human respiratory system and mechanics.ppt

8/21/2019 Human Respiratory System and Mechanics.ppt

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RESPIRATORY SYSTEM


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Organization and Functions of

the Respiratory System

Structural classifications:upper respiratory tract

lower respiratory tract.

Functional classifications:Conductingportion: transports air.

1. Nose

2. nasal cavity

3. Pharynx

4. Larynx

5. Trachea

6. progressively smaller airways, from the primary bronchito the bronchioles


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Organization and Functions of

the Respiratory System

Functional classifications: continued

Conductingportion: transports air.

Respiratoryportion: carries out gas exchange. respiratory bronchioles

alveolar ducts

air sacs called alveoli

Upper respiratory tract is all conducting

Lower respiratory tract has both conducting and

respiratory portions


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Respiratory System Functions1. Breathing (pulmonary ventilation):

consists of two cyclic phases: inhalation, also calledinspiration

exhalation, also calledexpiration

Inhalation draws gases intothe lungs.Exhalation forces gases outof the lungs.

2. Gas exchange: O2and CO2

External respiration

External environment and blood

Internal respiration

Blood and cells


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Respiratory System Functions3. Gas conditioning:

Warmed Humidified

Cleaned of particulates

4. Sound production: Movement of air over true vocal cords

Also involves nose, paranasal sinuses, teeth,lips and tongue

5. Olfaction (act or process of smelling): Olfactory epithelium over superior nasal

conchae

6. Defense:

Course hairs, mucus, lymphoid tissue


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Upper Respiratory Tract

Composed of

1. the nose

2. the nasal cavity

3. the paranasal sinuses

4. the pharynx (throat)

5. and associated structures. All part of the conductingportion of the

respiratory system.


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Upper Respiratory Tract


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Paranasal Sinuses

Paranasal sinuses:

In four skull bonespaired air spaces

decreaseskull bone weight

Named for the bones in which they are housed.frontal

ethmoidal

sphenoidal

maxillary Communicate with the nasal cavity by ducts.

Covered with the samepseudostratified ciliatedcolumnar epitheliumas the nasal cavity.


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Pharynx

Common to both the respiratory anddigestive systems.

Commonly called the throat.

Funnel-shaped

slightly wider superiorly and narrowerinferiorly.

Originates posterior to the nasal and oral

cavities Extends inferiorly near the level of the

bifurcation of the larynx and esophagus.

Common pathway for both air and food.


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Pharynx

Walls:

lined by a mucosa

contain skeletal muscles primarily used for

swallowing.

Flexible lateral wallsdistensible

to force swallowed food into the esophagus.

Partitioned into three adjoining regions:nasopharynx

oropharynx

laryngopharynx


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Nasopharynx Superiormost region of the pharynx.

Location: posterior to the nasal cavity

superior to the soft palate separates it from the posterior part of the oral cavity.

Normally, only air passes through.

Soft palate Blocks material from the oral cavity and oropharynx

elevates when we swallow.

Auditory tubes paired

In the lateral walls of the nasopharynx

connect the nasopharynx to the middle ear.

Pharyngeal tonsil posterior nasopharynx wall

single

commonly called the adenoids.


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Oropharynx The middle pharyngeal region.

Location: Immediately posterior to the oral cavity.

Bounded by the soft palate superiorly,

the hyoid bone inferiorly.

Common respiratory and digestive pathway both air and swallowed food and drink pass through.

2 pairs of muscular arches anterior palatoglossal arches

posterior palatopharyngeal arches

form the entrance from the oral cavity.

Lymphatic organs provide the first line of defense against ingested or inhaled foreignmaterials.

Palatine tonsils on the lateral wall between the arches

Lingual tonsils

At the base of the tongue.


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Laryngopharynx

Inferior, narrowed region of the pharynx.

Location:

Extends inferiorly from the hyoid bone

is continuous with the larynx and esophagus. Terminates at the superior border of the esophagus

is equivalent to the inferior border of the cricoid cartilage in thelarynx.

The larynx(voice box) forms the anterior wall

Lined with a nonkeratinized stratified squamousepithelium (mucus membrane)

Permits passage of both food and air.


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Lower Respiratory Tract

Conducting portion

Larynx

Trachea

Bronchibronchioles and their associated structures

Respiratory portionof the respiratory

systemrespiratory bronchioles

alveolar ducts

alveoli


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Larynx Short, somewhat cylindrical airway

Location:

bounded posteriorly by the laryngopharynx,

inferiorly by the trachea.

