respiratory system.tini st 2

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Respiratory SystemSuhart ini d rg ., M.B iotech

Physio logy-Biomedic Department

Dent istry Facu l ty o f Jember Universi ty

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The Respiratory System

The respiratory system works with the

cardiovascular system to exchange gases

between the air and blood (external

respiration) and between blood and tissuefluids (internal respiration).

Inspiration and expiration move air in and out

of the lungs during breathing. Cellular respiration is the final destination

where ATP is produced in cells.

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Respiratory System: Overview

Lungs: exchange surface

75 m2

Thin walled

Moist

Ribs & skin protect

Diaphragm & ribs pump air

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Functions of the Respiratory System

Figure 17-1: Overview of external and cellular respiration

Exchange O2Air to blood

Blood to cells

Exchange CO2 Cells to blood

Blood to air

Regulate blood pH Vocalizations

Protect alveoli

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Respiratory System: Overview

Figure 17-2 b: Anatomy Summary

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The Respiratory tract


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The respiratory tract

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The Respiratory Tract

Air is cleansed, warmed, and moistenedas it passes the cilia and mucus in thenostrils and nasal cavity.

In the nose, the hairs and the cilia act asa screening device.

In the trachea, the cilia beat upward,

carrying dust and mucus into thepharynx.

Exhaled air carries out heat and

moisture. 8


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The Nose

The two nasal cavities are divided by a

septum.

They contain olfactory cells, receive tear

ducts from eyes, and communicate with

sinuses.

The nasal cavities empty into the

nasopharynx.

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The Pharynx

The pharynx (throat) is a passagewayfrom the nasal cavities to oral cavities and

to the larynx.

The pharynx contains the tonsils; therespiratory tract assists the immune

system in maintaining homeostasis.

The pharynx takes air from the nose to thelarynx and takes food from the oral cavity

to the esophagus.

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The Larynx

The larynx is acartilaginous structurelying between the pharynxand the trachea.

The larynx houses thevocal cords.

A flap of tissue called theepiglottis covers theglottis, an opening to thelarynx

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The Trachea

The trachea, supported by C-shaped

cartilaginous rings, is lined by ciliatedcells, which sweep impurities up toward

the pharynx.

Smoking destroys the cilia.

The trachea takes air to the bronchial tree

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Cilia in the trachea

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The Bronchial

The trachea divides

into right and left

primary bronchi which

lead into the right and

left lungs.

The right and left

primary bronchi divide

into ever smallerbronchioles to

conduct air to the

alveoli. 14


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The Alveoli

Alveoli are the tiny air sacs of the lungs

made up of squamous epithelium andsurrounded by blood capillaries.

Alveoli function in gas exchange, oxygen

diffusing into the bloodstream and carbondioxide diffusing out.

Infant respiratory distress syndrome occurs

in premature infants where underdevelopedlungs lack surfactant (thin film of lipoprotein)

and collapse.15


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Alveoli and Pulmonary

Capillaries

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Filter, warm & moisten air Nose, (mouth), trachea, bronchi &

bronchioles

Huge increase in cross sectional area

Conduction of Air from Outside to Alveoli

Figure 17-4: Branching of the airways17


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THE MECHANICS OFrespiration


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Mechanism of Breathing

During breathing, air moves into the

lungs during inspiration (inhalation)

from the nose or mouth, then moves

out again during expiration

(exhalation).

