Questions and Answers
List the several functions of the respiratory system. (Hint : 8)
Acid/base regulation, phonation, olfaction, hormonal conversion, heat regulation, protection, air conduction/gas exchange, “air conditioning”
The transitional system is the same as the respiratory zone
True
What are the three FUNCTIONAL structures in the respiratory tract ?
The conductive system, the transitional system and the gas exchange system.
Which of the following structures is NOT part of the conductive system?
Signup and view all the answers
Which of the following structures within the respiratory system is noted in BOTH the Transitional system (aka respiratory zone) and the gas exchange system?
Signup and view all the answers
List the structures that are within the conductive system.
Signup and view all the answers
What is the primary function of the conducting system in the respiratory tract?
Signup and view all the answers
Healthy bronchioles contain goblet cells.
Signup and view all the answers
What are the outpocketings of gas exchange tissue found in respiratory bronchioles called?
Signup and view all the answers
The thin-walled structures in the exchange system are known as ______.
Signup and view all the answers
Match the following cell types with their relevant descriptions:
Signup and view all the answers
Which of the following is a non-specific defense mechanism of the respiratory system?
Signup and view all the answers
Mucociliary clearance is classified as a specific (immune-mediated) defense mechanism.
Signup and view all the answers
What is the primary function of the mucociliary escalator?
Signup and view all the answers
The process by which antibodies facilitate the destruction of pathogens is known as _______.
Signup and view all the answers
Match the following defense mechanisms of the respiratory system with their categories:
Signup and view all the answers
Histologically the nasal cavity, pharynx, larynx trachea and bronchi are mostly lined with ….
Signup and view all the answers
Which type of epithelium primarily lines the nasal cavity and bronchi?
Signup and view all the answers
Which cells are responsible for secreting mucus in the respiratory tract?
Signup and view all the answers
What type of cells are found submucosally in the nasal cavity and trachea?
Signup and view all the answers
Which anatomical structure is NOT lined by pseudostratified ciliated columnar epithelium?
Signup and view all the answers
What category of epithelia is Pseudostratified columnar epithelium?
Signup and view all the answers
What type of glands are primarily found in the lamina propria of the nasal cavity?
Signup and view all the answers
What is the main function of Bowman's glands located in the nasal cavity?
Signup and view all the answers
Which structure supports the lamina propria within the nasal cavity?
Signup and view all the answers
What type of cells are found in the olfactory epithelium?
Signup and view all the answers
What type of glands have lesser numbers compared to serous glands in the nasal cavity?
Signup and view all the answers
What type of epithelium lines the vestibular region of the nasal cavity?
Signup and view all the answers
Which region of the nasal cavity is primarily responsible for the clearance of inhaled particles?
Signup and view all the answers
What cells are responsible for producing mucus in the respiratory region?
Signup and view all the answers
How do the conchae turbinates function within the nasal cavity?
Signup and view all the answers
Which of the following best describes the olfactory region of the nasal cavity?
Signup and view all the answers
What occurs in response to injury in the respiratory epithelium?
Signup and view all the answers
What is the primary characteristic of the respiratory epithelium?
Signup and view all the answers
In the nasal cavity, what happens to the quality of inhaled air due to the presence of the mucociliary apparatus?
Signup and view all the answers
What type of epithelium lines the initial part of the larynx?
Signup and view all the answers
Which of these structures is primarily found in the larynx?
Signup and view all the answers
What type of epithelium replaces the lining after the vocal cords in the larynx?
Signup and view all the answers
Which of the following statements about the larynx is true?
Signup and view all the answers
Which of the following components is NOT part of the larynx?
Signup and view all the answers
What type of epithelium lines the trachea?
Signup and view all the answers
What type of cartilage supports the bronchi?
Signup and view all the answers
What distinguishes terminal bronchioles from bronchi?
Signup and view all the answers
What is a function of Club cells in the bronchioles?
Signup and view all the answers
What are seromucous glands primarily responsible for?
