ASTHMA

Asthma (from the Greek word means "panting") may be the common chronic inflammatory disease from the airways characterized by variable and recurring symptoms, reversible airflow obstruction, and bronchospasm.Symptoms include wheezing, coughing, chest tightness, and difficulty breathing. Asthma is clinically classified based on the frequency of symptoms, forced expiratory volume in 1 second (FEV1), and peak expiratory flow rate. Asthma can also be classified as atopic (extrinsic) or non-atopic (intrinsic). Asthma is really a disorder that causes the airways from the lungs to swell and narrow, resulting in wheezing, shortness of breath, chest tightness, and coughing.

Anatomy of lungs

In humans, the trachea divides in to the two main bronchi that go into the roots of the lungs. The bronchi still divide within the lung, and after multiple divisions, produce bronchioles. The bronchial tree continues branching until it reaches the amount of terminal bronchioles, which result in alveolar sacs. Alveolar sacs are made up of clusters of alveoli, like individual grapes inside a bunch. The individual alveoli are tightly covered with blood vessels and it is here that gas exchange actually occurs. Deoxygenated blood in the heart is pumped with the pulmonary artery to the lungs, where oxygen diffuses into blood and it is exchanged for co2 in the hemoglobin of the erythrocytes. The oxygen-rich blood returns towards the heart via the pulmonary veins to become pumped back into systemic circulation.

Human lungs can be found in two cavities on each side of the heart. Though similar to look at, the two are not identical. Both of them are separated into lobes by fissures, with three lobes around the right and two around the left. The lobes are further split into segments and then into lobules, hexagonal divisions from the lungs that are the tiniest subdivision visible towards the naked eye. The ligament that divides lobules is usually blackened in smokers. The medial border from the right lung is nearly vertical, as the left lung contains a cardiac notch. The cardiac notch is really a concave impression molded to support the shape of the heart.

Each lobe is encompassed by a pleural cavity, featuring its two pleurae. The parietal pleura lies from the rib cage, and the visceral pleura depends on the surface of the lungs. Among the pleura is pleural fluid. The pleural cavity helps the lubricate the lungs, in addition to providing surface tension to help keep the lung surface in touch with the rib cage.

Lungs will be to a certain extent 'overbuilt' and also have a tremendous reserve volume than the oxygen exchange requirements when resting. Such excess capacity is among the reasons that individuals can smoke for a long time without having a noticeable reduction in lung function while still or moving slowly; in situations such as these only a small area of the lungs are actually perfused with blood for gas exchange. Destruction of a lot of alveoli over time leads to the problem emphysema, which is associated with extreme difficulty breathing. As oxygen requirements increase because of exercise, a greater amount of the lungs is perfused, allowing your body to match its CO2/O2 exchange requirements. Additionally, because of the excess capacity, it's possible for humans to reside with only one lung, using the other compensating because of its loss.

The environment from the lung is very moist, that makes it hospitable for bacteria. Many respiratory illnesses would be the result of bacterial or viral infection from the lungs. Inflammation from the lungs is known as pneumonia; inflammation from the pleura surrounding the lungs is called pleurisy.

Vital capacity may be the maximum volume of air that an individual can exhale after maximum inhalation; it may be measured with a spirometer. In conjunction with other physiological measurements, the vital capacity might help make a diagnosis of underlying lung disease.

The lung parenchyma is strictly accustomed to refer solely to alveolar tissue with respiratory bronchioles, alveolar ducts and terminal bronchioles. However, many times, it includes any form of lung tissue, also including bronchioles, bronchi, arteries and lung interstitium

Physiology of lungs

Ventilation may be the exchange of air between your external environment and also the alveoli. Air moves by bulk flow from a place of high pressure to low pressure. All pressures within the respiratory system are in accordance with atmospheric pressure (760mmHg at sea level). Air will relocate or out of the lungs with respect to the pressure in the alveoli. Your body changes the pressure within the alveoli by changing the amount of the lungs. As volume increases pressure decreases so that as volume decreases pressure increases. There's two phases of ventilation; inspiration and expiration. During each phase your body changes the lung dimensions to make a flow of air either in or from the lungs.

The body has the capacity to stay at the dimensions of the lungs due to the relationship of the lungs towards the thoracic wall. Each lung is totally enclosed in a sac known as the pleural sac. Two structures bring about the formation of this sac. The parietal pleura is connected to the thoracic wall whereas the visceral pleura is connected to the lung itself. In-between these two membranes is really a thin layer of intrapleural fluid. The intrapleural fluid completely surrounds the lungs and lubricates the 2 surfaces so that they can slide across one another. Changing the pressure of the fluid also allows the lungs and also the thoracic wall to move together during normal breathing. Much the way in which two glass slides with water in-between options are difficult to pull apart, such may be the relationship of the lungs towards the thoracic wall.The rhythm of ventilation can also be controlled by the "Respiratory Center" that is located largely within the medulla oblongata of the brain stem. This really is part of the autonomic system and therefore is not controlled voluntarily (it's possible to increase or decrease breathing rate voluntarily, but which involves a different part of the brain). While resting, the respiratory center sends out action potentials that travel across the phrenic nerves into the diaphragm and also the external intercostal muscles from the rib cage, causing inhalation. Relaxed exhalation occurs between impulses once the muscles relax. Normal adults possess a breathing rate of 12-20 respirations each minute.

