Respiratory System

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Respiratory System

• The respiratory system is divided into two major
  components
• The air-conducting components
• The respiratory or gas-exchange components

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Air Conducting Portion

• Consists of the
• nasal cavities
• Pharynx
• Larynx
• Trachea
• Extrapulmonary bronchi
• Intrapulmonary bronchi and bronchioles
• Terminal bronchioles

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• Three layers
• 1) Mucosa
• ---epithelium pseudostratified ciliated columnar
  epithelium
• ---lamina propria CT, contain LC, PC, BV, LV
• Pseudostratified ciliated columnar epi.
• ciliated cell columnar, cilia
• goblet cell
• basal cell
• -pyramidal, basally-located
• -undifferentiated cell?ciliated cell or
  goblet cell
• brush cell
• -columnar, microvilli,
• -EM RER
• -function not very clear
• diffuse neuro-endocrine cell
• -less, pyramidal
• -function secret hormones to regulate
  contract of SM and secretion of gland

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Cilia on the surface of trachea
Ciliated cell
Goblet cell
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• 2) Submucosa
• LCT, with BV, LV and N
• tracheal gland mixed
• diffuse LT and LN
• S Ig A secretory component (secreted by epi.
  cell) Ig A ( produced by plasma cell)
• 3) Adventitia
• cartilage ring 16-20 C shaped
• circular ligament elastic F
• SM- posterior part (membrane part) SM, elastic
  F, tracheal gland

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Air Conducting Portion
functions ----- Filters, moistens, and warms air
before it enters lungs. -----Olfactory functions
to examine air and to protect against breathing
in harmful substances. -----Mucous tends to trap
foreign substances and then the cilia (of
pseudostratified ciliated columnar epithelium)
clear the foreign substances from the trachea and
bronchi of lungs. ----Cartilages found in trachea
and bronchi play an important role in keeping
airway open.
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Air Conducting Portion

• Bronchial Tree upside down tree with the
  trachea serving as the trunk of the tree and the
  bronchi as the primary branches
• Many smaller branches ending is small twigs
  (bronchioles)
• The leaves would represent the millions of
  alveoli.
• Extra-pulmonary bronchi are the left and right
  bronchi that branch off of the trachea and then
  enter the lungs.
• The intrapulmonary bronchi are the branches that
  form within the lungs.
• The larger sizes have hyaline cartilage which
  decreases with smaller bronchi. Eventually the
  cartilage is replaced with smooth muscle.
• Bronchioles have diameters of less than 5 mm.
  Terminal bronchioles have intact but greatly
  reduced amounts of smooth muscle in the wall.
  When this wall becomes incomplete, and contact
  with alveoli becomes evident, then the bronchiole
  changes to become a respiratory bronchiole.

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• ? from lobar bronchi to small bronchi
• ---Regulation of simplification (gradually)
• mucosa
• -epi. become thinner
• -goblet cell ?
• -lamina propria thinner, SM ?
• submucosa gland ?
• adventitia cartilage?cartilage ?decreasing
• ? bronchiole D lt 1mm
• ---continuous to change
• goblet cell, Gland, cartilage ? or disappear
• smooth muscle ?,circular mucosa plica ?
• ? terminal bronchiole D lt 0.5 mm
• ---goblet cell, gland, cartilage disappear
• ---SM form a whole layer of circumferential SM
• ---Wall
• simple columnar epi. two types of cells
• A layer of SM

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Clara cell

• Simple columnar epi
• i.   ciliated cell
• ii.  secreting cell Clara cell
• EM
• dome-shaped apical
• SER
• Secreting G contains proteolytase and oxidase
• function
• dissolve the mucus, secrete surfactant.
• biological transformation
• undifferentiated cell ? ciliated cell

Ciliated cell
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Respiratory Components

• The respiratory components consist of
• Respiratory bronchioles
• Alveolar ducts
• Alveolar sacs
• Alveoli

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Respiratory Components

• Respiratory bronchioles have incomplete walls
  such that alveoli make direct contact. This
  allows for gas exchange to occur.
• Alveolar ducts are where respiratory bronchioles
  branch. There is much greater space with alveoli
  exposed.
• Alveolar sacs are clusters of alveoli .
• Alveoli are single bubble like structures.

