Question

1. ist the 5 special senses and describe the difference between a special and a general sense receptor.
2. Remember, list and describe the functions of the Integumentary and muscle receptors.
3. Describe the locations, structures and functions of eyelids and associated accessory structures.
4. Describe the location, action and CN innervation of the extrinsic eye muscles. (Refer back to Chapter 11)
5. Describe the layers of the eyeball.
6. List the chambers of the eye and describe the fluids each contains.
7. Trace the path of light through the eye to the retina.
8. Describe the location, composition, and function of the lens.
9. Compare how rods and cones are connected to other retinal neurons.
10. Describe the events that convert light into a neural signal.
11. Describe the visual pathways to the brain.
12. Describe the location and structure of olfactory receptors.
13. Describe the location and structure of taste receptors.
14. Describe the pathway from gustatory receptors to the brain.
15. Describe how the sense of smell influences gustation.
16. Describe the structure and general functions of the outer, middle & inner ear.
17. Describe the location and functions of the cochlear apparatuses.
18. Describe how different areas of the vestibular membrane resonate in response to different frequencies of sound.
19. Describe how the Organ of Corti converts resonance of vestibular membrane to a neronal signal.
20. Describe pathway and processing of auditory impulses.
21. Describe how properties of sound are perceived by the brain.
22. Define “Equilibrium”, and list and describe the locations of the structures associated with the sense of equilibrium.
23. Identify the structures of maculae and describe their functions.
24. Describe the structure and function of cristae ampullares and semicircular canals.

Answer 1

1) The five senses are the five main tools that humans use to perceive the world. Those senses are sight,smell, hearing, taste, and touch. We see with our eyes, we smell with our noses, we listen with our ears, we taste with our tongue, and we touch with our skin.

Difference: General: Scattered throughout the body, and relatively simple in structure  Special:Receptors for the special senses—smell, taste, vision, hearing, and equilibrium— are anatomically distinct from one another and are concentrated in specific locations in the head.The human body has two basic types of senses, called special senses and general senses. Special senses have specialized sense organs that gather sensory information and change it into nerve impulses. ... General senses, in contrast, are all associated with the sense of touch. They lack special sense organs.Receptors associated with the skin, muscles, joints, and viscera make up the somatic senses. Special Senses: These include the senses of smell, taste, hearing, static equilibrium, dynamic equilibrium, and sight.

2) The integumentary system consists of the skin, hair, nails, glands, and nerves. Its main function is to act as a barrier to protect the body from the outside world. It also functions to retain body fluids, protect against disease, eliminate waste products, and regulate body temperature.

Functions:

• Protection. Microorganism, dehydration, ultraviolet light, mechanical damage.
• Sensation. Sense pain, temperature, touch, deep pressure.
• Allows movement. Allows movement muscles can flex & body can move.
• Endocrine. Vitamin D production by your skin.
• Excretion. ...
• Immunity. ...
• Regulate Temperature.
• The skin performs six primary functions which include, protection, absorption, excretion, secretion, regulation and sensation

3) locations, structures and functions of eyelids and associated accessory structures.

accessory structures of the eye - The external protective appendages and supplementary components of the eye, external to the eyeball, which contribute indirectly to vision and image formation; they include the eyebrows, the eyelids and eyelashes, the conjunctiva, the lacrimal apparatus and the extrinsic eye muscles.

An eyelid is a thin layer of skin that covers and protects the eye. The eye contains a muscle that retracts the eyelid to "open" the eye either voluntarily or involuntarily. Human eyelids contain a row of eyelashes that protect the eye from dust particles, foreign bodies, and perspiration.

Location: The eyelid is made up of several layers; from superficial to deep, these are: skin, subcutaneous tissue, orbicularis oculi, orbital septum and tarsal plates, and palpebral conjunctiva. The meibomian glands lie within the eyelid and secrete the lipid part of the tear film.

Structure:

The eyelid is made up of several layers; from superficial to deep, these are: skin, subcutaneous tissue, orbicularis oculi, orbital septum and tarsal plates, and palpebral conjunctiva. The meibomian glands lie within the eyelid and secrete the lipid part of the tear film.

Artery: lacrimal, superior palpebral, inferior pal...

Nerve: upper: infratrochlear, supratrochlear, su...

