STOP SMOKING !

       (NO SMOKING)

Biological consequences of smoking

Smoking can have major negative biological effects on the human body. Tobacco smoke contains, tar, nicotine, metals, the majority of the particulate matter that is inhaled by  a smoker is composed of tar. Within a particle of tar, there are many different harmful organic chemical identified as carcinogens and tumor initiators. Tar in its solid from is the component that stains the teeth and fingers of smokers. This substances also can stain and damage the lung tissue. Tar also increases the production of mucous and phlegm.

Nicotine has many harmful effects such as increased heart rate and blood pressure, constriction of blood vessels, and damage to the muscles, hormonal systems, and  metabolism. Nicotine can also increases platelet stickiness in the blood which can cause blockage and cause coronary diseases.

Carbon monoxide is formed when a cigarette is lit. It is odorless and tasteless and in large dose, it is fatal. Carbon monoxide is linked with coronary heart disease and affecting vision. Al though carbon monoxide is not a carcinogen, it is thought to contribute to certain cancer, including lung cancer. Carbon monoxide inhibits the respiratory systems ability to clean out the airways with mucus.

        When carbon monoxide enters the airways, it stays along with other toxic chemicals contained in cigarette             smoke. These toxins cause inflammation, impair lung functions, and increase the risk of long disease. Nitrogen oxides are found in high dose in cigarette smoke. It is responsible for causing lung damage leading to emphysema. Hydrogen cyanide is proven to have a Destructive effect on the cilia.

The cilia are a part of the long clearance system in humans. When the lung clearance system is damaged and toxic agents build up, the likelihood of developing a disease increases. Thirty different metals have been found in cigarette smoke. many of which have been linked to cancer. A few of the metals found are; arsenic, nickel, cadmium, chromium, and lead. Along with metals, radioactive compounds have been found in cigarettes, all of them being carcinogens.

Lung Cancer

 Lung cancer is also a respiratory disease, which is more common in men then in the women. The most common causes are smoking, industrial carcinogens and air pollution. Symptoms of lung cancer are cough with sputum, breathlessness and pleural chest pain. Cancer is very dangerous and fatal disease, which results from the uncontrolled cell division.

Tar of cigarettes is one of the major causes of the lung cancer. The chemicals produced by the smoke of cigarette damages the cells of the internal epithelium of lunge and air tubes which can lead to the thickening of their walls ultimately blocking them.

IMPORTANT P0INTS        v   Cigarette smoke contains five main ingredient I.e. nicotine, tar carbon monoxide, irritants and carcinogens (cancer producing).

                                                                                    

     v  Tar is the major cause of lung cancer. Tar is a brown black sticky substance. It is then deposits in lung where it passes into blood. It also damages the cell of wind pipe.

 v  Cigarette smoke also contain nicotine. It is a addictive drug and dissolves in fats of body. It is very difficult to excrete it from the body because it dissolves in fats and insoluble in water. Small quantity of nicotine in the blood stream speed up the activity of the nervous system.

v  Cancerous lung become brownish or blackish as compare to the lung of a healthy person. Because tar deposits on the lining of lungs branchial[S1]  tub.

v  Filters are used by smokers to filter the tar of the smoke so that it may not reach the lung.

 v  Observe the following photographs of lung of a healthy person and that of a smoker.

---

 [S1]

(STOP NO SMOKING)

The Eye

The eye is one of the natures wonders. It is a very sensitive organ of our body. The eye lie in the sockets in the skull. The eye is covered with the you study the internal structure of the human eye. If you see inside the eye from a side, you will observe that the eye has the following parts;

Photoreceptors

They are also known as visual receptors .Eye is the organ used as photoreceptor in human body. A pair of eyes is present in human beings whish are present in the orbits one the face.

       An eye is a very complex  structure. It is in the form of a ball. Eye consists of three layers; sclerotic, the retina, the nervous layer.

      The outer most white, tough, muscular layer is called sclera which covers the eye outside. Its anterior part is transparent and bulging to make cornea. The colorued  a small hole called pupil which control the amount of light entering the eye. It windens when light is dim and narrows when light is bright. Behind pupil a lens is present which focus images from different on the  retina. Lens is held by ciliary muscles and suspensory ligament  which control the focusing  of lens automatically. The chamber in betweens  lens and cornea is filled with a fluid called aquous humour which nourishes cornea, lense…


Observations
                                
1: Sclera (sclerotic coat)          2: Choroid        3: Cornea 4: Retina       5: Iris        6: pupil       7: Aqueous humour  8:Vitreous humour       9: Lens       10: Muscles                

HUMAN EYE




Choroid is the vascular layer of the eye and provides nourishment to the eye. The third innermost layer of the eye is retina. This  layer is composed of special type of neurons called rods and cones. Rods are used to perceive dim light. They give us the image of the object but not colours  and detail. Whereas cones are responsible for visualizing colours. The space between retina and lens is filled by a jelly like substance called vitreous humor which is also nutritive in function. Retina is the nervous layer composed of sensory neurons. Lens focuses the image of the object front of the eye on the retina which is transmitted to brain by optic nerve.The image is finally perceived by brain.

    
                               BULL EYE

Disorders of Eye

       Eyes send a huge amount of information to brain. Sometimes a defect occurs in the working of eyes which causes great disturbance in the life of a person. Some of these disorders are vary serious and lead to blindness but some disorders are easily curable. Two disorders generally known as long sightedness and short sightedness are very common. These defects occur in old age. In these disorders the lens of the eye is not able to adjust itself to focus the image on the retina. Hence the vision is disturbed.

    Sort sightedness or near sightedness ,is a common eye disorder in which a parson can see closer objects clearly but the distant objects are not clearly visible technically this disorder is known as myopia it is caused by an unusually long eyeball which makes light rays focus too far in front of the retina, or the back of the eye, instead of focusing on the surface of the retina. Because light is focused too early, a blurred image is left on the retina.

The disorder is corrected by using a concave lens is glasses. This lens focuses the rays on the retina and the person is again able to see correctly.

          Long sightedness or farsightedness, is a disorder in which a o person feels difficulty in focusing on near objects but can see far  objects clearly. This is because the image focuses at a point behind retina. The disorder is caused when the eyeball is to short or the shape of the lens is not round. Technically this disorder is known as hypermetropia or simply hyperopia.   

The disorder is corrected by using a convex lens in glasses. This lens focuses the rays on the retina and the person is again able to see correctly.