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Transcript
•The respiratory system includes the lungs and its
components
•Also included are all the tubes and anatomical
structures required to move the gases to and from
the lungs.
The respiratory system has 5 main functions:
1. Provide an area for gas exchange with the blood.
2. Provide a means to move gases to and from the
exchange surfaces.
3. Protect the respiratory surfaces from dehydration,
temperature, and invasion by pathogens.
4. Produce sounds.
5. Provide olfactory sensations to the CNS from the nasal
cavity.
To make it easier to study, we generally break up
the respiratory systems into Upper and Lower
halves…
Included in the Upper Respiratory system are the:
• nose
• nasal cavity
• paranasal sinus
• pharynx
The basic job of these structures is to filter, warm,
and humidify the incoming air.
Included in the Lower Respiratory system are the:
• larynx (voice box)
• trachea (windpipe)
• bronchi (first branches of the trachea)
• bronchioles (smaller bronchi of various types)
• alveoli (air sacs)
This list follows down into the lungs. The bronchioles and the
alveoli actually only exist in the lungs, themselves.
The “Respiratory Tract” is the name for the airways that carry
air (nothing else). It has a conducting portion (from nasal
cavity to terminal bronchioles, and a respiratory portion (from
the respiratory bronchioles to the alveoli).
Respiratory Anatomy
Upper Respiratory System:
The Larynx:
Looking down the throat / Vocal Cords
Bronchial Entrance into the Lungs
Lung Surface Maps:
The Bronchial Tree
At the Alveoli:
Respiratory Mucosa
This tissue lines the respiratory tubes and has two layers.
1. Respiratory Epithelum
a. Pseudostratified columnar epithelium
b. Cilia for mucus transport
c. Goblet cells for mucus production
d. In bronchioles, cuboidal cells with scattered cilia
2. Lamina Propria
a. This is an underlying layer of CT
b. Connects respiratory epithelium to visceral muscle
c. Contains mucous glands
Nasal Mucosa
• Prepares the air for arrival in the lower respiratory tract
• Warms and humidifies the incoming air by drawing it over the veins located in the
lamina propria
• Protects more delicate surfaces from chilling or drying out.
Nose Bleeds (epistaxis)
• High concentration of vessels in a vulnerable position in
the nose, which makes nose bleeds a common event.
• Potential causes include: Trauma, Drying infections,
Allergies, Hypertension, Clotting disorders.
The Mucus Escalator System:
•The goblet cells and mucous glands along the length of the respiratory
tract produce a sticky mucus that bathes exposed surfaces
•In the upper respiratory system, the cilia beat the mucus (along with any
trapped particles and/or mircroorganisms toward the pharynx
•In the lower respiratory system, the cilia beat the carpet of mucus up
toward the pharynx.
•When the mucus gets to the pharynx it is swallowed and eventually
taken out of the body.
•Filtration in the nasal cavity usually removes all particles of 10µm or
greater in size.
Larynx:
•Inspired air leaves the pharynx and goes through the glottis (a
narrow opening). The Larynx surrounds and protects the glottis.
•The larynx begins at the level of C4 or C5 and ends at level C6
•Laryngeal problems:
•An infection or inflammation here is known as laryngitis (commonly affects the
vibrational qualities of the vocal cords, hoarseness is common).
•Mild cases of laryngitis are temporary and seldom serious
•Bacterial or Viral infection of the epiglottis can be VERY dangerous because
the resulting inflammation could close off the glottis (blocking the airway) [acute
epiglottitis]
•A Tracheal Blockage exists when people inadvertently aspirate (inspire) foreign
objects into their larynx and or trachea. If the person can no longer breathe, an
immediate threat to life exists, and the airway must somehow be opened
(*LifeSavers story).
So… how do you deal with a blocked larynx ?
1. Heimlich Maneuver (Abdominal Thrust)
-
-
The rescuer applies compression to the victim’s
abdomen just inferior to the respiratory diaphragm.
