Respiratory System Preparatory Year 2024-2025 PDF

Respiratory System Preparatory Year  Objectives The students will be able to: Identify the respiratory system's organs and their functions. Describe the structure of the upper and lower respiratory tracts. Describe the respiratory system's accessory organs...

Respiratory System Preparatory Year  Objectives The students will be able to: Identify the respiratory system's organs and their functions. Describe the structure of the upper and lower respiratory tracts. Describe the respiratory system's accessory organs and their functions.  Organs of the Respiratory System Nose Pharynx Larynx Trachea Bronchi Lungs – alveoli Respiratory Tract  Upper Respiratory Tract Nose The only externally visible part of the respiratory system. Air enters the nose through the nostrils (nasal opening). The interior of the nose consists of a nasal cavity divided by a nasal septum.  Upper Respiratory Tract Nasal Cavity The nasal cavity is lined with respiratory mucosa that: ▪ Moistens air ▪ Traps incoming foreign particles Olfactory receptors: are the nerve ending responsible for sense of smell located on the superior surface of mucosa of the nasal cavity. Lateral walls have projections called conchae which increase surface area over which air pass. The nasal cavity is separated from the oral cavity by the palate.  Upper Respiratory Tract Paranasal Sinuses Cavities within bones surrounding the nasal cavity. There are 4 pairs of them located in: ▪ Frontal bone ▪ Sphenoid bone ▪ Ethmoid bone ▪ Maxillary bone Functions of paranasal sinuses ▪ Lighten the skull. ▪ Act as resonance chambers for speech. ▪ Produce mucus that drains into the nasal cavity.  Upper Respiratory Tract Pharynx Muscular passage from nasal cavity to larynx. Three regions of the pharynx: ▪ Nasopharynx superior region behind nasal cavity. ▪ Oropharynx middle region behind mouth. ▪ Laryngopharynx inferior region attached to larynx. The oropharynx and laryngopharynx are common passageways for air and food.  Upper Respiratory Tract Larynx (voice box) Located just below pharynx it is composed of several pieces of cartilages, the largest of this is thyroid cartilage, we call it (Adam’s apple). Two short fibrous bands (vocal cords) stretch across the interior of the larynx Vibrate with expelled air to create sound (speech).  Upper Respiratory Tract Larynx The space between cords is called glottis that is covered partially by epiglottis which is a flap of cartilage that acts like a door closing the larynx during swallowing to prevent food from entering trachea.  Lower Respiratory Tract Trachea It is a tube that connects larynx with bronchi through which air can reach lungs wormed, and humidified. Lined with ciliated epithelium. Its wall is reinforced with C- shaped hyaline cartilage to secure constant opening of its lumen and prevent its collapse.  Lower Respiratory Tract Lungs Occupy most of the thoracic cavity Apex is near the clavicle (superior portion) Base rests on the diaphragm (inferior portion) Each lung is divided into lobes by fissures: ▪ Left lung : two lobes ▪ Right lung : three lobes  Lower Respiratory Tract Coverings of the Lungs Pleura: is a thin membrane that is composed of two parts: Visceral pleura: covers the lung surface Parietal pleura: lines the walls of the thoracic cavity Pleural fluid: fills the area between layers of pleura.  Lower Respiratory Tract Bronchial Tree It includes the conducting zone and the respiratory zone. The conducting zone: extensively branching respiratory passageways that includes the: Primary bronchi (main bronchi),Secondary bronchi, Tertiary bronchi ,Bronchioles ,Terminal bronchioles. The respiratory zone consists of: ▪ Respiratory bronchioles ▪ Alveolar duct ▪ Alveoli ▪ It is a site for gas exchange.  Lower Respiratory Tract Alveoli Alveoli are the functional units of the respiratory system which are responsible for gas exchange between air and blood. There are gas-filled alveoli in the lungs, each in contact with blood vessels, so respiration takes place on that level.  Gas exchange Gas crosses the respiratory membrane by diffusion. ▪ Oxygen enters the blood ▪ Carbon dioxide enters the alveoli.  Accessory Organs of Respiration (Respiratory Muscles) Diaphragm Is the dome-shaped muscle separating thoracic cavity from abdominal cavity. It flattens out when it contracts during inspiration creating more space to the lungs to expand longitudinally (making chest longer from up to bottom). Intercostals Muscles Are located between ribs, when they contract, they also increase the size of the chest by increasing the antro- posterior diameter (from front to back) so lungs expand in width.  Function of the Respiratory System Breathing: is the movement of air in and out of the lungs. Air conditioning: as air passes through upper respiratory tract, it gets warmed and humidified. Production of Sound: it enables sound production as expired air passes over the vocal cords. Site for smell sensation. Gas Exchange  Mechanism of Breathing ▪ Breathing is the process that moves air into and out of lungs. ▪ It has two processes : Inspiration Expiration 1. Inspiration: Also called inhalation, moves air into the lungs. It is an active process. Diaphragm and intercostal muscles contract The size of the thoracic cavity increases Lung size is increases.  Breathing (Pulmonary Ventilation) 2. Expiration: Also called exhalation, moves air out of the lungs. It is a passive process. The respiratory muscles relax The thoracic cavity returns to its original size Lungs decrease in size as air leaves alveoli outward through respiratory passages. Thank You