Transcript respiratory system notes

Know your
basic parts


Supply the body with Oxygen
Dispose of Carbon dioxide

Respiratory zone:
◦ Actual site of gas
exchange
◦ (some exchange Respiratory
bronchioles, alveolar
ducts) alveoli (major
site)

Conducting zone:
◦ Conduits – purify,
humidify, and warm
incoming air
◦ Include all other
respiratory
passageways





Provide airway for
respiration
Moisten & warm air
Filter air (mucus & cilia)
(breath in thru nose & out
thru mouth)
Site of olfactory (smell)
receptors
Resonating chamber for
sound waves (hold your
nose closed & see how
you sound!)
Mucus traps the
“junk” and the
cilia sweeps it
up toward your
throat so you
can swallow it
or spit it out.
Smoking kills
cilia so
smoker’s
constantly have
to cough to
clear the mucus
out!


The cilia in your nose become sluggish & slow
when they are cold & do not move the mucus
down into your throat
Mucus in the nasal cavity accumulates &
dribbles out

Nasal Conchae
aka.
NasalTurbinates=
increase SA of
mucosa exposed
to air to help warm
& filter it – also
increase
turbulence (mini
tornado effect) of
air – more inhaled
particles swirled
onto mucus and

Nasal cavity
separated from
oral cavity by the
palate (roof of
mouth)
◦ Anterior – hard
palate
◦ Posterior – soft
palate



Lighten skull
Act a resonance chamber
Produce mucus

Pharynx serves as common passageway for
food (& fluids) and air.
Color code the 3
parts of the pharynx
on the diagram in
your notes
The names give you
location clues!

Nasopharynx – air only
◦ During swallowing, Soft palate & uvula rise
upward to close off nasopharynx which prevents
food & fluids from entering it

Oropharynx & Laryngopharynx – food,
liquids & air
◦ Food will be directed posteriorly to the esophagus
◦ Air will go anteriorly into the larynx





Pharyngeal tonsils: aka. Adenoids – located
in nasopharynx
Palatine tonsils: located in oropharynx
Lingual tonsils: located at base of tongue
All tonsils are lymph nodes & work with
immune system
You will be labeling these on the back page
diagram



Provides patent
(open) airway
Act as a switching
mechanism
(between
respiratory &
digestive systems)
Voice production
(location of vocal
cords)


Know this:
Laryngeal
prominence
on the
thyroid
cartilage
Seen
externally as
Adam’s
apple



9th cartilage
When air is flowing into the larynx – free edge
projects upward
During swallowing:
◦ Larynx is pulled upward
◦ Epiglottis is tipped back and down to cover
laryngeal inlet into trachea
◦ Routes food/fluid into esophagus


Initiated if anything other than air enters
the larynx
Pressure from air moves object upward out
of the larynx
◦ Reflex does not work when unconscious so not a
good idea:
 To give fluids to an unconscious person
 Also a reason why people in an
alcoholic coma often die from
aspirating their own vomit.

The ciliated
mucosa
(mucociliary
escalator)
continuously
propels the
mucus which
contains dust
particles and
debris to the
throat so it can
be expelled or
swallowed.



Diminishes ciliary activity
Coughing is ONLY method of preventing
mucus accumulation in the lungs
Smokers should never be given medications
that INHIBIT the cough reflex.



Trachea is reinforced internally by 16-20 C
shaped rings (Be able to explain – see
diagram on next slide also)
Outer portion of C – causes trachea to stay
patent (open) and not collapse
Inner portion (open part) of C – allow trachea
to be flexible and gives esophagus a place to
expand into upon swallowing.
 Heimlich
manuver is
the same
principle as a
cough
 Used to press
air out of
lungs in case
someone
cannot inhale
to initiate a
cough


-ostomy = cut a hole into
Used in cases of:
◦
◦
◦
◦
◦
Abnormalities
Cancers
Obstructions
Injuries to area
Etc.


Trachea divides into right and left primary
bronchi at the level of the sternal angle
(where manubrium and body of sternum
meet).
Inhaled objects usually lodge in the right
primary bronchus since it is wider, shorter,
and at a more vertical angle



Left lung is smaller, consisting of 2 lobes and
contains a cardiac notch
Right lung has 3 lobes
FYI: Bronchopulmonary segments
◦ Served by own artery, vein, and individual
segmental bronchus
◦ Left lung has 8 segments while right lung has 10.

