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!