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RS Histology
Respiratory System Histology
Question | Answer |
---|---|
Two Major portions of the Respiratory System | Conducting and Respiratory portion |
Conducting Portion function | Provides passage of air-No gas exchange |
Respiratory Portion function | Where Gas exchange takes place |
Which Parts of the Respiratory System make up the Conducting portion? | 1) Nose 2) Nasopharyngeal Cavitiy 3) Larynx 4) Trachea 5) Bronchi (Primary, Secondary, and Tertiary) 6) Terminal Bronchioles |
Major function of the conducting portion | To condition inspired air |
Before it enters the lung, inspired air is: | Cleansed, moistened, and warm |
Mucosa of the conducting portion is lined with | Specialized respiratory epithelium |
The lamina propria contains: | Numerous mucous and serous glands A rich superficial vascular network |
Which parts of Respiratory System make up the Respiratory portion? | 1) Respiratory bronchioles (the region of transition) 2) Alveolar ducts 3) Alveolar sac 4) Alveoli |
What is the function of the Alveoli? | *They are the main sites for the exchange of O2 and CO2 between inspired air and the blood |
Exchange of gases between the alveoli and the blood occurs by: | Passive Diffusion |
When blood first arrives at the pulmonary capillary at its arteriole end, the partial pressures of carbon dioxide and oxygen are: | 45 and 40 mmHg, respectively |
In the alveoli, the partial pressures of these gases, CO2 and O2, are | 45 and 105 mmHg respectively |
What function does this pressure difference serve? | It causes O2 to be taken up by the RBCs and CO2 to be released due to difference in pressure |
After the net diffusion of oxygen, what is the partial pressure of oxygen in the venous end? | 95 mmHg |
What percentage of CO2 is dissolved in the plasma? | 7% |
What percentage of CO2 combines with hemoglobin to form carbaminohemoglobin? | 23% |
Most CO2 is converted to protons by what? | Carbonic Anhydrase (70%) |
After conversion into protons, what happens? | The protons combine with hemoglobin, reversibly |
Generally, the respiratory epithelium is? | Pseudostratified Columnar Epithelium |
What 5 types of cells are contained on the pseudostratified columnar epthelium? | 1) Small granule (DNES) cells 2) Goblet cells (with mucus secreting granules) 3) Brush cells (with microvilli) 4) Serous cells (with secretory granules) 5) Ciliated columnar cells |
What do these 5 cell types have in common? | All of them rest on the basement membrane (but not all of them reach the surface) |
What is the most abundant cell type? | Ciliated columnar cells |
What are the main components of this cell type? | Basal bodies (where the cilia are inserted in the apical part) Apical Mitochondria (which supply ATP for ciliary beating) |
Which protein participates in the ciliary movement? | Dynein |
What substance prevents the formation of Dynein and leads to improper movement of cilia? | Nicotine |
Immotile cilia syndrome is also known as: | Kartagner syndrome |
This syndrome is caused by: | Immobility of cilia and flagella, sometimes induced by deficiency of dynein |
What are the clinical consequences of Kartagner syndrome? | 1) Infertility in men 2) Respiratory tract infections in both sexes |
What are mucous goblet cells? | Cells with apical mucous droplets, which are composed of glycoproteins and polysaccharides |
Describe the appearance of Brush cells? | Numerous microvilli on their apical surface Sensory receptors (afferent nerve endings on their basal surfaces) |
Small granule cells are: | Cells of the DNES which regulate local excretions or secretion of mucous and serous glands in the respiratory tract.They are also called Kulchitsky cells. |
Basal cells are: | Small rounded cells believed to be generative stem cells They differentiate into the other cell types mentioned (reserve cells) |
What are the layers of the respiratory tube? | 1) Mucosa 2) Submucosa 3) Supportive layer 4) Adventitia |
What layers make up the Mucosa? | 1) Epithelium 2) Lamina Propria 3) Muscularis mucosa (smooth muscle) |
What is the function of the Submucosa? | It houses mucous and seromucous glands |
The Supportive layer consists of: | Smooth muscle and cartilage |
Adventitia consists of: | Connective tissue coverings |
The Nasal cavity is divided into 3 layers. What are they? | 1) The Vestibule 2) The respiratory area 3) The Olfactory region |
What is the anatomical position of the vestibule in the nasal cavity? | It is the most anterior and dilated portion of the nasal cavity |
Describe the vestibule and its components | The vestibule is lined by skin Contains Sebaceous and sweat glands Thick short hairs called vibrissae |
What is the function of the vestibule? | Traps and filters out large particles from inspired air |
What is characteristic about the vestibule? | Its epithelium loses its keratinized nature and undergoes a transition into typical respiratory epithelium before entering the nasal fossa |
What type of cells cover the respiratory area of the nasal cavity? | Pseudo-stratified columnar cells Goblet cells |
The subepithelial connective tissue of the respiratory area: | Is rich with blood vessels and seromucous glands |
What is the anatomical position of the Olfactory in the nasal cavity? | Present in the roof and upper parts of the nasal cavity |
What are the constituents of the olfactory mucosa? | Olfactory epithelium Corium (lamina propria) Bowmans gland |
What type of epithelium is present in the Olfactory region? | Pseudostratified Columnar epithelium |
What are the cell types present in the epithelium of the Olfactory region? | 1) Supporting (sustinacular) columnar cells 2) Basal cells 3) Olfactory cells |
The Supporting columnar cells: | Have broad apexes, narrow bases, microvilli submerged in fluid, and a light yellow pigment |
Basal cells | Are present as a single layer at the base of the epithelium and are spherical or cone shaped |
