Kulpak UPN - Fisiologi Respirasi 1

8/12/2019 Kulpak UPN - Fisiologi Respirasi 1

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Functional Human Physiology

The Respiratory System


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Overview of Respiratory Function

Respiration = the process of gas exchange

Two levels of respiration:

Internal respiration (cellular respiration)

The use of O2with mitochondria to generate ATP

by oxidative phosphorylation

CO2is the waste product

External respiration (ventilation) The exchange of O2and CO2between the

atmosphere and body tissues


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Internal respiration (cellular

respiration)

Involves gas exchange between capillaries andbody tissues cells Tissue cells continuously use O2and produce CO2during

metabolism

Partial pressure (P) The PO2is always higher in arterial blood than in the

tissues

The PCO2is always higher in the tissues than in arterialblood

O2and CO2move downtheir partial pressuregradients O2moves out of the capillary into the tissues

CO2moves out of the tissues into the capillary


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External respiration (ventilation)

4 Processes: Pulmonary Ventilation Movement of air into the lungs (inspiration) and

out of the lungs (expiration)

Exchange of O2and CO2between lung airspaces and blood

Transportation of O2and CO2between the

lungs and body tissues Exchange of O2and CO2between the blood

and tissues


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Overview of Pulmonary Circulation

Deoxygenated blood

Under resting conditions, 5 liters of deoxygenated

blood are pumped to the lungs each minute from

the right ventricle CO2blood concentration is higher than O2blood

concentration in:

Systemic veins

Right atrium

Right ventricle

Pulmonary arteries


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Overview of Pulmonary Circulation

Oxygenated blood Transported from the pulmonary capillaries pulmonary

veins left atrium left ventricle aorta systemicarterial circulation

O2blood concentration is higher than CO2bloodconcentration in:

Alveoli

Pulmonary capillaries

Pulmonary veins

Left atrium

Left ventricle

Systemic arteries


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The Respiratory System

Cells continually useO2 & release CO2

Respiratory system

designed for gas

exchange

Cardiovascular

system transports

gases in blood Failure of either

system

rapid cell death from

O2 starvation


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Nose -- Internal Structurestwo nasal cavitieswith bony

outgrowths = nasal conchae(superior,

middle, inferior)nasal cavities separated by nasal

septumand nasal bone

lined with: pseudostratified ciliated

epithelial cells - mucus production

also are receptors for odors -lead to

nerves -> brain (smell)lacrimal glandsdrain into nasal

cavities

nasal cavities communicate with

cranial sinuses(air-filled chambers

within the skull)

nasal cavities empty into thenasopharynx- upper portion of the

pharynx

functions:warm, moisten, and filter

incoming air

Pseudostratified ciliated columnar with goblet

cells lines nasal cavity

-warms air due to high vascularity

-mucous moistens air & traps dust

-cilia move mucous towards pharynx


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Nasopharynx

From choanae to soft palate

openings of auditory (Eustachian) tubes frommiddle ear cavity

adenoids or pharyngeal tonsil in roof

Passageway for air only

pseudostratified ciliated columnar epithelium

with goblet

From soft palate to epiglottis

fauces is opening from mouth intooropharynx

palatine tonsils found in side walls, lingual

tonsil in tongue

Common passageway for food & air

stratified squamous epithelium

Oropharynx

Laryngopharynx

Extends from epiglottis to cricoid

cartilage

Common passageway for food &

air & ends as esophagus inferiorly

stratified squamous epithelium

The Pharynx


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Tortora & Grabowski 9/e2000 JWS 23-15

The Larynx

triangular box = voicebox top of the larynx - hole = glot t iswith the

epiglottis

Constructed of 3 single & 3 paired

cartilages

Epiglott is---leaf-shaped piece of elasticcartilage

during swallowing, larynx moves upward

epiglottis bends to cover glottis

thyro id cart i lage(Adams apple)

cr ico id cart i lage

arytenoid cart i lage for the attachment of truevocal cords

functions:

filters, moistens,

vocal

production


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Vocal Cords False vocal cord s

(ventricular folds) found

above the true vocalcords

True vocal cordsattach

to arytenoid cartilages True vocal cord contains

both skeletal muscle andan elastic ligament (vocal

ligament)

When intrinsic muscles of

the larynx contract they

move the cartilages &stretch vocal cord tight

When air is pushed past

tight ligament, sound is

produced


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The tighter the ligament, the higher the pitch

To increase volume of sound, push air harder

Vocal Cords


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Tortora & Grabowski 9/e2000 JWS 23-18


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Trachea

flexible cylindrical tube - Size is 5 in long & 1in diameter

sits anterior (in front of) the esophagus - Extends from larynx to T5

anterior to the esophagus and then splits into bronchi held upon by C rings of hyaline cartilage = tracheal cart i lage