Prevents swallowed materials fromentering the lower respiratory tract.

Conducts air into the lower respiratorytract.

Produces sounds.


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Larynx

Ninepieces of cartilage

three individual pieces

Thyroid cartilage

Cricoid cartilage Epiglottis

three cartilage pairs

Arytenoids: on cricoid

Corniculates: attach to arytenoids

Cuniforms:in aryepiglottic fold

held in place by ligaments and muscles.

Intrinsic muscles: regulate tension on true vocalcords

Extrinsic muscles: stabilize the larynx


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Trachea

A flexible, slightly rigid tubular organ

often referred to as the windpipe.

Extends through the mediastinum

immediately anterior to the esophagus

inferior to the larynx

superior to the primary bronchi of the lungs.

Anterior and lateral walls of the trachea are supported by15 to 20 C-shaped tracheal cartilages.

cartilage rings reinforce and provide some rigidity to thetracheal wall to ensure that the trachea remains open (patent) atall times

cartilage rings are connected by elastic sheets called anularligaments


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Trachea

At the level of the sternal angle, the trachea bifurcates into two

smaller tubes, called the right and left primary bronchi.

Each primary bronchus projects laterally toward each lung.

The most inferior tracheal cartilage separates the primary

bronchi at their origin and forms an internal ridge called thecarina.


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Bronchial Tree

A highly branched system air-conducting passages

originate from the left and right primary bronchi.

Progressively branch into narrower tubes as they divergethroughout the lungs before terminating in terminalbronchioles.

Primary bronchi Incomplete rings of hyaline cartilage ensure that they remain open.

Right primary bronchus shorter, wider, and more vertically oriented than the left primarybronchus.

Foreign particles are more likely to lodge in the right primarybronchus.

B hi l T


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Bronchial Tree Primary bronchi

enter the hilum of each lung

Also entering hilum: pulmonary vessels lymphatic vessels

nerves.

Secondary bronchi (or lobar bronchi) Branch of primary bronchus

left lung: two lobes

two secondary bronchi

right lung three lobes

three secondary bronchi. Tertiary bronchi (or segmental bronchi)

Branch of secondary bronchi

left lung is supplied by 8 to 10 tertiary bronchi.

right lung is supplied by 10 tertiary bronchi

supply a part of the lung called abronchopulmonary segment.


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Respiratory Bronchioles, Alveolar

Ducts, and Alveoli Contain small saccular outpocketings called alveoli.

An alveolus is about 0.25 to 0.5 millimeter in diameter.

Its thin wall is specialized topromote diffusion of gasesbetween the alveolus and the blood in the pulmonary

capillaries. Gas exchange can take place in the respiratory bronchioles and

alveolar ducts as well as in the lungs, which containapproximately 300400 million alveoli.

The spongynature of the lung is due to the packing of millionsof alveoli together.


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L G A


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Lungs: Gross Anatomy

Each lung has a conicalshape.

Its wide, concavebaserests upon the muscular

diaphragm.

Its relatively blunt superior region, called the apexor

(cupola), projects superiorly to a point that is slightlysuperior and posterior to the clavicle.

Both lungs are bordered by the thoracic wall anteriorly,

laterally, and posteriorly, and supported by the rib cage.

Toward the midline, the lungs are separated from each

other by the mediastinum.

The relatively broad, rounded surface in contact with the

thoracic wall is called the costal surfaceof the lung.


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Pleura and Pleural Cavities

The outer surface of each lung and the adjacentinternal thoracic wall are lined by a serousmembrane calledpleura, which is formed fromsimple squamous epithelium.

The outer surface of each lung is tightlycovered by the visceral pleura, while theinternal thoracic walls, the lateral surfaces ofthe mediastinum, and the superior surface ofthe diaphragm are lined by theparietal pleura.

The parietal and visceral pleural layers arecontinuous at the hilum of each lung.


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Pleura and Pleural Cavities

The outer surface of each lung is tightly covered by the visceral pleura,

while the internal thoracic walls, the lateral surfaces of the mediastinum,

and the superior surface of the diaphragm are lined by theparietal pleura.

Thepotential spacebetween these serous membrane layers is apleural

cavity.

The pleural membranes produce a thin, serous fluidthat circulates in the

pleural cavity and acts as alubricant, ensuring minimal friction duringbreathing.