Latin: Palpebra; (palpebra inferior, palpebra

Functions: An eyelid is a thin layer of skin that covers and protects the eye. The eye contains a muscle that retracts the eyelid to "open" the eye either voluntarily or involuntarily. Human eyelids contain a row of eyelashes that protect the eye from dust particles, foreign bodies, and perspiration.The main role of the eyelids is to protect the eye. It's vital that the surface of the eye (the cornea) remains constantly moist, so the eyelid is responsible for spreading the tear film evenly across the surface.

5) layers of the eyeball:

• Outer coat (fibrous tunic) The eye's outer layer is made of dense connective tissue, which protects the eyeball and maintains its shape. ...
• Middle coat (vascular tunic) ...
• Inner coat. ...
• The lens. ...
• The vitreous body (vitreous humour, vitreous) ...
• Anterior and posterior eye chamber.

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 nervous tunic, which consists of the retina.

The eye also contains three fluid-filled chambers. The volume between the cornea and the iris is known as the anterior chamber, while the volume between the iris and the lens is know as the posterior chamber, both chambers contain a fluid called aqueous humor. Aqueous humor is watery fluid produced by the ciliary body. It maintains pressure (called intraocular pressure or IOC) and provides nutrients to the lens and cornea. Aqueous humor is continually drained from the eye through the Canal of Schlemm. The greatest volume, forming about four-fifths of the eye, is found between the retina and the lens called the vitreous chamber. The vitreous chamber is filled with a thicker gel-like substance called vitreous humor which maintains the shape of the eye.

Light enters the eye through the transparent, dome shaped cornea. The cornea consists of five distinct layers. The outermost layer is called the epithelium which rests on Bowman's Membrane. The epithelium has the ability to quickly regenerate while Bowman's Membrane provides a tough, difficult to penetrate barrier. Together the epithelium and Bowman’s Membrane serve to protect the cornea from injury. The innermost layer of the cornea is called the endothelium which rests on Descemet's Membrane. The endothelium removes water from cornea, helping to keep the cornea clear. The middle layer of the cornea, between the two membranes is called the stroma and makes up 90% of the thickness of the cornea.

From the cornea, light passes through the pupil. The amount of light allowed through the pupil is controlled by the iris, the colored part of the eye. The iris has two muscles: the dilator muscle and the sphincter muscle. The dilator muscle opens the pupil allowing more light into the eye and the sphincter muscle closes the pupil, restricting light into the eye. The iris has the ability to change the pupil size from 2 millimeters to 8 millimeters.

Just behind the pupil is the crystalline lens. The purpose of the lens is to focus light on the retina. The process of focusing on objects based on their distance is called accommodation. The closer an object is to the eye, the more power is required of the crystalline lens to focus the image on the retina. The lens achieves accommodation with the help of the ciliary body which surrounds the lens. The ciliary body is attached to lens via fibrous strands called zonules. When the ciliary body contracts, the zonules relax allowing the lens to thicken, adding power, allowing the eye to focus up close. When ciliary body relaxes, the zonules contract, drawing the lens outward, making the lens thinner, and allowing the eye to focus at distance.

Light reaches its final destination at the retina. The retina consists of photoreceptor cells called rods and cones. Rods are highly sensitive to light and are more numerous than cones. There are approximately 120 million rods contained within the retina, mostly at the periphery. Not adept at color distinction, rods are suited to night vision and peripheral vision. Cones, on the other hand, have the primary function of detail and color detection. There are only about 6 million cones contained with in the retina, largely concentrated in the center of the retina called the fovea. There are three types of cones. Each type receives only a narrow band of light corresponding largely to a single color: red, green, or blue. The signals received by the cones are sent via the optic nerve to the brain where they are interpreted as color. People who are color blind are either missing or deficient in one of these types of cones.

6) List the chambers of eyes and describe the fluid content in it.

Three chambers of fluid: Anterior chamber (between cornea and iris), Posterior chamber (between iris, zonule fibers and lens) and the Vitreous chamber (between the lens and the retina).

The anterior chamber (AC) is the aqueous humor-filled space inside the eye between the iris and the cornea's innermost surface, the endothelium. Hyphema, anterior uveitis and glaucoma are three main pathologies in this area. ... The depth of the anterior chamber of the eye varies between 1.5 and 4.0 mm, averaging 3.0 mm.

Posterior chamber: The space in the eye behind the iris and in front of the lens. ... Produced by a structure alongside the lens called the ciliary body, the aqueous passes into the posterior chamber and then flows forward through the pupil into the anterior chamber of the eye.

