Respiratory System Anatomy Final Study Guide PDF

Functions of the Respiratory System - ​ Moves air to and from exchange surfaces of lungs ​ Warms, filters, and humidifies inhaled air ​ Produces sound involved in verbal communication ​ Contributes to smell (olfaction) ​ Protects the respiratory surfaces from irritants including dust,...

Functions of the Respiratory System - ​ Moves air to and from exchange surfaces of lungs ​ Warms, filters, and humidifies inhaled air ​ Produces sound involved in verbal communication ​ Contributes to smell (olfaction) ​ Protects the respiratory surfaces from irritants including dust, viruses, and bacteria ​ Assists in the regulation of blood volume, blood pressure, and body fluid pH Structures in the Upper vs. Lower Respiratory Tract - 1.​ Upper Respiratory Tract ○​ Structures: ​ Nose/Nasal Cavity: Passage for air, filters, warms, and humidifies air. ​ Pharynx: Throat, divided into nasopharynx, oropharynx, and laryngopharynx. ​ Larynx: Voice box, houses vocal cords, responsible for sound production. ​ Cartilage: ▪ 3 unpaired cartilages (thyroid, cricoid, epiglottis) ▪ 3 paired cartilages (arytenoid, corniculate, cuneiform ​ Function: Primarily involved in air intake, filtration, and warming. Also responsible for sound production. 1.​ Lower Respiratory Tract ○​ Structures: ​ Trachea: Windpipe, a cartilaginous tube that conducts air from the larynx to the bronchi.  ​ Bronchi: Two primary branches from the trachea that lead into each lung. ​ Bronchioles: Smaller branches of the bronchi within the lungs, leading to the alveolar ducts. ​ Alveoli: Small air sacs at the end of the bronchioles, where gas exchange occurs. ○​ Function: Involved in air passage to and from the lungs, and responsible for the exchange of gases (oxygen and carbon dioxide) in the alveoli. Definitions: ​ Respiratory Epithelium: Pseudostratified ciliated columnar epithelium. ​ Respiratory Membrane: Mucous membrane (mucosa). ​ Cilia: Move mucus and trapped particles up to the pharynx. ​ Goblet Cells: Produce mucus to trap debris and keep airways moist. ​ Exceptions: Oropharynx, laryngopharynx, and vocal cords are lined with stratified squamous epithelium due to higher mechanical stress Distinction Between Conducting vs. Respiratory Division - 1.​ Conducting Division ○​ Structures: ​ Nose ​ Pharynx ​ Larynx ​ Trachea ​ Bronchi ​ Bronchioles (before respiratory bronchioles) ○​ Function: No gas exchange occurs. These structures are responsible for moving air to the sites of gas exchange, warming, filtering, and humidifying the air as it travels to the lungs. 2.​ Respiratory Division ○​ Structures: ​ Respiratory Bronchioles: Smallest airways that have alveoli attached, allowing for some gas exchange. ​ Alveolar Ducts ​ Alveoli: The primary sites of gas exchange. ○​ Function: Responsible for gas exchange. Oxygen from the air diffuses into the blood, and carbon dioxide from the blood diffuses into the alveoli to be exhaled. Respiratory Structures from Nostrils to Pulmonary Capillaries (In Order) - 1.​ Nostrils (External Nares) ○​ Function: Entry point for air.  ○​ Epithelial Tissue: Stratified squamous epithelium (protective for external surface). 2.​ Nasal Cavity ○​ Function: Air passage, warming, moistening, and filtering of air. ○​ Epithelial Tissue: Pseudostratified ciliated columnar epithelium (with goblet cells for mucus production). 3.​ Pharynx (Nasopharynx, Oropharynx, Laryngopharynx) ○​ Function: Passageway for air and food. ○​ Epithelial Tissue: ​ Nasopharynx: Pseudostratified ciliated columnar epithelium. ​ Oropharynx & Laryngopharynx: Stratified squamous epithelium (due to increased abrasion). 4.​ Larynx ○​ Function: Voice production, air passage to trachea. ○​ Epithelial Tissue: Pseudostratified ciliated columnar epithelium (except for the vocal cords, which are stratified squamous). 5.​ Trachea ○​ Function: Air passage to the bronchi. ○​ Epithelial Tissue: Pseudostratified ciliated columnar epithelium (with goblet cells). 6.​ Primary Bronchi ○​ Function: Conducts air to each lung. ○​ Epithelial Tissue: Pseudostratified ciliated columnar epithelium. 7.​ Secondary and Tertiary Bronchi ○​ Function: Branches of the primary bronchi that continue to conduct air within the lungs. ○​ Epithelial Tissue: Pseudostratified ciliated columnar epithelium, transitioning to simple columnar epithelium as branches get smaller. 8.​ Bronchioles ○​ Function: Smaller air passages that conduct air to the alveolar ducts. ○​ Epithelial Tissue: Simple columnar epithelium, transitioning to simple cuboidal epithelium in the smallest bronchioles. 9.​ Alveolar Ducts ○​ Function: Passage to alveoli, minimal gas exchange. ○​ Epithelial Tissue: Simple squamous epithelium. 10.