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Lymphatic Drainage

Lymph nodesand vessels are located within the connective

tissue of the lung as well as around the bronchi and pleura.

The lymph nodes collect carbon, dust particles, and pollutants

that were not filtered out by the pseudostratified ciliated

columnar epithelium.


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LUNG MECHANICS


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MECHANICS

the branch of physics that deals with the action of

forces on bodies and with motion, comprised of

kinetics, statics, and kinematics.

the theoretical and practical application of this

science to machinery, mechanical appliances, etc.

the technical aspects of working of something;mechanism; structure.

the science of designing, constructing, and

operating machines

LUNG MECHANICS


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LUNG MECHANICSSome Terminologies and Facts

LUNG MECHANICS


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LUNG MECHANICS


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Spirometer

P l V l & C iti


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Pulmonary Volumes & Capacities


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Spirometry: capacities

Remember: A capacity is always a

sum of certain lung volumes

TLC = IRV + TV + ERV + RV VC = IRV+ TV + ERV

FRC = ERV + RV IC = TV + IRV


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Spirometry

4 volumes and 4 capacities Effort dependent

Values vary to height, age, sex &

physical training

IRV = 2.5 L * IC = 3 L

TV = 0.5 L * VC = 4.5 L

ERV = 1.5 L * FRC = 2.5 L

RV = 1 L * TLC = 5.5 L

S i t


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Spirometry

REMEMBER: Spirometry cannot measure

Residual Volume (RV) thus Functional

Residual Capacity (FRC) and Total Lung

Capacity (TLC) cannot be determined using

spirometry alone.

FRC and TLC can be determined by 1) Helium

dilution, 2) Nitrogen washout, or 3) body

plethysmography


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Physiological Lung Structure

Lung weighs 1.5% of body weight

1 kg in 70 kg adult

Alveolar tissue is 60% of lung weight

Alveoli have very large surface area

70 m2internal surface area

40 x the external body surface area

Short diffusion pathway for gases

Permits rapid & efficient gas exchange into blood

1.5 m between air & alveolar capillary RBC

Blood volume in lung - 500ml (10% of total blood volume)


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Respiratory Mechanics

Multiple factors required to alterlung volumes

Respiratory muscles generate force to inflate

& deflate the lungs Tissue elastance & resistance impedes

ventilation

Distribution of air movement within thelung, resistance within the airway

Overcoming surface tension within alveoli

Th B thi C l


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The Breathing Cycle

Airflow requires a pressure gradient

Air flow from higher to lower pressures

During inspiration alveolar pressure is sub-

atmospheric allowing airflow into lungs

Higher pressure in alveoli during expiration

than atmosphere allows airflow out of lung

Changes in alveolar pressure are generated

by changes in pleural pressure

MUSCLES OF BREATHING


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MUSCLES OF BREATHINGMuscles of Inspiration

MUSCLES OF BREATHING


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MUSCLES OF BREATHINGMuscles of Exspiration


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Inspiration


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InspirationActive Phase Of Breathing Cycle

Motor impulses from brainstem activate muscle

contraction Phrenic nerve (C 3,4,5) transmits motor stimulation to

diaphragm

Intercostal nerves (T 1-11) send signals to the externalintercostal muscles

Thoracic cavity expands to lower pressure in pleural spacesurrounding the lungs

Pressure in alveolar ducts & alveoli decreases Fresh air flows through conducting airways into terminal

air spaces until pressures are equalized

Lungs expand passively as pleural pressure falls

The act of inhaling is negative-pressure ventilation


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Muscles of Inspiration: Diaphragm

Most Important Muscle Of Inspiration Responsible for 75% of inspiratory effort Thin dome-shaped muscle attached to the lower ribs, xiphoid process,

lumbar vertebra

Innervated by Phrenic nerve (Cervical segments 3,4,5) During contraction of diaphragm

Abdominal contents forced downward& forwardcausing increase in verticaldimension of chest cavity

Rib margins are lifted& movedoutward causing increase in the transverse

diameter of thorax Diaphragm moves down1cm during normal inspiration

During forced inspiration diaphragm can move down 10cm

Paradoxical movement of diaphragm when paralyzed

Upward movement with inspiratory drop of intrathoracic pressure

Occurs when the diaphragm muscle is denervated


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Diaphragm


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Movement of Thorax During

Breathing Cycle


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Movement of Diaphragm


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Thoracic Wall Dimensional


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Thoracic Wall Dimensional

Changes During Respiration

Lateral dimensional changes occur

with rib movements.