Respiratory therapists and surgeons use this
info about the different bronchopulmonary
segments so they can treat the patient as
needed
◦ Even to the point of removing the diseased segment
and leaving the good tissue
 The
lungs weigh
approximately 2.5 pounds


Parietal vs. visceral
Function of pleural fluid
◦ Lubricate layers so they can slide across each other
◦ Cause them to cling tightly to each other through
surface tension (helps maintain pressure
differences necessary for inhaling/exhaling)

Begins as the
terminal
bronchioles which
feed into the
respiratory
bronchioles which
end in the alveoli
chambers where
gas exchange
(external
respiration) takes
place.



Composed of simple squamous – much
thinner than a sheet of paper
Membrane has gas on one side and blood on
the other.
Account for the largest portion of lung
volume and provide a tremendous surface
area for gas exchange



Gas exchanges occur through simple
diffusion
Approximate surface area = 50-70 square
meters (40x greater than skin SA)
A moist membrane is required so the TYPE
II cuboidal cells secrete a substance called
surfactant that coats the membrane &
interferes with surface tension.
 Pulmonary ventilation: air is moved in and
out of the lungs
 External respiration: gas exchange
between blood and alveoli
 Respiratory gas transport: CV system
transports oxygen and carbon dioxide
between lungs & tissues (discussed in
Blood chapter)
 Internal respiration: gas exchange
between blood & tissue cells
 Definition: Cellular respiration: actual use of
oxygen & production of carbon dioxide in the
 Pulmonary ventilation: - Moving air into and
out of the lungs
 Depends on pressure changes
 Breathing
 Inspiration = moving air into the lungs
 Expiration = moving air out of lungs
 Intrapulmonary pressure
 Pressure within the alveoli (lungs)
 Changes with phases of breathing
 Always equalizes itself with atmospheric pressure
 Intrapleural pressure
 Pressure within intrapleural space (between the
pleural membranes )
 Always 4 mmHg less than intrapulmonary pressure
 Any conditions that causes intrapulmonary
pressure to equal intrapleural pressure will
cause the lungs to collapse
 This means they lose the
ability to move air since
there is NO more pressure
difference

term for lung collapse

Air in the intrapleural
space due to trauma –
causes lung collapse
 Question: Why does breathing happen?
 ONLY acceptable answer: The RULE: Volume
changes lead to pressure changes which lead
to the flow of gases to equalize the pressure
Boyle’s
Law =
Pressure &
Volume
have an
INVERSE
relationship
.
 Main inspiratory muscles
 Diaphragm & external intercostals
 Thoracic dimensions change to increase
volume of thoracic cavity by 0.5 liters
 Intrapulmonary pressure drops 1-3 mmHg
and air rushes info normal quiet inspiration
 A deep forced (active) inspiration requires
activation of accessory muscles – see diagram
in notes
 A passive process dependent on natural lung
elasticity
 lungs recoil when inspiration stops – so
alveoli compress –which leads to a volume
 decreases -causing intrapulmonary pressure
to rise - gas outflows to equalize the
pressure with atmospheric pressure
 Forced (active) expiration requires contraction
of abdominals, etc – see diagram
 Bronchial sounds: produced by air rushing
through trachea & bronchi
 Vesicular sounds: produced by air filling
alveoli
 Wheezing:
whistling
sound
 Rales:
rasping
sound
 Basic Lung Sounds – Bronchial
 Auscultating The Lungs - Reference Guide
 Pulmonary ventilation can be influenced by 4
physical factors




Respiratory passage resistance
Lung compliance
Lung elasticity
Alveolar surface tension forces
 Resistance due to
increased friction
as air moves
through passages
 Smooth muscle
bronchoconstriction
Disorders such as
asthma – when
bronchi constrict
 Local accumulations
of mucus, infectious
material, and tumors
– also block air
passage
 The ease with which lungs can readily expand
 Affected by the elasticity of the lungs and the
thoracic cage which can be diminished by 2
main factors:
 Fibrosis of the lung tissue
 Ossification and/or muscle paralysis impairs
flexibility of the thoracic cage
 Essential for normal expiration
 Emphysema:
tissue becomes less elastic
and more fibrous
 loss of elasticity & increase in fibrous tissue causes
enormous effort to exhale – at end stages, alveolar
walls break down and surface area is lost for gas
exchange
Surface tension is caused by the tendency of
polar molecules such as water to stick to each
other with hydrogen bonds
 this can cause the walls of the alveoli to stick
together like plastic wrap every time you
exhale.
 Large amounts of energy /effort will be
required to simply re-expand the lungs and

allow you to inhale (IRDS)


