Download RSPT 1207 Cardiopulmonary Anatomy and Physiology

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RSPT 1207 Cardiopulmonary Anatomy and Physiology
UNIT 2: THE LOWER AIRWAYS – Part I
I. THE TRACHEA – is the beginning of the lower airways. Its function is to transfer
inhaled gas between the larynx (above) and the lungs (below).
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Location
a. Located almost midline in the chest
b. Immediately below the cricoid cartilage is the first cartilage ring of the
trachea
c. The great vessels of the heart are located immediately anterior and the
esophagus is located immediately posterior to the trachea.
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Description
a. 10-13 cm in length from the first ring to the bifurcation of the trachea
b. The adult trachea is 1.5 – 2.5 cm in diameter
c. Supported by 16-20 “C” shaped cartilage rings. The curve of the “C”
faces the sternum.
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THE CARINA – Bifurcation where the single structured trachea divides
Located at the angle of Louis (T3-4)
Site of the cough reflex. It contains a large network of tactile sensitive receptors
that induce coughing.
RIGHT AND LEFT MAINSTEM BRONCHUS – as the trachea bifurcates it
splits into two main bronchi
Continues to be protected by “C” rings
Diameter of both mainstems is approximately 1 cm
Right mainstem comes off the carina at a 20-30 degree angle, Left mainstem is at
a more sharp angle of 45 to 55 degrees
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LOBAR BRONCHI – Each mainstem branches out to each lobe of each lung.
Each lobe has a lobar bronchus which is named for the love it ventilates
Diameter of most lobar bronchi is 0.5 cm
The “C” cartilage that protected the trachea and the right and left mainstem
bronchus now have become cartilage plates
Lingula – a division of the LUL, that mirrors the RML
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SEGMENTAL BRONCHI – Each lobe of the lung is separated into 2 or more
segments.
Each segment has a segmental bronchi named after the segment that it ventilates
These bronchi are also supported by cartilage plates
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RIGHT
RUL
LEFT
LUL
o Right apical
o Posterior RUL
o Anterior RUL
RML
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o
RLL
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o
o
Lateral
Medial
Superior
Medial basal
Anterior basal
Lateral basal
Posterior basal
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o Apical-posterior
o Anterior
Lingula
o Superior
o Inferior
LLL o Superior
o Anteriomedial
o Lateral basal
o Posterior basal
SUBSEGMENTAL BRONCHI
Bifurcate from each segmental bronchi
Supported by cartilage plates
PERIPHERAL AIRWAYS AND RESPIRATORY ZONE
Peripheral airways – are non-cartilaginous airways
o Bronchioles – begin 5-14 generations below segmental bronchi, are 1-2
mm in diameter
o Terminal Bronchioles – transfer of gases end here, diffusion of gas
molecules through walls begin
Respiratory Zone – Where gas diffusion occurs and include three airways
o Respiratory bronchioles
o Alveolar ducts
o Alveolar sac
The tracheobronchular tree: http://courses.washington.edu/envh515/slide17.gif
THE LINING OF THE AIRWAYS – The internal walls of the airways are lined
with various tissues.
Epithelium – also called epithelial tissue
Mucous membrane – lies on top of epithelium
EPITHELIAL TISSUE
Cover Internal and external surfaces of the body
Two types: protective cells, glandular cells
The epithelium continually changes as we progress down the tracheobronchial
tree.
In the respiratory tract you will find 4 basic types of these cells:
o Stratified Squamous Epithelium
o Pseudo-Stratified Columnar Ciliated Epithelium
o Simple Cuboidal Epithelium
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o Simple Squamous Epithelium
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STRATIFIED SQUAMOUS EPITHELIUM – Simple cells that are stacked.
Thick Layer, flexible, protective
Location
a. Anterior 1/3 of the nasal cavity
b. Oral cavity
c. Oropharynx
d. Laryngopharynx
Can sustain abrasive action
Regenerates easily
PSEUDO-STRATIFIED COLUMNAR CILIATED EPITHELIUM – Cells are
so close together that they appear to be stacked. Thus, the term pseudo-stratified.