Signup and view all the answers
Which structure serves as the connection between the trachea and lungs?
Signup and view all the answers
What characteristic of the tracheal wall supports its structure?
Signup and view all the answers
Where are Club cells predominantly located?
Signup and view all the answers
What type of epithelium lines the respiratory bronchioles?
Signup and view all the answers
What distinguishes alveolar ducts from respiratory bronchioles?
Signup and view all the answers
What is the primary function of alveolar sacs?
Signup and view all the answers
What feature do the lip edges of the alveoli in alveolar ducts exhibit?
Signup and view all the answers
Which structure lacks smooth muscle in its composition?
Signup and view all the answers
What do the alveolar (septal) pores of Kohn allow for?
Signup and view all the answers
What is the composition of the pulmonary interstitium?
Signup and view all the answers
What is the histologic appearance of the respiratory bronchioles primarily characterized by?
Signup and view all the answers
What is the primary function of Pneumocyte Type I cells?
Signup and view all the answers
Which cell type accounts for 5% of alveolar surface area?
Signup and view all the answers
What condition is associated with the absence of surfactant in newborns?
Signup and view all the answers
Which component is NOT part of the Blood-Air Barrier?
Signup and view all the answers
How is surfactant characterized?
Signup and view all the answers
What triggers the production of surfactant in fetuses just prior to birth?
Signup and view all the answers
Which structure primarily acts as a secretory cell in the alveoli?
Signup and view all the answers
What percentage of the alveolar surface area is composed of Pneumocyte Type I cells?
Signup and view all the answers
Which of the following is part of the air-blood barrier?
Signup and view all the answers
What type of blood do pulmonary arteries carry from the right ventricle?
Signup and view all the answers
Which of the following arteries provides oxygenated blood to the major pulmonary vessels?
Signup and view all the answers
What role do pulmonary veins play in the pulmonary circulation?
Signup and view all the answers
What system innervates bronchial smooth muscle to cause contraction?
Signup and view all the answers
Which type of capillaries are present in the pulmonary blood supply?
Signup and view all the answers
Which of the following statements about bronchial arteries is true?
Signup and view all the answers
Study Notes
Conducting System
- Delivers air to the respiratory areas, essential for efficient gas exchange.
- Cleans, moistens, and warms incoming air for optimal conditions.
- Blood in venous plexuses of the nasal cavity regulates the temperature of inhaled air.
- Nasal cavity features hair and secretions that trap particulate matter, enhancing filtration.
Transitional System
- Acts as a transition zone between conducting and gas exchange areas of the respiratory system.
- Consists exclusively of respiratory bronchioles, which have walls featuring outpocketings called alveoli.
- Contains specific cells, including Club cells (formerly Clara cells), that are non-ciliated secretory cells.
- Healthy bronchioles are characterized by the absence of goblet cells, maintaining airflow efficiency.
Exchange System
- Composed of alveoli, which are crucial for oxygen and carbon dioxide exchange.
- Alveoli are thin-walled structures surrounded by pulmonary capillaries, facilitating gas diffusion.
- Lined by two types of epithelial cells: type I pneumonocytes (membranous) for structural support and type II pneumonocytes for surfactant production.
Non-Specific (Non Immune-Mediated) Defense Mechanisms
- Mucous Trapping: Mucus in the respiratory tract traps particles, pathogens, and allergens, preventing them from entering the lungs.
- Mucociliary Clearance (Mucociliary Escalator): Cilia move in a coordinated manner to transport trapped mucus up to the throat, where it can be expelled or swallowed, maintaining clear airways.
- Phagocytosis: Immune cells, such as macrophages, engulf and digest foreign particles and pathogens that reach the alveoli.
- Air Turbulence: Physical mechanisms like coughing and sneezing create turbulence in airflow, dislodging and expelling unwanted particles and microorganisms from the respiratory system.
Specific (Immune-Mediated) Defense Mechanisms
- Antibody Production: B-lymphocytes produce antibodies specific to pathogens, enhancing the immune response by targeting and neutralizing invaders.
