Respiratory System: Anatomy and Physiology
The
number of clients with chronic respiratory problems is increasing. Respiratory
disorders are common and rank as the fifth
leading cause of death in the
ANATOMY AND PHYSIOLOGY REVIEW
The two purposes of the respiratory system are to provide a source of oxygen for tissue metabolism and to remove carbon dioxide, the major waste product of metabolism. The respiratory system also influences the following functions:
• Acid-base balance
• Speech
• Sense of smell
• Fluid balance
• Thermoregulation
Upper Respiratory Tract
The upper airways consist of the nose, the sinuses, the pharynx (throat), and the larynx ("voice box").
NOSE AND SINUSES
The nose is the organ of smell, with receptors from cranial nerve I (olfactory) located in the upper areas. This organ is a rigid structure that contains two passages separated in the middle by the septum. The upper one third of the nose is composed of bone; the lower two thirds is composed of cartilage, which allows limited movement. The septum and interior walls of the nasal cavity are lined with mucous membranes that have a rich blood supply. The anterior nares (nostrils or external openings into the nasal cavities) are lined with skin and hair follicles, which help keep foreign particles or organisms from entering the lungs. The posterior nares are openings from the nasal cavity into the nasopharynx.
Three bony projections (turbinates) protrude into the nasal cavities from the walls of the internal portion of the nose. Turbinates increase the total surface area for filtering, heating, and humidifying inspired air before it passes into the nasopharynx. Inspired air entering the nose is first filtered by vibrissae in the nares. Particles not filtered out in the nares are trapped in the mucous layer of the turbinates. These particles are moved by cilia (hairlike projections) to the oropharynx, where they are either swallowed or expectorated. Inspired air is humidified by contact with the mucous membrane and is warmed by exposure to heat from the vascular network.
The paranasal sinuses are air-filled cavities within the bones that surround the nasal passages. Lined with ciliated epithelium, the purposes of the sinuses are to provide resonance during speech and to decrease the weight of the skull.
PHARYNX
The pharynx, or throat, serves as a passageway for both the respiratory and digestive tracts and is located behind the oral and nasal cavities. It is divided into the nasopharynx, the oropharynx, and the laryngopharynx.
The nasopharynx is located behind the nose, above the soft palate. It contains the adenoids and the distal opening of the eustachian tube. The adenoids (pharyngeal tonsils) are an important defense, trapping organisms that enter the nose or mouth. The eustachian tube connects the nasopharynx with the middle ear and opens during swallowing to equalize pressure within the middle ear.
The oropharynx is located behind the mouth, below the nasopharynx. It extends from the soft palate to the base of the tongue and is a shared passageway for breathing and swallowing. The palatine tonsils (also known as faucial tonsils) are located on the lateral borders of the oropharynx. These tonsils also guard the body against invading organisms.
The laryngopharynx is located behind the larynx and extends from the base of the tongue to the esophagus. The laryngopharynx is the critical dividing point where solid foods and fluids are separated from air. At this point, the passageway divides into the larynx and the esophagus.
LARYNX
The larynx is located above the trachea, just below the pharynx at the base of the tongue. It is innervated by the recurrent laryngeal nerves. The larynx is composed of several cartilages. The thyroid cartilage is the largest and is commonly referred to as the Adam's apple. The cricoid cartilage, which contains the vocal cords, lies below the thyroid cartilage. The cricothyroid membrane is located below the level of the vocal cords and joins the thyroid and cricoid cartilages. This site is used in an emergency for access to the lower airways. In this procedure, called a cricothyroidotomy (or cricothyrotomy), an opening is made between the thyroid and cricoid cartilage and results in a tracheostomy. The two arytenoid cartilages, which attach at the posterior ends of the vocal cords, are used together with the thyroid cartilage in vocal cord movement.
Inside the larynx are two pairs of vocal cords: the false vocal cords and the true vocal cords. The opening between the true vocal cords is the glottis. The epiglottis is a leaf-shaped, elastic structure that is attached along one edge to the top of the larynx. Its hinge-like action prevents food from entering the tracheobronchial tree (aspiration) by closing over the glottis during swallowing. The epiglottis opens during breathing and coughing.
Lower Respiratory Tract
The lower airways consist of the trachea; two mainstem bronchi; lobar, segmental, and subsegmental bronchi; bronchioles; alveolar ducts; and alveoli. The tracheobronchial tree is an inverted treelike structure consisting of muscular, cartilaginous, and elastic tissues. This system of continually branching tubes, which decrease in size from the trachea to the respiratory bronchioles, allows gases to move to and from the pulmonary parenchyma. Gas exchange takes place in the pulmonary parenchyma between the alveoli and the pulmonary capillaries.
TRACHEA
The trachea (windpipe) is located in front of (anterior to) the esophagus. It begins at the lower edge of the cricoid cartilage of the larynx and extends to the level of the fourth or fifth thoracic vertebra. The trachea branches into the right and left mainstem bronchi at the carina.