These cells contain microscopic cilia on their superior surface that extend into
the lumen of the airway.
Location:
a. Nasal cavity – level of the turbinates
b. Nasopharynx
c. Level of the vocal cords
d. Cartilaginous central airways
At the level of the bronchiole, ciliated cells begin to disappear
SIMPLE CUBOIDAL EPITHELIUM – Cubed- shaped cells. Single cells deep,
but thicker that simple squamous cells
Location:
a. Lumen of the Transitional bronchioles
b. Terminal bronchioles – columnar cells are gradually replaced by this
single layer of cubic cells
SIMPLE SQUAMOUS EPITHELIUM – These are simple cells, lie in a single
layer, form the walls of the alveoli
Location: In the alveoli
This is where gas diffusion occurs
Provides as thin an interface as possible between the air in the alveoli and blood
in the capillary.
The thickness of has a direct effect on the ability of gas to diffuse throughout the
membrane into the blood.
THE MUCOUS MEMBRANE
Covers the pseudo-stratified columnar ciliated epithelium
Majority of the internal surface of the tracheobroncial tree covered by the
mucous membrane
There are two glands involved in the production of mucous
o Submucosal glands
o Goblet cells
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SUB-MUCOSAL GLANDS – A collection of secreting glandular epithelium
cells.
Vary in size can be up to 1 mm in length
Location: In the layer of the airway call the Lamina Propria, close to
parasympathetic nerve endings
Connects to the bronchial surface with long, narrow ducts
Produce the majority of the mucous in the airways. Up to 100 mL of mucous a
day
Any type stimulation of the gland by the parasympathetic nerves will increase
mucous production
With chronic irritation, the number of submucosal glands will increase
GOBLET CELLS – Pseudo-stratified columnar ciliated epithelium that has lost
its cilia, has gained the ability to secret mucous
Location: scattered throughout the ciliated cells at a ratio of 1:5, or one goblet
cell for every 5 ciliated cells
Goblet cells will increase with prolonged irritation
XVII. MUCOUS
 Produced by mucous glands and goblet cells, mucous from both cells are the
same
 Sticky, viscous fluid
 Composition: 95% water, 5% glycoproteins, carbohydrates, DNA and cellular
debris
 When normal it is clear and low in viscosity
 When abnormal it will become thick and the color may change
 Mucous that is produced in the lower airway is called SPUTUM.
XVIII. THE MUCOCILIARY TRANSPORT SYSTEM
 Mucosa and the ciliated cells propel particles that are <10 microns out of the
tracheobronchial tree
 90% of these microns will enter the central airways and land on the muco-ciliary
bed
 Particles <2 microns can reach the alveolar ducts and sac
 The lack of cilia and mucous in these areas result in taking up to 24 hours to
travel to a ciliated area.
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HOW THE MUCOCILIARY TRANSPORT SYSTEM WORKS
Each Pseudo-stratified columnar ciliated epithelium cells has about 200 cilia on
its surface. Each cilium is approximately 6 micron tall. Each cilium can beat
1000-1500 times a minute.
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Cilia propel particles 2-9 microns toward the larynx at a rate of 10-20 mm per
minute. Cilia moves in a sequential motion called the meachronal wave which
propels particles in certain directions
Once enough mucous reaches the carina a cough is stimulated
Click to see Cilia movement
EFFECTS ON CILIA
The cilia propel in the watery SOL layer, and extend into the GEL layer of the
mucous membrane.
The cilia must be able to extend through the sol layer to the gel layer to
transport the mucous
Several factors can hinder the effectiveness of the cilia and the muco-ciliary
transport system
o Environmental factors
o Certain medications
o Smoking
 When someone inhales tobacco smoke, the gel layer becomes
thicker, mucous production increases and mucous dries faster
 The nicotine and other toxic substances paralyze the cilia
 Only when a person sleeps is when the cilia can function
correctly.
o Gravity – Because mucous must move upstream in the tracheobronchial
tree laying flat will help facilitate the exit of sputum.