Transcript Memmler`s The Human Body in Health and Disease

Memmler’s
The Human Body in Health and Disease
11th edition
Chapter 18
The Respiratory System
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Respiratory System Functions
• Supplies cells with oxygen
• Rids the body of carbon dioxide
• Also brings odorants to the nose
• Vibrates vocal cords for speech
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Phases of Respiration
Process of obtaining oxygen
from environment and
delivering it to cells
• Pulmonary ventilation
• External exchange of gases
• Internal exchange of gases
Overview of respiration. In ventilation, gases are moved into and out of the lungs.
In external exchange, gases move between the air sacs (alveoli) of the lungs and
the blood. In internal exchange, gases move between the blood and body cells.
The circulation transports gases in the blood.
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Respiratory System Structure
• Airways: passages through which air travels to the
lung
• Lungs: organ that absorbs oxygen and passes carbon
dioxide from blood into air
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Structures of the Respiratory Tract
Conducts air into lungs
• Nasal cavities
• Pharynx
• Larynx
• Trachea (windpipe)
The Conducting Zone Lining
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The Nasal Cavities
• Nostrils (nares)
• Nasal cavities
– Mucous membrane
• Filters foreign bodies
• Warms air
• Moistens air
– Conchae
• Nasal septum
• Sinuses
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The Pharynx
Throat (pharynx) carries air to respiratory tract and food
to digestive system
• Nasopharynx
– Superior portion
• Oropharynx
– Middle portion
• Laryngeal pharynx
– Inferior portion
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The Larynx
Larynx (voice box) is located
between the pharynx and
trachea
• Cartilage framework
– Thyroid cartilage
(Adam’s apple)
• Vocal folds (vocal cords)
– Used for speech
• Glottis
• Epiglottis
The Trachea
Trachea (wind pipe) conducts
air between larynx and
lungs
• Framework of separate
cartilages
• Horseshoe shaped
• Open at back for expansion
during swallowing
The Larynx and Trachea
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The Bronchi
• Trachea divides into two primary bronchi that enter
the lungs
• Hilum
• Epithelial tissue lining
– Pseudostratified
– Cilia
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The Lungs
• Mediastinum
• Lobes
–
Bronchial tree
–
Bronchioles
• Alveoli
• Diaphragm
• Pleura
–
Parietal pleura
–
Visceral pleura
–
Pleural space
Remember This!
• Gas exchange occurs in the respiratory zone—
the alveolar ducts and alveoli.
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Structures of the Lungs
Lung Structure
Lungs are divided into
lobes
Supply
Lobar bronchus
branching from main
bronchus
Lobes are divided into 2-5
Segmental bronchus
segments
Segments are divided into
Bronchiole
lobules
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The Lungs
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The Respiratory System
The respiratory
system.
(A) Overview.
(B) Enlarged section
of lung tissue showing
the relationship
between the alveoli
(air sacs) of the lungs
and the blood
capillaries.
(C) A transverse
section through the
lungs.
Zooming In:
What organ is located
in the medial
depression of the left
lung?
The Process of Respiration
• Ventilation of lungs
• Exchange of gases
• Transport of gases in blood
Pulmonary Ventilation
• Inhalation (inspiration) is active phase
• Compliance
• Exhalation (expiration) is passive phase
• Lung capacity
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Pulmonary
ventilation.
(A)Inhalation.
(B)Exhalation.
Zooming In:
What muscles
are located
between the
ribs?
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Gas Exchange
• Diffusion is movement of molecules from higher to
lower concentration
• External exchange
– Gases move between alveoli and capillary blood
• Internal exchange
– Gases move between blood and tissues
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Gas exchange. (A) External exchange between the alveoli and the blood. Oxygen
diffuses into the blood and carbon dioxide diffuses out, based on concentrations of the
two gases in the alveoli and in the blood. (B) Internal exchange between the blood
and the cells. Oxygen diffuses out of the blood and into tissues, while carbon dioxide
diffuses from the cells into the blood.