The Pathway of Air

When one breathes air in on the ocean level, the inhalation consists of different gases. These gases as well as their quantities are Oxygen making up 21%, Nitrogen which is 78%, Co2 with 0.04% yet others with significantly smallerportions. In the process of breathing, air goes into the nasal cavity with the nostrils and is filtered by coarse hairs (vibrissae) and mucous which are found there. The vibrissae filter macroparticles, that are particles of large size. Dust, pollen, smoke, and fine particles are held in the mucous that lines the nasal cavities (hollow spaces inside the bones of the skull that warm, moisten, and filter the environment). There are three bony projections within the nasal cavity. The highest, middle, and inferior nasal conchae. Air passes between these conchae through the nasal meatuses.

Air then travels beyond the nasopharynx, oropharynx, and laryngopharynx, which are the three portions that comprise the pharynx. The pharynx is really a funnel-shaped tube that connects our nasal and oral cavities towards the larynx. The tonsils which are area of the lymphatic system, form a diamond ring at the connection from the oral cavity and the pharynx. Here, they force away foreign invasion of antigens. And so the respiratory tract aids the defense mechanisms through this protection. Then your air travels with the larynx. The larynx closes in the epiglottis to prevent the passage of food or drink like a protection to our trachea and lungs. The larynx can also be our voicebox; it contains vocal cords, that produces sound. Sound is created from the vibration from the vocal cords when air passes through them.

The trachea, also is known as our windpipe, has ciliated cells and mucous secreting cells lining it, and it is held open by C-shaped cartilage rings. Among its functions is comparable to the larynx and nasal cavity, by means of protection from dust along with other particles. The dust will follow the sticky mucous and the cilia helps propel it support the trachea, to where it's either swallowed or coughed up. The mucociliary escalator extends in the top of the trachea all the way down towards the bronchioles, which we will discuss later. With the trachea, the air is now able to pass in to the bronchi. 

Inspiration

Inspiration is initiated by contraction from the diaphragm and in some cases the intercostals muscles once they receive nervous impulses. During normal quiet breathing, the phrenic nerves stimulate the diaphragm to contract and move downward in to the abdomen. This downward movement from the diaphragm enlarges the thorax. At the appropriate interval, the intercostal muscles may also increase the thorax by contacting and drawing the ribs upward and outward.

Because the diaphragm contracts inferiorly and thoracic muscles pull the chest area wall outwardly, the amount of the thoracic cavity increases. The lungs are held towards the thoracic wall by negative pressure within the pleural cavity, a very thin space full of a few milliliters of lubricating pleural fluid. The negative pressure within the pleural cavity is enough to contain the lungs open regardless of the inherent elasticity from the tissue. Hence, because the thoracic cavity increases in volume the lungs are pulled all sides to expand, creating a drop in the pressure (an incomplete vacuum) within the lung itself (but observe that this negative pressure continues to be not as great because the negative pressure inside the pleural cavity--otherwise the lungs would distance themself from the chest wall). Assuming the airway is open, air in the external environment then follows its pressure gradient down and expands the alveoli from the lungs, where gas exchange using the blood takes place. So long as pressure within the alveoli is gloomier than atmospheric pressure air continues to move inwardly, but when the pressure is stabilized air movement stops.

Expiration

During quiet breathing, expiration is generally a passive process and doesn't require muscles to operate (rather it is the consequence of the muscles relaxing). Once the lungs are stretched and expanded, stretch receptors inside the alveoli send inhibitory nerve impulses towards the medulla oblongata, causing it to prevent sending signals towards the rib cage and diaphragm to contract. The muscles of respiration and also the lungs themselves are elastic, then when the diaphragm and intercostal muscles relax it comes with an elastic recoil, which results in a positive pressure (pressure within the lungs becomes more than atmospheric pressure), and air moves from the lungs by flowing down its pressure gradient.

Even though respiratory system is primarily under involuntary control, and regulated through the medulla oblongata, we have some voluntary treatments for it also. This is because of the higher brain function from the cerebral cortex.

When under physical or emotional stress, more frequent and breathing is needed, and both inspiration and expiration will act as active processes. Additional muscles within the rib cage forcefully contract and push air quickly from the lungs. In addition to deeper breathing, when coughing or sneezing we exhale forcibly. Our stomach muscles will contract suddenly (if you find an urge to cough or sneeze), raising the abdominal pressure. The rapid rise in pressure pushes the relaxed diaphragm facing the pleural cavity. This will cause air to be forced from the lungs.

Another purpose of the respiratory system would be to sing and to speak. By exerting conscious treatments for our breathing and regulating air flow across the vocal cords we could create and modify sounds.

Homeostasis and Gas Exchange

Homeostasis is maintained through the respiratory system in two ways: gas exchange and regulating blood pH. Gas exchange is conducted by the lungs through the elimination of carbon dioxide, a waste product radiated by cellular respiration. As co2 exits the body, oxygen required for cellular respiration enters your body through the lungs. ATP, made by cellular respiration, offers the energy for the body to do many functions, including nerve conduction and muscle contraction. Insufficient oxygen affects thinking processes, sense of judgment, along with a host of other issues. 