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Pressures

Atmospheric pressure 760 mm Hg

Intrapleural pressure 756 mm Hg

pressure between pleural layers

Intrapulmonary pressure varies,

pressure inside lungs

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AIR IS A COMPRESSABLE GAS WHICH

OBEYS BOYLES LAW

P1V1 = P2V2

If Volume increases, Pressure must

decrease

As lungs expand, pressure inside falls

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INSPIRATION

Elevation of ribs expandslungs

Lowering of diaphragm by

contraction also expandslungs

Expansion of lungs causes

pressure inside to drop belowatmospheric pressure

Air rushes in to fill the

expanded lungs 22


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INSPIRATION

760 mm Hg

754 mmHg

Lungs

Intrapleural pressure

Airways

Atmosphere

Pleural Sac

Thoracic

Wall

759mm Hg

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Expiration/Exhalation

Muscles relax

Volume of thoracic cavity decreases

Volume of lungs decreases Intrapulmonary pressure increases (763

mm Hg)

Forced expiration is active

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EXPIRATION

Return of ribs to rest position causes

diminishing of lung volume

Return of diaphragm to rest position also

causes diminishing of lung volume

Diminishing of lung volume causes

pressure in lung to raise to a higher value

than atmospheric pressure

Air flows out of the lungs

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EXPIRATION

760 mm Hg

756 mmHg

Lungs

Intrapleural pressure

Airways

Atmosphere

Pleural Sac

Thoracic

Wall

761 mm Hg

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Expiration

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MUSCLES of RESPIRATION

INSPIRATION

Sternocleidomastoid

Scalenus

External Intercostals

Diaphragm

EXPIRATION

Internal intercostals

Abdominals

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BREATHING MUSCLES

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exTERNAL AND inTERNAL

RESPIRATION


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External Respiration

External respiration is the diffusion of

CO2 from pulmonary capillaries into

alveolar sacs and O2 from alveolar sacsinto pulmonary capillaries.

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EXTERNAL RESPIRATION

Ventilation or breathing: air moved in and

out of lungs

Oxygen and Carbon Dioxide exchange in

the lungs

Oxygen and Carbon Dioxide transported

by blood to and from tissues

Exchange of Oxygen and Carbon Dioxide

between tissue and blood

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INTERNAL RESPIRATION

CELLULAR METABOLISM

ANAEROBIC GLYCOLYSIS

AEROBIC OXIDATIVE METABOLISM IN

THE MITOCHONDRIA

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I l R i i


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Internal Respiration

Internal respiration is the diffusion of O2from systemic capillaries into tissues and

CO2 from tissue fluid into systemic

capillaries.

Oxyhemoglobin gives up O2, which diffuses

out of the blood and into the tissuesbecause the partial pressure of O2 of

tissues fluid is lower than that of the blood.36


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EXTERNAL AND INTERNAL

RESPIRATION

HEART

TISSUE

CELL

O2 + FOOD

CO2 + H2O

+ ATP

LUNGS

ATMOSPHERE

PULMONARY

CIRULATION

SYSTEMIC

CIRCULATION

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External and internal respiration

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GAS EXCHANGE


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PARTIAL PRESSURES

In a mixture of gasses, the total pressure

distributes among the constituents

proportional to their percent of the total

The concentration of a gas can therefore

be expressed as its partial pressure

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Partial Pressures in air

Oxygen = 21%

Nitrogen = 79%

Po2 = 160 mm Hg

PN2 = 600 mm Hg

Total Pressure =

760mm Hg

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DEAD SPACE VOLUME

At the height of expiration, about 150ml of

gas still occupies the respiratory tree

This old gas is necessarily mixed with

the incoming fresh air and further lowers

the PO2 to about 100 mmHg


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Partial Pressures

Oxygen is 21% of atmosphere

760 mmHg x .21 = 160 mmHg PO2

This mixes with old air already inalveolus to arrive at PO2 of 105 mmHg


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Partial Pressures

Carbon dioxide is .04% of atmosphere

760 mmHg x .0004 = .3 mm Hg PCO2

This mixes with high CO2 levels fromresidual volume in the alveoli to arrive at

PCO2 of 40 mmHg


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Gas Exchange

Partial Pressure Each gas in atmosphere contributes to the entire

atmospheric pressure, denoted as P

Gases in liquid Gas enters liquid and dissolves in proportion to its

partial pressure

O2 and CO2 Exchange by DIFFUSION PO2 is 105 mmHg in alveoli and 40 in alveolar

capillaries

PCO2 is 45 in alveolar capillaries and 40 in alveoli


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GAS EXCHANGE ACROSS PULMONARY /

