The respiratory system
FUNCTION:
Conduction of air - gas exchange (O2 CO2)
Conditioning of air: cleaning, moistening, warming
1, cleaning
- large dust particles are removed by vibrissae in
the nose
- smaller are trapped to the layer of mucus
performed by glands and by goblet cells
- ciliated epithelium remove the mucus layer from
deeper part toward oral cavity – swallowed or
expectorated
2, moistening
- glands are responsible for moistening of the air
3, warming
- rich superficial vascular network
The respiratory system
From the functional point of view the respiratory system is divided into:
conducting portion
upper – nasal cavity
– paranasal sinuses
– nasopharynx
lower – larynx
– trachea
– bronchi
– bronchioles
– terminal bronchioles
respiratory portion
- respiratory bronchioles
- alveolar ducts
- alveolar sacs
- alveoli – alveoli
Support and flexibility of respiratory system
Cartilage
- primarily hyaline + some elastic cartilage
- to support the wall of the conducting portion
- preventing collapse of the lumen
Elastic fibers
- flexibility
- the smallest bronchioles have the higher proportion of the elastic fibers
Smooth muscles
- contraction regulates air flow during inspiration and expiration
Ciliated pseudostratified columnar epithelium with goblet cells
(RESPIRATORY EPITHELIUM)
1.
2.
3.
4.
5.
ciliated columnar cells (300 cilia, move of overlying mucus towards oral cavity)
columnar cells with microvilli = brush cells
goblet cells (terminal bronchioles Clara cells)
undifferentiated short basal cells
small granule cells = Kulchitsky cells - neuroendocrine
AXONEME „9+2 patern“
9 pairs of peripheral microtubules +
•
one central pair
inserted into BASAL BODIES
(modified centrioles - 9 triplets)
two types of contractile proteins:
tubulin and ciliary dynein
rapid back-and-forth movement
,,beating motion,,
EPIGLOTTIS
• Elastic cartilage plate
epiglottis
• Tunica mucosa
- lamina epithelialis mucosae
- lamina propria mucosae: mixed glands
• lingual surface and laryngeal surface
EPIGLOTTIS
LARYNGEAL SURFACE
• epithelium thinner
• Lmp has no papillae (smooth)
Stratified
squamous ep.
nonkeratinized
LINGUAL SURFACE
• epithelium thicker
• lamina propria mucosae forms papillae
Stratified squamous
ep. nonkeratinized
papilla
LPM
LPM
- lower (last third) laryngeal
surface : respiratory ep.
• Tunica
Mixed glands
mucosa
- epithelium
- lamina propria mucosae
mixed glands
• Elastic cartilage plate in the centre
- openings - ducts from glands
cross the plate to laryngeal
surface
TRACHEA
1.Tunica mucosa
- pseudostratified columnar
ciliated epithelium
- lamina propria mucosae
(loose connective tissue)
,,border,, - long.oriented elastic fibers
2.Tela submucosa
- connective tissue
- tracheal glands = mixed
3. Tunica fibrocartilaginea
(fibromusculocartilaginea)
- C-shaped rings of hyaline cartilage (= ,,cartilaginea,,)
connected by anular ligaments (= ,,fibro,,)
- dorsal part – pars membranacea
contains trachealis muscle= smc (= ,,musculo,,)
4. Tunica adventitia
- loose connective tissue
TRACHEA
OESOPHAGUS
tracheal lumen
trachealis muscle
hyaline cartilage
Respiratory epithelium
basement membrane
Tunica mucosa
Tela submucosa
- gll.tracheales
Tunica fibrocartilaginea
- Hyaline cartilage
Tunica adventitia
gll.tracheales - seromucous
- tubuloacinar
TUNICA MUCOSA:
Lamina epithelialis mucosae
(thick BM)
Lamina propria mucosae
tracheal glands
Conducting portion:
LUNGS – pulmo
Branching of bronchial tree
Primary bronchi
Secondary bronchi
Bronchopulmonal
segment – anatomical
and functional unit of
the lungs
Pulmonary
lobules
Pulmonary
acinus
R+L
3 – 2 lobar
bronchi
Tertiary bronchi
9-12 small bronchi (↓5mm)
Bronchioles (↓ 1mm):
Terminal bronchioles
Respiratory bronchioles
2 and more
Alveolar ducts
Respiratory portion
Alveolar sacs
alveoli
Spiral orientation of muscles and
anastomosing cords of cartilage
SECONDARY AND TERCIARY BRONCHUS
TUNICA MUCOSA:
a) pseudostratified columnar
ciliated epithelium
b) lamina propria (LCT)
c) spiral smooth muscles (SM)
TELA SUBMUCOSA:
a) connective tissue
b) seromucous glands (G)
CARTILAGE (C): plates or islands
SMALL BRONCHI (diameter < 5 mm)
• epithelium – pseudostratified columnar ciliated
• less goblet cells
• lamina propria - seromucous glands decrease
• bundles of smooth muscle cells increase
• small islands of cartilage spliced by bundles of smooth muscle cells
epithelium pseudostartified
columnar ciliated
smooth muscle tissue
hyaline cartilage
Bronchioles (diameter less than 1 mm)
Main structural changes:
- epithelium changes
- glands are not present
- cartilage disappeared
- more smooth muscle cells and elastic fibers
Terminal bronchioles
- simple ciliated columnar-cuboidal epithelium
with less developed cilia
- with Clara cells
- collagen and elastic fibers
- more smooth muscles
Respiratory bronchioles
- simple ciliated cuboidal epithelium with Clara cells
- collagen & elastic fibers, smooth muscles
- the walls are interrupted by alveoli
- branched into alveolar ducts - ductuli alveolares
CLARA CELLS
- secretory granules
- decrease surface tension in the bronchioles
- enzyme P450 (s- ER): detoxication
- transport of IgA to the bronchial lumen
- lysosyme
terminal bronchiole
Terminal bronchiolus
Respiratory bronchiolus
Respiratory bronchiolus
- simple cuboidal ciliated ep.
- collagen & elastic fibers
- smooth muscles
respiratory bronchiol
ALVEOLAR DUCT - ductus alveolaris
- thin tube
- wall is interrupted by numerous alveoli
- in wall – smooth muscle cells formed sphincters, they are the most distal place of
smooth muscle presence
- enters into alveoli (atrium)
Respiratory portion
Capillaries
Respiratory
bronchiole
Alveolar
duct
Alveoli
Pore
Alveolar
duct
ALVEOLI
= saclike evaginations
•simple squamous epithelium:
pneumocytes type I (alveolar, membraneous) - squamous
pneumocytes type II (septal, granular) – cuboidal shape, produce surfactant
•wall is supported by network reticular and elastic fibers
GRANULAR PNEUMOCYTE:
• GER, GA
• Lamellar bodies limited by unit membrane – phospholipids synthesis and releasing of
surfactant (lipoprotein complex)
• FUNCTIONS:
- decrease surface tension in alveoli
- prevent collaps of alveoli
- make alveolar surface wet
- antibacterial
Interalveolar septum
1. Thin portion - blood-air barrier is composed of:
pneumocyte type I
fused basal laminae
endothelial cells
Function: gas exchange (O2, CO2)
2. Thick portion contains:
- fibroblasts, mast cells, macrophages,
- reticular, elastic and collagen fibers
BAB
Alveolar pores: equalize air pressure and permit collateral circulation of the air
Pleura
- is composed of visceral and parietal layer
- both layers are covered by mesothelium resting on a fine
connective tissue layer
- between these 2 layers is situated the pleural cavity with liquid
Respiratory
bronchiolus
Alveolar
sack