respiratory physiology and respiratory disorders
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Respiratory
Physiology and
Respiratory
DisordersREPORTED BY MARVIN GONZAGA
Mechanics of BreathingInspiration and Expiration
The diaphragm and the
intercostal muscles contract. The
diaphragm moves downwards
increasing the volume of the
thoracic (chest) cavity
1
The intercostal muscles pull
the ribs up expanding the rib cage
and further increasing this
volume
2
During expiration the
diaphragm and intercostal
muscles relax. This returns the
thoracic cavity to its original
volume, increasing the air
pressure in the lungs, and forcing
the air out.
3This increase of volume lowers the air
pressure in the alveoli to below atmospheric
pressure. Because air always flows from a
region of high pressure to a region of lower
pressure, it rushes in through the respiratory
tract and into the alveoli. This is called
negative pressure breathing, changing the
pressure inside the lungs relative to the
pressure of the outside atmosphere.
5
Nonrespiratory air movements
Movement Description
Coughing A long-drawn and deep inhalation followed by a complete
closure of the rima glottidis, which results in a strong
exhalation that suddenly pushes the rima glottidis open and
sends a blast of air through the upper respiratory passages.
Stimulus for this reflex act may be a foreign body lodged in the
larynx, trachea, or epiglottis.
Sneezing Spasmodic contraction of muscles of exhalation that forcefully
expels air through the nose and mouth. Stimulus may be an
irritation of the nasal mucosa.
Sighing A long-drawn and deep inhalation immediately followed by a
shorter but forceful exhalation.
Yawning A deep inhalation through the widely opened mouth producing
an exaggerated depression of the mandible. It may be
stimulated by
drowsiness, or someone else’s yawning, but the precise cause is
unknown.
Movement Description
Sobbing A series of convulsive inhalations followed by a single prolonged
exhalation. The rima glottidis closes earlier than normal after
each
inhalation so only a little air enters the lungs with each
inhalation.
Crying An inhalation followed by many short convulsive exhalations,
during which the rima glottidis remains open and the vocal folds
vibrate; accompanied by characteristic facial expressions and tear.
Laughing The same basic movements as crying, but the rhythm of the
movements and the facial expressions usually differ from those of
crying. Laughing and crying are sometimes indistinguishable.
Hiccupping Spasmodic contraction of the diaphragm followed by a spasmodic
closure of the rima glottidis, which produces a sharp sound on
inhalation. Stimulus is usually irritation of the sensory nerve
endings of the gastrointestinal tract.
Valsalva
(val-SAL-va)
maneuver
Forced exhalation against a closed rima glottidis as may occur
during periods of straining while defecating.
Nonrespiratory air movements….continued
Respiratory Volumes and Capacities
While at rest, a healthy adult averages 12 breaths a minute, with
each inhalation and exhalation moving about 500 mL of air into
and out of the lungs. The volume of one breath is called the tidal
volume (VT). The minute ventilation (MV )—the total volume of
air inhaled and exhaled each minute—is respiratory rate
multiplied by tidal volume:
MV =12 breaths/min x 500 mL/breath
= 6 liters/min
spirometer or respirometer -The apparatus
commonly used to measure the volume
of air exchanged during breathing and the
respiratory rate. The record is called a
spirogram.
Spirogram of lung volumes and capacities. The average
values for a healthy adult male and female are indicated,
with the values for a female in parentheses. Note that the
spirogram is read from right (start of record) to left (end of
record).
By taking a very deep breath, you can inhale
a good deal more than 500 mL. This
additional inhaled air, is about 3100 mL in an
average
adult male and 1900 mL in an average adult
female
Inspiratory
Reserve
Volume
If you inhale normally and then exhale as
forcibly as possible, you should be able to push
out considerably more air in addition to the
500 mL of tidal volume. There would be an
extra 1200 mL in males and 700 mL in
females.
Expiratory
Reserve
Volume
Even after the expiratory reserve volume is exhaled, considerable air
remains in the lungs. This volume cannot be measured by spirometry,
and amounts to about 1200 mL in males and 1100 mL in females.
Residual
Volume
Sum of inspiratory reserve
volume, tidal volume, and
expiratory reserve volume
(4800 mL in males and 3100
mL in females).
Vital
capacity
Sum of vital capacity
and residual volume
(4800 mL 1200 mL
6000 mL in males and
3100 mL 1100 mL
4200 mL in females).