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• ? respiratory bronchiole
• ---similar to terminal bronchioles
• simple ciliated columnar epi.
• smooth muscle
• ---place where connect with alveoli gradual
  changing
• simple cuboidal epi. ?simple squamous epi.
• less SM, elastic F
• ? alveolar duct 20-60 alveoli connect with it
• ---wall hard to see- opening part between two
  alveoli
• simple cuboidal epi. or squamous epi.
• SM single, EF- knob-liked structure
• ? alveolar sac
• ---many alveoli open to it
• ---no proper wall, no knob-liked structure
• ? alveoli

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Respiratory Components

• The lungs have an abundant blood supply.
• Capillary beds are abundant within the spaces
  adjacent to the alveoli.
• Alveoli walls consist of simple squamous
  epithelial cells which allow for rapid exchange
  of gases (diffusion).
• The many millions of alveoli produce a very large
  surface area (1/2 of a tennis court)
• Most abundant cells are the endothelial cells of
  the capillaries. These usually have small,
  elongated nuclei.

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• ?alveoli
• ---polygonal, with opening sac- 0.2mm in D,
  300-400 million/per lung, total area 70-80mm2
• ---wall
• epi. and basal lamina
• alveolar septum CT with BV, EF

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• a.alveolur epi
• ---type I alveolar cell
• LM flattened, 0.2um, N round
• EM
• plasmalemmal vesicles
• tight junction
• Function constitute the blood-air barrier
• ---type II alveolar cell scattered, 5-8/per
  alveoles
• LM
• cuboidal or round, with round N
• paler- stained, foamy cytoplasm
• EM
• secreting granules Osmiophilic multilamellar
  body
• -0.1-1.0 um
• -contains phospholipid, glycosaminoglycan and
  protein
• microvilli, mito, lysosome, RER, Golgi
• Function
• i. secreting surfactant
• ii. differentiated into type I
  alveolar cell

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neonatal respiratory distress syndrome
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• b. alveolar septum CT
• EF
• Fibroblast, macrophage, plasma cell, mast cell
• LV, N
• capillary endothelium basement membrane
• Blood-air barrier the structure through which
  the gaseous exchange takes place
• ---0.2-0.5 um
• ---components
• a layer of liquid
• type I alveolar cell and basement M
• CT
• capillary endothelial cell and BM

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• c. alveolar pore 10-15 um
• ---equalize( balance) the air-pressure between
  alveoli
• ---lober pneumonia- bacteria or inflammatory
  spread through the pore

• d. alveolar marcophage monocytes- MPS
• ---dust cell macrophage which phagocytose carbon
  or duct particles
• ---heart failure cell when lung
  congested(edema), the alveolar marcophage
  phagocytose RBC, digest the hemoglobin into
  hemosiderin(pigment) and accumulated them within
  macrophage

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Trachea Epithelium Hyaline cartilage
Mucous acini
Perichondrium
Serous acini
Adventitia fibrosa
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Pseudostratified Ciliated columnar Epithelium
Blood vessel
Hyaline cartilage
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cl cilia, gc goblet cell, bm basement
membrane
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Trachea trachealis muscle between hyline
cartilage
Trachealis muscle
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Bronchus contains hyaline cartilage
Cartilage Smooth muscle that Serves for
bronchoconstriction
Serous acini
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Intrapulmonary bronchus
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Bronchus with cartilage Pulmonary vein
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Intrapulmonary bronchus
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Intrapulmonary bronchus
Intrapulmonary bronchus With cartilage
Terminal bronchiole
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Terminal bronchiole Alveolar duct
Respiratory bronchiole
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Pulmonary artery and vein bronchiole (no
cartilage)
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Branching of bronchiole (no cartilage vissible)
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brespiratory bronchiole with alveolus (a) in
its wall, c and d alveolar ducts which are
lined almost entirely with alveoli, e individual
alveoli, f blood vessel.
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a two alveoli separated by thin interalveolar
septa, b smooth muscle in bronchiole, c blood
vessel d bronchiole no cartilage
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Alveoli separated by the thin interalveolar
septa. Reddish spots are RBC and dark spots are
nuclei of simple epithelium of capillaries
or alveoli.