CHAPTER
24
The Respiratory
System
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Learning Outcomes
24.1 Explain the functions of the respiratory system.
24.2 Explain the difference between internal respiration and external respiration.
24.3 Describe how the larynx produces voice sounds.
24.4 List the structures contained within the lungs.
24.5 Describe the coverings of the lungs and chest cavity.
24-2
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Learning Outcomes (cont.)
24.6 Describe the events that lead to the inspiration and expiration of air.
24.7 Explain how the brain controls breathing and how normal breathing patterns can be disrupted.
24.8 Describe how oxygen is transported from the lungs to body cells.
24-3
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Learning Outcomes (cont.)
24.9 Describe how carbon dioxide is transported from body cells to the lungs.
24.10List and explain various respiratory volumes and tell how they are used to diagnose respiratory problems.
24.11Describe the causes, signs and symptoms, and treatments of various diseases and disorders of the respiratory system.
24-4
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Introduction
• Function
– Move air in and out of lungs ( ventilation )
– Delivers oxygen (O
2
)
– Removes carbon dioxide (CO
2
)
• External respiration
– Occurs in the lungs
O
2
Lungs
CO
2
• Internal respiration
– Occurs in the hemoglobin
O
2
CO
2
CO
2
O
2
24-5
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24-6
Organs of the Respiratory System
 Nose
 Pharynx
 Larynx
 Trachea
 Bronchial tree
 Lungs
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Nasal Cavity
• Nasal septum divides the cavity into right and left portions
– Nares – openings of the nose
• Nasal conchae extend from walls of nasal cavity
• Mucous membrane warms and moistens the air
• Cilia help eliminate particles
24-7
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Paranasal Sinuses
• Air-filled spaces within the skull bones
– Open into the nasal cavity
• Give the voice its certain tone
• Reduce the weight of the skull
• Equalize pressure
• Skull bones with sinuses include:
– Frontal
– Sphenoid
– Ethmoid
– Maxillae bones
24-8
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24-9
Pharynx and Larynx
• Pharynx
– Serves both the respiratory and digestive systems
• Larynx
– Also called the “voice box”
– Moves air in and out of the trachea and produces voice
– Composed of three cartilages:
• Thyroid cartilage
• Epiglottic cartilage
• Cricoid cartilage
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24-10
Vocal Cords
• Stretched between the thyroid cartilage and the cricoid cartilage
• Upper – false cords
Posterior
Portion of
Tongue
• Lower – true vocal cords
• Glottis – the opening between the vocal cords
Glottis
• Stretch = pitch of voice
False
Vocal
Cords
True
Vocal
Cords
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Trachea
• Referred to as the windpipe
• Tubular organ made of rings of cartilage and smooth muscle
• Extends from the larynx to the bronchi
• Lined with cells possessing cilia
(microscopic hair-like projections)
Cilia move mucus up to the throat, where it is swallowed. Smoking destroys cilia.
Trachea
24-11
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Bronchial Tree
•
– Primary: First branches off trachea
– Secondary
– Tertiary
•
– Branch off tertiary bronchi
Bronchi
24-12
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24-13
Bronchial Tree (cont.)
•
– Thin sacs of cells surrounded by capillaries
– Secrete surfactant
• Fatty substance
• Helps maintains the inflation of the alveoli between inspirations
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Lungs
• Cone-shaped organs
• Right lung – three lobes
• Left lung – two lobes
membranes surrounding the lungs
The lungs contain connective tissue, the bronchial tree, nerves, lymphatic vessels, and blood vessels.
24-14
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Apply Your Knowledge
Which of the following sites would be the most lethal if obstructed by a foreign body?
ANSWER: a. Right bronchus b. Left bronchus c. Trachea
24-15
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The Mechanisms of Breathing
Inspiration
 Air rich in O
2 enters the lungs from the atmosphere
 The diaphragm contracts or flattens
 The intercostal muscles raise the ribs
Expiration
 Air rich in C0
2 exits the lungs
 The diaphragm relaxes
 The intercostal muscles lower the ribs
Breathing, or pulmonary ventilation , consists of inspiration
(inhalation) and expiration (exhalation).
24-16
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The Mechanisms of Breathing (cont.)
• Respiratory center of the brain
– Medulla oblongata – controls rhythm and depth of breathing
– Pons – controls the rate of breathing
• Other factors
– CO
2 levels in the blood
– pH of the blood
– Fear and pain
– Inflation reflex
24-17
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The Mechanisms of Breathing (cont.)