Gas Exchange

Gas exchange within the lungs and in the alveoli is between your alveolar air and the blood within the pulmonary capillaries. This exchange is because of increased concentration of oxygen, along with a decrease of C02. This process of exchange is performed through diff 

External Respiration

External respiration may be the exchange of gas between your air in the alveoli and also the blood within the pulmonary capillaries. An ordinary rate of respiration is 12-25 breaths each minute. In external respiration, gases diffuse either in direction across the walls from the alveoli. Oxygen diffuses from the air in to the blood and co2 diffuses out of the blood in to the air. Most of the co2 is carried towards the lungs in plasma as bicarbonate ions (HCO3-). When blood enters the pulmonary capillaries, the bicarbonate ions and hydrogen ions are transformed into carbonic acid (H2CO3) and then back to carbon dioxide (CO2) and water. This chemical reaction also melts away hydrogen ions. The removal of these ions provides the blood a more neutral pH, allowing hemoglobin to bind up more oxygen. De-oxygenated blood "blue blood" from the pulmonary arteries, generally comes with an oxygen partial pressure (pp) of 40 mmHg and CO2 pp of 45 mmHg. Oxygenated blood leaving the lungs through the pulmonary veins includes a O2 pp of 100 mmHg and CO2 pp of 40 mmHg. It ought to be noted that alveolar O2 pp is 105 mmHg, and never 100 mmHg. The reason why pulmonary venous return blood includes a lower than expected O2 pp could be explained by "Ventilation Perfusion Mismatch

Internal Respiration

Internal respiration may be the exchanging of gases in the cellular

The Passage Way In the Trachea to the Bronchioles

There is a point in the inferior portion of the trachea where it branches into two directions that make up the right and left primary bronchus. This time is called the Carina the keel-like cartilage plate in the division point. We're now at the Bronchial Tree. It's named so since it has a series of respiratory tubes that branch off into smaller and smaller tubes because they run throughout the lungs.

Causes

Asthma is brought on by inflammation in the airways. When an asthma attack occurs, the muscles all around the airways become tight and also the lining of the airways swells. This cuts down on the amount of air that may pass by.

In sensitive people, asthma symptoms could be triggered by inhaling allergy-causing substances (called allergens or triggers).

Common asthma triggers include:

Animals (pet hair or dander)

Dust 

Alterations in weather (most often cold temperature)

Chemicals in the air or perhaps in 

Pollen

Mold

Food 

Respiratory infections, like the common cold

Strong emotions (stress)

Cigarettes

Aspirin and other nonsteroidal anti-inflammatory drugs (NSAIDs) provoke asthma in certain patients.

Many people with asthma possess a personal or genealogy of allergies, for example hay fever (allergic rhinitis) or eczema. Others don't have any history of allergies.

Symptoms

Many people with asthma have attacks separated by symptom-free periods. Many people have long-term shortness of breath with instances of increased shortness of breath. Either wheezing or perhaps a cough may be the main symptom.

Asthma attacks may last for minutes to days, and may become dangerous when the airflow is severely restricted.

Symptoms include:

Cough without or with sputum (phlegm) production

Pulling in of your skin between the ribs when breathing (intercostal retractions)

Difficulty breathing that gets worse with exercise or activity

Wheezing, which:

Is available in episodes with symptom-free periods among

May be worse during the night or in early morning

Might have to go away on its own

Gets better when utilizing drugs that open the airways (bronchodilators)

Worsens when breathing in cold air

Worsens with exercise

Worsens with heartburn (reflux)

Usually begins suddenly

Click the link to see a video about wheezing.

Emergency symptoms:

Bluish color towards the lips and face

Decreased degree of alertness, such as severe drowsiness or confusion, throughout an asthma attack

Extreme breathlessness

Rapid pulse

Sweating 

Other symptoms that could occur with this disease:

Abnormal respiratory rate --breathing out takes a lot more than twice as long as inhaling Breathing temporarily stops

Heart problems

Tightness in the chest

Sings and tests

Allergy testing might be helpful to identify allergens in individuals with persistent asthma. Common allergens include:

Cockroach allergens

Dustmites

Molds

Pollens

Common respiratory irritants

Fumes from burning wood or gas

Pollution

Cigarettes

The doctor will use a stethoscope to hear the lungs. Asthma-related sounds might be heard. However, lung sounds are often normal between asthma episodes.

Tests can include:

Arterial blood gas

Blood tests to measure eosinophil count (a kind of white blood cell) and IgE (a kind of immune system protein called an immunoglobulin)

Chest x-ray

Breathing tests

Peak flow measurements

Complications

The complications of asthma could be severe. Some include:

Death

Decreased capability to exercise and be a part of other activities

Lack of sleep because of nighttime symptoms

Permanent alterations in the function of the lungs

Persistent cough

Trouble breathing that needs breathing assistance (ventilator) ements to medications and proven physiotherapy treatments of Asthma