8. Respiratory Histology Flashcards
What is the difference between the conduction portion and the respiratory portion of the system?
Conduction collects and warms air by nasal cavity/trachea, bringing it down to the bronchi and bronchioles
Respiratory portion passes air to alveoli for gas exchange, using alveolar ducts and sacs
Respiratory epithelium has pseudostratified columnar ciliated epithelium (remember cilia are never present on tru stratified epithelia). What is the lamina propria?
is a rich vascular network with a complex set of capillary loops
What do goblet cells in the respiratory epthelium do?
They synthesize and produce mucus released by exocytosis, mucus is used to collect dust/bad things!
The nasal cavities are divided by hyaline cartilage- nasal septum. What are the three regions of the nasal cavity and which takes up the most space?
Nasal vestibule (just barely inside)
Respiratory region 2/3 space (lined with mucosa)
Olfactory region 1/3 space (have olfactory mucosa)
What is the main functionof the nasal cavities?
adjust temperature and humidity of the air inspired
Since nasal vestible is just skin, it is expected that the type of cell be keratinized stratified squamous epithelium. What cells make up the respiratory region, posterior to the nasal vestibule?
Pseudostratified columnar ciliated epithelium
The olfactory mucosa is in the superior portion of the nose, and has receptors for sense of smell. What is the hallmark of this tissue (2)?
The tissue is dramatically thicker and it lacks goblet cells!, psuedo ciliated columnar eptihelium
Olfactory receptor cells signal to olfactory bulb to relay scent. What other cells are within the olfactory mucosa ?
Basal cells for reproduction
Brush cells
Sustentacular cells: support to olfactory receptor cells
The trachea is a short flexible air tube that serves as a conduit, extending from larynx to main bronchi. What are the four layers of the trachea?
- Mucosa (ciliate pseudo strat +elastic lamina propria)
- Submucosa (denser CT than lam propria)
- Cartilagenous (C shaped hyaline cartilage)
- Adventitia (CT that binds trachea to other structures)
What is charcteristic of bronchi?
Still pseudostratified, cells are shorter, fewer goblets, increased elastic fibers in lamina propria for expansion during inhalation!
What is characteristic of bronchioles (from bronchi)?
Large size are simple ciliated columnar, while small are simple cuboidal. Few goblet cells, no cartilage, lots of smooth muscle (=bronchoconstriction!) INC elastic fibers, some clara cells
What is characteristic of terminal bronchioles (from bronchioles)?
Simple cuboidal epithelium with CLARA cells, increased elastic and 1-2 layers of smooth muscle, brings in air into lungs
What are clara cells/what do they do?
Secrete a lipoprotein that prevents luminal adhesion with airway collapse (during expiration)
Respiratory bronchioles are the last structure before aveoli and have simple cuboidal epithelium and elastic fibers with smooth muscle. What do the respiratory bronchioles branch into? (4)
aveolar ducts
aveolar rings
aveolar sacs
alveoli
Alveolar ducts ends in alveolar sacs which are 2+ clusters of alveoli. What are alveolar rings?
aggregates of smooth muscle, collagen and elastic fibers that form rings around aveolar ducts
Alveoli are sacs that are lined with type I and II pneumocytes. Alveoli contain simple squamous epithelium, supporting tissue and blood vessels. What are the aveolar septum and pores?
Septum: wall of alveolar capillaries surrounded by elastin and collagen fibers
Pores: small openings that permit movement of air between alveoli
What are the main functions of type I pneumocytes (P1)?
Line almost entire alveolar surface, creating surface for gas exchange, they are elongated and flattened
What are the main functions of type I pneumocytes (p2) which are the most abudant of the two in alveoli?
Rounded cells covering 60% epithelium, Have SURFACTANT which reduces surface tension, preventing collapse during respiration
What is special about surfactant released by P2?
They have lamellar bodies rich in a mixture of phospholipids and proteins, which is excreted by exocytosis as SURFACTANT
What are the structures starting with the lumen, that need to be ‘gone through’ for gas exchange to occur?
Lumen of aveoli Through surfactant Through P1 Through basal lamina of P1 and erythrocytes Through endothelium of erythrocyte
What is the main cause of asthma?
recurrent obstruction of airflow due to bronchiole inflammationand smooth muscle contraction (bronchospasm)
Emphysema is permanent enlargement of air spaces distal to terminal bronchiole. Areas for gas exchange is lost in the disease (destruction of alveolar wall) and by chronic obstruction of airflow due to narrowing of bronchioles. How is this disease acquired?
SMoking cigarettes and chronic inhalation of particlate material (dust/construction)
What is commonly seen with pneumonia, inflammation of the lung tissue?
air spaces are filled with exudate containing WBCs RBCs and fibrin. Under examination lungs appear red, firm (lack of air spaces) and heavy (presence of exudate)
Lungs are housed in pleural cavities, lined by a serous membrane, the parietal and visceral pleura. What do they line?
Parietal pleura lines internal cavity and visceral pleura lines the organ (lungs). they are separated by pleural cavity contains serous fluid
What is characteristic of visceral pleura?
covered in flattened mesothelium. Has fibrous tissues of collagen and elastin fibers. Extends into the lungs as fibrous septa, continuous with lung parenchyma, and contains extensive lymphatic vessels