– Coughing
– Sneezing
– Laughing
– Crying
– Hiccups
– Yawning
– Speaking
24-18
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Apply Your Knowledge
Indicated whether each statement refers to (I) inhalation or (E) exhalation:
ANSWER:
24-19
I
2 enters the lungs from the atmosphere
E
2 exits the lungs
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The Transport of Oxygen and Carbon Dioxide in the Blood
24-20
• Most of the oxygen binds to hemoglobin
– Oxyhemoglobin
– Bright red in color
• Some oxygen remains dissolved in plasma
• If CO
2 combines with hemoglobin at O sites, it forms carboxyhemoglobin
2
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The Transport of Oxygen and Carbon Dioxide in the Blood
(cont.)
24-21
• Carbon dioxide gets into the bloodstream
– Reacts with water in plasma and forms carbonic acid
– Carbonic acid ionizes and releases hydrogen and bicarbonate ions
– Bicarbonate ions attach to hemoglobin
• Exhaled as waste product in the lungs
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Apply Your Knowledge
Describe what happens to carbon dioxide in the blood.
ANSWER: Carbon dioxide can combine with hemoglobin and form carboxyhemoglobin. Most reacts with water in plasma to form carbonic acid. The carbonic acid ionizes and releases hydrogen and bicarbonate ions. The bicarbonate ions then attach to hemoglobin and are exhaled as a waste product from the lungs.
24-22
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24-23
Respiratory Volumes
• Different volumes of air move in and out of lungs with different intensities of breathing
• Measured to assess health of respiratory system
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Respiratory Volumes (cont.)
Tidal Volume
Amount of air that moves in or out of the lungs during a normal breath
24-24
Inspiratory
Reserve
Volume
Expiratory
Reserve
Volume
Amount of air that can be forcefully inhaled following a normal inhalation
Amount of air that can be forcefully exhaled following a normal exhalation
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Respiratory Volumes (cont.)
Residual
Volume
Volume of air that always remains in the lungs even after a forceful exhalation
Vital
Capacity
Amount of air that can be forcefully exhaled after the deepest inhalation possible
24-25
Total Lung
Capacity
The total amount of air the lungs can hold
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Apply Your Knowledge
Match the following: ANSWER: a normal breath remains in the lungs can hold after deepest inhalation possible
A. Total lung capacity
B. Residual volume
C. Tidal volume
D. Vital capacity
24-26
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Snoring
•
•
•
Due to vibration of soft tissues when muscles of the palate, tongue, and throat relax
Affects approximately
50% of men and 25% of women over the age of
40
Causes daytime sleepiness
– May be associated with obstructive sleep apnea
• Common Causes
– Enlargement of tonsils or adenoids
– Being overweight
– Alcohol consumption
– Nasal congestion
– Deviated nasal septum
24-27
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Snoring (cont.)
Mayo Clinic’s Sleep Disorders Center rating of snoring:
24-28
Heard from close proximity
Heard from anywhere in the bedroom
Heard from just outside the bedroom door with door open
Heard outside the bedroom door with the door closed
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Snoring (cont.)
• Lifestyle modifications to reduce snoring
– Lose weight
– Change sleeping position
– Avoid using alcohol or medications that induce sleep
– Use nasal strips to widen the nasal passages
– Use dental devices to keep airways open
• Treatments
– CPAP
– Surgery ( uvulotomy )
– Laser surgery
24-29
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Common Diseases and Disorders
Disease Description
Allergic rhinitis
Hypersensitivity reaction to various airborne allergens
Asthma A condition in which the tubes of the bronchial tree become obstructed due to inflammation
Atelectasis Collapsed lung
Bronchitis Inflammation of the bronchi often follows a cold; one type of COPD
24-30
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Common Diseases and Disorders (cont.)
Disease
Chronic obstructive pulmonary disease (COPD)
Emphysema
Influenza
Description
A group of lung disorders that limit airflow to lungs and usually cause enlargement of the alveoli
A chronic condition associated with smoking that damages the alveoli; one type of COPD
A viral disease that attacks the respiratory system; commonly called the flu
24-31
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Common Diseases and Disorders (cont.)
Disease Description
Laryngitis
Legionnaire’s disease
An acute inflammation of the larynx causing hoarseness (dysphonia)
Acute bacterial pneumonia caused by
Legionnaire bacteria that usually grows in the standing water of air conditioning systems
Lung cancer Cancer closely associated with smoking and exposure to second-hand smoke; four types of lung cancers
Pleural effusion A buildup of fluid in the pleural cavity
24-32
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Common Diseases and Disorders (cont.)
Disease Description
Pleuritis / Pleurisy Inflammation of the membranes that cover the lungs, known as pleura
Pneumoconiosis Lung diseases that result from years environmental or occupational exposure to different types of dust; three types
Pneumonia/
Pneumonitis
An inflammation of the lungs that is most often caused by a bacterial, viral, or fungal infection
24-33
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Common Diseases and Disorders (cont.)