The trachea is composed of 6 to 10 C-shaped cartilaginous rings. The open portion of the С is the back portion of the trachea and contains smooth muscle that is shared with the esophagus. Low pressure must be maintained in endotracheal and tracheostomy tube cuffs to avoid causing erosion of this posterior wall and to avoid creating a tracheoesophageal fistula (abnormal connection between the trachea and the esophagus).
MAINSTEM BRONCHI
The mainstem, or primary, bronchi begin at the carina. The bronchus is similar in structure to the trachea. The right bronchus is slightly wider, shorter, and more vertical than the left bronchus. Because of the more vertical line of the right bronchus, it can be accidentally intubated when an endotracheal tube is passed. Similarly, when a foreign object is aspirated from the throat, it most often enters the right bronchus.
LOBAR, SEGMENTAL, AND SUBSEGMENTAL BRONCHI
The mainstem bronchi further branch into the five secondary (lobar) bronchi that enter each of the five lobes of the lung. Each lobar bronchus is surrounded by connective tissue, blood vessels, nerves, and lymphatics, and each branches into segmental and subsegmental divisions. The cartilage of these lobar bronchi is ringlike and resists collapse. The bronchi are lined with ciliated, mucus-secreting epithelium. The cilia propel mucus up and away from the lower airway to the trachea, where the mucus is either expectorated or swallowed.
BRONCHIOLES
The
bronchioles branch from the secondary bronchi and subdivide into smaller and
smaller tubes: the terminal and respiratory bronchioles. These
terminal and respiratory tubes are
less than
ALVEOLAR DUCTS AND ALVEOLI
Alveolar ducts, which resemble a bunch of grapes, branch from the respiratory bronchioles. Alveolar sacs arise from these ducts. The alveolar sacs contain clusters of alveoli, which are the basic units of gas exchange. A pair of healthy adult lungs contains approximately 300 million alveoli, which are surrounded by pulmonary capillaries. Because these small alveoli are so numerous and share common walls, the surface area for gas exchange in the lungs is extensive. In a healthy adult, this surface area is approximately the size of a tennis court. Acinus is a term used to indicate the structural unit consisting of a respiratory bronchiole, an alveolar duct, and an alveolar sac.
In the walls of the alveoli, specific cells (type II pneumocytes) secrete surfactant, a fatty protein that reduces surface tension in the alveoli. Without sufficient surfactant, atelectasis (collapse of the alveoli) ultimately occurs. In atelectasis, gas exchange is reduced because the alveolar surface area is reduced.
LUNGS
The lungs are sponge-like, elastic, cone-shaped organs located in the pleural cavity in the thorax. The apex (top) of each lung extends above the clavicle; the base (bottom) of each lung lies just above the diaphragm (the major muscle of inspiration). The lungs are composed of millions of alveoli and their related ducts, bronchioles, and bronchi. The right lung, which is larger than the left, is divided into three lobes: upper, middle, and lower. The left lung, which is somewhat narrower than the right lung to make room for the heart, is divided into two lobes.
The hilum is the point at
which the primary bronchus, pulmonary blood
vessels, nerves, and lymphatics enter each lung.
Innervation of the chest wall is via the phrenic (pleura) and intercostal (diaphragm,
ribs, and muscles) nerves. Innervation
of the bronchi is via the vagus nerve.
The pleura is a continuous smooth membrane composed of two surfaces that totally enclose the lung. The parietal pleura lines the inside of the thoracic cavity and the upper surface of the diaphragm. The visceral pleura covers the lung surfaces, including the major fissures between the lobes. These two surfaces are lubricated by a thin fluid that is produced by the cells lining the pleura. This lubrication allows the surfaces to glide smoothly and painlessly during respirations.
Blood flow through the lungs occurs via two separate systems: bronchial and pulmonary. The bronchial system carries the blood necessary to meet the metabolic demands of the lungs. The bronchial arteries, which arise from the thoracic aorta, are part of the systemic circulation and do not participate in gas exchange.
The pulmonary circulation is composed of a highly vascular capillary network. Oxygen-depleted blood travels from the right ventricle of the heart into the pulmonary artery, which eventually branches into arterioles that form the capillary networks. The capillaries are enmeshed around and through the alveoli, the site of gas exchange. Freshly oxygenated blood travels from the capillaries and through the venules to the pulmonary veins and then to the left atrium. From the left atrium, oxygenated blood flows into the left ventricle, where it is pumped throughout the systemic circulation.
Accessory Muscles of Respiration
Breathing occurs through changes in the size of and pressure within the thoracic cavity. Contraction and relaxation of specific skeletal muscles (and the diaphragm) cause changes in the size and pressure of the thoracic cavity. Accessory muscles of respiration include the scalene muscles, which elevate the first two ribs; the sternocleidomastoid muscles, which raise the sternum; and the trapezius and pectoralis muscles, which fix the shoulders. In addition, various back and abdominal muscles are used when the work of breathing is increased.
