Respiratory system

The Respiratory System

• The respiratory system is essential for life, as it involves the exchange of oxygen and carbon dioxide.
• It consists of inhalation and exhalation.
• Ventilation is the process of moving air in and out of the lungs.
• The diaphragm is a dome-shaped muscle that contracts and relaxes to allow breathing, and the phrenic nerves stimulate it.
• The only structure that goes through the diaphragm is the esophagus
• Respiration is a process of breathing
• Inhalation is the process of taking in air
• Exhalation is the process of breathing out
• External respiration occurs in the lungs (gas exchange between air in alveoli and blood in pulmonary capillaries)
• Internal respiration occurs at the cellular level (gas exchange between tissue cells and blood in systemic capillaries)

Major Structures and Their Functions

• Nose (Nostrils/Nares): Exchanges air; warms, moisturizes, and filters inhaled air.
• Sinuses: Produce mucus, lightening the skull bones, and aiding sound production.
• Pharynx: Transports air back and forth between the nose and trachea.
• Larynx: Makes speech possible.
• Epiglottis: Closes the trachea during swallowing.
• Trachea: Transports air between the pharynx and bronchi.
• Bronchi: Transport air to the lungs. They divide into smaller and smaller tubes called bronchioles.
• Alveoli: Air sacs that exchange gases with pulmonary capillary blood. The alveoli produce a surfactant that makes them stable for optimal breathing.
• Lungs: Bring oxygen into the body and remove carbon dioxide and other waste. Lung tissue is divided into lobes. Right lung has three lobes (upper, middle, and lower) while left lung only has two (upper and lower).

Structures of the Respiratory System

• Upper respiratory tract(nose, mouth, pharynx, epiglottis, and larynx, and trachea): The initial segment of the respiratory system that filters, warms, and moistens incoming air.
• Lower respiratory tract(the bronchial tree and lungs): The part of the respiratory system that conveys air to the lungs and facilitates gas exchange.

The Nose

• The nostrils (nares) are the external openings of the nose.
• The nasal septum divides the nose into two sections.
• Cilia in the nostrils filter incoming air to remove debris.
• Mucous membranes line the nose and other parts of the respiratory system.
• Mucus moisturizes, warms, and filters the air; it is produced by mucous membranes.
• Olfactory receptors are nerve endings that sense smell.

The Tonsils

• Tonsils and adenoids are part of the lymphatic system.
• They protect the body from infection.
• Palatine tonsils are located in the back of the mouth, while nasopharyngeal (adenoid) tonsils are located behind the nose and the roof of the mouth.

The Paranasal Sinuses

• Air-filled cavities lined with mucous membranes in the skull bones.
• A sinus is a sac or cavity.

The Pharynx

• The pharynx (throat) is a shared pathway for air and food.
• It has three divisions: nasopharynx, oropharynx, and laryngopharynx.

Larynx and Cartilages

• The larynx (voice box) is located between the pharynx and trachea.
• Larynx is protected and supported by nine cartilages, the thyroid cartilage (Adam's apple) is the largest.
• Vocal cords are housed within the larynx
• Protective mechanisms for swallowing ensure only air goes into the lungs.

The Trachea

• The trachea transports air to and from the lungs.
• It is located in front of the esophagus.
• Flexible C-shaped cartilage rings hold the trachea open.

The Bronchi

• Two large tubes (primary bronchi) branch from the trachea.
• Bronchi convey air into the lungs (singular, bronchus).
• Refer to as the bronchial tree.
• Branch into smaller and smaller bronchioles.
• Bronchi have cartilage rings

The Alveoli

• Very small grapelike clusters, alveoli, are at the ends of bronchioles.
• Gas exchange occurs in alveoli (oxygen and carbon dioxide).
• A network of capillaries surrounds each alveolus.

The Lungs

• The essential organs of respiration.
• Divided into lobes (subdivisions of an organ), Right lung has three lobes, while the left has two.

The Mediastinum

• The middle section of the chest cavity between the lungs.
• Contains the heart, its vessels, esophagus, trachea, bronchi, thymus gland, and lymph nodes.

The Pleura

• Thin, moist, slippery membranes covering the lungs and the thoracic cavity.
• Parietal pleura lines the thoracic cavity.
• The visceral pleura covers the lungs.
• Pleural cavity is the space between parietal and visceral pleura.

The Diaphragm

• The diaphragm is a dome-shaped muscle separating the thoracic cavity from the abdomen.
• Its contraction and relaxation are essential for breathing.
• The phrenic nerve stimulates the diaphragm for breathing.
• The only structure passing through the diaphragm is the esophagus.

Respiratory Processes

• Inhalation: Diaphragm contracts; thoracic cavity expands.
• Exhalation: Diaphragm relaxes; thoracic cavity gets smaller.

Medical Specialties

• Otolaryngologist: Diagnoses and treats diseases of the head and neck, including ears, nose, and throat.
• Pulmonologist: Diagnoses and treats lung diseases.
• Thoracic Surgeon: Performs operations on the organs in the chest cavity, including heart, lungs, and esophagus.

Respiratory Pathologies

• Chronic Obstructive Pulmonary Disease (COPD): Group of lung diseases where bronchial airflow is blocked. Examples include Chronic bronchitis and emphysema.
• Chronic Bronchitis: Inflammation and narrowing of the bronchial tubes due to recurrent exposure to irritants, often cigarette smoke.
• Emphysema: Progressive loss of lung function, usually due to smoking. Alveoli enlarge and lose their function leading to decreased gas exchange.
• Asthma: Inflammatory disease of the bronchial tubes, often triggered by allergies.
• Airway Inflammation: Swelling and clogging of bronchial tubes with mucus.
• Bronchospasm: Contraction of smooth muscles in bronchial walls, tightening the airway.

Other Pathologies

• Upper Respiratory Infections (URI): Common cold and acute nasopharyngitis.

• Allergic Rhinitis: Allergic reaction to airborne allergens.

• Epistaxis: Nosebleed.

• Sinusitis: Inflammation of the sinuses.

• Pharyngitis: Sore throat, inflammation of the pharynx.

• Laryngospasm: Sudden closure of the larynx.

• Laryngitis: Inflammation of the larynx.

• Bronchiectasis: Permanent dilation of the bronchi due to chronic infection.

• Pleural Effusion: Excess fluid in the pleural space.

• Pneumothorax: Air in the pleural space.

• Pyothorax/Empyema: Pus in the pleural space.

• Pneumonia: Serious inflammation of the lungs

• Eupnea: Normal breathing.

• Apnea: Temporary absence of breathing.

• Bradypnea: Abnormally slow breathing.

• Tachypnea: Abnormally rapid breathing.

• Dyspnea: Difficult or labored breathing.

• Hemoptysis: Coughing up blood.

• Anoxia: Absence of oxygen in tissues.

• Hypoxia: Insufficient oxygen in tissues.

• Cyanosis: Bluish discoloration of tissues due to lack of oxygen.

• Expectoration: Coughing up and spitting out saliva, mucus, or fluid.

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