Total
Lung
Capacity
Structures of Voice Production
Respiratory Sounds
Image
Sound originates from the vibration of the
vocal folds, but other structures are necessary
for converting the sound into recognizable
speech. The pharynx, mouth, nasal cavity, and
paranasal sinuses all act as resonating
chambers that give the voice its human and
individual quality. We produce the vowel
sounds by constricting and relaxing the
muscles in the wall of the pharynx. Muscles of
the face, tongue, and lips help us enunciate
words.
Pitch is controlled by the tension on the vocal
folds. If they are pulled taut by the muscles,
they vibrate more rapidly, and a higher pitch
results. Decreasing the muscular tension on
the
vocal folds causes them to vibrate more slowly
and produce lower-pitch sounds. Due to
androgens (male sex hormones), vocal folds
are usually thicker and longer in males than
in females, and therefore vibrate more slowly.
This is why a man’s voice generally has a
lower range of pitch than that of a woman.
Whispering is accomplished by closing all but
the posterior portion of the rima glottidis.
Because the vocal folds do not vibrate during
whispering, there is no pitch to this form of
speech. However, we can still produce
intelligible speech while whispering by
changing the shape of the oral cavity as we
enunciate. As the size of the oral cavity
changes, its resonance qualities change, which
imparts a vowel-like pitch to the air as it
rushes toward the lips.
External and Internal Respiration
External respiration or pulmonary gas exchange is the
diffusion of O2 from air in the alveoli of the lungs to
blood in pulmonary capillaries and the diffusion of
CO2 in the opposite direction. External respiration in
the lungs converts deoxygenated blood (depleted of
some O2) coming from the right side of the heart into
oxygenated blood (saturated with O2) that returns to
the left side of the heart.
The left ventricle pumps oxygenated blood into the
aorta and through the systemic arteries to systemic
capillaries. The exchange of O2 and CO2 between
systemic capillaries and tissue cells is called internal
respiration or systemic gas exchange. As O2 leaves the
bloodstream, oxygenated blood is converted into
deoxygenated blood. Unlike external respiration,
which occurs only in the lungs, internal respiration
occurs in tissues throughout the body.
Gas ExchangeSummary of chemical reactions that occur during gas
exchange. (a) As carbon dioxide (CO2) is exhaled, hemoglobin
(Hb) inside red blood cells in pulmonary capillaries unloads
CO2 and picks up O2 from alveolar air. Binding of O2 to Hb-H
releases hydrogen ions (H+). Bicarbonate ions (HCO3-) pass into
the RBC and bind to released H+, forming carbonic acid
(H2CO3). The H2CO3 dissociates into water (H2O) and CO2, and
the CO2 diffuses from blood into alveolar air. To maintain
electrical balance, a chloride ion (Cl-) exits the RBC for each
HCO3- that enters (reverse chloride shift). (b) CO2 diffuses out
of tissue cells that produce it and enters red blood cells, where
some of it binds to hemoglobin, forming carbaminohemoglobin
(Hb–CO2). This reaction causes O2 to dissociate from
oxyhemoglobin (Hb–O2). Other molecules of CO2 combine with
water to produce bicarbonate ions (HCO3-) and hydrogen ions
(H+). As Hb buffers H+, the Hb releases O2 (Bohr effect). To
maintain electrical balance,a chloride ion (Cl-) enters the RBC
for each HCO3 that exits (chloride shift).
(a) Exchange of O2 and CO2 in pulmonary capillaries (external respiration)
(b) Exchange of O2 and CO2 in systemic capillaries (internal respiration)
Control of Respiration
Respiratory
Center
clusters of neurons located bilaterally in the medulla oblongata
and pons of the brain stem divided into three areas (1) the
medullary rhythmicity area in the medulla oblongata; (2) the
pneumotaxic area in the pons; and (3) the apneustic area, also
in the pons
Medullary
Rhythmicity
Area
controls the
basic rhythm
of respiration.
Establishes the
basic rhythm of
breathing.
While the
inspiratory area
is active, it
generates nerve
impulses for
about 2 seconds
Inspiratory
Arearemain inactive
during quiet
breathing.
However,
during forceful
breathing nerve
impulses from
the inspiratory
area activate
the expiratory
area
Expiratory
Area
Pneumotaxic
Area
Transmits inhibitory impulses to the
inspiratory area. When more active, breathing
rate is more rapid.