Respiratory Changes Associated with Aging
Many changes associated with older clients result from heredity and a lifetime of exposure to environmental stimuli (e.g., cigarette smoke, bacteria, air pollutants, and industrial fumes and irritants). Table 27-1 shows the age-related changes in the partial pressure of arterial oxygen (Pao2).
Respiratory disease is a major cause of acute illness and chronic disability in older clients. Although respiratory function normally declines with age, there is usually little difficulty with the demands of ordinary activity. However, the sedentary older adult often reports feeling breathless during exercise.
It is difficult to determine which respiratory changes in older adults are related to normal aging and which changes are pathologic and associated with respiratory disease or exposure to pollutants. In addition, age-related disorders of the neuromuscular and cardiovascular systems may cause abnormal respiration, even if the lungs are normal.
The respiratory system is situated in the thorax, and is
responsible for gaseous exchange between the circulatory system and the outside
world. Air is taken in via the upper airways (the nasal cavity, pharynx and
larynx) through the lower airways (trachea, primary bronchi and bronchial tree)
and into the small bronchioles and alveoli within the lung tissue.
Move the pointer over the coloured regions of the diagram; the names will
appear at the bottom of the screen)
The lungs are divided into lobes; The left lung is composed of the upper lobe, the lower lobe and the lingula (a small remnant next to the apex of the heart), the right lung is composed of the upper, the middle and the lower lobes.
Mechanics of Breathing
To take a breath in, the external intercostal muscles contract, moving the ribcage up and out. The diaphragm moves down at the same time, creating negative pressure within the thorax. The lungs are held to the thoracic wall by thepleural membranes, and so expand outwards as well. This creates negative pressure within the lungs, and so air rushes in through the upper and lower airways.
Expiration is mainly due to the natural elasticity of the lungs, which tend to collapse if they are not held against the thoracic wall. This is the mechanism behind lung collapse if there is air in the pleural space (pneumothorax).
Physiology of Gas Exchange
Each branch of the bronchial tree eventually sub-divides to form very narrow terminal bronchioles, which terminate in the alveoli. There are many millions of alveloi in each lung, and these are the areas responsible for gaseous exchange, presenting a massive surface area for exchange to occur over.
Each alveolus is very
closely associated with a network of capillaries containing deoxygenated blood
from the pulmonary artery. The capillary and alveolar walls are very thin,
allowing rapid exchange of gases by passive
diffusion along concentration gradients.
CO2 moves into the alveolus as the concentration is
much lower in the alveolus than in the blood, and O2 moves out of the alveolus as the continuous flow of
blood through the capillaries prevents saturation of the blood with O2 and allows maximal transfer across the
membrane.
Ventilation
In respiratory physiology, ventilation (or ventilation rate) is the rate at which gas enters or leaves the lung. It is categorized under the following definitions:
|
Measurement |
Equation |
Description |
|
Minute ventilation |
tidal volume * respiratory rate[1][2] |
the total volume of gas entering the lungs per minute. |
|
Alveolar ventilation |
(tidal volume – dead space) * respiratory rate [1] |
the volume of gas per unit time that reaches the alveoli, the respiratory portions of the lungs where gas exchange occurs. |
|
Dead space ventilation |
dead space * respiratory rate[3] |
the volume of gas per unit time that does not reach these respiratory portions, but instead remains in the airways (trachea, bronchi, etc.). |
Control
Ventilation occurs under the control of the autonomic nervous system from parts of the brain stem, the medulla oblongata and the pons. This area of the brain forms the respiration regulatory center, a series of interconnected brain cells within the lower and middle brain stem which coordinate respiratory movements. The sections are the pneumotaxic center, the apneustic center, and the dorsal and ventral respiratory groups. This section is especially sensitive during infancy, and the neurons can be destroyed if the infant is dropped and/or shaken violently. The result can be death due to "shaken baby syndrome".[9]
The breathing rate increases with the concentration of carbon dioxide in the blood, which is detected by peripheral chemoreceptors in the aorta and carotid artery and central chemoreceptors in the medulla. Exercise also increases respiratory rate, due to the action of proprioceptors, the increase in body temperature, the release of epinephrine, and motor impulses originating from the brain.[10] In addition, it can increase due to increased inflation in the lungs, which is detected by stretch receptors.
Inhalation
Inhalation is initiated by the diaphragm and supported by the external intercostal muscles. Normal resting respirations are 10 to 18 breaths per minute, with a time period of 2 seconds. During vigorous inhalation (at rates exceeding 35 breaths per minute), or in approaching respiratory failure, accessory muscles of respiration are recruited for support. These consist ofsternocleidomastoid, platysma, and the scalene muscles of the neck. Pectoral muscles and latissimus dorsi are also accessory muscles.