Elevationof the ribs increases the

lateral dimensions of the thoracic

cavity, while depressionof the ribsdecreases the lateral dimensions of

the thoracic cavity.


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Inspiration Expiration

Muscles that Move the Ribs


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Muscles that Move the Ribs The scaleneshelp increase thoracic cavity dimensions

by elevating the first and second ribs during forcedinhalation.

The ribs elevateupon contraction of the external

intercostals, thereby increasing the transverse

dimensions of the thoracic cavity during inhalation.

Contraction of the internal intercostals depressesthe

ribs, but this only occurs during forcedexhalation.

Normal exhalation requires no active muscular effort. A small transversus thoracisextends across the inner

surface of the thoracic cage and attaches to ribs 26.

It helps depress the ribs.

Muscles that Move the Ribs


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Two posterior thorax muscles also assist with respiration.

These muscles are located deep to the trapezius and

latissimus dorsi, but superficial to the erector spinaemuscles.

The serratus posterior superiorelevates ribs 25 during

inhalation, and the serratus posterior inferiordepresses ribs812 during exhalation.

In addition, some accessory musclesassist with respiratory

activities.

Thepectoralis minor, serratus anterior, andsternocleidomastoidhelp with forced inhalation, while the

abdominal muscles(external and internal obliques,

transversus abdominis, and rectus abdominis) assist in active

exhalation.


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Muscles of Inspiration


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External Intercostal Muscles

The external intercostal muscles connect to adjacent ribs Responsible for 25% of inspiratory effort

Motor neurons to the intercostal muscles originate in the respiratorycenters of the brainstem and travel down the spinal cord. The motornerves leave the spinal cord via the intercostal nerves. These originatefrom the ventral rami of T1 to T11, they then pass to the chest wallunder each rib along with the intercostal veins and arteries.

Contraction of EIM pulls ribs upward & forward

Thorax diameters increasein both lateral & anteroposterior directions

Ribs move outward in bucket-handle fashion Intercostals nerves from spinal cord roots innervate EIMs

Paralysis of EIM does not seriously alter inspiration becausediaphragm is so effective but sensation of inhalation is decreased

Muscles of respiration


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Accessory Muscles

These muscles assist with forcedinspirationduring periods of stress or exercise

Scalene Muscle Attach cervical spine to apical rib

Elevate the first two ribs during forced inspiration

Sternocleidomastoid Muscle

Attach base of skull (mastoid process) to top ofsternum and clavicle medially

Raise the sternum during forced inspiration

Boyles Law


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y The pressure of a gas decreases if the volume of

the container increases, and vice versa.

When the volume of the thoracic cavity increases even

slightly during inhalation, the intrapulmonary pressure

decreases slightly, and air flows into the lungs

through the conducting airways. Air flows into the lungs from a region of higher

pressure (the atmosphere) into a region of lower

pressure (the intrapulmonary region).

When the volume of the thoracic cavity decreases

during exhalation, the intrapulmonary pressure

increases and forces air out of the lungs into the

atmosphere.


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Goals of Respiration

Primary Goals Of The Respiration System

Distribute air & blood flow for gas

exchange

Provide oxygen to cells in body tissues

Remove carbon dioxide from body

Maintain constant homeostasis for

metabolic needs


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Functions of Respiration

Respiration divided into fourfunctional events:

1.Mechanics of pulmonary ventilation2.Diffusion of O2 & CO2between alveoli and

blood

3.Transport of O2

& CO2

to and from tissues

4.Regulation of ventilation & respiration

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External & Internal Respiration

External Respiration

Mechanics of breathing

The movement of gases

into & out of body Gas transfer from lungs

to tissues of body

Maintain body &

cellular homeostasis

Internal Respiration

Intracellular oxygen

metabolism

Cellular transformation Krebs cycleaerobic

ATP generation

Mitochondria & O2

utilization


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REGULATION OFBREATHING

Respiratory Cycle and its control


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Respiratory Cycle and its control

Respiration rate is the number of

breaths per minute

Human respiration rate is controlled

by a part of the brain called themedulla

Sends signals to adjust levels of oxygen

present in your body by changing your

breathing rate

Ventilation Control by RespiratoryC f h B i


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Centers of the Brain

The trachea, bronchial tree, and lungs are innervatedby the autonomic nervous system.

