Respiratory tract Flashcards
What are the functions of the respiratory system
Air conduction/gas exchange, phonation, olfaction, heat regulation, air condition (temperature and moisture), protection, acid base regulation, hormone conversation
What is the transitional system
composed of the respiratory bronchioles
What is the gas exchange system
composed of the respiratory bronchioles and alveoli
What does the conductive system do?
Brings air to the respiratory portion
cleanses, moistens and warms the incoming air
Blood in venous plexus in mucous membrane of nasal cavity regulates temperature of inhaled air
Hair and secretion in the nasal cavity trap particulate matter
What do the transitional system do?
A transition zone between the conducting (ciliated) and gas exchange (alveolar system) areas of the respiratory tree
Consists exclusively of respiratory bronchioles* which are lined by (similar to terminal bronchioles):
* “Club cells” (formerly known as Clara cells)
* Non-ciliated secretory cells
* Only a few ciliated cells.
* Healthy bronchioles do not have goblet cells
What does the exchange system fdo?
Composed of alveoli; thin-walled structures enveloped by a rich network of capillaries: the pulmonary capillaries.
Alveoli are lined by epithelial type I (membranous) and type II pneumonocytes (also know as pneumocytes)
What are the histological features of the conductive system
Nasal cavity, pharynx, larynx, trachea and bronchi are mostly lined by pseudostratified ciliated, columnar epithelium with secretory goblet cells and submucosal serous cells.
What are the defense mechanisms of the respiratory system
Non-specific (non immune- mediated):
– Mucous trapping
– Mucociliary clearance
(mucociliary escalator)
– Phagocytosis
– Air turbulence (generated by coughing and sneezing).
- Specific (immune-mediated):
– Antibody production
– Antibody-mediated phagocytosis
– Cell-mediated immunity
What is the nasal cavity lined with?
cavity is lined by ciliated pseudostratified columnar epithelium with goblet cells.
What does the nasal lamina propria contain?
The lamina propria contains tubulo-alveolar glands* (arrow) mainly serous, with lesser numbers of mucous and mixed glands
Where is the olfaction (bowmans gland) located?
The nasal cavity
What supports the lamina propria of the nasal cavity ?
submucosa
The olfactory epitelium contains?
olfactory sensory cells
Nasal cavity; vestibular region
Initial, external part of the nasal cavity has a cutaneous mucous membrane, haired skin and glands.
The vestibular region is lined with stratified squamous keratinized epithelium.
Nasal cavity respiratory region
The largest part of the nasal cavity is lined with pseudostratified columnar ciliated epithelium with goblet cells. This combination of cells is known as the Mucociliary apparatus, responsible for clearance.
Projections from the lateral wall CONCHAE TURBINATES narrow the lumen of the nasal cavity and increase the area of contact of inhaled air with respiratory mucous membrane, thus regulating the quality and quantity of inhaled air.
What is the mucociliary appartus
Pseudostratified Ciliated Columnar Epithelium
Goblet cells produce mucinogen granules
Movement of cilia removes mucus with trapped airborne inhaled particles such as dust and microorganisms
Both constitute a cleaning apparatus of upper respiratory passages
Where are goblet cells present
along the airways to levels of large bronchioles
What do the goblet cells do?
Secretion traps particulate matter
* Reaction to injury:
– Increased numbers of these cells (hyperplasia) in smokers
What is metaplasia?
a change from ciliated pseudostratified epithelium to squamous stratified epithelium
Cilated epithelial cells
Each has numerous cila on its surface, tips have “claws” od dynein and “beat” in unision (but movement resembles a wave from cell to cell) to move mucus
cells are connected by gap junctions
Dysfunction caused immotile cilia syndrome
Olfactory region of the nasal cavity
lined with olfactory epithelium, much thicker than respiratory epithelium, lacks goblet cells.
Where is Olfactory epithelium located?
in the dorsal part of the nasal cavity
What epithelium is thicker between olfactory and respiratory epithelium
olfactory
What are the cells involved with olfactory epithelium
Olfactory neurons — smell = olfaction (axons of olfactory neurons = Cr N. 1)
Supporting (sustentacular cells)
Basal cells – stem cells for others
NO GOBLET CELLS
What are both the respiratory and the olfactory regions rich in?
Swell bodies - distended with blood
What does the lamina of the serous olfactory gland contain
serous olfactory glands and non- myelinated axons of olfactory neurons form nerve bundles Cr. N. 1
What are nasal cavity cells and structures
- Ciliated columnar epithelial cells
- Goblet cells - secrete mucus
- Basal cells - stem cells for other types
- Neuroendocrine cells
- Brush cell - microvilli
- Olfactory epithelium
What is the vomeronasal organ
chhemoreception, sexual behavior, mainly used to detect pheromones
What is the larynx
Includes cartilage, vocal folds, skeletal muscle
* Initial part of the larynx is lined by stratified squamous epithelium
* After the vocal chords the lining changes to pseudostratified ciliated columnar epithelium
Describe the trachea
The trachea is lined by ciliated pseudostratified columnar epithelium.
The lamina propria and the submucosa are not clearly demarcated in the trachea,
Serous glands are seen in the lamina propria/submucosa.