Under normal conditions, the diaphragm is the primary driver of inhalation. When the diaphragm contracts, the ribcage expands and the contents of the abdomen are moved downward. This results in a larger thoracic volume and negative pressure (with respect to atmospheric pressure) inside the thorax. As the pressure in the chest falls, air moves into the conducting zone. Here, the air is filtered, warmed, and humidified as it flows to the lungs.
During forced inhalation, as when taking a deep breath, the external intercostal muscles and accessory muscles aid in further expanding the thoracic cavity. During inhalation the diaphragm contracts.
Exhalation
Exhalation is generally a passive process; however, active or forced exhalation is achieved by the abdominal and the internal intercostal muscles. During this process air is forced or exhaled out.
The lungs have a natural elasticity: as they recoil from the stretch of inhalation, air flows back out until the pressures in the chest and the atmosphere reach equilibrium.[11]
During forced exhalation, as when blowing out a candle, expiratory muscles including the abdominal muscles and internal intercostal muscles, generate abdominal and thoracic pressure, which forces air out of the lungs.
Gas exchange
The major function of the respiratory system is gas exchange between the external environment and an organism's circulatory system. In humans and other mammals, this exchange facilitatesoxygenation of the blood with a concomitant removal of carbon dioxide and other gaseous metabolic wastes from the circulation.[12] As gas exchange occurs, the acid-base balance of the body is maintained as part of homeostasis. If proper ventilation is not maintained, two opposing conditions could occur: respiratory acidosis, a life threatening condition, and respiratory alkalosis.
Upon inhalation, gas exchange occurs at the alveoli, the tiny sacs which are the basic functional component of the lungs. The alveolar walls are extremely thin (approx. 0.2 micrometres). These walls are composed of a single layer of epithelial cells (type I and type II epithelial cells) close to the pulmonary capillaries which are composed of a single layer of endothelial cells. The close proximity of these two cell types allows permeability to gases and, hence, gas exchange. This whole mechanism of gas exchange is carried by the simple phenomenon of pressure difference. When the air pressure is high inside the lungs, the air from lungs flow out. When the air pressure is low inside, then air flows into the lungs.
Immune functions
Airway epithelial cells can secrete a variety of molecules that aid in the defense of lungs. Secretory immunoglobulins (IgA), collectins (including Surfactant A and D), defensins and other peptides and proteases, reactive oxygen species, and reactive nitrogen species are all generated by airway epithelial cells. These secretions can act directly as antimicrobials to help keep the airway free of infection. Airway epithelial cells also secrete a variety of chemokines and cytokines that recruit the traditional immune cells and others to site of infections.
Most of the respiratory system is lined with mucous membranes that contain mucosal-associated lymphoid tissue, which produces white blood cells such as lymphocytes.
Metabolic and endocrine functions of the lungs
In addition to their functions in gas exchange, the lungs have a number of metabolic functions. They manufacture surfactant for local use, as noted above. They also contain a fibrinolytic system that lyses clots in the pulmonary vessels. They release a variety of substances that enter the systemic arterial blood and they remove other substances from the systemic venous blood that reach them via the pulmonary artery. Prostaglandins are removed from the circulation, but they are also synthesized in the lungs and released into the blood when lung tissue is stretched. The lungs also activate one hormone; the physiologically inactive decapeptide angiotensin I is converted to the pressor, aldosterone-stimulating octapeptide angiotensin II in the pulmonary circulation. The reaction occurs in other tissues as well, but it is particularly prominent in the lungs. Large amounts of the angiotensin-converting enzyme responsible for this activation are located on the surface of the endothelial cells of the pulmonary capillaries. The converting enzyme also inactivates bradykinin. Circulation time through the pulmonary capillaries is less than one second, yet 70% of the angiotensin I reaching the lungs is converted to angiotensin II in a single trip through the capillaries. Four other peptidases have been identified on the surface of the pulmonary endothelial cells.
Vocalization
The movement of gas through the larynx, pharynx and mouth allows humans to speak, or phonate. Vocalization, or singing, in birds occurs via the syrinx, an organ located at the base of the trachea. The vibration of air flowing across the larynx (vocal cords), in humans, and the syrinx, in birds, results in sound. Because of this, gas movement is extremely vital for communicationpurposes.
Temperature control
Panting in dogs, cats and some other animals provides a means of controlling body temperature. This physiological response is used as a cooling mechanism.
Coughing and sneezing
Irritation of nerves within the nasal passages or airways, can induce coughing and sneezing. These responses cause air to be expelled forcefully from the trachea or nose, respectively. In this manner, irritants caught in the mucus which lines the respiratory tract are expelled or moved to the mouth where they can be swallowed. During coughing, contraction of the smooth muscle narrows the trachea by pulling the ends of the cartilage plates together and by pushing soft tissue out into the lumen. This increases the expired airflow rate to dislodge and remove any irritant particle or mucus.
