Mader 9e

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Outline

• Gas Exchange Surfaces
• Water Environments
• Gills
• Land Environments
• Lungs
• Human Respiratory System
• Inspiration versus Expiration
• Respiration and Health
• Respiratory Disorders

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Gas Exchange Surfaces

• Respiration
• The events associated with gas exchange between
  the cells and the external environment
• Consists of
• Ventilation
• External Respiration
• Internal Respiration

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Gas Exchange Surfaces

• For diffusion to be effective, gas-exchange
  regions must be
• Moist
• Thin
• Relatively large
• Effectiveness of diffusion is enhanced by
  vascularization
• Delivery to cells is promoted by respiratory
  pigments (like hemoglobin)

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Water Environments

• Gasses of air can dissolve in water
• However
• When saturated, water contains small fraction of
  the O2 in same volume of air, and
• Water is much more viscous than air
• Aquatic animals expend more energy to breathe
  than do terrestrial animals

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Gas Exchange

• Hydras and planarians
• Small animals with large surface area
• Most of their cells exchange gases directly with
  the environment
• Larger aquatic animals
• Often have gills
• Finely divided vascularized outgrowths of inner
  body surface
• Gills of bony fishes
• Outward extensions of pharynx
• Ventilation is brought about by combined action
  of the mouth and gill covers (operculum)
• Countercurrent Exchange

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Animal Shapes and Gas Exchange
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Anatomy of Gills in Bony Fishes
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Land EnvironmentsTracheae

• Insects and other terrestrial arthropods
• A respiratory system consists of branched
  tracheae
• Oxygen enters tracheae at spiracles
• Tracheae branch until end in tracheoles that are
  in direct contact with body cells

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Tracheae of Insects
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Land EnvironmentsLungs of Vertebrates

• Terrestrial vertebrates have evolved lungs
• Vascular outgrowths from lower pharyngeal region
• Lungs of amphibians
• Possess a short tracheae which divides into two
  bronchi that open into lungs
• Many also breathe to some extent through skin
• Reptiles
• Inner lining of lungs is more finely divided in
  reptiles than in amphibians
• Lungs of birds and mammals are elaborately
  subdivided
• All terrestrial vertebrates, except birds, use a
  tidal ventilation system
• Air moves in and out by the same route

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Ventilation in Frogs
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Ventilation inTerrestrial Vertebrates

• Inspiration in mammals
• Create negative pressure in lungs
• The rib cage is elevated
• The diaphragm lowers
• Thoracic pressure decreases to less than
  atmospheric pressure
• Atmospheric pressure forces air into the lungs
• Expiration in mammals
• Create positive pressure in lungs
• The rib cage is lowered
• The diaphragm rises
• Thoracic pressure increases to more than
  atmospheric pressure
• Forces air out the lungs

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Lungs

• Birds use a one-way ventilation mechanism in
  lungs
• Results in a higher partial pressure of oxygen in
  the lungs
• Oxygen uptake with each breath is greater than in
  other vertebrates

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Respiratory System in Birds
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Human Respiratory System

• As air moves through upper respiratory system
• It is filtered to free it of debris
• Warmed, and
• Humidified
• When air reaches lungs
• It is at body temperature, and
• Its humidity is 100

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The Human Respiratory Tract
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Human Respiratory System

• Air passes from pharynx through glottis
• Larynx and trachea
• Permanently held open by cartilage rings
• Facilitates movement of air
• When food is swallowed
• The larynx rises, and
• The glottis is closed by the epiglottis
• Backward movement of soft palate covers the
  entrance of nasal passages into the pharynx

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Human Respiratory System

• Trachea divides
• Forms two primary bronchi
• Bronchi enter the right and left lungs
• Bronchi branch until there are a great number of
  tiny bronchioles
• Each bronchiole terminates in an elongated space
  enclosed by alveoli

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Ventilation

• Humans breathe using a tidal mechanism
• Volume of thoracic cavity and lungs is increased
  by muscle contractions that lower the diaphragm
  and raise the ribs
• Create negative pressure in the thoracic cavity
  and lungs, and then air flows into the lungs
  during inspiration

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Inspiration Versus Expiration
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External and Internal respiration
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Hemoglobin
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Gas Exchange and Transport

• Breathing stimulus
• Increased H and CO2 concentrations in the blood
• Not affected by O2 levels
• Oxygen diffuses into pulmonary capillaries
• Most combines with hemoglobin in red blood cells
  to form oxyhemoglobin
• CO2 diffuses out of pulmonary capillaries
• Most carbon dioxide is transported in the form of
  bicarbonate ion
• Some carbon dioxide combines with hemoglobin to
  form carbaminohemoglobin

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Hemoglobin Saturationin Relation to Temperature
and Acidity
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Respiration and Health

• Upper Respiratory Tract Infections
• Strep Throat
• Streptococcus pyogenes
• Sinusitis
• Infection of sinuses
• Tonsillitis
• Infection of tonsils
• Laryngitis
• Infection of larynx

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CommonBronchial and Pulmonary Diseases
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Respiration and Health

• Lower Respiratory Tract Infections
• Acute bronchitis
• Infection of primary and secondary bronchi
• Pneumonia
• Viral or bacterial infection of the lungs where
  bronchi and alveoli fill with fluid
• Pulmonary tuberculosis
• Caused by tubercle bacillus

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Disorders

• Pulmonary fibrosis
• Fibrous connective tissue builds up in the lungs
• Chronic bronchitis
• Airways inflamed and filled with mucus
• Emphysema
• Alveoli are distended and walls are damaged
  reducing surface area available for gas exchange

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Disorders

• Asthma
• Airways are unusually sensitive to specific
  irritants
• When exposed to the irritants, the smooth muscles
  in the bronchioles undergo spasms
• Lung Cancer
• Begins with thickening and callusing of the cells
  lining the airways

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Review

• Gas Exchange Surfaces
• Water Environments
• Gills
• Land Environments
• Lungs
• Human Respiratory System
• Inspiration versus Expiration
• Respiration and Health
• Respiratory Disorders

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