THE OVERVIEW OF RESPIRATORY SYSTEM

Main organs in respiratory system are lungs. Respiratory system also know as oxygen delivery system is a set of organs that allows a person to breath oxygen and exchange carbon dioxide throughout the body ( respiration). The integrated systems of organs involved in the intake of oxygen and exchange of carbon dioxide are following:

1.Nasal passages

2. Larynx

3.Trachea

4. Bronchial tubes

5. And lungs.

Types of respiratory system

1. Internal respiratory system

2. External respiratory system

Internal respiratory system

Bringing oxygen to the cells and removing carbon dioxide from the cell is known as internal respiratory system.

External respiratory system

Exchange of gases (oxygen and carbon dioxide) between the body and the outside environment is known as external respiratory system.

Structures involved in respiratory system

1. Nose

2.Nasal cavity

3. Pharynx (that divided into esophagus and trachea)

4. Larynx (voice box)

5.Trachea (that divided into two tubes known as Bronchus)

6. Bronchus (that divide into Bronchioles)

7. Alveoli (Tiny sacs at the end of the bronchioles. IN adult human lungs the main alveolar number is approximately 480 million. The alveoli is composed of alveolar epithelial cells and capillary cells).

8. Lungs (Right lung that contain 3 lobes. Left lung is usually smaller in size than the right lung because of the presence of heart)

9. Diaphragm(that separated respiratory system to digestive system).

Functions of the respiratory system

Exchange of gases

Filters inhaled air

Phonation (production of sound)

Regulate blood PH

Contains receptors for smell.

Breathing

Breathing is commonly refereed as pulmonary ventilation.

Phases of breathing

1. Inhalation (inspiration)

2. Exhalation (expiration)

Inhalation (Active process)

Inspiration is the process of bringing air into the lungs (inhalation). It is the active phase of breathing since the muscles are contracting. During inspiration, the diaphragm contracts and the thoracic cavity enlarges. Due to the decreased interalveolar pressure, air can now enter the lungs.

Exhalation (Passive process)

Expiration is the process of releasing air from the lungs throughout the breathing cycle (exhalation). During expiration, the thoracic volume decreases and the interalveolar pressure increases as a result of the diaphragm relaxing and tissue elastically recoiling.

Divisions of respiratory system

1. Upper respiratory system

2. Lower respiratory system

Upper respiratory tract

The upper respiratory system or tract consists of the following structures:

Nose

Nasal cavity

Sinuses

Pharynx

Larynx.

Note

Nostrils are the two opening of the nasal cavity through which the air entered. Human mouth and nasal cavity is separated by hard palate. Nasal cavity and mouth is opened in the common paths that is than divided into two pathways. One is termed as esophagus (food pipe) and the other one is termed as trachea (wind pipe). This common pathway is termed as laryngopharynx that is covered by epiglottis.

Lower respiratory tract

The lower respiratory tract consists of the following structures:

Trachea

Bronchial Tree

Lungs

Structures of upper respiratory system

Nose

The upper respiratory system’s nose is what allows, filters air (through cilia) warms, and moistens air as it enters the body. The external nares are another name for the nose that contain the paranasal sinuses, which actually warm the air that enters.

Nasal Cavity

The palatine bone, which divided the nasal cavity from the mouth, is contained in the hard palate (A condition known as cleft palate results from improper palatine bone development and makes it difficult to speak and swallow).

Sinuses

Two tiny holes, known as nostrils, can be found in the human nose and are separated by a septum (septum is made up of cartilage tissue which is flexible material and not hard as bone). Sinuses are the air containing spaces that open and drain into nose.

Pharynx

The pharynx — also known as the throat (12 to 14cm long tube) is a space that is utilized by both the digestive and respiratory systems. The pharynx extends inferiorly near the level of the larynx and esophagus and originates in the posterior part of the oral and nasal cavities. The skeleton muscles that covers the pharynx’s walls contains the mucosa that are used for swallowing. Additionally, the flexible lateral walls of the pharynx force food to be swallowed completely into the esophagus.

Parts of Pharynx

The pharynx is made up of three parts:

1. Nasopharynx (The nasopharynx continues into the nasal cavity, which aids in conditioning the air that is inspired. It contains the pharyngeal tonsils which help in the body immune defense).

2. Oropharynx (Both voluntary and involuntary swallowing are assisted by the oropharynx. It contains the palatine tonsils which help in the body defense).