Apneustic
Area
sends stimulatory impulses to the inspiratory
area that activate it and prolong inhalation.
The result is a long, deep inhalation. When
the pneumotaxic area is active, it overrides
signals from the apneustic area.
Regulation of breathing in
response to changes in blood
PCO2, PO2, and pH (H
concentration) via negative
feedback control.
Respiratory Disorders
A disorder characterized by chronic airway inflammation,
airway hypersensitivity to a variety of stimuli, and
airway obstruction. At least partially reversible, either
spontaneously or with treatment. Triggers include
allergens such as pollen, house dust mites, molds, or a
particular food. Other common triggers are emotional
upset, aspirin, sulfiting agents (used in wine and beer
and tokeep greens fresh in salad bars), exercise, and
breathing cold air or cigarette smoke.
Asthma
Chronic
Obstructive
Pulmonary
Disease
Characterized by chronic and recurrent obstruction of
airflow, which increases airway resistance. The
principal types of COPD are emphysema and chronic
bronchitis. its most common cause is cigarette smoking
or breathing secondhand smoke. Other causes include
air pollution, pulmonary infection, occupational
exposure to dusts and gases, and genetic factors.
Emphysema Characterized by destruction of the walls of the alveoli,
producing abnormally large air spaces that remain
filled with air during exhalation. Generally caused by a
long-term irritation; cigarette smoke, air pollution, and
occupational exposure to industrial dust are the most
common irritants.
Chronic
Bronchitis
characterized by excessive secretion of bronchial mucus
accompanied by a productive cough (sputum is raised) that
lasts for at least three months of the year for two
successive
years. Cigarette smoking is the leading cause of chronic
bronchitis.Lung
Cancer
Most people with lung cancer die within a year of the initial
diagnosis; the overall survival rate is only 10–15%. Cigarette
smoke is the most common cause of lung cancer. Roughly
85% of lung cancer cases are related to smoking, and the
disease is 10 to 30 times more common in smokers than
nonsmokers. Exposure to secondhand smoke is also
associated with lung cancer and heart disease.
Bronchogenic
Carcinoma
The most common type of lung cancer which starts in
the epithelium of the bronchial tubes.
Lung
Pneumonia An acute infection or inflammation of the alveoli.
Inflammation and edema cause the alveoli to fill
with fluid, interfering with ventilation and gas
exchange. The most common cause of pneumonia is
the pneumococcal bacterium Streptococcuspneumoniae, but other microbes may also cause
pneumonia.
Tuberculosis
(TB)
An infectious, communicable disease produced by
the bacterium Mycobacterium tuberculosis. In
many people, symptoms—fatigue, weight loss,
lethargy, anorexia, a low-grade fever, night sweats,
cough, dyspnea, chest pain, and hemoptysis—do not
develop until the disease is advanced.
Coryza The common cold. A group of viruses called
rhinoviruses is responsible for about 40% of all
colds in adults. Typical symptoms include
sneezing, excessive nasal secretion, dry cough, and
congestion.
Influenza
(flu)
Caused by a virus. Its symptoms include chills,
fever (usually higher than 101°F 39°C), headache,
and muscular aches. Influenza can become life-
threatening and may develop into pneumonia.
Pulmonary
Edema
An abnormal accumulation of fluid in the interstitial
spaces and alveoli of the lungs. The edema may arise
from increased permeability of the pulmonary capillaries
(pulmonary origin) or increased pressure in the
pulmonary capillaries (cardiac origin); the latter cause
may coincide with congestive heart failure.
Cystic
Fibrosis
An inherited disease of secretory epithelia that affects the airways,
liver, pancreas, small intestine, and sweat glands. The cause is a
genetic mutation affecting a transporter protein. Because
dysfunction of sweat glands causes perspiration to contain excessive
sodium chloride (salt), measurement of the excess chloride is one
index for diagnosing CF.
Sudden
Infant Death
Syndrome
The sudden, unexpected death of an apparently healthy infant
during sleep. It rarely occurs before 2 weeks or after 6 months of
age, with the peak incidence between the second and fourth
months. The exact cause is unknown but, may be due to an
abnormality in the mechanisms that control respiration or low
levels of oxygen in the blood.
Severe Acute
Respiratory
Syndrome
A respiratory illness caused by a new variety of coronavirus.
Symptoms of SARS include fever, malaise, muscle aches,
nonproductive (dry) cough, difficulty in breathing, chills,
headache, and diarrhea.
Thank You!
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