Chapter 5 The Respiratoy System - PowerPoint Presentation

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Chapter 5The Respiratoy System

Abdullah A. AlrumayhBSc EMS, MSc Cardiovascular, Lecturer  Department of Basic Sciences, PSCEMShttp://fac.ksu.edu.sa/aalrumayh

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Learning Objectives

Discuss the relevance of understanding the function and structure of the respiratory system to conditions commonly found in the field.State the primary functions of the respiratory system.Identify the organs of the respiratory system and describe their functions.

Describe the structure and function of the larynx and the speaking mechanism.

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Learning Objectives

State the roles of visceral and parietal pleura in respiration.

State the changes in air pressure within the thoracic cavity during respiration.

Describe the factors that influence the respiration rate.

Identify the respiratory areas of the brain that control inspiration as well as exhalation.

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Learning Objectives

Explain the diffusion of gases in external and internal respiration. Explain how respiration affects the pH of certain body fluids.Describe how oxygen and carbon dioxide are transported in the blood.

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The Respiratory System

Includes the organs and structures associated with breathing, gas exchange, and the entrance of air into the body

These structures are divided into two groups:

Upper airway

Lower airway

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The upper Airway

Inspired air flows into the body through either the nose or

mouth

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Nasopharynx

The nasal cavity

Nasopharynx and nasal passages, including the

turbinates

Warm, filter, and humidify air

Nasal mucosa

Olfactory receptors

Extends from the internal nares to the uvula

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External nares or nostrils

The external openings of the nasopharynx Internal naresThe posterior opening from the nasopharynx into the pharynxNasal septumSeparates the nasopharynx into two partsHard palate

Nasopharynx Cont.

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Nasopharynx Cont.

Conchae

Three bony ridges contained within the lateral walls of the nasopharynx

Turbinates

Bony convolutions formed by the conchae that help maintain laminar flow

Meatus

Passageway below each turbinate

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Oropharynx

The oral cavityAir enters more rapidly and directly

Air is less moist

Extends from the uvula to the epiglottis

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Pharynx

The throatPoint where the nasopharynx and oropharynx connect posteriorly to form a common cavity

Composed of the nasopharynx, oropharynx, and the laryngopharynx

Leads to the separate openings of the respiratory system and the digestive system

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Lower Airway

Structures of the lower airway

Larynx

Trachea

Mainstem bronchi

Secondary bronchi

Bronchioles

Alveolar duct

Alveoli

Lungs

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Larynx

The voice boxA rigid, hollow structure made of cartilageThyroid cartilage (Adam’s apple)

Vestibular folds

Superior portion of the vocal cords (false vocal cords)

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Larynx

True vocal cords

Inferior portion of the vocal cords

Glottis

The true vocal cords plus the opening between them

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Trachea

The windpipeExtends downward anterior to the esophagusBranches into right and left mainstem bronchi at the level of the fifth thoracic vertebraCarina

A projection of the lowest portion of the tracheal cartilage

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Mainstem Bronchi

Beyond the carina, air enters the lungs through the mainstem bronchi.

Hilum

Point of entry for the bronchi, vessels, and nerves into each lung

Mainstem bronchi divide into secondary bronchi.

Lead to separate lobes of the lung

Secondary bronchi branch into tertiary bronchi.

Continue to branch, eventually becoming bronchioles

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Bronchioles

Very small subdivisions of the bronchi

Respiratory bronchioles

Develop from the final branching of the bronchiole

Each respiratory bronchiole divides to form alveolar ducts.

Alveolar duct

End in clusters known as alveoli

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Alveoli

Alveoli Tiny sacs of lung tissue in which gas exchange takes placeLung contains approximately 300 million alveoli.