​Alveoli (Pulmonary Alveolar Sacs) ○​ Function: Primary site of gas exchange. ○​ Epithelial Tissue: Simple squamous epithelium (for efficient gas exchange). Respiratory Defense Mechanisms - 1. Hairs (Vibrissae) ​ Location: Found in the nostrils (nose). ​ Function:  ○​ Block Debris: The hairs act as a first line of defense, physically blocking larger particles, dust, and debris from entering the respiratory tract. ○​ Protection: Prevents harmful particles from traveling deeper into the airways and lungs. 2. Mucus ​ Produced by: Goblet cells in the respiratory epithelium. ​ Function: ○​ Traps Debris: Mucus traps inhaled particles, dust, bacteria, and other pathogens in the nasal cavity and along the respiratory epithelium. ○​ Moisture: Helps keep the respiratory tissues moist, protecting them from drying out and facilitating smooth airflow. 3. Mucociliary Escalator Clearance Mechanism ​ Location: Found in the conducting airways (trachea, bronchi, etc.). ​ Function: ○​ Role of Cilia: The cilia on the respiratory epithelium beat in a rhythmic, coordinated motion. ○​ Movement of Mucus: The cilia push the mucus (which contains trapped debris) from the lower airways(bronchi, trachea) upwards toward the upper airways (pharynx, larynx) ○​ Clearance: Once the mucus reaches the upper airways, it is either swallowed or expelled through coughing, helping to clear the debris from the respiratory system Structures that Make Up the Respiratory Membrane - ***The respiratory membrane is the site of gas exchange between the air in the alveoli and the blood in the capillaries 1.​ Alveolar Epithelium ○​ Type I Alveolar Cells (Squamous Epithelium): Thin, flat cells that line the alveoli and facilitate gas exchange. ○​ Type II Alveolar Cells: Produce surfactant, which reduces surface tension and prevents alveolar collapse. 2.​ Capillary Endothelium ○​ Endothelial Cells: Thin, flattened cells that form the walls of the capillaries, providing a surface for gas exchange. ○​ Fenestrations: Small pores that allow for the passage of gases and small molecules between the blood and alveolar space. 3.​ Basement Membranes ○​ Fused Basement Membranes: The basement membranes of the alveolar epithelium and capillary endothelium are often fused, allowing for efficient gas exchange by shortening the distance gases must diffuse Key Features that Facilitate Gas Exchange ​ Thin Membrane: ○​ Allows gases to diffuse quickly (0.5 micrometers thick).  ​ Large Surface Area: ○​ Millions of alveoli provide a large area for gas exchange. ​ Concentration Gradient: ○​ Oxygen moves from alveoli to blood; carbon dioxide moves from blood to alveoli. ​ Surfactant: ○​ Reduces surface tension, helping alveoli expand Pleural Cavities and Membranes - 1. Pleura ​ Description: The lungs are surrounded by a serous membrane called the pleura, which consists of two layers. 2. Parietal Pleura ​ Location: Lines the inner surface of the thoracic wall, the mediastinum, and the diaphragm. ​ Function: Provides a protective covering to the thoracic cavity and helps in maintaining a frictionless surface for lung movement. 3. Visceral Pleura ​ Location: Covers the outer surface of the lungs. ​ Function: Serves to reduce friction as the lungs expand and contract during breathing, while also providing a barrier to infections. 4. Pleural Cavity ​ Description: The space between the parietal and visceral pleura. ​ Contents: Contains a thin layer of serous fluid that serves as a lubricant. ​ Function: ○​ Lubrication: Reduces friction between the two pleural layers, allowing smooth movement of the lungs during breathing. ○​ Surface Tension: Maintains a pressure gradient that helps in lung expansion during inhalation Structures with Smooth Muscle and Connective Tissue in the Respiratory Tract - 1. Nasal Cavity ​ Smooth Muscle: Found in the walls of the nasal cavity, primarily in the conchae, helping to regulate airflow. ​ Connective Tissue: Includes fibrous tissue for structural support and cartilage to maintain the shape of the nasal passages. 2. Trachea ​ Smooth Muscle: Present in the trachealis muscle, which connects the ends of the C-shaped cartilage rings. It helps regulate the diameter of the trachea. ​ Connective Tissue: The submucosa contains connective tissue, including collagen and elastin, for flexibility and support. 3. Bronchi ​ Smooth Muscle: Present in the walls of both primary and secondary bronchi, regulating airflow and bronchoconstriction or dilation.  ​ Connective Tissue: Contains cartilage plates and connective tissue in the walls for structural support and elasticity. 4. Bronchioles ​ Smooth Muscle: Bronchioles have more smooth muscle relative to cartilage, allowing for more control over airflow and resistance. ​ Connective Tissue: Composed of elastic fibers for expansion and recoil, aiding in ventilation. 