Rings of cartilage, which are incomplete dorsally, support the tracheal wall.
Note: birds have complete rings of cartilage
A connective tissue adventitia completes the wall of the trachea
What is number 1 and 2
1: Hyaline cartilage and 2: Esophagus
What are the arrows pointed at?
What are the arrows pointed at?
Understand this image
What does the trachea branch into
2 bronchi, brouchus has plates of hyaline cartilage
Describe the Bronchus
The trachea bifurcates into the bronchi, which enter the lung and branch extensively
.
Bronchi are lined by ciliated pseudostratified columnar epithelium
Smooth muscle surrounds the lamina propria followed externally by connective tissue containing mixed bronchial glands (circle) and plates of hyaline cartilage (arrow).
Mixed seromucous glands secrete mucin, lactoferrin, and lysozyme (bacteriostatic/cidal)
Label this image
Describe Bronchioles
Bronchi branch into bronchioles
Bronchioles lack cartilage and glands
Bronchioles are subdivided into:
- terminal bronchioles (top arrow)
- respiratory bronchioles (bottom)
What are terminal bronchioles
Lined by ciliated cuboidal cells with few to no goblet cells.
A muscularis mucosae is still present in terminal bronchioles
What are the bronchiolar exocrine cells
Club cells
What are club cells
Located in terminal and respiratory bronchioles
* Bulge at surface
- Secretory: source of surfactant- like substance which aids in maintaining patency of airway
- Metabolizeairbornetoxins,may have immune function
- metabolizing xenobiotic* compounds (*substances that are foreign to the body or to an ecological system)
What are respiratory bronchioles?
Respiratory bronchioles are lined by ciliated cuboidal epithelium (ARROW) which becomes flattened distally.
Have incomplete muscularis mucosae
Respiratory bronchioles subdivide into alveolar duct
What are the alveolar ducts?
Alveolar ducts are part of the exchange system and they empty into alveolar sacs and alveoli.
The walls of alveolar ducts are composed entirely of alveoli lined with simple squamous epithelial cells
The edge surrounding the opening of each alveoli of an alveolar duct contains smooth muscle cells
Alveolar ducts empty into alveolar sacs and alveoli.
The presence of smooth muscle (SM) gives the lip of the alveolus a knob-like appearance on sections.
Alveolar sacs
Alveolar ducts branch into alveolar sacs which lack smooth muscle.
Alveoli are lined by two distinct epithelial cells: Pneumocytes type I and pneumocytes type II.
What is pulmonary edema?
alveolar spaces filled with proteinaceous fluid.
Alveolar pores
Neighboring alveoli connect with each other via pores, providing equalization of pressure and collateral ventilation if a bronchiole is obstructed.
Pores allow macrophage passage from one alveolus to another.
Pulmonary interstitum
interconnecting networks of intestitial stromal tissue supporting the blood and lymphatic vessels, nerves, bronchi, bronchioles, and alveoli
Pulmonary septum
Diving wall - composed of interstitium plus cell
Alveolar septum and interstitum
Contians fibroblasts, capillaries
Dust cells
Collagen type III present in the alveolar wall
Collagen type I is present in conducting airways
Elastic fibers
Pneumocyte Type I
also known as Squamous Alveolar TYPE 1 Cell
- Form walls of alveoli
- Pneumocyte Type I cells compose 95% of alveolar surface area
- Extremely thin, have occluding junctions to prevent fluid passage
- Gas permeability is desired function
- Are not mitotic
- Organelles are grouped around nucleus
Pneumocyte Type II
also known as Granular Alveolar Type II Cell
- Pneumocyte type II cells account for 5% of alveolar surface area
- Secretory cell.
- Surfactant is produced via lamellar bodies
- Can be mitotic → Produces type I and type II cells
Understand this image
Mono-molecular layer of phospholipoprotein
- Functions to reduce surface tension, reducing effort needed to inflate alveoli, thus preventing alveolar collapse (known as Atelectasis)
- Constantly produced by Type II Cells
- Cortisol stimulates production of surfactant in fetus just prior to parturition
- Absence of surfactant in newborns is know as Hyaline Membrane Disease
Air-Blood Barrier
- Cytoplasm of pneumocyte type I covered by surfactant
- Two fused basal laminae of alveolar epithelium and endothelium of capillary
- Endothelium
What are the dust cells
Alveolar macrophages
Mononuclear macrophages system
Pulmonary blood supply:
Dual blood supply
pulmonary arteries (from right heart) unoxygenated blood from the right ventricle (low pressure)
PULMONARY VEINS return all blood(oxygenated)from the lung to heart (left atrium) – (low pressure)
bronchial arteries (from left heart, aorta, bronchoesophageal) – oxygenated blood to the large bronchi, the major pulmonary vessels, and the pulmonary lymph nodes (high pressure)
Lymphatic Vessels to Lymph nodes: drain towards hilum, none in alveolar walls
Lungs
Covered by visceral pleural composed of connective tissue and lined by simple squamous epithelium
Interstitium: Connective tissue supports the bronchial tree and separates the lung into lobules.
What are the thoracic wall, diaphragm and mediastinum lined by
by the parietal pleura, composed of simple squamous epithelial cells also known as mesothelial cells.