- Antibody-Mediated Phagocytosis: Antibodies coat pathogens, promoting their recognition and ingestion by phagocytic cells, enhancing the clearance of infections.
- Cell-Mediated Immunity: T-lymphocytes directly attack infected cells and coordinate the immune response, playing a crucial role in defending against intracellular pathogens.
Conducting System
- Responsible for delivering air to the respiratory portion.
- Cleans, moistens, and warms incoming air through mucous membranes.
- Blood in venous plexuses within the nasal cavity regulates the temperature of inhaled air.
- Nasal cavity contains hair and secretions that trap particulate matter.
Transitional System
- Serves as a transition between the conducting (ciliated) area and the gas exchange (alveolar) area of the respiratory tree.
- Composed entirely of respiratory bronchioles, which have walls with outpocketings of gas exchange tissue (alveoli).
- Lined primarily by club cells (formerly Clara cells), non-ciliated secretory cells, and a few ciliated cells.
- Healthy bronchioles lack goblet cells, distinguishing them from other bronchial structures.
Exchange System
- Comprises alveoli, which are thin-walled and surrounded by a dense network of pulmonary capillaries for gas exchange.
- Alveoli are lined with two types of epithelial cells:
- Type I pneumonocytes (membranous) for structural support.
- Type II pneumonocytes (pneumocytes) responsible for surfactant production.
Defense Mechanisms of the Respiratory System
-
Non-specific (non immune-mediated) defenses include:
- Mucous trapping of particles and pathogens.
- Mucociliary clearance, also known as the mucociliary escalator, which helps expel trapped material.
- Phagocytosis by immune cells to eliminate pathogens.
- Air turbulence generated by coughing and sneezing to remove irritants.
-
Specific (immune-mediated) defenses involve:
- Antibody production to target specific pathogens.
- Antibody-mediated phagocytosis that enhances immune responses.
- Cell-mediated immunity, involving T cells to attack infected cells.
Epithelial Lining
- Nasal cavity, pharynx, larynx, trachea, and bronchi are mainly lined by pseudostratified ciliated, columnar epithelium.
- This lining features secretory goblet cells and submucosal serous cells for mucus and enzyme production.
Nasal Cavity Structure
- The lamina propria is rich in tubulo-alveolar glands, primarily serous, contributing to nasal secretion.
- Contains a minor quantity of mucous and mixed glands, aiding in moisture and protection.
- Olfactory function is supported by Bowman's glands, which produce odorant-binding proteins essential for the sense of smell.
- The submucosa serves as a supportive layer beneath the lamina propria, providing structural integrity and containing blood vessels and nerves.
- Olfactory epithelium houses olfactory sensory cells, which are critical for detecting airborne scents and initiating the olfactory signal pathway.
Nasal Cavity Overview
- The nasal cavity is a bone-supported space in the skull, divided by the nasal cartilaginous septum into left and right halves.
- Each half contains three distinct regions: Vestibular, Respiratory, and Olfactory.
Vestibular Region
- This is the external part of the nasal cavity, characterized by a cutaneous mucous membrane with haired skin and glands.
- Lined with stratified squamous keratinized epithelium, providing initial protection.
Respiratory Region
- The largest section, lined with pseudostratified columnar ciliated epithelium containing goblet cells.
- The Mucociliary apparatus is formed by these cells, facilitating the clearance of inhaled particles.
- Lateral wall projections, known as Conchae Turbinates, narrow the lumen, enhancing the contact area between inhaled air and the respiratory mucous membrane for better air quality control.
Mucociliary Apparatus
- Composed of pseudostratified ciliated columnar epithelium and goblet cells that produce mucinogen granules.
- Cilia work to remove mucus laden with airborne particles such as dust and microorganisms, effectively cleaning the upper respiratory passages.
Goblet Cells
- Present along the airway up to large bronchioles, these cells secrete mucus that traps particulate matter.