The
respiratory system is the system in the human body that enables us to breathe.
The
act of breathing includes: inhaling and exhaling air in the body; the
absorption of oxygen from the air in order to produce energy; the discharge of
carbon dioxide, which is the byproduct of the process.
The parts of the respiratory system
The
respiratory system is divided into two parts:
Upper respiratory tract:
This
includes the nose, mouth, and the beginning of the trachea (the section that
takes air in and lets it out).
Lower respiratory tract:
This
includes the trachea, the bronchi, broncheoli and the lungs (the act of
breathing takes place in this part of the system).
The
organs of the lower respiratory tract are located in the chest cavity. They are
delineated and protected by the ribcage, the chest bone (sternum), and the
muscles between the ribs and the diaphragm (that constitute a muscular
partition between the chest and the abdominal cavity).
The trachea – the tube connecting the throat to the bronchi.
The act of breathing
The
act of breathing has two stages – inhalation and exhalation
· Inhalation – the intake of air into the lungs through expansion of chest volume.
· Exhalation – the expulsion of air from the lungs through contraction of chest volume.
Inhalation and exhalation involves muscles:
1. Rib muscles = the muscles between the ribs in the chest.
2. Diaphragm muscle
Muscle
movement – the diaphragm and rib muscles are
constantly contracting and relaxing (approximately 16 times per minute), thus
causing the chest cavity to increase and decrease.
During inhalation – the
muscles contract:
Contraction
of the diaphragm muscle – causes the diaphragm to flatten, thus enlarging the
chest cavity.
Contraction
of the rib muscles – causes the ribs to rise, thus increasing the chest volume.
The
chest cavity expands, thus reducing air pressure and causing air to be
passively drawn into the lungs. Air passes from the high pressure outside the
lungs to the low pressure inside the lungs.
During exhalation – the
muscles relax:
The
muscles are no longer contracting, they are relaxed.
The
diaphragm curves and rises, the ribs descend – and chest volume decreases.
The
chest cavity contracts thus increasing air pressure and causing the air in the
lungs to be expelled through the upper respiratory tract. Exhalation, too, is
passive. Air passes from the high pressure in the lungs to the low pressure in
the upper respiratory tract.
Inhalation and exhalation are involuntary and therefore their
control requires an effort.
Changes
in chest volume during inhalation and exhalation – note that it only shows the
movement of the diaphragm, not that of the rib muscles.
What Do We Measure And How Do We Measure It?
The
respiratory airways include the respiratory apertures (mouth and nose), the
trachea and a branching system of long, flexible tubes (bronchi) that branch of
to shorter and narrower tubes (broncheoli) until they end in sacs called the
pulmonary alveoli.
The
lungs encompass the entire system of tubes branching out from the main bronchi
to the alveoli.
Measuring
the functioning of the lungs is a medical tool for diagnosing problems in the
respiratory system.
Measurements of lung function
2. Air
volume (in liters) – lung capacity
· Maximum lung volume is known as TLC (total lung capacity). It can be obtained by maximum strenuous inhalation.
· Essential air volume is the maximum volume utilized by the lungs for inhalation, also known as VC (vital capacity).
· Residual volume (RV) is the volume of air remaining in the lungs after strenuous exhalation when the lungs feel completely empty. Residual volume prevents the broncheoli and the alveoli from sticking together. Residual volume is approximately 1.5 liters (adults).
· The differential between total lung capacity and residual volume is the maximal volume utilized by the lungs in order to breath. It is known as vital capacity(VC). In an adult, the VC is between 3.5 and 4.5 liters.
· Tidal Volume or VT is the volume of air displaced between normal inspiration and expiration. In a healthy adult the tidal volume is approximately 500 milliliters.
2. Rate of airflow through the respiratory airways (into
and out of the lungs).This measures the effectiveness of airflow.
3. Efficiency
of diffusion of oxygen from the pulmonary alveoli into the
blood (not dealt with in this unit).
TLC (total lung capacity) of
children
Examining lung function
The
most common, accessible and efficient method of measuring lung function is by
means of a
spirometer. Its purpose is to
diagnose obstructive diseases of the respiratory system. It produces a diagram
(graphic depiction) of the volume of air expired in a given time (liter/minute)
The
spirometer shows the rate at which air is expelled from the lungs. It measures
the total lung capacity up to the residual volume (this test does not show the
rate at which oxygen is absorbed).
If the
airways are blocked the rate of the airflow of the lungs decreases. This will
show on the diagram and thus indicate that there is a problem in the airways.
The
most common obstruction stems from excessive phlegm, or from swelling of the
inner wall of the air ways.
The
most common problem of blockage of the air ways is asthma. people suffering
from asthma it take longer to empty the lungs than healthy people. For example,
during the first second of exhalation, only half of the vital air capacity in
their lungs is expelled as opposed to 90% in healthy people. The rest is
exhaled much later.