The autonomic nerve fibers that innervate the heart

also send branches to the respiratory structures. The involuntary, rhythmic activities that deliver and

remove respiratory gases are regulated in the

brainstem.

Regulatory respiratory centers are located within the

reticular formationthrough both the medulla

oblongataandpons.


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CHEMICAL CONTROL OF BREATHING


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CHEMICAL CONTROL OF BREATHING


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PULMONARY VENTILATION

Pulmonary Ventilation


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Pulmonary ventilation is a measure of the rate of ventilation,referring to the total exchange of air between the lungs and the

ambient or surrounding air.Pulmonary Ventilation is the total volume of gas per minuteinspired or expired.

The main purpose of ventilation is to maintain an

optimal composition of alveolar gas

Alveolar gas acts as stabilizing buffer compartment betweenthe environment & pulmonary capillary blood

Oxygen constantly removed from alveolar gas by blood

Carbon dioxide continuously added to alveoli from blood

O2replenished & CO2removed by process of ventilation, by simplediffusion.

The two ventilation phases (inspiration & expiration) providethis stable alveolar environment

Breathing is the act of creating inflow & outflow of air between

the atmosphere and the lung alveoli


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Lung Volume and Capacities


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Lung Volume and Capacities


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Lung Volumes and Capacities


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Intrathoracic Pressure


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Intrapulmonary Pressure


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Composition of Inspired Air,E i d Ai d Al l Ai


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Expired Air and Alveolar Air

Carriage of Gases by blood


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Compliance of the LungsC li i f th di t ibilit f th l


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Compliance is a measure of the distensibility of the lungs

Compliance = change in lung volume/ change in lung

pressure

Cpulm= DVpulm/ Dppulm

Normal static compliance is 70-100 ml of air/cm of H2Otranspulmonary pressure

Different compliances for inspiration & expirationbased on the elastic forces of lungs

Compliance reducedby higher or lower lung volumes, higherexpansion pressures, venous congestion, alveolar edema,atelectasis & fibrosis

Compliance increasedwith age & emphysema secondary to

alterations of elastic fibers

Elastic Forces of the LungS f Ai fl id


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Elastic Lung Tissue

Elastin & Collagen fibers of

lung parenchyma

Natural state of these fibers

is contracted coils

Elastic force generated by

the return to this coiled state

after being stretched and

elongated

The recoil force assists todeflate lungs

Surface Air-fluid

Interface

2/3 of total elastic force in

lung

Surface tension of H2O

Complex synergy between air

& fluid holds alveoli open

Without air in the alveoli a

fluid filled lung has only lung

tissue elastic forces to resistvolume changes

Surfactant in the alveoli fluid

reduces surface tension,

keeps alveoli from collapsing

Factors Determining Airway Resistance


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Factors Determining Airway Resistance

Lung Volume Linear relationship between lung volumes & conductance

of airway resistance

As lung volume is reduced - airway resistance increases

Bronchial Smooth Muscle Contraction of airways increases resistance

Bronchoconstriction caused by PSN, acetylcholine, lowPco2,direct stimulation, histamine, environmental, cold

Density & Viscosity Of Inspired Gas Increased resistance to flow with elevated gas density

Changes in density rather than viscosity have moreinfluence on resistance

Organs in the Respiratory System


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STRUCTURE FUNCTION

nose / nasal cavitywarms, moistens, & filters air as it is

inhaled

pharynx (throat) passageway for air, leads to trachea

larynxthe voice box, where vocal chords are

located

trachea (windpipe)

keeps the windpipe "open"

trachea is lined with fine hairs calledciliawhich filter air before it reaches the

lungs

bronchi

two branches at the end of the trachea,

each lead to a lung

bronchioles

a network of smaller branches leading from

the bronchi into the lung tissue &

ultimately to air sacs

alveolithe functional respiratory units in the lung

where gases are exchanged

Malfunctions Diseases of the Respiratory System


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asthma

severe allergic reaction

characterized by the

constriction of bronchioles

bronchitis

inflammation of the lining of

the bronchioles

emphysema

condition in which the alveoli

deteriorate, causing the lungs

to lose their elasticity

pneumonia

condition in which the alveoli

become filled with fluid,

preventing the exchange ofgases

irregular & uncontrolled

human respiratory system and mechanics.ppt

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