Disease Description
Pneumothorax A collection of air in the chest around the lungs, which may cause atelectasis
Pulmonary edema
Pulmonary embolism
A condition in which fluids fill spaces within the lungs, making it very difficult for the lungs to oxygenate the blood
A blood clot (embolism) that travels usually from the legs and blocks an artery in the lungs
24-34
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Common Diseases and Disorders (cont.)
Disease
Respiratory distress syndrome (RDS)
Severe acute respiratory syndrome
(SARS)
Sinusitis
Description
Syndrome in which a lack of surfactant in the lungs allows the alveoli to collapse on exhalation, resulting in poor oxygenation
A viral respiratory disease that is very contagious and sometimes fatal
An inflammation of the membranes lining the sinuses of the skull
24-35
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Common Diseases and Disorders (cont.)
Disease Description
Sudden infant death syndrome
(SIDS)
Tuberculosis
A syndrome without characteristic signs or symptoms; usually a baby with this disorder simply goes to sleep and never wakes up
Primarily a respiratory disease caused by various strains of the bacterium
Mycobacterium tuberculosis
Upper respiratory
(tract) infection
(URI)
Coryza , or the common cold
24-36
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Apply Your Knowledge
The medical assistant working for a general practitioner is taking the medical history of a new patient. The patient states, “Even after sleeping 8 to 9 hours, I still feel really tired.” The patient’s spouse states, “Well, you sure snore loud, as if the sleep is so good.” Which of the following is a possible cause for the excessive fatigue?
ANSWER: a. Sleep apnea b. Depression c. Tuberculosis
24-37
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In Summary
24.1 The function of the respiratory system is to move air in and out of the lungs in a process known as ventilation, respiration, or breathing.
24.2 The exchange of oxygen and carbon dioxide in the lungs is called external respiration. The same exchange within the hemoglobin of red blood cells is internal respiration.
24.3 The larynx contains the vocal cords, which stretch between the thyroid and cricoid cartilages. The muscles of the lower (true) vocal cords stretch and relax them to produce different sounds.
24-38
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In Summary (cont.)
24.4 The lungs contain connective tissue, the bronchial tree, nerves, lymphatic vessels, and blood vessels.
The left lung consists of two lobes (upper and lower), and the right lung consists of three lobes (upper, middle, and lower).
Within each lung are the primary, secondary, and tertiary branches of the bronchi, the bronchioles, and the alveoli.
24.5 The lungs are covered by, and the chest cavity is lined with, the pleura. The outer membrane is the parietal pleura and the inner membrane is the visceral pleura.
24-39
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In Summary (cont.)
24.6 During inspiration, the diaphragm contracts and the intercostal muscles raise the ribs, increasing the space in the thoracic cavity.
This decreases the pressure within the cavity so that the air outside the body passively flows into the thoracic cavity.
During expiration, the diaphragm relaxes, pushing up into the thoracic cavity, and the intercostal muscles lower the ribs, forcing the air to flow out of the body.
24-40
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In Summary (cont.)
24.7 Breathing is controlled by the respiratory center of the brain located in the pons and medulla oblongata.
Carbon dioxide levels and pH levels of the blood also affect breathing. Everyday situations such as coughing, sneezing, laughing, crying, hiccups, yawning, and speaking also alter breathing patterns.
24.8 Most of the oxygen in the bloodstream binds to the hemoglobin within red blood cells, resulting in oxyhemoglobin, although a small amount does not bind to hemoglobin and remains dissolved in the plasma.
24-41
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In Summary (cont.)
24.9 Carbon dioxide binds to hemoglobin, resulting in carboxyhemoglobin.
Most of the carbon dioxide that enters the body reacts with water in blood and cerebral spinal fluid to form carbonic acid.
As carbonic acid ionizes, it releases hydrogen and bicarbonate ions, which attach to hemoglobin making its way back to the lungs to be exhaled.
24-42
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In Summary (cont.)
24.10 Respiratory volumes are measured to check the health of the respiratory system.
The volumes are listed here and the normal capacities are found in the chapter: tidal volume, inspiratory and expiratory reserve volumes, residual volume, inspiratory capacity, functional residual capacity, vital capacity, and total lung capacity.
24-43
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In Summary (cont.)
24.11 The diseases and disorders of the respiratory system are many and varied, as are the causes and treatments of these diseases. Many of the more common respiratory disorders, with their individual causes and treatments, are discussed in detail in the
Pathophysiology section of this chapter.
24-44
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End of Chapter 24
~Edith Wharton
24-45
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