A
spirometer examination takes only a few seconds. It is completely safe but
there is a need for the patient to cooperate in order to obtain accurate
results.
Stages of the examination:
1. The patient is asked to inhale as deeply as possible.
2. The patient is asked to exhale strenuously into the spirometer.
3. The patient is asked to continue to expel air for a few seconds, despite the strong urge to breathe in.
4. The test is repeated twice or three times.
Respiratory rate
Children
in the upper classes of elementary school breathe about 20 times per minute.
Every
breath causes an inhalation of approximately 7 milliliters of air volume per
kilogram of body weight.
A
child who weighs 30 kilos inhales approximately 210 milliliters of air volume
(210X30). In other words, in the duration of a minute some 4200 milliliters of
air volume enters and be expelled from the lungs.
Athletes
breathe slightly deeper and slower. With every breath they inhale approximately
10 milliliters of air per kilogram. Thus an athletic child who weighs 30 kilos
will only breathe 15 times in the duration space of a minute. Each inhalation
will require some 300 milliliters of air volume. In the space of a minute 4500
milliliters of air volume will enter and be expelled from the his lungs. We can
deduce from this that athletes ventilate their airways in a much more efficient
way.
When
we are under strain we breathe faster and more deeply. Since the lungs contain
a reserve of air, we do not become tired because lack of air (oxygen) is
causing respiratory restriction, but because of strain and tiredness in our
respiratory and heart muscles.
When
we are under emotional stress (before an exam, in distress, or feeling very
frightened) we breathe faster, but our breathing is shallower. For example,
under stress we inhale 30 times per minute but at a rate of only 4 milliliters
per kilo. In other words, overall only 3600 milliliters per minute are passing
through our airways, so we feel “short of breath.”
During
severe asthma attacks, the breathing of asthma patients is shallower and at a
higher rate. Their breathing is thus not very efficient.
Functions of Organs in Respiratory System
Respiration begins when oxygen enters into the body through the nose and the mouth. The oxygen then travels through the trachea and pharynx where the trachea divides into two bronchi. Here the bronchi are divided into bronchial tubes, in the chest cavity, so air can be directly moved into the lungs.
Nose
The nose is the primary upper respiratory organ in which air enters into and exits from the body. Cilia and mucus line the nasal cavity and traps bacteria and foreign particles that enter in through the nose. In addition, air that passes through the nasal cavity is humidified and moistened.
The nasal septum divides the nose into two narrow nasal cavities: one area is responsible for smell and the other area is responsible for respiration. Within the walls of the nasal cavity there are frontal, nasal, ethmoid, maxillary, and sphenoid bones. Cartilage helps form the shape of the nose.
Pharynx
Besides the nose, air can enter into the lungs through the mouth. The pharynx is a tubular structure, positioned behind the oral and nasal cavities, that allows air to pass from the mouth to the lungs. The pharynx contains three parts: The nasopharynx, which connects the upper part of the throat with the nasal cavity; the oropharynx, positioned between the top of the epiglottis and the soft palate; and the laryngopharynx, located below the epiglottis.
Larynx
From the pharynx, air enters into the larynx, commonly called the voice box. The larynx is part of the upper respiratory tract that has two main functions: a passageway for air to enter into the lungs, and a source of vocalization. The larynx is made up of the hyoid bone and cartilage, which helps regulate the flow of air. The epiglottis is a flap-like cartilage structure contained in the larynx that protects the trachea against food aspiration.
Bronchi
The bronchi allow the passage of air to the lungs. The trachea is made of c-shaped ringed cartilage that divides into the right and left bronchus. The right main bronchus is shorter and wider than the left main bronchus. The right bronchus is subdivided into three lobar bronchi, while the left one is divided into two lobar bronchi.
Lungs
The lungs are spongy, air-filled organs located on both sides of the chest cavity. The left lung is divided into a superior and inferior lobe, and the right lung is subdivided into a superior, middle, and inferior lobe. Pleura, a thin layer of tissue, line the lungs to allow the lungs to expand and contract with ease.
Respiration is the primary function of the lungs, which includes the transfer of oxygen found in the atmosphere into the blood stream and the release of carbon dioxide into the air.
Alveoli
The average adult has about 600 million alveoli, which are tiny grape-like sacs at the end of the respiratory tree. The exchange of oxygen and carbon dioxide gases occurs at the alveolar level. Although effort is required to inflate the alveoli (similar to blowing up a balloon), minimal effort is needed to deflate the alveoli (similar to the deflating of a balloon).
Diaphragm
The diaphragm is a muscular structure located between the thoracic and abdominal cavity. Contraction of the diaphragm causes the chest or thorax cavity to expand, which occurs during inhalation. During exhalation, the release of the diaphragm causes the chest or thorax cavity to contract.