This elevates the abdomen sharply and hopefully
exhales enough air to dislodge the blockage.
2. Intubation/Tracheotomy
-
If the blockage results from swelling of the tissues a
new path must be found.
Professionals can insert a plastic tube through the
glottis (intubation).
If blockage is immovable or larynx crushed, need to
cut a hole (tracheotomy).
RESPIRATORY DISORDERS
Cystic Fibrosis (CF)
• Most common, lethal, inherited disease affecting
Caucasians of northern European descent
• Frequency of 1 in 2500 births
• Results from a defective gene on Chromosome #7
• Generally don’t live past 30 years
• COD is massive infection of lungs and associated heart
failure
•Mucus so thick the Mucus Escalator stops working,
blocking small bronchioles and makes breathing difficult
Tuberculosis (TB)
• Bacterial infection of the lungs (Mycobacterium tuberculosis)
• The bacteria colonize the airways and the lung tissue.
• Symptoms vary, but generally include:
- Coughing
- Chest Pain
- Fever
- Night Sweats - Fatigue
- Weight loss
• Called this because the bacteria produce “tubercles” on the
lungs of TB patients (hardened lumps/bacteria colonies).
• Used to be TB wards in hospitals/highly contagious
• Thanks to a STRONG vaccination program, TB has been
virtually eradicated in developed countries, but it’s still a big
problem in developing nations.
Pneumonia
• Develops from a viral infection or other stimulus that causes
an inflammation of the lobules of the lungs.
• As the inflammation develops, fluid leaks into the alveoli,
which constricts the bronchioles and makes breathing difficult.
• Becomes more likely when respiratory defenses are already
compromised by other factors (like another illness, smoking,
etc.)
• Patients with “full blown” cases of pneumonia need to be
hospitalized.
•Bacterial Pneumonia can be successfully treated with strong
antibiotics. Viral pneumonia is more difficult to treat
• Scarring caused during the first case of pneumonia can make
the patient more susceptible to contracting it again.
Pulmonary Embolism
• The lungs have a low blood pressure. Because of this they
are susceptible to blockages from masses in the blood (fat,
thrombus, clot, air bubbles, etc.)
• This blockage is known as a pulmonary embolism (and the
thing doing the blocking is called an embolus).
• If a pulmonary embolism remains in place for several hours,
the alveoli will PERMENENTLY collapse
• If the embolism occurs in a major blood vessel, the
increased resistance may put extra strain on the right ventricle
and could cause Congestive Heart Failure (CHF).
Decompression Sickness
• Painful condition that accompanies a sudden drop in ambient
pressure.
• Air is mostly Nitrogen gas (that we don’t use). During a
sudden pressure drop the N2 bubbles out of solution, into the
blood, causing a soda can-like fizz.
• The bubbles can form in the blood and collect in the joints.
The resulting pressure pushing the joints apart causes a
condition known as “the bends”.
• Bubbles can also from in the CSF. This could cause a
serious problem called an air embolism (or brain embolism).
• This occurs most often to SCUBA divers, and people in
airplanes that suddenly loose cabin pressure.
• The cure is to force the N2 gas back into solution, by
increasing the ambient pressure, and then SLOWLY bringing
the ambient pressure down.
• This is accomplished by the use of a Decompression
(Hyperbaric) Chamber.
Carbon Monoxide Poisoning
• This has killed entire families through faulty, leaky
furnaces, or space heaters. If you run a car in a closed
garage, this will affect you as well.
• CO competes with O2 for binding sites on the heme
groups, and usually wins the site.
• At 0.1% of inspired air being CO, survival will be
impossible (without medical assistance)
• Treatments may include giving the patient pure O2, and/or
a total blood transfusion.
• A tell-tale sign of CO poisoning is blue fingernail beds (of
course if the person has nail polish on, it may be
impossible to tell. That’s why must ambulance units carry
nail polish remover.