Alveolocapillary membrane

Lies between the alveolus and the capillary

Very thin, consisting of one cell layer

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Lungs

The primary organs of breathingRight lung has three lobes

Upper lobe

Middle lobe

Lower lobe

Left lung has two lobes

Lingula – portion of the left lung that forms the equivalent of the middle lobe in the right lung

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Lungs

Pleura Membranes of connective tissue that envelop the lungs and line the pleural cavity

Pleural cavity

Inner borders of the rib cage

Visceral pleura

Parietal pleura

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Lungs

Pleural spacePotential space that exists between the visceral and parietal pleuraNormally, the two membranes are close together and a space does not exist

Hemothorax

A collection of blood in the pleural space

Hemopneumothorax

A collection of blood & air in the pleural space

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Lungs

Blood flow in the lung – two waysDeoxygenated blood in the heart flows from the right ventricle to the lungs via the pulmonary arteries. Blood supply for the lung tissue

Bronchial arteries

Bronchial veins

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Respiration

Ventilation – process of moving air in and out of the lungsInspiration = inhalation

Expiration = exhalation

Atmospheric pressure

The force that moves air into the lungs

Normal air pressure = 760 mm Hg

Pressure on the inside of the lungs and alveoli is almost equal to outside air pressure.

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Respiration

When inside pressure decreases, atmospheric pressure pushes outside air into the airways.Phrenic nerve impulses stimulate the diaphragm to contract.Thoracic cavity enlarges, internal pressure falls, atmospheric pressure forces air into the airways

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Respiration

There is an opposing effect in the alveoli.Surface tension is created by the attraction of water molecules.SurfactantA mixture of lipids and proteinsWhen deeper breath is required, muscles contract more forcefully.

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Expiration

Occurs because of the elastic recoil of tissues as well as surface tension

Diaphragm lowers, compressing the abdomen.

Lungs, thoracic cage, and abdominal organs return to original shapes.

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Expiration

Diaphragm is pushed upward.Surface tension decreases the diameters of the alveoli, increasing alveolar pressure.Air inside the lungs is forced out.Normal resting exhalation is a passive process.

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Respiratory Volumes andCapacities

Total volume of the lungs can be divided into volumes and capacities.Useful for diagnosing problems with ventilationSpirometer A device used to measure air volumes during breathing.

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Respiratory Volumes

Tidal volume – volume of air inspired during a single respiratory cycleInspiratory reserve volume – additional air that enters the lungs during forced inspirationExpiratory volume – additional air that is expelled upon forceful expiration

Residual volume – volume of air remaining in the respiratory passages and lungs after any level of expiration

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Respiratory Capacities

Respiratory capacity – combination of two or more respiratory volumesVital capacity – combination of the inspiratory reserve volume and the expiratory reserve volumeInspiratory capacity – tidal volume plus inspiratory reserve volume

Functional residual capacity

– expiratory reserve volume plus residual volume

Total lung capacity

– vital capacity plus residual volume

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Respiratory Volumes

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Control of Breathing

Respiratory control has both involuntary and voluntary components.Involuntary centers of the brain regulate respiratory muscles.Respiratory minute volume is adjusted in response to sensory information from the lungs, respiratory tract, and a variety of other sites.

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Respiratory Areas of the Brain

Located in the medulla oblongataThe main signal for the body to increase respiration is an increase in CO2 concentration in the blood.Voluntary control of respiration reflects activity in the cerebral cortex.

Affects output of the respiratory center in the medulla oblongata and pons or of motor neurons in the spinal cord

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Respiratory Areas of the Brain

Medullary respiration centerConsists of the dorsal and ventral respiratory groups and the respiratory group of the ponsDorsal respiratory groupImportant in stimulating the muscles of inspiration

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Respiratory Areas of the Brain

Ventral respiratory group

Controls other respiratory muscles

Pontine respiratory group (pons)

May also control the basic rhythm of breathing

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Respiratory Areas of the Brain

Factors that affect breathing rate and depthCertain chemicalsEmotional statesLung stretching capacityLevels of physical activity

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Respiratory Areas of the Brain

Central chemoreceptors in the medulla oblongata sense carbon dioxide and hydrogen ion changes in the CSF.Peripheral chemoreceptors in the carotid bodies and aortic bodies sense changes in blood oxygen levels and increase breathing rate.

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Respiratory Areas of the Brain

Inflation reflexOccurs when stretched lung tissues stimulate stretch receptors in the visceral pleura, bronchioles, and alveoliDuration of inspiratory movements is shortenedEmotional upset usually increases breathing rate.If breathing stops, blood levels of carbon dioxide and hydrogen ions rise and oxygen levels fall.Hyperventilation

Deep, rapid breathing that lowers blood carbon dioxide levels

Prolonged breath holding causes abnormally low blood oxygen levels.

