Lecture 8 1/29/24 Flashcards
What are the characteristics of larynges in birds?
-two larynges present
-anterior larynx similar to mammals
-caudal larynx/syrinx found at caudal end of trachea by bifurcation
What are the characteristics of the trachea in birds?
-overlapping, complete cartilage rings
-lined by resp. epithelium over glands
-increasing goblet cells and decreasing glands moving caudally
-lots of elastin fibers in submucosa
What are the characteristics of the syrinx?
-voice box in birds
-located at tracheal bifurcation
-wall composed of internal and external tympanic membranes
-supported by intersyringeal cartilages and pessalus/bone wedge
What are the characteristics of the bronchi?
-conduction portion
-trachea divides into primary bronchi
-extensive branching occurs of primary bronchi into secondary bronchi into tertiary bronchi
-increasingly narrow diameter leads to more inertia
What type of epithelium lines the bronchi?
ciliated pseudostratified columnar that becomes flatter as the diameter becomes smaller (eventually cuboidal)
What structures surround the bronchi?
-smooth muscle
-glands
-plates of cartilage
-collagen
-adjacent blood vessels
-BALT
How do the bronchi walls change as the diameter narrows?
-folds in the bronchi increase with smaller diameter
-larger bronchi are more smooth
What is BALT?
dense unencapsulated lymphoid tissue adjacent to the bronchi that provides immune surveillance
What are the characteristics of the bronchioles?
-arise after the smallest branches of the bronchi
-no cartilage or glands
-surrounded by smooth muscle
-mucosa typically folded
What happens to the epithelium as bronchioles become smaller?
-epithelium shortens and loses cilia with decreased diameter
-goes from ciliated, pseudostratified columnar to ciliated, simple cuboidal to non-ciliated, simple cuboidal
What are the characteristics of terminal bronchioles?
-last of the strictly conducting portion
-cuboidal epithelium
-transitions to the respiratory bronchioles
What are the characteristics of respiratory bronchioles?
-transition zone between conducting and gas exchange
-branch from ends of terminal bronchioles
-lined by cuboidal epithelium that flattens distally
-wall has smooth muscle
-alveoli in the walls
What are the characteristics of club cells?
-located within respiratory bronchioles
-often indistinct
-make club cell secretory protein
What are the effects of club cell secretory protein?
-anti-inflammatory
-important for metabolism
What are the characteristics of alveolar ducts?
-branch from respiratory bronchioles
-entrance composed of circumferential smooth muscle
-walls composed of alveoli
-ducts branch into alveolar sacs
What are the characteristics of alveolar sacs?
-groups of individual alveoli
-branch off the alveolar ducts
-gas exchange occurs within individual alveoli
What are the characteristics of alveoli?
-where gas exchange occurs
-lined by type 1 and type 2 pneumocytes
-separated by alveolar septa composed of type 1 pneumocytes, collagen, and elastin
What are the characteristics of type 1 pneumocytes?
-simple squamous
-very thin
-allows for gas diffusion
What are the characteristics of type 2 pneumocytes?
-cuboidal
-thicker
-not good for gas exchange
-produce pulmonary surfactant
-proliferate to repair if type 1 pneumocytes are damaged
What is the blood-air barrier?
fused basement membrane, endothelial cells, and type 1 pneumocytes
What are the characteristics of the alveolar septa?
-composed of small amount of collagen and elastin
-allows for compliance/changes in size and shape
What are the characteristics of alveolar macrophages?
-within alveolar lumens and septa
-provide immune surveillance and clean up
What are the interlobular septa?
connective tissue (collagen) divisions between lung lobules
What are the two blood supplies within the lungs?
-pulmonary vascular system (primary)
-bronchial vascular system (secondary)
What is the blood flow path followed by the pulmonary vascular system?
-deoxygenated blood from right atrium
-pulmonary arterial trunk
-right and left pulmonary arteries at hilus along mainstem bronchi
How do the arterial branches of the pulmonary vascular system arrange?
they follow the branches of the bronchi
Which elastic arteries are seen in the pulmonary vascular system?
-proximal pulmonary artery
-main pulmonary trunk
-larger pulmonary arteries
Which type of artery is seen at the level where bronchi become bronchioles?
muscular arteries
What happens as the pulmonary arteries continue to follow the bronchi and bronchioles?
-become smaller
-become discontinuous in the pulmonary arterioles
-lead to pulmonary capillaries
-blood becomes oxygenated
-blood exits through pulmonary venules and veins
What are the characteristics of the bronchial vascular system?
-minor system
-provides oxygenated blood to structures within the lung itself
-also follows bronchial tree
What are the two types of pleura?
-visceral/covering lungs
-parietal/covering inner thoracic wall
What type of epithelium forms the pleura?
simple squamous
