retina as just after seeing a bright light.

Which vessel contains valves?

Unlike arteries, veins contain valves that ensure blood flows in only one direction. (Arteries don’t require valves because pressure from the heart is so strong that blood is only able to flow in one direction.)

What is the function of Tunica interna?

The innermost layer of the vein is the tunica intima. This layer consists of flat epithelial cells. These cells allow fluid to flow smoothly and are interspersed with valves that ensure the flow continues in one direction. This continuous layer of epithelial cells holds cells and fluid within the vessel lumen.

Which tunic of an artery contains epithelium?

The wall of an artery consists of three layers. The innermost layer, the tunica intima (also called tunica interna), is simple squamous epithelium surrounded by a connective tissue basement membrane with elastic fibers. The middle layer, the tunica media, is primarily smooth muscle and is usually the thickest layer.

What triggers vasodilation?

Vasodilation occurs naturally in your body in response to triggers such as low oxygen levels, a decrease in available nutrients, and increases in temperature. It causes the widening of your blood vessels, which in turn increases blood flow and lowers blood pressure.

What is the vasoconstriction?

Vasoconstriction is the narrowing (constriction) of blood vessels by small muscles in their walls. When blood vessels constrict, blood flow is slowed or blocked. Vasoconstriction may be slight or severe. It may result from disease, drugs, or psychological conditions.

Does cold cause vasoconstriction or vasodilation?

Too coldToo hotHeat loss from skinDecreasesIncreases

What is atheroma made up of?

Atheromas are raised lesions that protrude into the vessel lumen and contain a soft, yellow, grumous (thick and lumpy) core consisting mainly of cholesterol and cholesterol esters, covered by a white, fibrous cap.

What is Myointimal proliferation?

Abstract. Myointimal hyperplasia (MIH) is an arterial wall smooth muscle cell (SMC) proliferative disorder. This process is responsible for a significant number of early and long-term arterial reconstructive and graft failures.

Which type of tissue is present in subendothelial layer?

A subendothelial layer, consisting of delicate connective tissue with branched cells lying in the interspaces of the tissue; in arteries of less than 2 mm in diameter the subendothelial layer consists of a single stratum of stellate cells, and the connective tissue is only largely developed in vessels of a considerable …

What's the difference between a shirt and a tunic?

is that shirt is an article of clothing that is worn on the upper part of the body, and often has sleeves, either long or short, that cover the arms while tunic is a garment worn over the torso, with or without sleeves, and of various lengths reaching from the hips to the ankles.

Is a tunic a dress or shirt?

A tunic is a loose-fitting shirt that looks sort of like a long shirt or a short dress. For a fashionable summer look, you might pair trousers with a comfortable tunic that extends past your waist. The ancient Greeks and Romans were early fans of the tunic, and the loose-fitting garment remains popular in modern times.

What part of speech is the word tunic?

part of speech:noundefinition 2:a short coat with a stiff high collar, worn as part of a uniform by soldiers or the like.related words:mantle