- In response to injury (such as smoking), there is an increase in the number of goblet cells (hyperplasia) and a potential change from ciliated pseudostratified epithelium to squamous stratified epithelium (metaplasia).
Olfactory Region
- Lined with olfactory epithelium that is significantly thicker than the respiratory epithelium and does not contain goblet cells.
- Located in the dorsal part of the nasal cavity, it is involved in the sense of smell (olfaction).
- Comprising olfactory neurons (axons correspond to Cranial Nerve I), sustentacular cells for support, and basal cells that function as stem cells for regeneration.
Venous Plexuses
- Both the olfactory and respiratory regions feature rich venous plexuses known as "swell bodies," which can become engorged with blood, potentially influencing nasal congestion and airflow.
Larynx Structure
- Composed of cartilage, vocal folds, and skeletal muscle, which contribute to its functionality and support.
- The initial part of the larynx is lined with stratified squamous epithelium, providing protection against friction and abrasion from airflow and sound production.
Epithelium Transition
- Past the vocal folds, the lining transitions to pseudostratified ciliated columnar epithelium, which aids in filtering and moistening incoming air.
- This change in epithelial type reflects the differing roles of each section of the larynx, with the initial section focused on protection and the subsequent section emphasizing airway function.
Trachea
- Lined by ciliated pseudostratified columnar epithelium for effective mucus clearance and protection.
- The lamina propria and submucosa appear indistinct, reflecting a unique structural feature.
- Presence of serous glands within the lamina propria/submucosa contributes to moisture and enzyme secretion.
- Supported by incomplete rings of cartilage, which are not fully formed on the dorsal side to allow flexibility; birds possess complete cartilage rings.
- The connective tissue adventitia encases the trachea, providing additional structural support.
- The trachea bifurcates into bronchi, which lead into the lungs and undergo extensive branching.
- Bronchi are lined with ciliated pseudostratified columnar epithelium similar to the trachea.
- Surrounding the lamina propria is smooth muscle and connective tissue, containing mixed bronchial glands.
- Mixed seromucous glands secrete mucin, lactoferrin, and lysozyme, which possess bacteriostatic and cidal properties.
Bronchioles
- Bronchioles arise from the branching of bronchi and are characterized by the absence of cartilage and glands.
- Classified into terminal bronchioles and respiratory bronchioles based on their function and structure.
Terminal Bronchioles
- Lined by ciliated cuboidal or columnar cells, with a reduced presence of goblet cells.
- Contain muscularis mucosae, which aids in regulating airflow.
Club Cells (Bronchiolar Exocrine Cells)
- Located in terminal and respiratory bronchioles, identifiable by surface bulging.
- Serve secretory functions, producing a surfactant-like substance that maintains airway patency.
- Play a role in metabolizing airborne toxins and may have immune functions.
- Involved in metabolizing xenobiotic compounds, which are substances foreign to the body or ecological systems.
Respiratory Bronchioles
- Predominantly developed in cats and dogs, lined with ciliated cuboidal epithelium that flattens distally.
- Possess incomplete muscularis mucosae, leading to a histological appearance similar to terminal bronchioles, with interruptions by alveoli.
- Subdivide into alveolar ducts.
Alveolar Ducts
- Integral to the respiratory exchange system, emptying into alveolar sacs and alveoli.
- Composed entirely of alveoli, lined with simple squamous epithelial cells.
- Edges of alveoli contain smooth muscle cells, giving them a knob-like appearance in sections.
Alveolar Sacs
- Formed by branches of alveolar ducts, lack smooth muscle.
- Consist of two distinct types of epithelial cells: pneumocytes type I (thin for gas exchange) and type II (produce surfactant).
Alveolar Pores (Pores of Kohn)
- Connect neighboring alveoli, facilitating pressure equalization and collateral ventilation in case of bronchiole obstruction.
- Allow macrophage passage between alveoli.
Interstitium
- Refers to the stroma, or space between cells, filled with an extracellular matrix (ECM) that includes structural, adhesive, and absorptive components.