5. Alveoli ​ Connective Tissue: The interalveolar septum is made of elastic connective tissue, which allows alveoli to expand and contract during breathing. ​ Smooth Muscle: Smooth muscle fibers are found around the terminal bronchioles, but not directly in the alveolar sacs key points on respiratory centers, chemoreceptors, and the role of the hypothalamus in regulating respiration - Location of Respiratory Centers: ​ Medulla Oblongata: ○​ Contains Ventral Respiratory Group (VRG) and Dorsal Respiratory Group (DRG) ○​ Controls the rhythm and rate of breathing ​ Pons: ○​ Contains Pontine Respiratory Group (PRG) ○​ Modifies and fine-tunes the breathing rhythm (e.g., during exercise or speaking) Chemoreceptors in the Respiratory Centers ​ Central Chemoreceptors: ○​ Located in the medulla oblongata ○​ Monitor changes in CO2 levels and pH in cerebrospinal fluid ○​ Increase breathing rate and depth if CO2 increases or pH decreases (increased acidity) ​ Peripheral Chemoreceptors: ○​ Located in carotid bodies and aortic bodies ○​ Detect changes in O2 levels in the blood ○​ Increase breathing rate if O2 levels drop Hypothalamus and Respiratory Regulation ​ Emotional Response: ○​ Modifies breathing rate in response to stress, fear, or anxiety ○​ Can cause rapid or shallow breathing ​ Temperature Regulation: ○​ Increases breathing rate to help cool the body during high temperatures ○​ Decreases breathing rate in low temperatures to conserve heat Primary and Accessory Respiratory Muscles - Primary Respiratory Muscles 1.​ Diaphragm ○​ Action: The main muscle of respiration. When contracted, it moves downward, increasing the thoracic cavity's volume and causing inhalation. ○​ Function: Responsible for about 75% of normal breathing (inhalation). 2.​ External Intercostal Muscles ○​ Action: Contract to elevate the ribs, expanding the chest cavity. ○​ Function: Facilitate inhalation by increasing the volume of the thoracic cavity. Accessory Respiratory Muscles 1.​ Scalene (anterior, middle, posterior) ○​ Action: Elevate the first two ribs. ○​ Function: Aid in deep inhalation by expanding the upper portion of the thoracic cavity. 2.​ Sternocleidomastoid ○​ Action: Elevates the sternum. ○​ Function: Assists in forced inhalation by increasing thoracic cavity volume. 3.​ Pectoralis Minor ○​ Action: Elevates the ribs. ○​ Function: Helps expand the thoracic cavity during forced inhalation. 4.​ Serratus Anterior ○​ Action: Elevates the ribs. ○​ Function: Assists with forced inhalation by expanding the chest cavity. 5.​ Pectoralis Major ○​ Action: Helps in elevating the chest. ○​ Function: Aids in deep inhalation by expanding the rib cage. 6.​ Abdominal Muscles (Rectus Abdominis, External Obliques, Internal Obliques, Transversus Abdominis) ○​ Action: Compress the abdominal cavity. ○​ Function: During forced exhalation, these muscles push the diaphragm upwards, aiding in the expulsion of air from the lungs. 7.​ Internal Intercostal Muscles ○​ Action: Depress the ribs. ○​ Function: Involved in forced exhalation by decreasing the volume of the thoracic cavity Sympathetic and Parasympathetic Innervation of the Bronchial Tree and Lungs - Sympathetic Innervation: ​ Origin: T1-T5 spinal segments ​ Effect: ○​ Bronchodilation (widening of airways) ○​ Vasoconstriction (decreases blood flow)  ○​ Decreased mucus production ○​ Increased heart rate and force of contraction Parasympathetic Innervation: ​ Origin: Vagus nerve (CN X) ​ Effect: ○​ Bronchoconstriction (narrowing of airways) ○​ Vasodilation (increased blood flow) ○​ Increased mucus production ○​ Slows heart rate Vagus Nerve and Phrenic Nerve in the Respiratory System - Vagus Nerve ​ Function: ○​ Bronchoconstriction: The vagus nerve, as part of the parasympathetic nervous system, causes the smooth muscles in the bronchioles to contract, reducing the diameter of the airways. ○​ Increase in Mucus Secretion: The vagus nerve also stimulates mucus production in the airways, which helps trap and clear debris and pathogens. Phrenic Nerve (Paired) ​ Function: ○​ Contraction of Diaphragm: The phrenic nerve innervates the diaphragm, the primary muscle of respiration. When the phrenic nerve stimulates the diaphragm, it contracts, leading to inhalation by expanding the thoracic cavity and allowing air to enter the lungs Definitions: Pulmonary Ventilation: The process of moving air into and out of the lungs, allowing for the exchange of oxygen (O₂) and carbon dioxide (CO₂) between the atmosphere and the alveoli Eupnea: Normal, restful breathing that occurs at a regular rate and depth Hyperpnea: An increase in the depth and rate of breathing, typically in response to increased metabolic demands (e.g., during exercise)