Chapter 14 The Respiratory System. Mosby items and derived items © 2008 by Mosby, Inc., an...

Chapter 14Chapter 14The Respiratory SystemThe Respiratory System

Mosby items and derived items © 2008 by Mosby, Inc., an affiliate of Elsevier Inc.

STRUCTURAL PLANSTRUCTURAL PLAN

Basic plan of respiratory system would be Basic plan of respiratory system would be similar to an inverted tree if it were hollow; similar to an inverted tree if it were hollow; leaves of the tree would be comparable to leaves of the tree would be comparable to alveoli, with the microscopic sacs enclosed alveoli, with the microscopic sacs enclosed by networks of capillaries (Figure 14-1)by networks of capillaries (Figure 14-1)

Passive transport process of diffusion is Passive transport process of diffusion is responsible for the exchange of gases that responsible for the exchange of gases that occur during respiration.occur during respiration.


RESPIRATORY TRACTSRESPIRATORY TRACTS

Upper respiratory tract—nose, pharynx, Upper respiratory tract—nose, pharynx, and larynxand larynx

Lower respiratory tract—trachea, bronchial Lower respiratory tract—trachea, bronchial tree, and lungstree, and lungs


RESPIRATORY MUCOSARESPIRATORY MUCOSA

Specialized membrane that lines the air Specialized membrane that lines the air distribution tubes in the respiratory tree (Figure distribution tubes in the respiratory tree (Figure 14-2)14-2)

More than 125 mL of mucus produced each day More than 125 mL of mucus produced each day forms a “mucous blanket” over much of the forms a “mucous blanket” over much of the respiratory mucosarespiratory mucosa

Mucus serves as an air purification mechanism by Mucus serves as an air purification mechanism by trapping inspired irritants such as dust and pollentrapping inspired irritants such as dust and pollen

Cilia on mucosal cells beat in only one direction, Cilia on mucosal cells beat in only one direction, moving mucus upward to pharynx for removalmoving mucus upward to pharynx for removal


NOSENOSE

StructureStructure Nasal septum separates interior of nose into Nasal septum separates interior of nose into

two cavitiestwo cavities Mucous membrane lines noseMucous membrane lines nose Frontal, maxillary, sphenoidal, and ethmoidal Frontal, maxillary, sphenoidal, and ethmoidal

sinuses drain into nose (Figure 14-3)sinuses drain into nose (Figure 14-3) FunctionsFunctions

Warms and moistens inhaled airWarms and moistens inhaled air Contains sense organs of smellContains sense organs of smell


PHARYNXPHARYNX

Structure (Figure 14-4)Structure (Figure 14-4) Pharynx (throat) about 12.5 cm (5 inches) longPharynx (throat) about 12.5 cm (5 inches) long Divided into nasopharynx, oropharynx, and Divided into nasopharynx, oropharynx, and

laryngopharynxlaryngopharynx Two nasal cavities, mouth, esophagus, larynx, Two nasal cavities, mouth, esophagus, larynx,

and auditory tubes all have openings into pharynxand auditory tubes all have openings into pharynx Pharyngeal tonsils and openings of auditory Pharyngeal tonsils and openings of auditory

tubes open into nasopharynx; tonsils found in tubes open into nasopharynx; tonsils found in oropharynxoropharynx

Mucous membrane lines pharynxMucous membrane lines pharynx FunctionsFunctions

Passageway for food and liquidsPassageway for food and liquids Air distribution; passageway for airAir distribution; passageway for air


LARYNXLARYNX

Structure (Figure 14-5)Structure (Figure 14-5) Several pieces of cartilage form frameworkSeveral pieces of cartilage form framework

• Thyroid cartilage (Adam’s apple) is largestThyroid cartilage (Adam’s apple) is largest

• Epiglottis partially covers opening into larynxEpiglottis partially covers opening into larynx

Mucous liningMucous lining Vocal cords stretch across interior of larynxVocal cords stretch across interior of larynx

FunctionsFunctions Air distribution; passageway for air to move to Air distribution; passageway for air to move to

and from lungsand from lungs Voice productionVoice production


TRACHEATRACHEA

Structure (Figure 14-6)Structure (Figure 14-6) Tube about 11 cm (4.5 inches) long that Tube about 11 cm (4.5 inches) long that

extends from larynx into the thoracic cavityextends from larynx into the thoracic cavity Mucous liningMucous lining C-shaped rings of cartilage hold trachea openC-shaped rings of cartilage hold trachea open

Function—passageway for air to move to Function—passageway for air to move to and from lungsand from lungs