Olfactory cells | Bipolar neurons with nuceli below those of the supporting cells Nonmotile cilia rise from their apexes (dendrites)Respond to odorous substances by generating a receptor potential, Afferent axons unite in small bundles and synapse with the olfactory lobe |
This region of the olfactory mucosa contains Bowman's gland and facilitates the access of odoriferous substances | Lamina Propria, or Corium |
What are the nasal sinuses? | 1) Frontal 2) Ethmoidal 3) Maxillary |
Nasal sinuses | Lined with thinner respiratory epithelium, contain few goblet cells, few glands in the lamina propria and are continuous with the underlying periosteum |
The trachea extends from the level of ____ to _____ | C6 to T4 (the bifurcation point) |
Which structures are extra pulmonary? | The Trachea and the primary bronchus |
How many secondary bronchi do we have? | 3 in the right lung 2 in the left lung |
What comes after the secondary bronchi? | Segmental (tertiary) bronchi |
What size is a tertiary bronchus? | 5mm or less |
Each bronchiole enters a ____ | pulmonary lobule |
Each large bronchiole gives how many terminal ones? | 5-7 |
What size is a terminal bronchiole? | 0.5mm |
What are the constituents of terminal bronchioles? | Clara cells (no cilia) and neuropethilial bodies |
The trachea is made up of: | C-shaped rings of hyaline cartilage that keep the tracheal lumen open |
The musculature of the trachea consists of: | A Fibroelastic ligament and bundle of smooth muscle (trachealis) which binds to the perichondrium and closes the rings POSTERIORLY. Some longitudinal muscles may be found behind the trachealis. |
Trachea contains the same 5 types of cells in the mucosa as: | The pseudostratified columnar epithelium |
What is the function of the fibroelastic ligament in the trachea? | It prevents overdistension of the lumen |
What is the function of the muscle of the trachea (trachealis)? | Regulation of the lumen -- Cough reflex |
Bronchi are divided into: | 1) Extrapulmonary bronchi (Primary) 2) Intrapulmonary bronchi (Secondary and tertiary) |
The extrapulmonary bronchus | Resembles the trachea |
The intrapulmonary bronchus | Has a complete muscular layer and cartilaginous plates instead of rings |
What are the differences between the Trachea and bronchi? | 1) Narrower lumen in bronchi 2) Irregular bronchial cartilage plates 3) Smooth muscle layer consisting of spirally arranged bundles between the lamina proproa and submucosa |
What is the purpose of this smooth muscle layer in the bronchi? | Its contraction leads to the folded appearance of the bronchial mucosa |
What are 3 more differences between the trachea and bronchi? | 4) The lamina propria is rich in elastic fibers and contains an abundance of mucous and serous glands 5) Fewer goblet cells 6) Numerous lymphovytes and lymphatic nodules are present (infiltrated by the adventitia) |
Extra pulmonary bronchi are made up of: | 1) Pseudostratified ciliated columnar epithelium 2) Prominent basement membrane 3) Relatively thin lamina propria 4) Submucosa with seromucous glands 5) C shaped hyaline cartilage rings |
Intra pulmonary bronchi are made up of: | 1) Pseudostatified ciliated columnar changing into ciliated simple columnar in smaller branches 2) Interlacing spiral of smooth muscle below the lamina propria 3) Decreasing seromucous glands 4) Gradually disappearing plates of cartilage |
What types of cells are in the bronchioles? | Ciliated columnar to ciliated cuboidal Goblet cells decrease and clara cells appear |
What is characteristic about the smooth muscle in bronchioles? | Heavier in the bronchioles than elsewhere |
What structures aren't present in the bronchioles? | Seromucous glands and cartilage |
What types of cells are in the respiratory bronchioles? | Cuboidal epithelium with some cilia Clara cells/no goblet cells |
Describe the structure of respiratory bronchioles | Thin supporting wall of connective tissue Incomplete layer of smooth muscle Outpocketing of alveoli increasing at lower levels |
Parts of the bronchioles are: | 1) Clara cells 2) Neuroepithelial bodies 3) Chemoreceptors |
Clara cells: | 1) Are Devoid of cilia 2) Secrete proteins that protect the bronchiolar lining against oxidative pollutants and inflammation |
Neuroepithelial bodies: | contain secretory granules and recieve cholinergic nerve endings |
Chemoreceptors: | react to changes in gas composition within the airway |
Elastic fibres: | Longitudinal elastic fibers are present in all the segments of the bronchial system (in the L.propria) |
The smaller the bronchioles: | The higher proportion of elastic fibers |
One of the most important of respiratory is that it contains: | Hyaline cartilage |
Why are lungs made up of elastic tissue? | For the purpose of inflation and deflation |
How do you treat a patient who has no respiration? | An endotracheal tube to open the air passage |
Obstruction of the respiratory pathway is resolved with: | a tracheostomy |
How is a tracheaostomy performed? | Making an incision in the suprasternal notch on the anterior aspect of the neck and opening a direct airway |
Each alveoli is surrounded by: | A network of capillaries |
Each lung has ten segments called: | Bronchopulmonary segments |
What is the sequence of the types of epithelium while you go down the respiratory tract? | Pseudostratified ciliated columnar --> Simple columnar ciliated --> simple cuboidal ciliated --> clara cells --> simple squamous (alveoli) |
What other function does the nose have? | The olfactory function |
What is the olfactory function responsible for? | Sense of smell |
The wall of the alveolus is composed of what type of cells? | Type 1 alveolar cells (simple squamous epithelium) Type 2 alveolar cells (Surfactant secreting cells) |
What is the function of sufactant? | Distension of the alveoli |
If type 2 alveolar cells are deficient in an infant, this causes: | Respiratory Distress syndrome |