Respiratory System PDF

Respiratory System Respiratory System two lungs airways - responsible for transporting air into the lungs, heat, moisten and clean the air so that it can enter the lungs. In the lungs, gaseous exchange will take place, capturing oxygen from the air and eliminating carbon dioxide. The re...

Respiratory System Respiratory System two lungs airways - responsible for transporting air into the lungs, heat, moisten and clean the air so that it can enter the lungs. In the lungs, gaseous exchange will take place, capturing oxygen from the air and eliminating carbon dioxide. The respiratory tract is formed by: nasal cavity, mouth, pharynx, larynx, trachea, bronchi and bronchioles. Respiratory epithelium Most of the respiratory tract is composed of pseudostratified columnar epithelium with cilia. It also has goblet cells that secrete mucus to trap particles or microorganisms suspended in the air. The cilia of this epithelium will move the mucus towards the pharynx, so that it is eliminated by expectoration or swallowing. Olfactory mucosa In the upper part of the nasal cavity, it is the olfactory region. Between the epithelial cells, bipolar neurons are interspersed with their dendrites oriented towards the nasal cavity, and their axons (which exit from the opposite side) pass through the ethmoid bone to reach the olfactory nerve. The odoriferous particles that are in suspension in the air stimulate the dendrites of these neurons and create an action potential that will be conducted through the olfactory nerve. Olfactory Receptors: Location and Structure | JoVe Pharynx It is a tubular organ that begins at the end of the nasal cavity and extends to the opening of the larynx and esophagus. It is an organ common to the respiratory and digestive apparatus. It is divided into three regions: - Nasopharynx: the first part at the end of the nasal cavity. It is lined by respiratory epithelium. - Oropharynx: located after the nasopharynx, communicates with the mouth. In the connective tissue there are important accumulations of lymphoid tissue known as tonsils. - Laryngopharynx: the last fragment, communicates with the larynx and esophagus. In its walls we also find smooth and skeletal muscles that intervene in swallowing.  Larynx It is a short and rigid tube located between the pharynx and the trachea. In the mucosa there are folds called vocal cords that contain an elastic connective tissue attached to muscles that control phonation. In the upper part there is a membrane of elastic cartilage, the epiglottis, which closes the entrance to the larynx during swallowing to avoid the passage of food or liquids to the respiratory system. Inside the larynx we have a respiratory epithelium.  Trachea It is a tube of about 12 cm length located after the larynx. Its wall is reinforced by rings of hyaline cartilage that prevent the trachea from collapsing. These rings are not closed on the back. In that area, the wall of the trachea contains smooth muscle that will control the diameter of the trachea. The interior of the trachea is lined by respiratory epithelium. Trachea - Concept | JoVe  Bronchial tree The trachea bifurcates into two primary bronchi that will penetrate the lungs. Inside the lung, primary bronchi are divided into secondary (lobar) and tertiary (segmental) bronchi. In these bronchi there are no rings of cartilage. They continue with the respiratory epithelium and the conjunctiva with elastic fibers, glands and lymphoid elements. The smooth muscle appears as two layers surrounding the entire wall of the bronchus. Bronchioles Tertiary bronchi branch into bronchioles, which are less than 1mm in diameter. In the bronchioles there is no cartilage, and the epithelium is simple cuboidal. Clara cells will appear in the epithelium; these cells have a protein secretion that also helps to eliminate toxins from the inhaled air. In addition, this secretion is tensoactive, maintaining surface tension to keep the bronchioles open. The Bronchial Tree - Concept | Anatomy and Physiology | JoVe Each bronchiole is subdivided to give rise to several terminal bronchioles, which constitute the final stretch of the respiratory tract. The terminal bronchioles branch to give rise to the respiratory bronchioles, which end in the so-called alveolar sacs. These alveolar sacs do not have their own walls but are formed by a sequence of pulmonary alveoli. Alveoli They are small sacks with thin walls that allow the exchange of oxygen and carbon dioxide between the air and the blood. Functional unit of the lung. The walls of the alveoli are coated by two types of cells. Type 1 pneumocytes are alveolar cells that line most of the alveolar surface. They are flattened cells that are closely linked to each other and act as an epithelium. Type 2 pneumocytes are alveolar cells that secrete pulmonary surfactant proteins to reduce surface tension and prevent the alveoli from collapsing. In addition, within the alveoli there are alveolar macrophages. They live in the lumen of the alveoli and phagocytize dust particles or inhaled microorganisms to maintain the sterile environment inside the lungs. Alveoli and Alveolar Ducts - Concept | Anatomy and Physiology | JoVe Lungs The right lung is subdivided into three lobes and the left into only two, due to the space occupied by the heart. In their medial zone, they all present a notch, the hilum, through which pulmonary arteries and veins, as well as lymphatic vessels, enter and leave. The lobes are separated from each other by connective walls. The lobes are divided into bronchopulmonary segments In the thoracic cavity, there is a serous membrane covering the lungs, the pleura, that allows the lungs to move without friction during ventilation. The Human Respiratory System: Lungs and Bronchi - Biology | JoVe Airways and Gas Exchange - YouTube