The vitreous chamber is the largest of the three chambers and is located behind the lens and in front of the optic nerve. Thischamber is filled with a thick, clear gel-like substance called thevitreous humor (also vitreous body). The humor plays a crucial role in supporting the posterior side of the lens.

7) Trace the path of light through the eye to the retina.: Light from everything around you enters the pupil of your eye and is focused by thecornea onto the lens. The lens further focuses and flips the light onto the back of theretina. This information is sent to your brain through the optic nerve.

Light passes through the front of the eye (cornea) to the lens. The cornea and the lens help to focus the light rays onto the back of the eye (retina). The cells in the retina absorb and convert the light to electrochemical impulses which are transferred along the optic nerve and then to the brain.Light enters the eye through the cornea, the clear, curved layer in front of the iris and pupil. The cornea serves as a protective covering for the front of the eye and also helps focus light on the retina at the back of the eye.The visual pathway is the pathway over which a visual sensation is transmitted from the retina to the brain. This includes a cornea and lens that focuses images on the retina, and nerve fibers that carry the visual sensations from the retina through the optic nerve.Light passes through the front of the eye (cornea) to the lens. The cornea and the lens help to focus the light rays onto the back of the eye (retina). The cells in the retina absorb and convert the light to electrochemical impulses which are transferred along the optic nerve and then to the brain.

8) Location, composition, and function of the lens.

Location: The Lens. The lens is composed of transparent, flexible tissue and is located directly behind the iris and the pupil. It is the second part of your eye, after the cornea, that helps to focus light and images on your retina.

Composition:The lens capsule is a smooth, transparent basement membrane that completely surrounds the lens. The capsule is elastic and is composed of collagen. It is synthesized by the lens epithelium and its main components are Type IV collagen and sulfated glycosaminoglycans (GAGs).

Function:The lens is located in the eye. By changing its shape, the lens changes the focal distance of the eye. In other words, it focuses the light rays that pass through it (and onto the retina) in order to create clear images of objects that are positioned at various distances.

10) Describe the events that convert light into a neural signal.

Light enters the visual system through the eye and strikes the retina at the back of it. The retina is composed of specialized cells, the rods and cones, which convert lightenergy into neural activity. ... When light strikes these pigments, they change form, causing a cascade of chemical reactions in these photoreceptors.

In response to varying ambient light levels, rods and cones of eye function both in isolation and in tandem to adjust the visual system. Changes in the sensitivity of rods and cones in the eye are the major contributors to dark adaptation.Light energy goes into eyes stimulate photoreceptor in eyes. However, as an energy wave, energy is passed on through light at different wavelength. Light, as waves carry energy, contains energy by different wavelength. ... As light enters the eye, the 11-cis-retinal is isomerized to the all-"trans" form.he structure of the eye responsible for converting light waves into action potentialsis the retina. The neural layer of the retina is composed of three main types of cells: the photoreceptors, the bipolar neurons and the ganglion cells.

11) Describe the visual pathways to the brain

The visual pathway consists of the series of cells and synapses that carry visualinformation from the environment to the brain for processing. It includes the retina, optic nerve, optic chiasm, optic tract, lateral geniculate nucleus (LGN), optic radiations, and striate cortex.The primary visual pathway consists of the retina, optic nerve, lateral geniculate nucleus (LGN) of the thalamus, and the visual cortex of occipital lobe. ... The primary visual pathway is subdivided into multiple, specialized pathways that simultaneously encode the signal in parallel.The information about the image via the eye is transmitted to the brain along the optic nerve. Different populations of ganglion cells in the retina send information to the brainthrough the optic nerve. About 90% of the axons in the optic nerve go to the lateral geniculate nucleus in the thalamus.Ganglion cells gather this information along with other information about color, and send their output into the brain through the optic nerve. ... Most projections from the retina travel via the optic nerve to a part of the thalamus called the lateral geniculate nucleus (LGN), deep in the center of the brain.The information from the retina — in the form of electrical signals — is sent via the optic nerve to other parts of the brain, which ultimately process the image and allow us to see.It is often said that 2/3 (60%+) of the brain is "involved" in vision. However possibly less than 20% of the brain is dedicated to "visual-only" functioning. The other 40% is doing vision+touch, or vision+motor, or vision+attention, or vision+spatial navigation, or vision+meaning, etc.

The visual cortex of the brain is that part of the cerebral cortex which processesvisual information. It is located in the occipital lobe. Visual nerves run straight from the eye to the primary visual cortex to the visual association cortex.