SYSTEMIC CAPILLARIES

Both oxygen and

carbon dioxide

diffuse down their

concentration (partial

pressure) gradients

Inspired Air PO2 = 160mmHg

PCO2 = 0.03mmHg

LUNG

PO2 = 100mmHg

PCO2 = 40mmHg

PULMONARY/SYSTEMIC

CAPILLARIES

PO2 = 100mmHg

PCO2 = 40mmHg

PO2 = 40mmHg

PCO2 = 46mmHg

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GAS EXCHANGE ACROSS SYSTEMIC

CAPILLARIES

Both oxygen and

carbon dioxide

diffuse down their

concentration (partial

pressure) gradients

TISSUEPO2 < 40mmHg

PCO2 > 46mmHg

PO2 = 40mmHg

PCO2 = 46mmHg

SYSTEMIC CAPILLARIES

PO2 = 100mmHg

PCO2 = 40mmHg


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Most CO2 is carried as bicarbonate ions.

The enzyme carbonic anhydrase, in redblood cells, speeds up the conversion of

bicarbonate and H+

to H2O and CO2;CO2 enters alveoli and is exhaled.

Hemoglobin (Hb) takes up oxygen fromalveoli and becomes oxyhemoglobin(HbO2).

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After CO2 diffuses from tissue cells into theblood, it enters red blood cells where asmall amount is taken up by hemoglobin,forming carbaminohemoglobin.

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CO2 + Hb => HbCO2


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Lung volumes

and

capacities

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LUNG VOLUMES

Tidal Volume (TV): 500 ml

Inspiratory reserve volume (IRV): 3 liters

Expiratory reserve volume (ERV): 1 liter

Residual volume (RV): 1.2 liters

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LUNG CAPACITY:


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LUNG CAPACITY:

RELATIONSHIPS IC = IRV + TV

FRC = ERV + RV

VC = IRV + TV + ERV

TLC = VC + RV

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LUNG VOLUMES & CAPACITY

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Lung Volumes: Spirometer


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Measurements Tidal volume:

Inspiratory reserve Expiratory reserve

Residual

Vital capacity

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Measurements

Figure 17-12: The recording spirometer

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Controls of respiration

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RESPIRATORY CONTROL


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RESPIRATORY CONTROL

Pons: Pneumotactic center Fine tuning over medullary centers Switches off inspiration

Pons: Apneustic center Fine tuning over medullary centers

Blocks switching off of inspiritory neurons Medulla: Dorsal respiratory group Inspiratory neurons

Pacemaker activity

Expiration occurs when these cease firing

Medulla: Ventral respiratory group Both inspiratory and expiratory neurons Inactive during normal quiet breathing

Rev up inspiratory activity when demands for ventilation arehigh


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Controls of rate and depth of


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Controls of rate and depth of

respiration Arterial PO2

When PO2 is VERY low, ventilation increases

Arterial PCO2

The most important regulator of ventilation, smallincreases in PCO2, greatly increases ventilation

Arterial pH

As hydrogen ions increase, alveolar ventilation

increases, but hydrogen ions cannot diffuse into CSFas well as CO2

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REGULATORY OF RESPIRATION


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REGULATORY OF RESPIRATION:ACID_BASE BALANCE


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Respiratory diseases

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F t Aff ti V til ti


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Factors Affecting Ventilation

Figure 17-2e: Anatomy Summary

Airway Resistance

Diameter

Mucous blockage

Bronchoconstriction Bronchodilation

Alveolar compliance

Surfactants Surface tension

Alveolar elasticity65


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Resistance and Disease

Colds

Asthma: Constriction of small airways, excess

mucus, and histamine-induced edema

Bronchitis: Long term inflamitory responsecausing thickened walls and overproduction of

mucous

Emphysema: Collapse of smaller airways and

breakdown of alveolar walls

Alveolar surface tension

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