Emphysema
• Chronic, progressive condition characterized by shortness of
breath and an inability to tolerate physical exertion.
• This is caused by a destruction of the exchange surfaces in
the alveoli.
• As they become destroyed, the alveoli merge, and fill with
fibrous tissue across which gas exchange will not occur.
• Emphysema is linked to inspiring air containing fine
particulate matter (cigarette smoke, etc.).
• Emphysema also seems to be a “normal” part of aging (66%
of males, and 25% of females have detectable levels of
emphysemic changes in their lungs after the age of 65).
Respiratory Physiology
External respiration is all processes involved in the exchange
of gases between the fluids of the body, and the outside
environment.
Internal respiration is cellular respiration (gas exchange
between the fluids of the body and the body’s cells.
Ext. Resp. + Int. Resp. = we commonly call Respiration
This involves 4 integrated processes:
1.
2.
3.
4.
Pulmonary ventilation
Gas Diffusion across the respiratory membrane
The storage and transport of O2 and CO2.
The exchange of dissolved gases
Interruption of the respiration process would cause the body’s
tissues to become oxygen starved (Hypoxic)
Hypoxia: Low tissue O2 levels place severe limits on metabolic
activity. (literally means “few oxygen”)
Anoxia: Cells are completely cut off from O2. This condition
will kill quickly. (literally means “without oxygen”)
The Respiratory Cycle:
The respiratory cycle is a single inhalation and exhalation
event.
The tidal volume (TV) is that amount of air that moves into or
out of your lungs during one respiratory cycle.
Modes of Breathing:
There are two basic types of breathing, based on the muscle
activity involved:
1. Quiet Breathing (eupnoea) {this is how we usually breathe}
-
Inhalation requires muscular contractions, but
exhalation is passive.
-
Two types of quiet breating:
a. Diaphragmatic (deep) breathing
i.
When diaphragm muscles contract, air is
drawn in
ii. When diaphragm muscles relax, exhalation
occurs
b. costal (shallow) breathing
i. thoracic volume changes because the rib
cage changes shape
ii. Inhalation occurs when intercostal
muscles elevate the ribs
iii. Exhalation occurs passively when these
muscles relax (elastic rebound).
2. Forced Breathing (hyperpnoea)
• active inspiratory and expiratory movements
• causes accessory muscles to assist with inspiration
• contraction of intercostal muscles and abdominal
muscles (in extreme cases) forces the exhalation.
Respiratory Performance and Volume Relationships
Resting Tidal Volume (~500ml): The amount of air you move
in a single quiet respiratory cycle.
Epiratory Reserve Volume [ERV](~1000ml): The amount of
air you can voluntarily expel after you have completed a
normal quiet respiratory cycle (forced exhalation).
Residual Volume [RV](~1150ml): The amount of air that
remains in your lungs after a maximum forced exhalation.
Inspiratory Reserve Volume [IRV](~3300ml in ♂’s,~1900ml in
♀’s): The amount of air you can take in over and above the
tidal volume.
Volume Capacity Equations…
TV + IRV = inspiratory capacity
ERV + RV = functional residual capacity
ERV + TV + IRV = vital capacity (VC)
This is the amount of air movable in a single respiratory cycle (in males it’s
about 4.8 liters in females about 3.1 liters).
VC + RV = Total Lung Capacity (~6L in ♂‘s and 4.2L in ♀‘s)
Pulmonary Function Tests:
• Monitor several aspects of respiratory function.
• A spirometer is a device used to measure VC, ERV, and IRV.
• A pneumotachometer measures the rate of air movement in
the respiratory cycle.
• A peak flow meter measures the maximum rate of air
movement during a forced expiration
• People with Asthma tend to have reduced pulmonary
function. These devices will show a reduction in VC, ERV, and
peak flow in asthmatics.
The End
Join us for our next exciting
chapter…
The Digestive System
Or to paraphrase Sherlock Homes:
It’s Alimentary my dear Watson!