- Pulmonary interstitium supports blood and lymphatic vessels, nerves, bronchi, bronchioles, and alveoli.
- Divided into three compartments:
- Bronchovascular interstitium surrounding main bronchi and pulmonary vessels.
- Interlobular interstitium providing support to small blood and lymph vessels.
- Alveolar interstitium supporting alveolar walls containing pulmonary capillaries with no lymphatic vessels.
Effects of Pulmonary Changes
- Conditions such as pulmonary edema, emphysema, and inflammation can affect interstitial compartments.
Alveolar Septum and Interstitium
- Contains fibroblasts, capillaries, and “dust” cells (macrophages).
- Collagen type III is found in the alveolar walls, while collagen type I is present in conducting airways.
- Elastic fibers contribute to the structural integrity and function of the pulmonary system.
Pneumocyte Type I
- Squamous Alveolar Type I Cells form the walls of alveoli.
- Comprise 95% of the total alveolar surface area, optimizing gas exchange.
- Extremely thin structure with occluding junctions to prevent fluid infiltration.
- Function primarily in gas permeability and are not capable of mitosis.
- Organelles are concentrated around the nucleus for efficient function.
Pneumocyte Type II
- Granular Alveolar Type II Cells account for 5% of the alveolar surface area.
- Serve as secretory cells that produce surfactant through lamellar bodies.
- Capable of mitosis, allowing them to generate both Type I and Type II cells.
Surfactant
- A mono-molecular layer of phospholipoprotein essential for lung function.
- Functions to lower surface tension in the alveoli, facilitating inflation and preventing atelectasis (alveolar collapse).
- Continuously produced by Type II cells; cortisol stimulates surfactant production in fetuses before birth.
- Lack of surfactant in newborns can lead to Hyaline Membrane Disease.
Blood-Air Barrier
- Composed of four key components:
- Vascular endothelium
- Basement membrane of the endothelial cell
- Basement membrane of Type I pneumocyte
- Cytoplasm of the Type I pneumocyte
- The Air-Blood Barrier includes additional structures:
- Surfactant covering the cytoplasm of Type I cells
- Two fused basal laminae from alveolar epithelium and capillary endothelium
- Endothelial cells facilitating gas exchange.
Air-Blood Barrier Pathway
- Oxygen travels through the alveolar air, surfactant, and the cytoplasm of Type I cells, passing through the basal laminae of both type I cells and endothelial cells before reaching capillary red blood cells (RBCs).
Pulmonary Macrophages
- Alveolar Macrophages (PAMs) are key immune cells in the lungs.
- Intravascular Macrophages (PIMs) play a role in the immune response within blood vessels.
Pulmonary Blood Supply
- Pulmonary Arteries: Transport unoxygenated blood from the right ventricle, characterized by low pressure.
- Bronchial Arteries: Supply oxygenated blood to the large bronchi, major pulmonary vessels, and pulmonary lymph nodes; originate from the left heart and aorta.
- Dual Blood Supply: Representation of functional (pulmonary arteries) and nutritive (bronchial arteries) components in the pulmonary system.
- Anastomoses: Exist between bronchial and pulmonary arteries within the walls of medium-sized bronchi and bronchioles, particularly notable in horses, cattle, and sheep.
Pulmonary Veins
- Return all oxygenated blood from the lungs to the left atrium of the heart, occurring at low pressure.
Capillary Structure
- Continuous Type: Provides a barrier for gas exchange, ensuring the proper function of pulmonary capillaries.
Lymphatic Vessels
- Drain towards the hilum of the lung; there are no lymphatic vessels within alveolar walls.
Innervation
- Parasympathetic System: Influenced by the vagus nerve, promotes bronchoconstriction.
- Sympathetic System: Involves middle cervical and cervicothoracic ganglia, facilitating bronchodilation.
- Smooth Muscle Contraction: Involuntary process affecting bronchi, bronchioles, and vessels.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Description
Describe the functions of the respiratory tract, distinguishing features of each section of the respiratory tract etc.
