Respiratory System PDF

# Respiratory System - Supplies the body with oxygen and disposes of CO2 - Respiration must occur: - **Pulmonary ventilation:** air must be moved in and out of the lung so that the gases in the air sacs (alveoli) of lungs are always being replaced. - This movement is often called ventilat...

# Respiratory System - Supplies the body with oxygen and disposes of CO2 - Respiration must occur: - **Pulmonary ventilation:** air must be moved in and out of the lung so that the gases in the air sacs (alveoli) of lungs are always being replaced. - This movement is often called ventilation. - **External respiration:** gas exchange needs to happen between blood and air @ lung alveoli. - O2 in air sacs diffuse into blood. - CO2 in blood diffuses into air sacs. - **Transport of respiratory gases:** O2 & CO2 have to be transported between the lungs and cells in the body. - Blood from the cardiovascular system is the transporting fluid. - **Internal respiration:** @systemic capillaries, gases must be exchanged between blood and tissue cells. ## Anatomy of Respiratory System - Organs of the respiratory system are divided into 2 groups: - **Conducting zone:** respiratory passageways that carry air to the sites of gas exchange. - Filters, humidifies, and warms incoming air - Allow air to be less harsh and dusty - **Respiratory zone:** actual site of gas exchange in lungs - Composed of the terminal respiratory passageways that contain alveoli (respiratory bronchioles, alveolar ducts, alveolar sacs) ## The Nose and Paranasal sinuses - **Functions of the nose:** - Provides an airway for respiration - Moistens and warms entering air - Filters inhaled air to cleanse it of foreign particles - Resonating chamber for speech - Olfactory receptors ## Nasal Cavity - Nasal cavity is lined with 2 kinds of mucosa: - **Olfactory mucosa:** near roof of nasal cavity, houses smell receptors. - **Respiratory mucosa:** mucus lines a majority of the nasal cavity, and forms a sheet that can trap dust, bacteria, pollen, etc. - Nasal conchae and nasal mucosa work together during inhalation to filter, heat, and moisten air. - During exhalation they reclaim heat & moisture. ## The Pharynx - **Pharynx:** funnel-shaped passageway that connects nasal cavity & mouth superiorly, and larynx & esophagus inferiorly. - Level w/ C2 vertebrae - Commonly known as the throat - **Nasopharynx:** directly posterior to nasal cavity. - Serves only as an airway - When you swallow, soft palate & uvula close to keep food out of nasal cavity - **Pharyngeal tonsil:** lymphoid organ that destroys pathogens entering the nasopharynx - **Tubal tonsil:** provides middle ear protection from infection that may spread from the pharynx - **Oropharynx:** lies posterior to oral cavity - Swallowed food & inhaled air can pass through. - Lined w/ stratified squamous epithelium because of increased friction & greater chemical trauma due to food being swallowed - **Two kinds of tonsils:** - **Palantine tonsils:** lie in lateral walls of throat. - **Lingual tonsils:** cover posterior surface. ## Laryngopharynx - Common passageway for air and food, is lined with stratified squamous epithelium. - Conducts food & fluids to stomach ## The Larynx - Larynx (Voicebox) extends C4 to C6, and attaches to Hyoid bone. - **3 primary functions:** - Producing vocalizations - Providing an open airway - Contains switching mechanism that sends food and air to proper channels. - **Nine types of cartilages** connected by membranes & ligaments - **Thyroid cartilage:** resembles an upright open book, anterior midline of neck. - **Adam’s apple:** larger in men. - **Cricoid cartilage:** top of trachea, forms a complete ring - **3 pairs of small cartilages** that lie superior to cricoid: - **Arytenoid:** anchors vocal cords. - **Corniculate** - **Cuneiform** - **Epiglottis:** made of elastic cartilage, is covered in mucosa - Attaches to posterior aspect of the tongue. - Covers & seals laryngeal inlet when swallowing to prevent food from entering respiratory tubes - **Voice production:** - Vocal cords vibrate to produce basic sounds of speech. - Vestibular folds are false vocal cords that enhance high frequency sounds. ## The Trachea - Trachea (windpipe) descends from larynx into mediastinum - Contains 16-20 C-shaped rings of hyaline cartilage - Flexible enough for bending and elongation but rings prevent it from collapsing. - Contraction of trachealis muscle decreases trachea’s diameter. - Expels irritants when coughing or sneezing. - **The Bronchial Tree:** - **Primary Bronchi:** largest conduits in the bronchial tree. - **Bronchial Tree:** a system of respiratory passages that branches within the lungs. - **Primary Bronchi** divide into **lobar bronchi:** 3 on the right and 2 on the left. - **Branches** into **segmental bronchi** - **Respiratory Zone:** end part of the respiratory tree - **Alveoli:** air exchange chambers. - **First respiratory zone branches** from the terminal bronchioles, they’re called **respiratory bronchioles**. - Lead into **alveolar ducts** and eventually leads into the terminal clusters of alveoli called **alveolar sacs**. ## The Lungs - **Anatomy of the lungs** - Paired lungs & pleural sacs occupies the thoracic cavity lateral to the mediastinum. - Deep to the clavicle is the lung’s **apex**, rounded superior tip. - **Base** of the lung rests on the diaphragm. - **Hilum:** an indentation on the medial surface of the lung. - Entering & exiting point for blood vessels, bronchi, lymphatic vessels. - **Left and right lung differ in size:** - **Cardiac notch:** deviation in the left lung that accommodates the heart. - **Lungs have deep fissures** that creates **lobes**. - Each lobe contains **bronchopulmonary segments**, that limit the spread of some diseases within the lungs. - **Blood Supply and Innervation:** - **Pulmonary arteries** deliver deoxygenated blood to the lung to be oxygenated. - **Pulmonary veins** - **VBA (vein before artery):** position of pulmonary vessels around bronchial arteries and veins provide and drain systemic blood to and from the lung tissues. - Small vessels enter and exit the hilum. - **Innervated by:** sympathetic, parasympathetic, and visceral sensory fibers that enter lungs through pulmonary plexus. ## The Pleurae - **Pleura:** around each lung is a flattened sac w/ a serous membrane wall. - **Outer layer of sac is parietal pleura**. - **Inner layer directly on lungs is visceral pleura.** - **Pleural cavity:** space between parietal and visceral pleurae ## Ventilation - **Mechanism of ventilation:** - **Pulmonary ventilation (Breathing)** has two different phases. - **Inspiration:** air flows into the lungs. - **Inspiratory Muscles** - diaphragm and intercostal muscles - increase the volume of the thorax. - When diaphragm contracts, it moves inferiorly and flattens. - Stimulated by phrenic nerve. - External intercostal muscles contract to raise the ribs. - Innervated by intercostal nerves - **Expiration:** - In healthy people, it’s a passive process. - Thoracic & pleural cavity decrease in volume.