16339 respiratory system

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Copyright 2003 Pearson Education, Inc. publishing as Benjamin Cummings.

RESPIRATORY SYSTEM

PowerPoint Lecture Slide Presentation by Robert J. Sullivan, Marist College

Human Biology


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Basic function The cells of the body need energy for their chemical activity that

maintains homeostasis.

The respiratory system provides the route by which the supply of

oxygen present in the atmospheric air gains entry to the body and itprovides the route of excretion of carbon dioxide.

The condition of the atmospheric air entering the body variesconsiderably according to the external environment, e.g. it may be dry,cold and contain dust particles or it may be moist and hot.

Air breathed in moves through the air passages to reach the lungs, it iswarmed or cooled to body temperature, moistened to becomesaturated with water vapour and 'cleaned' as particles of dust stick tothe mucus which coats the lining membrane.

Blood provides the transport system for these gases between the lungsand the cells of the body.


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Types & Parts (Organs) Exchange of gases between the blood and the lungs is called external

respiration

Exchange of gases between the blood and the cells internal respiration.

ORGANS OF RESPIRATORY SYSTEM

Nose

Pharynx

Larynx

Trachea Two bronchi (one bronchus to each lung)

Bronchioles and smaller air passages

Two lungs and their coverings, the pleura

Muscles of respiration the intercostal muscles and the diaphragm


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Human Respiratory System

Figure 10.1


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Components of the UpperRespiratory Tract

Figure 10.2


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Passageway for respiration

Receptors for smell

Filters incoming air to filter larger foreign

material Moistens and warms incoming air

Resonating chambers for voice

Upper Respiratory Tract Functions


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Nose

The nasal cavity is the first of the respiratory organs and consists of a large irregularcavity divided into two equal passages by a septum.

The posterior bony part of the septum is formed by the perpendicular plate of theethmoid bone and the vomer.

Lining of the nose

The nose is lined with very vascular ciliated columnar epithelium (ciliated mucousmembrane) which containsmucus-secreting goblet cells


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Respiratory function of the nose

The nose is the first of the respiratory passages through which theinspired air passes. The function of the nose is to begin the process bywhich the air is warmed, moistened and 'filtered'.

The projecting conchae increase the surface area and causeturbulence, spreading inspired air over the whole nasal surface.

The large surface area maximises warming, humidification and filtering.

Olfactory function of the nose

The nose is the organ of the sense of smell. There are nerve endings

that detect smell, located in the roof of the Nose

The nerve ending stimulated by chemical substances given off byodorous materials. The resultant nerve impulses are conveyed by theolfactory nerves to the brain where the sensation ofsmell is perceived


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Pathway from nose to laryngopharyx


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Pharynx The pharynx is a tube 12 to 14 cm long that extends from the base of the

skull to the level of the 6th cervical vertebra.

It lies behind the nose, mouth and larynx and is wider at its upper end

The nasopharynx, oropharynx & laryngopharynx. Mucous membrane lining (Ciliated Columunar Epithelial)

Fibrous tissue.

Muscle tissue.

Functions

Warming and humidifying Taste (olfactory nerve endings of the sense of taste)

Hearing (auditory tube allows air to enter the middle ear)

Protection (tonsils produces antibodies in response to antigens)

Speech (resonating chamber for the sound)


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Components of the Lower

Respiratory Tract

Figure 10.3


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Functions:

Larynx: maintains an open airway, routes food

and air appropriately, assists in sound production

Trachea: transports air to and from lungs

Bronchi: branch into lungs

Lungs: transport air to alveoli for gas exchange

Lower Respiratory Tract


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LARYNX The larynx or 'voice box' extends from the

root of the tongue and the hyoid bone tothe trachea.

Adams apple in male growth of larynx

The larynx is composed of severalirregularly shaped cartilages attached toeach other by ligaments and membranes.

1 thyroid cartilage

1 cricoid cartilage 2 arytenoid cartilages

1 epiglottis

Ligaments and membranes

FUNCTION: SOUND & SPEECH


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TRACHEA The trachea or windpipe is a continuation of the larynx and extends

downwards to about the level of the 5th thoracic vertebra

The trachea is composed of from 16 to 20 incomplete (C-shaped) ringsof hyaline cartilages lying one above the other.

The cartilages are incomplete posteriorly.

Connective tissue and involuntary muscle join the cartilages and formthe posterior wall where they are incomplete.

The soft tissue posterior wall is in contact with the oesophagus

FUNCTIONS

Support and patency

Mucociliary escalator.

Cough reflex.

Cough reflex.


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BRONCHI AND SMALLER AIR PASSAGES

They are lined with ciliated columnar epithelium.

The bronchi progressively subdivide into

bronchioles,

terminal bronchioles,

respiratory bronchioles,

alveolar ducts

alveoli.

