Respiratory system Flashcards
What are the different ways to classify a glandular epithelia?
- According to cell number → Unicellular (Goblet cells) vs Mutlicellular (sweat glands)
- Fate of secretion → Exocrine (salivary glands) vs Endocrine (endocrine pancreas)
- Way the secretory product leaves the cell → Merocrine (sweat gland) vs Holocrine (sebaceous gland) vs Apcorine (mammary gland)
- Ducts → Simple (gastric gland) vs Compound (salivary gland)
- Secretory protion → Tubular (sweat gland) vs Acinar {Mucous (sublingual) vs Serous (parotid)}
What is the difference between an exocrine and and endocrine gland?
Endocrine:
- Releases secretory product through a duct on a surface
Exocrine:
- No duct
- Production of hormone released direclty to the blood stream → act far from site of secretion
- In maturation, the duct disappears → mass of cell detached from epithelium → capillaries
What are the 4 possibilities for glandular classifications based on the secretory portion?
*For simple ducts
- Simple tubular (Gastric gland)
- Simple coiled tubuler (sweat gland)
- Simple branched tubular (Pyloric glands)
- Simple branched acinar (sebaceous)
*acinus = 1, acini = more than 1
What are the different possibilities of glandular classifications based on secretory portion?
*For compound ducts
- Compound Tubulo-Acinar (Submandibular gland)
- Compound Tubular
- Compound Acinar (Parotid/Sublingual glands)
What are the 2 portions of the respiratory system?
Conducting portion:
Nasal cavity → Nasopharynx → Oropharynx → Larynx → Trachea → Bronchi → Bonchioles (regular and terminal bronchioles)
Respiratory portion:
Respiratory bronchioles → Alveolar ducts → Alveolar sacs → Lung alveoli
What are the fuctions of the conducting and respiratory portions of the respiratory system?
Conducting portion: warming, humidifying, cleaning, and delivery of air
*Structure to ensure uninterropted supply of air (cartilage, smooth muscles, CT → provide rigidity, flexibility and extensibility)
*Possess glands and ciliated cells to remove foreign particles
Respiratory portion: site for gas exchange (O2, CO2)
What are the general components of the conducting portion of the trachea? (layers)
Lumen → Outside:
Lumen → Epithelium (Mucosa) → Lamina propria (Mucosa) → Submucosa (contains glands) → smooth muscles + Hyalin cartilage → Adventitia (dense irregular CT)
In the trachea, how is the Epithelium of the mucosa classified?
How is the Lamina propria classified?
Pseudo stratified columnar ciliated epithelium with goblet cells
Lamina Propria = Loose C.T., contains elastic fibers, capillaries
What structures are considered to be in the submucosa of the trachea?
- Denser C.T.
- Glands (serous and mucous acini)
- A bit of Trachealis muscle (smooth muscles)
How is the CT of the adventitia classified?
Dense irregular C.T.
What are the features of the serous acinus and the mucous acinus in the submucosa of the trachea?
Serous Acinus:
- Pyramidal cells
- Small lumen
- Acidophilic granules (which are?)
- Myoepithelial cells
- BM
- Aqueous secretions to humidify the air and facilitate breathing
Mucous Acinus:
- Columnar cells w/ ground/basal nucleus
- Secretes mucus to stick to foreign particles
- Pale cytoplasm (doesn’t stain well with eosin)
- No myoepithelial cells
**FINISH AND CONFIRM
What are the different cells found on the BM of the pseudo stratified columnar ciliated epithelium of the mucosa? (respiratory epithelium)
- Goblet cells → columnar, triangular nucleus, secrete mucous, Unicellular glands
- Ciliated cells → Columnar, most abundant, 100s of cilia (up to 5um long)
- Brushy cells (sensory cells?) → not seen in light microscope, CD8 precursors
- Small Granule cells → granules stained with Argentaffin, granules contain serotonin (permeabilty of capillaries), norepinephrine (smooth muscle constriction)
- Short cells → stem cells giving rise to the other types
How does the respiratory epithelium change in smoking individuals?
Smoking causes Squamous Metaplasia
Short cells stop producing a pseudo stratified epithelium → produce squamous, dry epithelium
What place of sections will cilia never be found in?
Longitudinal section
What is the general structure of a cilia?
- Basal body at the base
- Axoneme is the “continuation” of the basal body
- Axoneme is covered by a plasma membrane
*1 Axoneme/cilia
What is the structure of a single microtubule?
Wall of 1 complete microtubule composed or 13 protofilaments (alternation of a and b tubulin)
+ end = where a/b-tubulin dimers are added for growth of the microtubule
- end = where a/b-tubulin dimers are removed for shortening of the microtubule
What is the structure/composition of an Axoneme?
- 9 peripheral doblets of microtubules (1 complete + 1 incomplete/10 protofilaments)
- 1 central pair of complete microtubules
- Radial Spokes → connects outer doublet to central pair
- Nexin → connects outer doblet between eachother
- Dynein Arm → Allow for movement of the cilia (2/doblet)
- Inner sheath → surrounds the central pair
- Tectins → small stabilizing protein inside outer complete microtubules
How is the basal body different/similar to the axoneme in cilia?
Basal body has peripheral triplets of microtubules (1 complete + 2 incomplete) → 2/3 are continuous with the axoneme peripheral doblets
Protein Linker in basal body is the equivalent of Nexin in the axonemes (not the same)
What are centrioles?