16 to 20 incomplete rings

open side facing esophagus contains smooth muscle

layers:

mucosa= pseudostratified columnar with cilia & goblet cellssubmucosa= loose connective tissue & seromucous glands

splits into the right and left primary bronchi - enter the lungs

functions

:conducts

air into thelungs,

filtration,

moistens

mucosasubmucosa


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Trachea and Bronchial Tree

Pr imary bronc hisupply each lung

Secondary bronc hisupply each lobe of the lungs (3 right + 2 left)

Tert iary bron chisplits into successive sets of in t ralobular b ronchio lesthatsupply each bronchopu lmonary segment ( right = 10, left = 8)

IL bronchioles split into Terminal b ronch io les-> these split into RespiratoryBronchio les

each RB splits into multiple alveolar ducts which end in an alveolar sac


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Structure of Respiratory System

Respiratory zoneregion of gas exchange occurs only in

respiratory bronchioles and the terminal alveoli sacs

Conducting zoneairways that conduct air to therespiratory zone


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Anatomy of the Respiratory Zone

Gas exchange occurs

between the air and

the blood within the

alveoli


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Anatomy of the Respiratory Zone

Alveoli (singular is alveolus)

Tiny air sacs clustered at the distal ends of

the alveolar ducts

Alveoli have a thin respiratory membraneseparating the air from blood in pulmonary

capillaries


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Respiratory Membrane

The thin alveolar wall consists of:

The fused alveolar and capillary walls

Alveolar epithelial cells

Capillary endothelial cells

The basement membrane

Sandwiched between the alveolar epithelial cells

and the endothelial cells of the capillary


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Lung Alveoli and Pulmonary

Capillaries

Gas exchange occurs

across the 300 million

alveoli (60-80 m2total

surface area)

Alveolusone cell-layer

thick

Total air-blood barrier

only 2 thin cells across

Between lung air and

blood: 1 alveolar cell

and 1 endothelial cell


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Respiratory Membrane

Gas exchanges occurs across therespiratory membrane

It is < 0.1 m thick

Lends to very efficient diffusion

It is the site of external respiration and

diffusion of gases between the inhaled air

and the blood

Occurs in the pulmonary capillaries


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Structures of the Thoracic Cavity

A container with a single opening, the

trachea

Volume of the container changes

Diaphragm moves up and down

Muscles move the rib cage in and out

Volume of the thoracic cavity increases by

enlarging all diameters diameter = volume


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Conducting Zone

Warms and humidifies inspired airreaches respiratory

zone at 37 C Mucus lining filters and cleans inspired airmucous

moved by cilia to be expectorated


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Boyles Law

Volume and pressure are inverselyrelated

volume = pressure

Air always flows from an area of higher

pressure to an area of lower pressure

Decreased pressure in the thoracic cavity in

relation to atmospheric pressure causes air

to flow into the lungs The process of inspiration


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Structures of the Thoracic Cavity

Pleura

Parietal pleura: A membrane that lines the

interior surface of the chest wall

Visceral pleura: A membrane that lines theexterior surface of the lungs

Intrapleural space

A thin compartment between the two pleurae

filled with intrapleural fluid


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Pulmonary Pressures

Pressure gradient

The difference between intrapulmonary and

atmospheric pressures

4 Pulmonary Pressures Atmospheric pressure

Intra-alveolar (Intrapulmonary) pressure

Intrapleural pressure

Transpulmonary pressure


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Pulmonary Pressures

Atmospheric pressure

The pressure exerted by the weight of the air in theatmosphere (~ 760 mmHg at sea level)

Intra-alveolar (Intrapulmonary) pressure

The pressure inside the lungs


The pressure inside the pleural space

Transpulmonary pressure The difference between the intrapleural and intra-

alveolar pressure


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Pleural Pressures


The pressure inside the pleural space or cavity

This cavity contains intrapleural fluid, necessary

for surface tension

Surface tension

The force that holds moist membranes together

due to an attraction that water molecules have

for one another

Responsible for keeping lungs patent


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Intrapulmonary and Intrapleural Pressures

During inspiration, intrapulmonary pressure is about -3 mm

Hg pressure; during expiration is about +3 mm Hg Positive transmural pressure (intrapulmonary minus

intrapleural pressure) keeps lungs inflated


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Surface Tension

The force of attraction between liquidmolecules

Type II alveolar cells secrete surfactant Creates a thin fluid film in the alveoli

Surfactant (a phospholipoprotein) reducesthe surface tension in the alveoli It interferes with the attraction between fluid

molecules

Decreasing surface tension reduces theamount of energy required to expand thelungs

Laplaces Law


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Surface Tension

Law of Laplacestates that pressure in

alveolus is directly

proportional to ST; and

inversely to radius of

alveoli Thus, pressure in smaller

alveoli would be greater

than in larger alveoli, if

ST were same in both

Greater pressure of

smaller alveolus would

cause it to its empty air

into the larger one


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Inspiration

Drawing or pulling air into the lungs Atmospheric pressure forces air into the lungs

