Respiratory system

 The respiratory system (or ventilatory system) is the biological system of an organism that introduces respiratory gases to the interior and performs gas exchange. In humans and other mammals, the anatomical features of the respiratory system include airways, lungs, and the respiratory muscles. Molecules of oxygen and carbon dioxide are passively exchanged, by diffusion, between the gaseous external environment and the blood. This exchange process occurs in the alveolar region of the lungs. Other animals, such as insects, have respiratory systems with very simple anatomical features, and in amphibians even the skin plays a vital role in gas exchange. Plants also have respiratory systems but the directionality of gas exchange can be opposite to that in animals. The respiratory system in plants also includes anatomical features such as holes on the undersides of leaves known as stomata

What makes up the respiratory system?

The respiratory system is made up of the organs involved in the interchanges of gases, and consists of the:

• Nose
• Mouth (oral cavity)
• Pharynx (throat)
• Larynx (voice box)
• Trachea (windpipe)
• Bronchi
• Lungs

The upper respiratory tract includes the:

• Nose
• Nasal cavity
• Ethmoidal air cells
• Frontal sinuses
• Maxillary sinus
• Sphenoidal sinus
• Larynx
• Trachea

The lower respiratory tract includes the:

• Lungs
• Airways (bronchi and bronchioles) 
• Air sacs (alveoli)

What are the functions of the lungs?

The lungs take in oxygen, which the body's cells need to live and carry out their normal functions. The lungs also get rid of carbon dioxide, a waste product of the cells.

The lungs are a pair of cone-shaped organs made up of spongy, pinkish-gray tissue. They take up most of the space in the chest, or the thorax (the part of the body between the base of the neck and diaphragm).

The lungs are enveloped in a membrane called the pleura.

The lungs are separated from each other by the mediastinum, an area that contains the following:

• Heart and its large vessels
• Tachea (windpipe)
• Esophagus
• Thymus
• Lymph nodes

The right lung has three sections, called lobes. The left lung has two lobes. When you breathe, the air:

• Enters the body through the nose or the mouth
• Travels down the throat through the larynx (voice box) and trachea (windpipe)
• Goes into the lungs through tubes called main-stem bronchi
  
  • One main-stem bronchus leads to the right lung and one to the left lung
  • In the lungs, the main-stem bronchi divide into smaller bronchi
  • And then into even smaller tubes called bronchioles
  • Bronchioles end in tiny air sacs called alveoli

Lung Diseases

When you breathe, your lungs take in oxygen from the air and deliver it to the bloodstream. The cells in your body need oxygen to work and grow. During a normal day, you breathe nearly 25,000 times. People with lung disease have difficulty breathing. Millions of people in the U.S. have lung disease. If all types of lung disease are lumped together, it is the number three killer in the United States.

The term lung disease refers to many disorders affecting the lungs, such as asthma, chronic obstructive pulmonary disease, infections like influenza, pneumonia and tuberculosis, lung cancer, and many other breathing problems. Some lung diseases can lead to respiratory failure.

Asthma

  Asthma is a chronic disease that affects your airways. Your airways are tubes that carry air in and out of your lungs. If you have asthma, the inside walls of your airways become sore and swollen. That makes them very sensitive, and they may react strongly to things that you are allergic to or find irritating. When your airways react, they get narrower and your lungs get less air. This can cause wheezing, coughing, chest tightness and trouble breathing, especially early in the morning or at night.

When your asthma symptoms become worse than usual, it's called an asthma attack. In a severe asthma attack, the airways can close so much that your vital organs do not get enough oxygen. People can die from severe asthma attacks.

Asthma is treated with two kinds of medicines: quick-relief medicines to stop asthma symptoms and long-term control medicines to prevent symptoms.