3. Laryngopharynx (It is the bottom section of the pharynx where respiratory track divides into esophagus and larynx.The laryngopharynx aids in the development of the voice and speaking).

Larynx (vocal cords)

The larynx is a tube that is 2 inches long in humans and is a part of the upper respiratory system. It allows air to move from the throat (pharynx) to the trachea on the way to the lungs, and is smaller in women than in men since a large larynx typically results in a deeper voice. Additionally, it is known as the the voice box, sometimes referred to as the vocal cords, which aid in sound production. The larynx is placed at the level of the Adams apple in the middle of the neck (Adams apple is refer as neck bone that is located between fourth and sixth cervical vertebrae).

Parts of Larynx

The larynx is made up of following parts

1. Epiglottis: The epiglottis is the skin that covers the larynx’s aperture and serves to keep food and other objects out of the respiratory system.

2. False vocal cords: The vestibular folds, commonly referred to as false vocal cords, are the structures that shut the larynx when food is swallowed to prevent it from entering the trachea and lungs (lower respiratory system).

3. Thyroid cartilage: Adams apple is another name for thyroid cartilage.

4. Vocal cords: When air flows through vocal cords or vocal folds, they open, close, and vibrate to produce sound and speech.

Structures of lower respiratory system

Trachea

The crucial component of the lower respiratory system is the trachea, also referred to as the windpipe. The larynx (voice box) is connected to the bronchi through a U-shaped tube that is 4 inches (10 centimetres) long. There are 16 to 20 cartilage rings in the trachea. The most common type of flexible connective tissue is cartilage. Each ring of tracheal cartilage was coated with moist tissue called mucosa. The goblet cells are found in the mucosa. Mucus is a sticky substance produced by goblet cells in the mucosa. Mucus catches dust and other microscopic particles during inhalation to prevent them from entering the lungs. Small cilia, which resemble tiny hairs, are found in the inner layer of the trachea and move rhythmically to expel mucus.

The trachealis muscle is located between each ring of cartilage in the trachea. Trachealis muscle contracts during cough it helps to expel air with greater force. The manubriosternal joint is a fibrocartilage joint that allows a hinge joint-like movement and allows the body to move forward during deep inspiration, at the level of the sternum angle (also called Louis angle). It lies between the T4 and T5 thoracic vertebrae at the level of the intervertebral disc. Sternal angle in males is 163 degrees and in female is 165 degrees) trachea is divided into two smaller tubes called the right and left bronchi.

Parts of trachea

1. Cervical trachea (in neck).

2. Thoracic trachea (in chest).

Bronchi

The bronchi are two large tubes that bring air to the lungs from the trachea. The bronchi also has cilia. The primary bronchus splits into two bronchi, which are referred to as the secondary bronchus (lobar bronchi). The secondary bronchus also splits into two bronchi, which are referred to as the tertiary bronchus (segmental bronchi). At the end of the tertiary bronchus, there are terminal bronchioles, which are also referred to as respiratory bronchioles.These bronchioles have formed small ducts (alveolar ducts) that are open in alveolar sacs called alveoli, where the process of gas exchange takes place.

Lungs

From the diaphragm, which separates the abdominal cavity from the respiratory cavity, to the clavicles, the lung is the main organ of the respiratory system. And the lungs are separated by the mediastinum which divided into sections and lobes. Lungs are divided into two sections: the right lung has three lobes by an oblique or horizontal fissure, is higher up in the body because the liver is on the right side, and is slightly larger than the left lung, which has two lobes by an oblique fissure.

Visceral pleura, a protective membrane that covers the lung, Nevertheless, the parietal pleura line the superior surface of the diaphragm and the lateral surface of the mediasternum of the internal thoracic wall. At each lung’s hilus, these two pleura — visceral or parietal — continue. A cavity that contain a fluid known as the pleural fluid separates the visceral or parietal pleura. As a lubricant, this pleural fluid moves around in the pleural cavity to keep breathing friction to a minimum.

How lungs work

The oxygen from the air that humans breathe in moves into their blood during inhalation (breathing). In contrast, carbon dioxide, which is actually waste gas, moves into the lungs and is exhaled (breath out) from the body. The trachea, muscles of the chest wall, the diaphragm, blood vessels, blood capillaries, and other tissues of the respiratory system enable breathing and gas exchange.