Having a little red button not far from his desk must give a President an enormous _________ .
Without a __________ you’ll never be able to hit the ball correctly.
Some people say that a _________ is the only thing that makes difficult situations bearable.
He went ahead and arrested his uncle through a ________ .
One of the major tasks of parents should be to give their children a ________ .
His inborn _______ led him to the slopes of the Himalayas.
At high altitudes one is apt to lose one’s ________ .
His _________ is so strong, he protests to umpires on behalf of his opponent.
Personally, I don’t call putting dead fish in friend’s beds a sign of a healthy ____________ .
Text 1 Read the text and give answers to the questions. What does the physiology of vision rely upon?
Describe the function of the lens, pupil, and retina.
Which organs comprise the refracting media?
Describe the procedure of forming the image.
What is the point of visual acuity?
What is strabismus?
Physiology of Vision
The physiology of vision relies upon two different types of cells in the retina: the rod-shaped cells (rods) and cone-shaped cells (cones). The rods permit vision when there is poor light. They form the outlines of objects and are primarily concerned with twilight vision. They detect movement in the environment and use a visual pigment called rhodopsin. The cones are most concerned with daylight vision. The cones enable one to see details and are responsible for colour vision. When light energy stimulates the rods and cones in the retina, chemical reactions rapidly take place in these visual receptors. These events give rise to nerve impulses, which are transported over the optic nerve and optic tract to the visual cortex of the brain where they are interpreted. No visual receptors are found at a region of the retina called the optic disk, and therefore, this portion of the retina is called the blind spot. The image reaching the retina occurs in the inverted position due to the optical properties of the lens of the eye, but the image is made upright by the cortex of the occipital lobe of the brain.
The pathway of light to the eye begins at the clear cornea, which lies at the surface of the eye. Light then passes through the pupil, which varies in size according to the distance of the object being viewed: the pupil is smaller when the object is close and larger when the object is far away. Light rays then pass through the aqueous humour to the lens, the principal structure of light focusing. The lens is elastic and focuses light rays on the retina. This process of light focusing based on lens elasticity is called accommodation. When the object is distant, the lens becomes flattened; when the object is near, the lens becomes more rounded (convex). The lens changes its shape chiefly by the activity of the ciliary muscle acting on the suspensory ligament. During accommodation for near vision, for example, the ciliary muscle contracts and releases tension of the suspensory ligament, thereby, allowing the lens to become more convex due to its natural elasticity and tendency to assume the shape of a sphere.
The lens, cornea, aqueous humour, and vitreous humour all represent refracting media, which are media that focus light rays and cause them to converge on the fovea centralis of the retina (a tiny depression that has a high concentration of cone cells and is the point of visual acuity (sharpest vision)), where the image is formed. The fovea is surrounded by a yellowish spot called the macula. The area served by an eye is called the external visual field. The external visual field usually overlaps that of the other eye, and this overlap is responsible for three dimensional image. The extrinsic muscles of the eye bring about the movements of the eyeball that help one see a single image. Persons having strabismus (cross-eyes) have a condition in which the eyes do not converge together, and the person sees two images instead of one.
Text 2 Read the text and give answers to the questions. What are the two main functions of the ear?
What is intensity?
What is the pitch determined by?
How is sound transmitted?
When does hearing loss appear?
Physiology of Hearing
The ear has two distinct functions. The auditory component is concerned with the sensation of hearing, while the vestibular portion provides information to the brain about the movement and position of the head. The sensory elements of both components are hair cells in the inner ear. These are excited by the bending of hairs and are referred to as mechanoreceptors. The mechanoreceptors perceive the vibrations as sound. The human ear can distinguish among the properties of sound, which include intensity, pitch, and timbre. Intensity or loudness is measured in units called decibels. Pitch is determined by the frequency of vibrations, with higher frequencies producing higher-pitched sounds. The range of frequencies, to which the human ear is sensitive, is from 20 to 20.000 hertz (vibration cycles per second). Timbre refers to the quality of sound and depends on the presence of several frequencies.
Sound is transmitted through the ear by passing through the external auditory meatus and causing the tympanic membrane to vibrate. These vibrations are transferred to the ossicles of the middle ear (the malleus, incus and stapes) and amplified as they reach the oval window. Vibrations of the oval window cause the fluid of the scala vestibuli to vibrate. This disturbance causes certain portions of the basilar membrane to bulge into the cochlear duct. Basilar membrane movement stimulates the hair cells of the organ of Corti, which results in the conduction of impulses along the cochlear nerve. Vibrations of the fluid of the scala vestibuli are transferred to the scala tympani and spread as the round window bulges toward the middle ear. Damage to this conduction system, the nerve fibres, or receptor cells results in hearing loss or deafness.
Read the paragraph. Select the correct word to complete the sentences.
(Pitch / Ditch / Pinna) is a musical term which is similar in meaning to the scientific term frequency. The (rarefaction / waves / frequency) of a sound represents the number of vibrations that occur in one second. However, the sensations of these frequencies are commonly referred to as the pitch of a (frequency / sound / noise). Objects that vibrate more rapidly, that is, have more (frequencies / vibrations / waves) per second will have a (meaner / lower / higher) pitch than objects that vibrate more slowly. So, on a guitar the strings that produce notes with a higher pitch vibrate (faster / slower / much slower). Another term for frequency is (lengths / cycles / waves) per second. The unit for frequency is (hertz / decibel / wave).
