Biological Role of Respiration, Histology and Defense Mechanisms Flashcards
Main compartments of the respiratory system
- conduction zone
- respiratory zone
- musculo-elastic ventilation apparatus
Conduction zone
where and role?
conditioning of inhaled air
neck
Respiratory zone
where and role?
site of gas exchange
lungs
Musculo-elastic ventilation apparatus role
drives ventilation
What happens to the structure of the airways and vessels as they progress?
divide into successions of bifurcations
What is mucosa?
membrane that lines the nasal cavity
made of layers of epithelial cells overlying a layer of loose connective tissue
lined by lymphoid tissue all the way
Types of sinuses
maxillary sinus - cheekbone
ethmoid sinuses
sphenoid sinus
frontal sinus
How is turbulence created?
turbinate bones in nasal cavity which form narrow passageways
drives air in and out of sinuses
Defence mechanisms against particles
vibrissae prevent large particles entry
mucus which covers lining trap smaller particles
Respiratory epithelium characteristics
lots of goblet cells
below epithelium: sponge-like mucosa, due to extensive venous plexus
Actions of venous plexus in mucosa
mediate exchange of moisture with the air
filling status regulates flow of air through nasal cavities
swell during infections of nasal cavity
Other epithelium in nasal cavity
olfactory which conveys sense of smell
top of nasal cavity
Histology of trachea
horse shoe shaped cartilage
seromucous glands in submucosa
smooth muscle completes rings partially formed by cartilage
pseudostratified ciliated epithelium with mucous producing goblet cells
What is mucociliary clearance?
mucus transported towards pharynx by beating movement of cilia
Bronchus histology
cartilage which varies between generations
1st: several rods spanning most of circle
later: single small plate
lumen bordered by respiratory epithelium
sometimes - incomplete ring of smooth muscle between epithelium and cartilage
may be submucosal glands
Difference between bronchi and larger bronchioli
bronchioli: no cartilage , complete smooth muscle, no submucosal glands, fewer goblet cells in epithelium
Histology of smaller bronchioli
epithelium is cuboidal with ciliated and non-ciliated club cells
complete ring of smooth muscle
higher ratio of muscle ring thickness to luminal diameter than bronchi
Club cells role
protective role
generate serous secretions
What do terminal bronchioles do?
give rise to respiratory bronchioles that have cuboidal epithelium and alveoli built in their walls
Characteristics of tissue around alveoli and nearby airways
connective tissue contain numerous elastin fibres
What do alveoli have to make gas exchange more efficient?
alveolar pores - allows quicker filling as it dampens turbulence of air
What is the blood-air barrier?
space which oxygen crosses to enter the lungs
What is the blood-air barrier made of?
ultra thin walls of capillary endothelium and type 1 cells (pneumocyte)
Pulmonary arteries function and structure
provide blood supply to alveolar capillary networks
elastic arteries with comparatively thin walls
Bronchial circulation role and structure
provide blood supply to bronchi from the aorta
small, strong muscular wall, little elastin
What is surfactant?
compound made of phospholipids, proteins and carbohydrates
made by type 2 alveolar cells
What does surfactant do?
reduce surface tension so water in the alveolar surafce does not exert strong capillary forces so expansion of the lung is not inhibited
Distinguishing type 1 pneumocyte
only nuclei discernible, flat at air interface
looks similar to flat endothelial cells
Distinguishing endothelial cells
ideally: nucleus curved around capillary
looks similar to type 1 pneumocyte
Distinguishing type 2 pneumocytes
corners of alveoli, roundish cells with light content and light granular nuclei
Distinguishing macrophages
within alveoli
larger than type 2 pneumocytes
cytoplasm often dirty
nuclei larger than type 2 pneumocytes with heterochromatin spots
Where are the lymph vessels of the lungs?
in the septa next to the vessels of pulmonary circulation
also in the interstitial layer adjacent to the pleura
Where can carbon be deposited?
lymph nodes and macrophages
What is Waldeyer’s Ring?
series of tonsils (aggregates of lymph follicles) at the anterior pharynx, very close under surface of the skin
Defense against pathogens in the airways and alveoli
mucus of airways contain immunoglobulins, mainly IgA
alveoli: alveolar macrophages
