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Eyes: How They Work, Anatomy and Common Condition

 The eye is a complex sensory organ that allows us to see the world around us. The eye works by gathering light from the environment and converting it into electrical signals that can be interpreted by the brain. The basic structure of the eye includes the cornea, iris, pupil, lens, retina, and optic nerve. The cornea is the transparent outer layer of the eye that helps to focus incoming light. The iris is the colored part of the eye that regulates the amount of light that enters the eye through the pupil, which is the black circular opening in the center of the iris. The lens is a clear, flexible structure located behind the iris that helps to focus light onto the retina. The retina is a thin layer of tissue that lines the back of the eye and contains photoreceptor cells called rods and cones. These cells convert light into electrical signals that are sent to the brain via the optic nerve. The rods are responsible for the low light vision and detecting motion, while the cones are resp
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ASTHMA

Asthma also called bronchial asthma is a disease that affects your lungs. It's a chronic (ongoing) condition that doesn't go away and needs ongoing medical management.                                                                        Asthma affects more than 25 million people in the  U.S. currently. This includes more than 5 million children.. Asthma can be life-threatening if you don't get treatment. 

Types of Asthma:-

Asthma is divided into types based on the causes and the severity of the symptoms. healthcare providers identify asthma as:

*  Intermittent: This type of asthma comes and goes so you can feel normal in between asthma flares 

*  Persistent: Persistent asthma means you have symptoms much of the time. Symptoms can be mild, moderate, or severe. Healthcare provider base asthma severity on how often you have symptoms. they also consider how well you can do things during an attack.

Asthma has multiple causes

*Allergic: some people's allergies can cause an asthma attack. allergens include things like molds and pet dander.

*Nonallergic: Outside factors can cause asthma to flare up. Exercise, stress, illnesses, and weather may cause a flare.

    Symptoms:

Asthma symptoms vary from person to person. You may have infrequent asthma attacks, have symptoms only at certain times - such as when exercising - or have symptoms all the time.

Asthma signs and symptoms include: 

* Shortness of breath.

* Chest tightness or pain.

* Wheezing when exhaling, Which is a common sign of asthma in children.

* Trouble sleeping caused by shortness of breath, coughing, or wheezing.

* Coughing or wheezing attacks that are worsened by a respiratory virus, such as a cold or the flu.

Signs that your asthma is  probably worsening include:

* Asthma signs and symptoms that are more frequent and bothersome.

* Increasing difficulty breathing, as measured with a device used to check how well your lungs are working (peak flow meter)

* The need to use a quick-relief inhaler more often.

For some people, asthma signs and symptoms flare up in certain situations:

* Exercise-induced asthma, Which may be worse when the air is cold and dry.

* Occupational asthma, triggered by workplace irritants such as chemical fumes, gases, or dust.

* Allergy-induced asthma, triggered by airborne substances, such as pollen, mold spores, cockroach waste, or particles of skin and dried saliva shed by pets (pet dander)


Causes 

It isn't clear why some people get asthma and others don't, but it's probably due to a combination of environmental and inherited (genetic) factors.

Asthma triggers

Exposure to various irritants and substances that trigger allergies (allergens) can trigger signs and symptoms of asthma. Asthma triggers are different from person to person and can include:

* Airborne allergens, such as pollen, dust mites, mold spores, pet dander, or particles of cockroach waste

* Respiratory infections, such as the common cold 

* Physical activity

* Cold air

* Air  pollutants and irritants, such as smoke 

* Certain medications, including beta blockers, aspirin, and nonsteroidal anti-inflammatory drugs, such as ibuprofen (Advil, Motrin IB, others) and naproxen sodium (Aleve)

* Strong emotions and stress

* Sulfites and preservatives added to some types of foods and beverages, including shrimp, dried fruit, processed potatoes, beer, and wine

* Gastroesophageal reflux disease (GERD), a condition in which stomach acids back up into your throat.


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