Put these sentences in the correct order.
We are able to hear sounds because they stimulate the auditory cells of the ear.
As the oval window picks up the vibrations, it transfers them to the cochlea in the inner ear.
As the vibrations pass between the ossicles, they are amplified.
At the end of this passage is the eardrum. As the sound waves hit the eardrum, they cause it to vibrate.
Hearing begins with the outer ear, when the pinna or earflap collects sound waves and directs them down the external auditory passage (ear canal).
The base of the stirrup vibrates against the oval window, which is a membrane that separates the middle ear from the inner ear.
The cochlea contains the sensory cells that produce impulses in the auditory nerve.
The vibrations from the eardrum are received by the hammer, which passes them to the anvil and then to the stirrup.
These impulses are transmitted to the brain where they are interpreted. At the end of the cochlea is the round window which functions as a pressure “safety valve” releasing the pressure in the cochlea caused from the vibrations of the oval window.
These are called the hammer, anvil and stirrup.
The vibrations of the eardrum are picked up by three small bones in the middle ear called the ossicles.
Pre-Text Assignments I. Learn the following words.
III. Add negative prefixes to the following words.
1. sufficient _______________
2. regular _______________
3. ability _______________
4. sensitive _______________
5. natural _______________
6. supervised _______________
7. proper _______________
8. allow _______________
9. appropriate _______________
10. normal _______________
11. common _______________
12. frequent _______________
IV. Find explanations on the right to the words in italics.
clouding of the lens
abnormality in position of the eye
abnormal increase in intraocular pressure
blocked sebaceous gland duct
Diseases of the Eye
Two common disorders of the eye are myopia and hyperopia. In myopia (nearsightedness), the image forms in front of the retina. This condition is due to elongation of the eyeball, or it may be caused by insufficient adjustment of a lens during accommodation. Glasses with biconcave lenses are used to focus the image on the retina. In hyperopia (farsightedness), the image forms behind the retina and is blurred because the eyeball is too short or because the lens is too flat to permit nearby vision. This defect often happens as the lens loses elasticity with age. Glasses with biconvex lenses are used to focus the image on the retina.
Astigmatism is caused by irregular curvature of a lens or cornea. It results in a light refraction so that the rays fall on different areas of the retina, thereby producing a blurry image. Astigmatism is the inability to separate two closely placed points. The condition is corrected by using cylinder-shaped lenses.
Another visual defect is colour blindness resulting from the inability of cones to react to certain colours of the spectrum. For example, a person may be colour blind to red and green colours. In this case, red and green cannot be distinguished because of the lack of cones sensitive to red and green. Colour blindness is usually a sex-linked genetic trait carried by females and expressed in males.
Cataract is a clouding of the lens. The lens is made up mainly of water and protein. Over time, protein can build up, clouding the light passing through the eye and making sight blurred or fuzzy. For most people, cataracts are a natural result of aging. Often cataracts develop in both eyes at the same time. The symptoms vary, but include a gradual blurring of vision, halos around lights, and double vision. The very worst cataracts – where the iris appears almost entirely clouded – can cause a total loss of vision. Cataracts develop for a variety of reasons, including long-term exposure to ultraviolet light, exposure to radiation, secondary effects of diseases such as diabetes, hypertension and advanced age, eye injury or trauma (possibly much earlier); they are usually a result of denaturation of lens protein. Genetic factors are often a cause of congenital cataracts and positive family history may also play a role in predisposing someone to cataracts at an earlier age, a phenomenon of “anticipation” in pre-senile cataracts. Risks that can be reduced:
drugs: some eye drops used to treat eye problems contain steroids. If unsupervised and taken over a long time, they can cause cataract;
diabetes: proper treatment can reduce the risk of cataract;
dehydration: people who have suffered severe dehydration seem more likely to suffer from cataract.
Correction of the disorder can be improved by surgical removal of the cataract and, in the case of a lens cataract, the implanting of a small intraocular lens. Special contact lenses or appropriate eyeglasses are other options.
Glaucoma is an abnormal increase in the intraocular pressure of the eyeball. The aqueous humour does not drain from the eye chamber as quickly as it is produced, causing a compression of both the blood vessels in the eyeball and the optic nerve. Retinal cells consequently die, and the optic nerve may waste away, thereby, producing blindness. Loss of vision develops gradually, and people may not realise they have it. On reaching an advanced stage, glaucoma is extremely difficult and expensive to treat. Glaucoma is often associated with ageing, though it is not confined to the elderly. People with glaucoma in their family history are far more likely to be at risk. The key to reducing the incidence of glaucoma is early diagnosis.
A sty (hordeolum) is a localized inflammation of a sebaceous gland of the eyelid. This common infection results from blocked glands within the eyelid. When the gland is blocked, the sebum produced by the gland occasionally backs up and extrudes through the wall of the gland, forming a lump (chalazion), which can be red, painful, and nodular. Frequently, bacteria can infect the blocked gland, causing increased inflammation, pain, and redness of the eye, and even redness of the surrounding eyelid and cheek tissue. The lump frequently goes away when the blockage of the gland opening is relieved. Furthermore, the infection goes away when the pus is drained from the sty.
Persons having strabismus (cross-eyes) have a condition in which the eyes do not converge together, and a person sees two images instead of one.
I. Find synonyms on the right to the words in italics.