Centrioles are paired barrel-shaped organelles located in the cytoplasm of animal cells near the nuclear envelope. Centrioles play a role in organizing microtubules that serve as the cell’s skeletal system
- 1 centriole = 9 triplets of microtubules (similar to axoneme)
- Microtubules grow from centrioles in the cells
What are the main roles of microtubules in the cell?
- Carry vesicles around the cell with the help of motor proteins walking on the microtubules
- Motor protein = Kinesin - Movement of Cilia
- Motor protein = Dynein - Involved in Cytokenisis (cell division) by pulling on chromosomes (makes kinetochore by attaching to centrosomes)
- During cell division, centrioles are on the sides of the cell and allow for microtubules to pull and divide the cell in 2
Which 2 mutations affect the axoneme?
- Primary Ciliary Dyskinesia (PCD)
- No movement of the cilia bc lack of Dynein arms
- Impairs mucus clearing (bronchiectasis)
- Chronic sinusitis
- Situs Inversus (Kartagener’s syndrome) 50% of patients → all organs are on other side of normal
- Male infertility (spermatosoa’s tail ahs axoneme for motility) - Radial Spoke Protein Mutations
- Result in immotile cilia and sperm
- Radial spokes are composed of at least 20 other proteins
Which 3 bronchi types terminate the conducting portion?
- Pulmonary Bonchi
- Regular Bronchioles
- Terminal Bonchioles
What are the characteristics of pulmonary bronchi tissues?
Mucosa:
Wavy Epithelium, less goblet cells,
Lamina propria → loose CT with LOTS of capillaries to warm air
Submucosa:
- Only serous glands (no more mucous)
- Complete layer of smooth muscle cells (4-5 layers)
- Hyalin cartilage
Aventitia:
- Mixed with the lungs
What are the characteristics of regular bronchioles tissues?
Mucosa:
- Most Wavy Epithelia → Simple Columnar Ciliated Epithelium without Goblet cells (no more short cells)
Submucosa:
~2 layers of smooth muscle cells
- Thin Lamina propria
- No cartilage
Adventitia:
- Hard to see mixed with lungs
What are the characteristics of the Terminal Bronchiole tissue?
Mucosa
- Less wavy than regular bronchiole
- Columnar Ciliated and non-ciliated “club cells”
- Very thni LP (last structure with LP)
Submucosa:
- Thin SM cell layer
- No cartilage or glands
No distinguishable Adventitia
*Last structure with complete wall + Last structure of the conducting portion
What are club cells?
Where are they found?
- Start as Columnar/Cuboidal cells and get shorter and shorter
- Not ciliated (no basal body compared to ciliated cells)
- Appear clear, almost transparent
- Produce surfactant
- Found in terminal brochioles, respiratory bronchioles and alveolar ducts
What are characteristics/tissues found in Respiratory bronchioles?
*Wall of respiratory bronchioles is interrupted and opens onto alveolar sacs
Mucosa:
- Only club cells, no Lamina Propria
Submucosa:
- Thin, protruded SM layer
No distinguishable Adventitia
What are characteristics/tissues found in the Alveolar duct?
Mucosa:
- Only club cells (very short, almost squamous)
- Highly interrupted, only pieces of mucosa (fist protrusions)
Submucosa:
- Discontinuous SM
Which cells and structures line Alveolar sacs and Alveoli?
Pneumocytes type I → Squamous, covers the whole surface
Pneumocytes type II → Bulky, Small granules, Stain pale, less in number, Usually in corners, Secrete surfactant
In the septi → Important capillary network for gas exchange (endothelial cells sharing a BM with pneumocytes)
Inside the lungs → Macrophages
In the septi → Reticular fibers (Collagen Type III)
*Collagen type I, III, IV (BM)
What happens to macrophages in the alveoli/alveolar sacs when they encounter foreign particles?
- They eat it → carried to lysosomal compartment
- Can’t digest it (ex: polluant)
- Macrophage migrates to the septum
- Macrophage (which can normally move around) is fixed into the septum and stays there (impairs elastic fibers synthesis)
*Eventually they will dye and release their contents including lysosomal compartments → release proteolytic enzymes + elastase which degrades elastic fibers from the septum → Emphysema
What organelles are found in Pneumocytes Type II?
Small lamellar bodies fuse to become bigger → fuse with the PM and release their contents everywhere in the alveoli
Lamellar bodies contain surfactant protein A, B, C, D + Phospholipids (Lecithin primarily) → helsp reducing surface tension of the pneumocytes type I
What composes the Blood-Air barrir in the alveoli?
Alvolar lumen - Penumocyte type I - Joint BM - Endothelial cells - Capillary lumen (with erythrocytes)
What reaction is catalysed by Carbonic Anydrase?
H2CO3 ←→ CO2 + H2O
*For transport of CO2 under the H2CO3 form in RBC
What are the 3 main ways by which CO2 is transported in the bloodstream?
- Dissolved gas
- Bicarbonate (H2CO3 by carbonic anhydrase)
- Carbaminohemoglobin bound to hemoglobin
What causes the Respiratory distress syndrome of the newborn?
When premature new-born → can’t produce surfactant → collapse of airways during expiration
What is the last structure which has Gands in its submucosa?
Intrapulmonary bronchi → only serous
What is the last structure which has Hyalin Cartilage in its submucosa?
Intrapulmonary bronchi
What is the last structure which has a Lamina Propria in its mucosa?
Terminal bronchioles (end of the conducting zone)
What is the last structure which has a distinguishable adventitia?
Regular bronchioles (but hard to see)
