Respiratory system

• • The respiratory system is the network of organs and tissues that help you breathe. It includes your airways, lungs and blood vessels. The muscles that power your lungs are also part of the respiratory system. These parts work together to move oxygen throughout the body and clean out waste gases like carbon dioxide
• •  to obtain oxygen from the external environment and supply it to the cells and to remove from the body the carbon dioxide produced by cellular metabolism.
• Nasal cavity

  • consists of all the bones, tissues, blood vessels, and nerves that make up the space inside the nose. The most important functions of the nasal cavity include warming and humidifying the air as you breathe and acting as a barrier for the immune system to keep harmful microbes from entering the body.
• • Nostril is the common name for the two anterior nares  (singular: naris) – the external openings in human nose that leads to the nasal cavity . They are the connection between air in the environment and the airways, through the posterior or internal nares, the inner opening of the nasal cavity into the pharynx
• • Larynx Is a hollow tube in the middle of your neck, just above your trachea (windpipe) and behind your esophagus. It makes it possible for you to make sounds, which is why it’s also called your voice box. It also lets air pass from your throat to your trachea and on to your lungs.
• Paranasal sinuses

  • are a group of four paired air-filled spaces that surround the nasal cavity
• • The human oral cavity refers to the mouth, and all its parts including the lips, tongue, teeth, and the roof and floor of the mouth . Primarily belonging to the digestive system, the oral cavity also plays an important role in respiration 
• • Your pharynx (throat) is a multitasking muscular funnel that helps you breathe and directs food and liquid to your digestive system. You can keep your pharynx healthy by quitting smoking and protecting yourself from infections.
• • The epiglottis is a cartilaginous flap that extends in front and above the laryngeal inlet, or more specifically the rima glottidis (glottis).
• • The trachea (also called the windpipe) is the large tube that brings air from the nasal passages, throat, and larynx (the upper respiratory tract) to the two large airways that branch off into each lung (bronchi). An important function of the trachea is warming and moisturizing the air, as well as catching debris and microbes before they can enter the lungs
• Right primary bronchus

  •  Is wider, shorter, and more vertical than the left main bronchus, and it enters the right lung at roughly the level of the fifth thoracic vertebra. The right main bronchus has 3 subdivisions, which become secondary bronchi also known as lobar bronchi, which deliver air to the 3 lobes of the right lung. 
• • The superior lobe of the lungs have inferior borders extending posteriorly to the fourth rib for right and left lung, and extending anteriorly in front of the fourth rib on right, and in front of the sixth rib on left.
• • Only the right lung has a middle lobe. As the name implies, this lobe is located between the upper and lower (also called the superior and inferior) lobes. Each lobe receives air from its own branch of the bronchial tree, called lobar (or secondary) bronchi. Within the lungs, these bronchi are divided into smaller tubes. The smallest of these tubes is called a bronchiole. Bronchioles control the exchange of gases with the alveoli, which are tiny air sacs in the lungs.
• Inferior lobe right lungs

  • It’s shorter than your left lung, but also wider than your left lung. Both of your lungs are covered with a protective covering called pleural tissue
• Left primary bronchus

  •  Is  smaller in size, but longer in length (~5 cm, as opposed to 2-3 cm long) than the right main bronchus. The left main bronchus enters the root of the left lung opposite to the sixth thoracic vertebra, passes underneath the aortic arch, and crosses in front of the esophagus, the thoracic duct, and the descending aorta.
• Alveoli

  • are tiny, balloon-shaped air sacs located at the end of the bronchioles, the branch-like tubes in the lungs. The alveoli move oxygen and carbon dioxide (CO2) molecules into and out of your bloodstream.
• • The bronchi are the two large tubes that carry air from your windpipe to your lungs. You have a left and right main bronchus in each lung. After the main bronchi, these tubes branch out into segments that look like tree branches. Many respiratory conditions, such as asthma or bronchitis, can affect your bronchi
• • Bronchioles are air passages inside the lungs. They branch off like tree limbs from the bronchi—the two main air passages through which air flows from the trachea (windpipe) after being inhaled through the nose or mouth.
• • The superior lobe of the left lung is subdivided into four bronchopulmonary segments; the apicoposterior, anterior, superior lingular, and inferior lingular bronchopulmonary segments. Each of these bronchopulmonary segments has its own segmental bronchus and segmental artery
• • The diaphragm is the primary muscle used in respiration, which is the process of breathing. This dome-shaped muscle is located just below the lungs and heart. It contracts continually as you breathe in and out
• • The inferior lobe forms the base of the left lung and a portion of the costal and mediastinal surfaces.