Transport of Oxygen
• Most oxygen in capillary blood binds to hemoglobin
• Oxygen must separate from hemoglobin to enter cells
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Transport of Carbon Dioxide
• 10% is dissolved in plasma and fluid in red blood cells
• 15% is combined with protein of hemoglobin and plasma
proteins
• 75% dissolves in blood fluids and is converted to
bicarbonate ion
– First combines with water to form carbonic acid
– Carbonic acid ionizes (separates) into hydrogen and
bicarbonate ions
– Carbonic anhydrase enzyme speeds conversion
– Buffers blood to keep pH steady
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Respiratory Cycle
• Respiratory cycle: sequence of pressure and volume
changes during a single breath
– Intrapulmonary pressure: pressure in the
airway and alveoli
– At rest, matches atmospheric pressure
– During inspiration, increased lung volume reduces
pressure
– During exhalation, reduced volume raises pressure
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Physical Factors That Affect Respiration
• Rate at which lungs fill and empty is affected by the
ability of the
– Diaphragm and muscles of torso to alter the
volume of the chest cavity
– Bony thorax and spine to move
– Lungs to respond to musculoskeletal forces
– Airways to accommodate air flow
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Compliance and Elastance
• Compliance: ease with which the lungs can be
distended to accommodate increased volume
• Elastance: ability of the lungs to return to their
original dimension at the transition point
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Volume Changes and Air Flow
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Volume Changes and Air Flow
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Regulation of Respiration
Fundamental respiratory pattern
• Controlled by central nervous system centers
– Partly in medulla (main control center), partly in
pons (modifies patterns set in the medulla)
• Modified by receptors detecting changes in blood
chemistry
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Nervous Control
• Control center is located in medulla and pons of brain
stem
• Motor nerve fibers extend into spinal cord
• Fibers extend through phrenic nerve to diaphragm
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Spirometer Measurements
• Capacity: a combination of two or more volumes
• Functional residual capacity: volume of air in lungs
at the transition point
• Tidal volume: amount of air moved in and out during
quiet breathing
• Vital capacity: total amount of air that can be moved
in one breath with maximum inhalation and exhalation
• Total lung capacity: entire volume of air the lungs
can hold
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Gas Partial Pressures in Liquids
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External Gas Exchange
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Gas Transport
• CO2 + H2O  H2CO3  H+ + HCO3–
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Oxygen Transport and Gas Exchange
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Carbon Dioxide Transport
• Three ways that carbon dioxide is carried in blood are
– As a gas dissolved in plasma (about 10%) or
attached to hemoglobin (about 10%)
– As highly soluble chemical, bicarbonate (about
80%)
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Carbon Dioxide Transport (cont’d)
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Chemical Control
• Central chemoreceptors
– Located near medullary respiratory center
– Respond to raised CO2 level (hypercapnia)
• Peripheral chemoreceptors
– Located in neck and aortic arch
– Respond to oxygen level considerably below
normal
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Abnormal Ventilation
• Hyperventilation
– High oxygen level and low CO2 level (hypocapnia)
– Increases blood pH
• Hypoventilation
– Insufficient air in alveoli
– Decreases blood pH
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Breathing Patterns
• Measured in breaths per minute
• Adults: 12 to 20
• Children: 20 to 40
• Infants: more than 40
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Some Terms for Altered Breathing
• Hyperpnea
• Hypopnea
• Tachypnea
• Apnea
• Dyspnea
• Orthopnea
• Kussmaul respiration
• Cheyne-Stokes respiration
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Results of Inadequate Breathing
• Cyanosis
• Hypoxia
• Hypoxemia
• Suffocation
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Disorders of the Respiratory System
• Infection
• Allergies
• Environmental factors
• Lung cancer
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Disorders of the Nasal Cavities and
Related Structures
• Paranasal sinuses
– Sinusitis
– Polyps
• Nasal septum
– Deviated septum
• Mucous membranes
– Epistaxis
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Infection
• Upper respiratory infection (URI)
• Common cold (acute coryza)
• Respiratory syncytial virus (RSV)
• Croup
• Influenza
• Pneumonia
–
Bronchopneumonia
–
Lobar pneumonia
–
Pneumocystis pneumonia (PCP)
• Tuberculosis
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Hay Fever and Asthma
Hypersensitivity to allergens
• Watery discharge from eyes and nose
• Seasonal or chronic
• Inflammation of airway tissues
• Spasm in bronchial tubes
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Chronic Obstructive Pulmonary
Disease (COPD)
Also called chronic obstructive lung disease (COLD)
• Includes both chronic bronchitis and emphysema
• Normal air flow obstructed
• Reduced exchange of oxygen and carbon dioxide
• Air trapping and overinflation of lungs
• Dyspnea
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Sudden Infant Death Syndrome (SIDS)
Also called crib death
• Unexplained death
• Seemingly healthy infant
• Under 1 year old
• Usually occurs in sleep
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Respiratory Distress Syndrome (RDS)
Covers a range of inflammatory disorders
• Acute respiratory distress syndrome (ARDS) or shock
lung
– Usually appears in adults
• Respiratory distress syndrome of the newborn
– Formerly called hyaline membrane disease
– Appears in premature newborns
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Cancer
• Lung cancer
– Most common cause of cancer-related deaths
– Most important cause is cigarette smoking
• Cancer of larynx
– Linked to cigarette smoking and alcohol
consumption
– High cure rate
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Disorders Involving the Pleura
• Pleurisy
– Inflammation of pleura
• Pneumothorax
– Air in pleural space
• Hemothorax
– Blood in pleural space
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The Lungs
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Age and the Respiratory Tract
• Tissues lose elasticity, become more rigid
• Decreased compliance, lung capacity
• Increased susceptibility to infection
• Increased incidence of emphysema
• Reduced capacity for exercise
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Special Equipment for Respiratory
Treatment
• Bronchoscope
• Oxygen therapy
• Suction apparatus
• Tracheostomy tube
• Artificial respiration apparatuses
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End of Presentation
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