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Gas Exchange

Alveoli carry on exchange of gasses between air and blood.Alveoli – microscopic air sacs clustered around the distal ends of the alveolar ductsEach alveolus consists of a tiny space inside a thin wall.The inner lining of the alveolus is made up of a simple squamous epithelium.

Dense networks of capillaries are found near each alveolus.

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Gas Exchange

Respiratory membraneAt least two thicknesses of epithelial cells and a fused basement membrane layer separating the air in the alveolus from the blood in a capillaryWhere blood and alveolar air exchange gases

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Diffusion

Process by which a gas dissolves in a liquidOccurs from regions of highest pressure toward regions of lower pressureThe pressure of a gas determines how it diffuses from one region to another.Carbon dioxide diffuses from blood into alveolar air.Oxygen diffuses from alveolar air into blood. As long as breathing continues, alveolar partial oxygen pressure stays relatively constant, at 104 mm Hg.

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Diffusion

PaO2 = partial pressure of oxygenPaCO2 = partial pressure of carbon dioxide

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About 98% of oxygen transported by blood binds the iron-containing protein hemoglobin in red blood cells.Remainder dissolves in plasmaIn the lungs, oxygen that dissolves in blood combines rapidly with the iron atoms of hemoglobin to form oxyhemoglobin.

Gas Transport

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Gas Transport

As PaO

2

decreases, oxyhemoglobin molecules release oxygen, diffusing into nearby cells that have depleted their oxygen supplies in cellular respiration.

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Gas Transport

Carbon dioxide levels increase in blood as blood becomes more acidic or blood temperatures rises.Causes more release of oxygenMore oxygen is released to skeletal muscles during physical exercise.Increases carbon dioxide concentrationDecreases pHRaises temperature

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Gas Transport

HypoxiaA deficiency of oxygen reaching the tissuesMay be caused by hypoxemia, anemic hypoxia, inadequate blood flow, or cellular defects

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Gas Transport

Blood transport carbon dioxide to the lungs either as:Carbon dioxide dissolved in plasmaPart of a compound formed by bonding to hemoglobinA bicarbonate ionThe amount of dissolved carbon dioxide in the plasma is determined by its partial pressure.The higher the partial pressure of carbon dioxide in the tissues, the more of it will go into solution.Only about 7% of carbon dioxide transported by the blood is in this form.

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Carbon dioxide differs from oxygen in that it bonds with the amino groups of the “globin” or protein portion of these molecules. Hemoglobin can transport both oxygen and carbon dioxide at the same time.

CarbaminohemoglobinFormed when carbon dioxide loosely bonds with hemoglobinDecomposes readily in regions of low carbon dioxide partial pressureGas Transport

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Gas Transport

Bicarbonate ionsFormed by the most important carbon dioxide transport mechanismCarbon dioxide reacts with water to form carbonic acidCarbonic anhydraseAn enzyme in red blood cells that speeds the reaction of carbon dioxide and waterResults in carbonic acid that releases hydrogen and bicarbonate ionsNearly 70% of carbon dioxide transported by the blood is in this form

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Gas Transport

Carbon dioxide diffuses into the alveoli in response to relatively low partial pressure of carbon dioxide in alveolar air.Hydrogen and bicarbonate ions in red blood cells simultaneously recombine to form carbonic acid.Quickly yields carbon dioxide and water

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Summary

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Ref.

Anatomy, Head and Neck, Nasal Concha: https://www.ncbi.nlm.nih.gov/books/NBK546636/Anatomy and Normal Microbiota of the Respiratory Tract: https://courses.lumenlearning.com/microbiology/chapter/anatomy-and-normal-microbiota-of-the-respiratory-tract/ANS Control of Breathing: https://www.apsubiology.org/anatomy/2020/2020_Exam_Reviews/Exam_3/CH22_ANS_Control_of_Breathing.htmTRANSPORT OF GASES: https://opentextbc.ca/anatomyandphysiology/chapter/22-5-transport-of-gases/