ObstructionObstruction Blockage of trachea occludes the airway, and if Blockage of trachea occludes the airway, and if

blockage is complete, causes death in minutesblockage is complete, causes death in minutes Tracheal obstruction causes more than 4000 Tracheal obstruction causes more than 4000

deaths annually in the United Statesdeaths annually in the United States


BRONCHI, BRONCHIOLES, AND BRONCHI, BRONCHIOLES, AND ALVEOLIALVEOLI

StructureStructure Trachea branches into right and left bronchiTrachea branches into right and left bronchi Each bronchus branches into smaller and Each bronchus branches into smaller and

smaller tubes eventually leading to bronchiolessmaller tubes eventually leading to bronchioles Bronchioles end in clusters of microscopic Bronchioles end in clusters of microscopic

alveolar sacs, the walls of which are made up alveolar sacs, the walls of which are made up of alveoli (Figure 14-7)of alveoli (Figure 14-7)

FunctionFunction Bronchi and bronchioles—air distribution; Bronchi and bronchioles—air distribution;

passageway for air to move to and from alveolipassageway for air to move to and from alveoli Alveoli—exchange of gases between air and Alveoli—exchange of gases between air and

blood (Figure 14-8)blood (Figure 14-8)


LUNGS AND PLEURALUNGS AND PLEURA

Structure (Figure 14-9)Structure (Figure 14-9) Size—large enough to fill the chest cavity, except for Size—large enough to fill the chest cavity, except for

middle space occupied by heart and large blood vesselsmiddle space occupied by heart and large blood vessels Apex—narrow upper part of each lung, under collarboneApex—narrow upper part of each lung, under collarbone Base—broad lower part of each lung; rests on Base—broad lower part of each lung; rests on

diaphragmdiaphragm Pleura—moist, smooth, slippery membrane that lines Pleura—moist, smooth, slippery membrane that lines

chest cavity and covers outer surface of lungs; reduces chest cavity and covers outer surface of lungs; reduces friction between the lungs and chest wall during friction between the lungs and chest wall during breathing (Figure 14-10)breathing (Figure 14-10)

Function—breathing (pulmonary ventilation)Function—breathing (pulmonary ventilation)


RESPIRATIONRESPIRATION

Mechanics of breathing (Figure 14-11)Mechanics of breathing (Figure 14-11) Pulmonary ventilation includes two phases Pulmonary ventilation includes two phases

called called inspirationinspiration (movement of air into lungs) (movement of air into lungs) and and expirationexpiration (movement of air out of lungs) (movement of air out of lungs)

Changes in size and shape of thorax cause Changes in size and shape of thorax cause changes in air pressure within that cavity and changes in air pressure within that cavity and in the lungsin the lungs

Air pressure differences actually cause air to Air pressure differences actually cause air to move into and out of the lungsmove into and out of the lungs



InspirationInspiration Active process—air moves into lungsActive process—air moves into lungs Inspiratory muscles include diaphragm and Inspiratory muscles include diaphragm and

external intercostalsexternal intercostals• Diaphragm flattens during inspiration—increases Diaphragm flattens during inspiration—increases

top-to-bottom length of thoraxtop-to-bottom length of thorax

• External intercostals contraction elevates the ribs— External intercostals contraction elevates the ribs— increases the size of the thorax from the front to the increases the size of the thorax from the front to the back and from side to sideback and from side to side

Increase in the size of the chest cavity reduces Increase in the size of the chest cavity reduces pressure within it; air then enters the lungspressure within it; air then enters the lungs



ExpirationExpiration Quiet expiration is ordinarily a passive processQuiet expiration is ordinarily a passive process During expiration, thorax returns to its resting size and During expiration, thorax returns to its resting size and

shapeshape Elastic recoil of lung tissues aids in expirationElastic recoil of lung tissues aids in expiration Expiratory muscles used in forceful expiration are Expiratory muscles used in forceful expiration are

internal intercostals and abdominal musclesinternal intercostals and abdominal muscles• Internal intercostals—contraction depresses the rib cage Internal intercostals—contraction depresses the rib cage

and decreases the size of the thorax from the front to backand decreases the size of the thorax from the front to back• Contraction of abdominal muscles elevates the diaphragm, Contraction of abdominal muscles elevates the diaphragm,

thus decreasing size of the thoracic cavity from the top to thus decreasing size of the thoracic cavity from the top to bottombottom

Reduction in the size of the thoracic cavity increases its Reduction in the size of the thoracic cavity increases its pressure and air leaves the lungspressure and air leaves the lungs