In the absence of cartilage the smooth muscle in the walls of the bronchioles becomesthicker and is responsive to autonomic nerve stimulation and irritation. Ciliated columnarmucous membrane changes gradually to non-ciliated cuboidal shaped cells in the distalbronchioles.

FUNCTION: Control of air entry. The diameter of the respiratory passages maybe altered by contraction or relaxation of the involuntary muscles in their walls,thus regulating the volume of air entering the lungs.

These changes are controlled by the autonomic nerve supply: parasympatheticstimulation causes constriction and sympathetic stimulation causes dilatation


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LUNGS There are two lungs, one lying on each side of the midline in the

thoracic cavity. They are cone-shaped and are described as having anapex, a base, costal surface and medial surface.

The right lung is divided into three distinct lobes: superior, middle andinferior.

The left lung is smaller as the heart is situated left ofthe midline. It isdivided into only two lobes: superior and inferior.

The pleura consists of a closed sac of serous membrane which containsa small amount of serous fluid. The lung is invaginated into this sac so

that it forms two layers: one adheres to the lung and the other to thewall of the thoracic cavity

The lungs are composed of the bronchi and smaller air passages,alveoli, connective tissue, blood vessels, lymph vessels and nerves.


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Gas exchange by blood supply The pulmonary artery divides into two, one branch

conveying deoxygenated blood to each lung. Within

the lungs each pulmonary artery divides into manybranches which eventually end in a dense capillarynetwork around the walls of the alveoli.

The walls of the alveoli and those of the capillarieseach consist of only one layer of flattened epithelialcells. The exchange of gases between air in thealveoli and blood in the capillaries takes place acrossthese two very fine membranes.


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Gas Exchange Between the Bloodand Alveoli

Figure 10.8A


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RESPIRATION Inflation and deflation of the lungs occurring with each breath ensures

that regular exchange of gases takes place between the alveoli and theexternal air.

The expansion of the chest during inspiration occurs as a result ofmuscular activity, partly voluntary and partly involuntary. The mainmuscles of respiration in normal quiet breathing are the intercostalmuscles and the diaphragm.

Cycle of respiration

This occurs 12 to 15 times per minute and consists of three phases:

inspiration expiration

pause.


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Respiratory Cycle

Figure 10.9


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Inspiration/Expiration: air in/air out

Cycle:

Relaxed state: diaphragm and intercostal musclesrelaxed

Inspiration: diaphragm contracts, pulling muscle down,intercostal muscles contract elevating chest wall and

expanding volume of chest, lowering pressure inlungs, pulling in air

Expiration: muscles relax, diaphragm resumes domeshape, intercostal muscles allow chest to lower

resulting in increase of pressure in chest and expulsionof air

Process of Breathing: PressureGradient


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Lung volumes and vital capacity Tidal volume: volume of air inhaled and

exhaled in a single breath Dead space volume: the air that remains in the

airways and does not participate in gasexchange

Vital capacity: the maximal volume that can beexhaled after maximal inhalation

Inspiratory reserve volume: the amount of airthat can be inhaled beyond the tidal volume

Measurement of Lung Function


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Measurement of Lung Capacity

Figure 10.10A


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Lung volumes and vital capacity (continued)

Expiratory reserve volume: the amount of airthat can be forcibly exhaled beyond the tidalvolume

Residual volume: the amount of air

remaining in the lungs, even after a forcefulmaximal expiration

Measurement: spirometer

Measurement of Lung Function(cont.)


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Transport of gases in blood


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Gases diffuse according to their partialpressures

External respiration: gases exchanged between airand blood

Internal respiration: gases exchanged with tissuefluids

Oxygen transport: bound to hemoglobin in redblood cells or dissolved in blood plasma

Carbon dioxide transport: dissolved in blood

plasma, bound to hemoglobin, or in the form oflasma bicarbonate

Gas Exchange & Transport:A Passive Process


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Carotid and aortic bodies: sensitive tocarbon dioxide, pH, and oxygen levels

Conscious control: resides in higher brain

centers; ability to modify breath is limited

Regulation of Breathing:Nervous System Involvement


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Respiratory center in the medulla oblongata:

establishes basic breathing pattern Chemical receptors: monitor carbon dioxide,

hydrogen ions, and oxygen levels

Medulla: sensitive to hydrogen ions incerebrospinal fluid resulting from carbondioxide in blood

Regulation of Breathing:Nervous System Involvement


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Breathing (ventilation): air in to and out oflungs

External respiration: gas exchangebetween air and blood

Internal respiration: gas exchangebetween blood and tissues

Cellular respiration: oxygen use to produceATP, carbon dioxide as waste

Four Respiration Processes

16339 respiratory system

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