Surfactant – interferes with cohesion of water
molecules so less energy needed to expand
lungs – this is one of the things that keeps
our lungs partially expanded at all times. (the
other thing is the pressure difference
previously discussed)
Secreted by Type II cells in lungs
AKA:
Hyaline
Membrane Disease
Caused by lack of
surfactant due to
prematurity
28 weeks of
gestation is
considered



Measurements made as part of pulmonary
function tests;
Volumes that move in and out during the
normal breathing cycle, and with deliberate
additional effort
can be measured directly by spirometry with
the subject breathing through a closed circuit
in and out of a cylinder inverted over water,
or into a vitalograph, or by
pneumotachograph
Table 1: Lung volumes
Tidal Volume
Inspiratory and
expiratory
reserve volumes
Vital capacity
Volume of inspired/expired air moving in and
out with each breath
Used when tidal volume increases above that at
rest
Forced expiratory
volume in1s
Volume that can be inspired/expired after full
expiration/inspiration
Volume exhaled in the first second, with maximal
effort after full inspiration
Functional residual
capacity
Volume remaining in the lungs at endexpiration; decreases as tidal volume increases
Residual volume
Remains after a maximal expiratory effort;
cannot be exhaled
Vital capacity + residual volume
Total lung capacity
Internal
& External Respiration
Events #2 & 4
 Used to
determine the
individual
pressures of
each gas in a
mixture of
gases
 Based on % of
total of 760
mmHg of total
atmospheric
pressure
 Gas exchanges that occur:
Between the blood and the alveoli AND
Between the blood and the tissue cells
Take place by simple diffusion
Depends on partial pressures of oxygen & carbon
dioxide that exist on opposite sides of the
exchange membrane (Dalton’s law of partial
pressures)
 Always flowing from high to low




 states
that the solubility of a gas in a liquid is
directly proportional to the pressure of that
gas above the surface of the solution (IOW:
the higher the pressure of the gas, the more
gas will be shoved into the liquid thus
increasing solubility)
 Solubility (of a gas) and partial pressure have
a direct relationship
 The
solubility coefficient of the gas also
affects this process – the higher the #, the
more the gas “likes” to dissolve into a liquid
(based on molecular structure, etc.)
 Each gas will dissolve in a liquid in
proportion to the ratio between its partial
pressure gradient and its solubility
coefficient
 CO2 = .57
 O2 = .024
 N2 = .012
 Solubility
& temperature have an inverse
relationship.
 Increase in temperature causes increase in
kinetic energy causes more molecular motion
which allows molecules to break the
intermolecular bonds and escape from
solution
 And vice versa

Partial pressure gradients
and gas solubilities
 Oxygen = has low
solubility but steep
partial pressure gradient
(105 mmHg in alveoli –
40 mmHg in blood = 65
mmHg pressure
gradient)
 Carbon dioxide = has
solubility ~20x greater
than oxygen but partial
pressure gradient is only
5 mmHg
 Partial pressure gradients and gas
solubilities
 Due to the ratios of solubility coefficients and
pressure gradients:
 ~Equal amounts of gases are exchanged
 Thickness of respiratory membranes
 0.5 to 1.0 micrometers
 edematous (swollen) tissue can be caused by
congestion and pneumonia - hinders diffusion
leading to hypoxia oxygen deprivation
 Surface Area
 50-70 square
meters for gas
exchange
 Emphysema or
cancer
 Walls of alveoli
break down
 Less surface area
for gas exchange
 The phrenic &
intercostal nerves
transmit impulses to
the respiratory
muscles
 Irritation to phrenic
nerve is responsible
for hiccups (spasm
of diaphragm
muscle)
 Neural centers are
located in medulla &
pons
 Eupnea = normal respiration rate
 Approx 12-15 breaths per min




Hyperpnea = higher than normal rate
Apnea = No rate
Dyspnea = general term for abnormal rate
Physical factors, conscious control, emotional
factors, and chemical factors all influence rate
& depth of breathing.
 Deep & rapid respiration, too much CO2 is
vented out of the body so:
 Not enough acid production
 H2O + CO2 = H2CO3 (carbonic acid)
 Respiratory alkalosis results
 Treatment: trap the CO2 and
rebreathe it till breathing returns
to normal
 Slow & shallow respiration with not adequate
expiration so CO2 is not vented out of the body
 Production of excess acid
 H2O + CO2 = H2CO3 (carbonic acid)
 Respiratory acidosis results
 Usually caused by disease process:
 COPD
 Asthma
 Obesity
 Trauma
 Pneumonia