Exchange of gases in lungs (Figure 14-12)Exchange of gases in lungs (Figure 14-12) Carbaminohemoglobin breaks down into carbon dioxide and Carbaminohemoglobin breaks down into carbon dioxide and

hemoglobinhemoglobin Carbon dioxide moves out of lung capillary blood into alveolar Carbon dioxide moves out of lung capillary blood into alveolar

air and out of body in expired airair and out of body in expired air Oxygen moves from alveoli into lung capillariesOxygen moves from alveoli into lung capillaries Hemoglobin combines with oxygen, producing oxyhemoglobinHemoglobin combines with oxygen, producing oxyhemoglobin

Exchange of gases in tissuesExchange of gases in tissues Oxyhemoglobin breaks down into oxygen and hemoglobinOxyhemoglobin breaks down into oxygen and hemoglobin Oxygen moves out of tissue capillary blood into tissue cellsOxygen moves out of tissue capillary blood into tissue cells Carbon dioxide moves from tissue cells into tissue capillary Carbon dioxide moves from tissue cells into tissue capillary

bloodblood Hemoglobin combines with carbon dioxide, forming Hemoglobin combines with carbon dioxide, forming

carbaminohemoglobincarbaminohemoglobin


BLOOD TRANSPORTATION OF GASESBLOOD TRANSPORTATION OF GASES

Transport of oxygenTransport of oxygen Transport of carbon dioxide Transport of carbon dioxide

Volumes of air exchanged in pulmonary ventilation (Figure 14-13)Volumes of air exchanged in pulmonary ventilation (Figure 14-13) Volumes of air exchanged in breathing can be measured with a Volumes of air exchanged in breathing can be measured with a

spirometerspirometer Tidal volume (TV)—amount normally breathed in or out with each Tidal volume (TV)—amount normally breathed in or out with each

breathbreath Vital capacity (VC)—greatest amount of air that one can breathe out in Vital capacity (VC)—greatest amount of air that one can breathe out in

one expirationone expiration Expiratory reserve volume (ERV)—amount of air that can be forcibly Expiratory reserve volume (ERV)—amount of air that can be forcibly

exhaled after expiring the tidal volumeexhaled after expiring the tidal volume Inspiratory reserve volume (IRV)—amount of air that can be forcibly Inspiratory reserve volume (IRV)—amount of air that can be forcibly

inhaled after a normal inspirationinhaled after a normal inspiration Residual volume (RV)—air that remains in the lungs after the most Residual volume (RV)—air that remains in the lungs after the most

forceful expirationforceful expiration Rate—usually about 12 to 18 breaths a minute; much faster during Rate—usually about 12 to 18 breaths a minute; much faster during

exerciseexercise


REGULATION OF RESPIRATION REGULATION OF RESPIRATION (Figure 14-14)(Figure 14-14)

Regulation of respiration permits the body to adjust to varying Regulation of respiration permits the body to adjust to varying demands for oxygen supply and carbon dioxide removaldemands for oxygen supply and carbon dioxide removal Most important central regulatory centers in medulla are called Most important central regulatory centers in medulla are called

respiratory control centersrespiratory control centers (inspiratory and expiratory centers) (inspiratory and expiratory centers) Under resting conditions, nervous activity in the respiratory control Under resting conditions, nervous activity in the respiratory control

centers produces a normal rate and depth of respirations (12 to 18 per centers produces a normal rate and depth of respirations (12 to 18 per minute)minute)

Respiratory control centers in the medulla are influenced by Respiratory control centers in the medulla are influenced by “inputs” from receptors located in other body areas:“inputs” from receptors located in other body areas: Cerebral cortex—voluntary (but limited) control of respiratory activityCerebral cortex—voluntary (but limited) control of respiratory activity Receptors that influence respirationReceptors that influence respiration

• Chemoreceptors respond to changes in carbon dioxide, oxygen, and blood Chemoreceptors respond to changes in carbon dioxide, oxygen, and blood acid levels—located in carotid and aortic bodiesacid levels—located in carotid and aortic bodies

• Pulmonary stretch receptors—respond to the stretch in lungs, thus Pulmonary stretch receptors—respond to the stretch in lungs, thus protecting respiratory organs from overinflationprotecting respiratory organs from overinflation

Chapter 14 The Respiratory System. Mosby items and derived items © 2008 by Mosby, Inc., an...

Documents

Transcript of Chapter 14 The Respiratory System. Mosby items and derived items © 2008 by Mosby, Inc., an...