The diaphragm moves downward, decreasing

intra-alveolar pressure

The thoracic rib cage moves upward and outward,

increasing the volume of the thoracic cavity

Surface tension

Holds the pleural membranes together, which assistswith lung expansion

Surfactant reduces surface tension within the alveoli


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Inspiration

During inspiration, forces are generated that

attempt to pull the lungs away from the

thoracic wall

Surface tension of the intraplueral fluid holdthe lungs against the thoracic wall,

preventing collapse


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Expiration

Pushing air out of the lungs Results due to the elastic recoil of tissues

and due to the surface tension within thealveoli

Expiration can be aided by: Thoracic and abdominal wall muscles that pull

the thoracic cage downward and inward,decreasing intra-alveolar pressure

This compresses the abdominal organs upwardand inward, decreasing the volume of thethoracic cavity


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Muscles of Breathing - Inspiration

Quiet Breathing Muscles include: External intercostals

Diaphragm

Contract to expand the rib cage and stretch the

lungs = volume of the thoracic cavity intrapulmonary volume

intrapulmonary pressure (relative to atmosphericpressure)

Decreased pressure inside the lungs pulls air intothe lungs down its pressure gradient untilintrapulmonary pressure equals atmosphericpressure


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Forced or Deep Inspiration Involves several accessory muscles:

Sternocleidomastoid

Pectoralis minor

Scalenes (neck muscles)

Maximal in thoracic volume

Greater in intrapulmonary pressure

More air moves into the lungs At the end of inspiration, the intrapulmonary

pressure equals atmospheric pressure

Muscles of Breathing - Inspiration

M l f B hi E i i


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Quiet Breathing Passive process Depends on the elasticity of the lungs

Muscles of inspiration relax The rib cage descends

The lungs recoil

intrapulmonary volume

intrapulmonary pressure Alveoli are compressed, thus forcing air out

of the lungs

Muscles of Breathing - Expiration

M l f B thi E i ti


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Forced Expiration

It is an active process

Occurs in activities such as blowing up a balloon,

exercising, or yelling

Abdominal wall muscles are involved in forcedexpiration

Function to the pressure in the abdominal cavity forcing

the abdominal organs upward against the diaphragm

volume of thethoracic cavity

pressure in the thoracic cavity

Air is forced out of the lungs

Muscles of Breathing - Expiration


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Brain (medulla

and higher

centers) sendsimpulse to

inspire.

Diaphragm contracts down,

increasing the vertical dimension

of the thorax.

Intercostals and

interchondral

muscles contract

expanding lateral

and anterior-

posterior

dimensions of the

thorax.

Negative air

pressure iscreated in the

lungs

Pressure is

equalized

in the

lungs.

Air isdrawn

into the

lungs.

Gas is

expelled

from thelungs.

Diaphragm and rib-

cage relax

decreasing the

vertical, lateral and

anterior-posterior

dimensions of the

thorax.

Contraction of the

diaphragm,

intercostals and

interchondral

muscles stop and

elastic recoil brings

them to released

position.

Abdominal and

intercostals

muscles contract

decreasing

thoracic volume.

Positive air

pressure is

created in thelungs.

INSPIRATION EXPIRATION

F t Aff ti P l


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Factors Affecting Pulmonary

Ventilation

Lung compliance

The ease with which the lungs may be

expanded, stretched, or inflated

Depends primarily on the elasticity of thelung tissue

Elasticity refers to the ability of the lung to recoil

after it has been inflated

F t Aff ti P l


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Ventilation

Lung and thoracic cavity tissue has a

natural tendency to recoil, or become

smaller

Lung recoil is essential for normal expirationand depends on the fibroelastic qualities of

lung tissue

In normal lungs there is a balance betweencompliance and elasticity

F t Aff ti P l


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Recoil pressure is inverselyproportional to

compliance

Increased compliance results in decreased recoil

Example: Emphysema Results in difficulty resuming the shape of the lung

during exhalation

Decreased compliance results in increased recoil

Example: Cysitc fibrosis Results in difficulty expanding the lung because of

increased fibrous tissue and mucous


Ventilation

F t Aff ti P l


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Airway Resistance (Poiseuilles Law) Opposition to air flow in the respiratory passageways

Resistance and air flow are inverselyrelated

airway resistance = air flow (and vice versa)

Airway resistance is most affected by changes in thediameter of the bronchioles

diameter of the bronchioles = airway resistance

Examples:

Asthma

Bronchiospasm during an allergic reaction

A high resistance to air flow produces a greater energy costof breathing


Ventilation


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To Be Continued

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Kulpak UPN - Fisiologi Respirasi 1