Oxygen saturation
Oxygen saturation is a term referring to the concentration of oxygen in the blood. The human body requires and regulates a very precise and specific balance of oxygen in the blood. Normal blood oxygen levels are considered 95-100 percent. If the level is below 90 percent, it is considered low resulting in hypoxemia. Blood oxygen levels below 80 percent may compromise organ function, such as the brain and heart, and should be promptly addressed. Continued low oxygen levels may lead to respiratory or cardiac arrest. Oxygen therapy may be used to assist in raising blood oxygen levels. Oxygenation occurs when oxygen molecules (O2) enter the tissues of the body. For example, blood is oxygenated in the lungs, where oxygen molecules travel from the air and into the blood. Oxygenation is commonly used to refer to medical oxygen saturation.
In medicine, oxygen saturation (SO2), commonly referred to as "sats", measures the percentage of hemoglobin binding sites in the bloodstream occupied by oxygen. At low partial pressures of oxygen, most hemoglobin is deoxygenated. At around 90% (the value varies according to the clinical context) oxygen saturation increases according to an oxygen-hemoglobin dissociation curve and approaches 100% at partial oxygen pressures of >10 kPa. A pulse oximeter relies on the light absorption characteristics of saturated hemoglobin to give an indication of oxygen saturation.
Physiology
This balance is maintained for the most part by chemical processes in the body to sustain aerobic metabolism and life. Using the respiratory system, red blood cells, specifically the hemoglobin, gather oxygen in the lungs and distribute it to the rest of the body. The needs of the body's blood oxygen may fluctuate such as during exercise when more oxygen is required [2] or when living at higher altitudes. A blood cell is said to be "saturated" when carrying a normal amount of oxygen. Both too high and too low levels can have adverse effects on the body.
Measurement
An SaO2 (arterial oxygen saturation) value below 90% causes hypoxemia (which can also be caused by anemia). Hypoxemia due to low SaO is indicated by cyanosis. Oxygen saturation can be measured in different tissues:
· Venous oxygen saturation (SvO2) is measured to see how much oxygen the body consumes. Under clinical treatment, a SvO2 below 60% indicates that the body is in lack of oxygen, andischemic diseases occur. This measurement is often used under treatment with a heart-lung machine (extracorporeal circulation), and can give the perfusionist an idea of how much flow the patient needs to stay healthy.
· Tissue oxygen saturation (StO2) can be measured by near infrared spectroscopy. Although the measurements are still widely discussed, they give an idea of tissue oxygenation in various conditions.
· Peripheral capillary oxygen saturation (SpO2) is an estimation of the oxygen saturation level usually measured with a pulse oximeter device. It can be calculated with the pulse oximetryaccording to the following formula:
Blood circulation: Red = oxygenated (arteries), Blue = deoxygenated (veins)
Medical significance
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Effects of decreased oxygen saturation[4] |
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SaO2 |
Effect |
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85% and above |
No evidence of impairment |
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65% and less |
Impaired mental function on average |
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55% and less |
Loss of consciousness on average |
Healthy individuals at sea level usually exhibit oxygen saturation values between 96% and 99%. An SaO2 (arterial oxygen saturation) value below 90% causes hypoxemia (which can also be caused by anemia). Hypoxemia due to low SaO is indicated by cyanosis, but oxygen saturation does not directly reflect tissue oxygenation. The affinity of hemoglobin to oxygen may impair or enhance oxygen release at the tissue level. Oxygen is more readily released to the tissues when pH is decreased, body temperature is increased, arterial partial pressure of carbon dioxide (PaCO2) is increased, and 2,3-DPG levels (a byproduct of glucose metabolism also found in stored blood products) are increased. When the hemoglobin has greater affinity for oxygen, less is available to the tissues. Conditions such as increased pH, decreased temperature, decreased PaCO2, and decreased 2,3-DPG will increase oxygen binding to the hemoglobin and limit its release to the tissue.
Example pulse oximeter
Pulse oximetry is a method used to measure the concentration of oxygen in the blood. A small device that clips to the body (typically a finger but may be other areas), called a pulse oximeter, uses a special light to estimate the amount of oxygen in the blood. The clip attaches to a reading meter by a wire to collect the data. Oxygen levels may also be checked through an arterial blood gas test (ABG), where blood taken from an artery is analysed for oxygen level, carbon dioxide level and acidity.
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Mechanism of Breathing |
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This is the process by which the lungs expand to take in air then contract to expel it. The cycle of respiration, which occurs about 15 times per minute, consists of three phases: Inspiration, Expiration and Pause Proper breathing involves all the muscles of the head,
neck, thorax and abdomen, in addition to the involuntary musculature of the
larynx, trachea and bronchi.
