The Respiratory System!
U of Mich Med site
RESPIRATORY SYSTEM
The function of the respiratory system is to provide O2 and to remove CO2 from the blood
Segments
Conducting Portion consisting of the nasal cavity, larynx, trachea, bronchi and bronchioles
Transitional Portion formed by the respiratory bronchioles
Respiratory Portion formed by the alveolar duct, alveolar sac and the lung alveoli
Function
Maintain an open passageway for air passage, condition air headed for lungs (by increasing
humidity and temperature)
Combination of conducting and respiratory functions: Keep airways open for easy air
passage, condition air headed for lungs (by increasing humidity and temperature)
and start of gas exchange.
Exchange of O2 and CO2 between air and blood
Features
Presence of cartilage and smooth muscle cells in airways
Presence of smooth muscle cells, but NO cartilage
No cartilage or smooth muscle cells, presence of alveolar sacs.
GENERAL PLAN OF THE CONDUCTING PORTION (TRACHEA)
Muscle
Cartilage
Submucosa
Epithelium*
Lamina Propria
Adventitia
* Pseudo stratified columnar ciliated epithelium with goblet cells
Mucosa
GENERAL PLAN OF THE CONDUCTING PORTION (TRACHEA)
Pseudo stratified columnar ciliated epithelium with goblet cells
Mucosa
Lamina Propria ( loose C.T. , elastic fibers, capillaries)
Submucosa
C.T. and Glands
Cartilage
Muscle
In the trachea, hyaline cartilage
Adventitia
Dense irregular C.T.
Trachealis Muscle
(smooth muscle)
Acinar Glands
(in submucosa)
Cartilage
Epithelium
Poor stain
packed with glycoproteins
Nucleus at base
Sticky secretion
Acidophilic
Central, round nucleus
Watery fluid
Serous Acinus
Mucous Acinus
PSEUDO STRATIFIED COLUMNAR
CILIATED EPITHELIUM
Ciliated Cells
Goblet Cell
Brush Cell
BM
* Epinephrine, Serotonin
** Squamous Metaplasia
Small Granule
Short Cell (stem ?)
Cell (Argentaffin *)
(250-300 cell cilia) Microtubule Core
Basal Body
Z.A. + Actins (Microfilaments)
Centrioles
(Nucleation Center)
Desmosome
+ Intermediate Filaments
Microtubules
Cytoskeleton
Microfilaments (Actins) 10 nm
Intermediate Filaments 15 nm *
Microtubules 25 nm
* Cytokeratin, Vimentin, Desmin, Neurofilaments
MTs are essential for a broad range of cell functions, most notab
Mitosis – segregation of chromosomes
Transport – molecular motors (Kinesins and Dynein)
Cell Motility – Cilia and Flagella
Cell shape and Polarity (eg. Axon in neurons)
Positioning of membrane enclosed organelles (golgi and ER)
Cilium
Microtubule core a( xoneme)
AXONEME
9 pairs of microtubules
Basal Body
(B.B.)
1 central pair
Centrioles
PM
Basal Body
B.B.
Microtubules
Each centriole of the pair shown in the
centrosome has the same structure of the basal
body.
Each centriole (or basal body) is a cylinder, 0.2
m wide X 0.4 m long
Cilium
Axoneme
24nm
Cross section
Basal body
Basal Body
(Centriole)
9
Dynein Arm
Radial
8 Spokes
B
Central
Pair
A
7
6
5
Outer
Doublet
Tektin
Central
Sheath
Nexin bridge
Triplets
The stable MTs in the cilium
are arranged in a
characteristic pattern of nine
outer doublet MTs – A and B.
One MT (A) in each doublet is
complete while the other (B)
contains only 11
protofilaments. They are
fused and share a common
wall.
Composed of 9 sets of
triplet MTs. Each MT triplet
contains one complete MT
(A tubule) and 2 attached
incomplete MTs (B & C
tubules) which share walls
with the adjacent MTs.
Other proteins from crosslink between these triplet
Protein Linker
MTs
Ciliary movement the axoneme is mediated by axonemal and ciliary dynein.
The tail region of the dynein attaches to the A tubule while the head region
with the motor interacts with the B tubule of the adjacent doublet.
B.B.
PM
M
Anatomy of Respiration
Trachea
Conducting
Pulmonary Bronchi
Regular
Bronchioles
Transitional
Respiratory
Terminal
Bronchioles
Respiratory
Bronchioles
Alveolar Ducts
Alveoli
Alveolar sacs
GENERAL PLAN OF THE CONDUCTING PORTION (TRACHEA)
Muscle
Cartilage
Submucosa
Epithelium*
Lamina Propria
Adventitia
* Pseudo stratified columnar ciliated epithelium with goblet cells
Mucosa
EP
LP
HC
EP
LP
SM
SM
Adventitia
HC
Glands
Note: As you move down the airway - less goblet cells,
- less mucous acini, more serious acini
- cartilage pieces - no c-rings
17-7
SM
SM
LP
EP
LP
Adventitia
* asthma
EP
EP
SM
EP
LP
LP
SM
* Clara cells
EP*
SM
EP*
SM
* Clara cells
Arrows indicate knobs of mucosa
Respiratory
Bronchiole
Alveolar
Duct
Alveoli
Septum
Alveolar Sac
Bronchial Tree - Fig. 17-16
Fig.17-19
Pneumocyte II
Macrophage
Pneumocyte I
Alveolar Lumen
Septum
Endothelium
(Capillary)
Septum
THE BLOOD-AIR BARRIER
Surfactant
BM
H2CO3
O2
CO2
H2CO3 + Carbonic Anhydrase = CO2 + H2O
MVB
(MVB)
The lamellar bodies contain the surfactant proteins A,B, C and D and phospholipids,
primarily lecithin, which help to reduce the surface tension of the pneumocytes I.