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Whole body Breathing |
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Most of us breathe in three of four different ways. These ways of breathing can be called high, low, middle or complete breathing. 1. High breathing refers to breathing that takes place primarily in the upper part of the chest and lungs. Also called “calvicular breathing” or “collarbone breathing”, it involves movement of the ribs, collarbone and shoulders. High breathing is naturally shallow and a large percentage of the oxygen fails to reach the alveoli and enter into gaseous exchange. This is the least desirable form of breathing as only the
upper lobes of the lungs are used which have only a small air capacity. The
upper rib cage is fairly rigid and so not much expansion of the ribs can take
place. High breathing is a common cause of digestive, constipation and gynaecological problems. 2. Middle breathing is a way of breathing in which mainly the middle
parts of the lungs are filled with air. 3. Low Breathing refers to respiration which takes place primarily in
the lower part of the chest and lungs. It consists mainly of the movement of
the abdomen in and out and the corresponding movement of the diaphragm. It is
sometimes also called “abdominal breathing” and “diaphragmatic breathing.” This type of breath is far superior to high or middle breathing for new reasons: More air is taken in when inhaling due to greater movement of the lungs and the fact that the lower lobes of the lungs have a larger capacity than the upper lobes. The diaphragm acts like a second heart. Its piston-like movements expand the base of the lungs, allowing them to suck in more venous blood. The increase in the venous circulation improves the general circulation. The abdominal organs and the solar plexus, a very important nerve centre, are massaged by and down movements of the diaphragm. 4. Whole Body Breathing involves the entire respiratory system and not only includes the of the lungs used in high, low and middle breathing, but expands the lungs so as to take in more air than the amounts inhaled by each of these three kinds of breathing together when employed in shallow breathing. The complete breath is not just deep breathing; it is the deepest possible breathing. Not only does raise his shoulders, collarbone and ribs, as in high breathing, and also extend his abdomen and lower his diaphragm, as in low breathing, but he does both as much is needed to expand his lungs to their fullest capacity. This type of breathing should only be utilised when doing breathing exercises. The rest of the time it is best to use low breathing by pushing the stomach out slightly when inhaling, and then just letting the stomach fall back to its original position in the exhale. |
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Corrective Breathing |
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"To be wholly alive is to breathe deeply, to move freely, and to feel fully. Breath is the most fundamental, tangible link to life." Incorrect breathing manifests itself in: Sleeping Disturbances/ Insomnia Anxiety / Irritability / Panic Attacks Confused thinking / Fatigue Allergies Asthma Digestive Problems Elevated blood pressure Back problems, tension and headache Immune System Dysfunction Healthy cells need oxygen. Oxygen is essential for assimilation of nutrients and the detoxification and elimination of waste products. It is the main energy source for our brain function Physiological Benefits include: Relaxes the entire body and nervous system, where tensions and
anxieties are held Emotional Benefits include: Clarity of Thought All of these (and much more) are well documented in various western publications both within and outside of the medical community. Many doctors are beginning to recommend breathing exercises to their patients as a means of coping with various health problems. While the jury is still out regarding the absolute mechanism behind the effectiveness of breathing, most researchers believe that the deep relaxation of both mind and body are central to health. |
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Fertility Breathing |
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Fertility Breathing increases oxygen levels to our cells, expands the working capacity of respiratory system and supports the functioning of the endocrine system. Working together with acupuncturists Rangana has developed a unique breathing system incorporating the acupuncture channels. The channels used are those associated with fertility and help to bring energy and blood flow to the centre of the body. Using this method to build on the acupuncture treatments the client is able to practise at home in between sessions. This method is particularly useful through IVF when a good pelvic blood flow is essential. Clients also find it a useful relaxation method. Physiological Benefits include: Helps circulate oxygen around the body Increases ovarian and uterine blood flow Reduces hormonal treatment side effects Helps embryo implantation oxygenating the placenta Regulates the Hypothalamus Pituitary Ovarian (HPO) axis Calms the effects of endometriosis Emotional Benefits include: Increases sense of control over one’s life Enhances quality of life and health Restructures negative thoughts and behaviour patterns Reduces stress |
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Pregnancy Breathing |
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How
does it work? In
what stage of pregnancy I can start? Visualization will teach you to mentally “see” and affect structures within your body e.g. your muscles, your cervix, your hormones. You will also be taught how to communicate with your baby within your womb. Benefits Creates Space Breathing opens the body, ribcage, abdomen, diaphragm, and spine. Circulation More fluid, diaphragm acts as a lift pump from lower half of body. Extra Oxygen Baby placenta Cleansing 60-70% of toxins released through exhalation. Digestion Massage the abdominal organs Backache At the end of the exhalation the diaphragm releases the lumbar spine, lower ribs open during inhalation touching parts of the spine that needs opening and decompressing. Attention Concentration and focus improved, helps with emotional seesaw of pregnancy and during labour, quietens the mind. Relaxation Slow, deep and rhythmic breathing causes a reduction in the heart rate and relaxation of the muscles. |
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