Anatomy

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Anatomy PhysiologyBio 2402 Lecture

• Instructor Daryl Beatty
• Chapter 22
• Respiratory System

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Functions of the Respiratory System

• Exchange of oxygen and carbon dioxide
• Voice production
• Regulation of plasma pH
• Olfactory
• Infection prevention

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Respiratory System

• Consists of the respiratory and conducting zones
• Respiratory zone
• Site of gas exchange
• Consists of bronchioles, alveolar ducts, and
  alveoli

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Respiratory System

• Conducting zone
• Conduits for air to reach the sites of gas
  exchange
• Includes all other respiratory structures (e.g.,
  nose, nasal cavity, pharynx, trachea)
• Respiratory muscles diaphragm and other muscles
  that promote ventilation

PLAY
InterActive Physiology Anatomy Review
Respiratory Structures, page 3
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Respiratory System
Figure 22.1
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Major Functions of the Respiratory System

• Respiration four distinct processes must happen
• Pulmonary ventilation moving air into and out
  of the lungs
• External respiration gas exchange between the
  lungs and the blood
• Transport transport of oxygen and carbon
  dioxide between the lungs and tissues
• Internal respiration gas exchange between
  systemic blood vessels and tissues

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Pulmonary Ventilation

• Exchange of air between the lungs and the
  atmosphere.
• What must exist for air to move?
• When breathing in, where is pressure higher?
• When breathing out, where is pressure higher?

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External Respiration

• Is the Exchange of carbon dioxide and oxygen
  between the blood and lungs
• Always follows the pressure gradient
• Where is O2 pressure higher?
• Where is CO2 pressure higher?

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Internal Respiration

• Is the Exchange of carbon dioxide and oxygen
  between the blood and tissues
• Always follows the pressure gradient
• Where is O2 pressure higher?
• Where is CO2 pressure higher?

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Cellular Respiration

• NOT directly a part of the respiratory system
• Sum of all metabolic activity in the cell
• Where does it occur?
• What gas is used?
• What gas is produced?

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Breathing

• Breathing, or pulmonary ventilation, consists of
  two phases
• Inspiration air flows into the lungs
• Expiration gases exit the lungs

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Respiratory Tract

• Divided into upper tract and lower tract
• 1.Upper Respiratory Tract
• Nose, pharynx and larynx
• 2.Lower Respiratory Tract
• Trachea, bronchi, and lungs

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Two Zones of the Respiratory System

• Conducting zone
• Where gases are physically transported
• Respiratory zone
• Where O2 and CO2 are exchanged between air and
  blood

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Conducting Zone

• Structures
• Nasal cavity, nasopharynx, oropharynx,
  laryngopharynx, larynx, trachea, bronchi, and all
  bronchioles except respiratory bronchioles.
• Functions
• Transport of air to respiratory zone
• Filtering, humidifying, and warming

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Conducting Zone Structures

• Nose and nasal cavity
• Nasopharynx
• Oropharynx
• Laryngopharynx
• Larynx
• Trachea
• Bronchi
• Most bronchioles

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Nose

• RoofFrontal, sphenoid ethmoid
• WallsMaxillaePalatines Conchae
• Floor is the hard palate

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Nasal Conchae
Functions? How do they affect surface
area? How do they affect airflow? This helps
with what 3 processes?
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Conducting Zone Continued
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Pharynx

• Nasopharynx
• Oropharynx
• Laryngopharynx

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Nasopharynx

• Contains 2 auditory tubes openings (Eustacian
  Tubes) Allows the middle ear to equalize pressure

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Oropharynx

• Bottom of the uvula to top of the epiglottis

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Laryngopharynx

• Top of the epiglottis to the division between
  larynx and esophagus

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Larynx

• Routes food and air
• Tube composed of 9 cartilage members

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Vocal Folds or Cords

• Vocal folds paired folds of laryngeal mucosa
  just deep to the thyroid cartilage. They contain
  the elastic vocal ligaments. Theyre also known
  as the true vocal cords. Function?

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Glottis

• Glottis space between the vocal folds

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Trachea

• Runs from larynx to the 2 primary bronchi
• Ends at the carina

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Trachea on dissection
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Trachea and Esophagus
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Hyaline Cartilage in Trachea
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What happens to air in the conducting zone?

• Humidity will?
• Temperature goes (up or down)?
• Bacteria particles will?
• O2 and CO2 content will?

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Lung Anatomy

• Left lung has 2 lobes superior and inferior,
  separated by an oblique fissure.
• Right lung has 3 lobes superior, middle, and
  inferior, separated by the oblique and horizontal
  fissures.

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Lungs on Dissection
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Pleurae and Pleural Cavity

• Double layered serosa that covers each lung.
• Parietal pleura lines the thoracic wall, the
  superior surface of the diaphragm, and the
  mediastinum.
• Visceral pleura covers the lungs themselves.
• Between the visceral and parietal layers is the
  pleural cavity.
• What does it contain? Why?

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Bronchi

• Trachea splits to yield 2 primary bronchi.
• Right primary bronchus is wider, shorter, and
  more vertical than the left primary bronchus.
• Why?
• Primary bronchi split to yield secondary bronchi.
  
• 3 bronchi on the right, 2 on the left.
• One secondary bronchus per lobe of the lung.
• Secondary bronchi yield tertiary bronchi, then
  quaternary bronchi, and so on until the tubes
  have a diameter of lt1mm. Smaller ones are known
  as bronchioles.

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Bronchial Tree
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As you go to smaller bronchi

• The amount of cartilage present will
• The relative amount of smooth muscle present
  will
• The number of cilia will
• The available surface area will
• The thickness of the epithelium will

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Bronchioles

• Airways with a diameter of lt1mm.
• Lack cartilage
• Last airways without alveoli (exchange sites) are
  terminal bronchioles
• First airways with alveoli are respiratory
  bronchioles

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Exchange Zone

• Structures
• Respiratory bronchioles, alveolar ducts, alveolar
  sacs, alveoli.
• Functions
• GAS EXCHANGE between alveolar air and blood.
• What type of epithelium would you expect to find
  in the respiratory zone?
• WHY?

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Exchange zone

• Respiratory bronchioles
• Are the beginning of the exchange zone.
• Give rise to alveolar ducts
• Alveolar ducts
• Tubes consisting of side-by-side alveoli
• Give rise to alveolar sacsdead ends consisting
  of nothing but alveoli.

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Alveoli

• Sites of external respiration
• 300 million Why so many?
• Simple squamous epithelium
• Made up of 2 cell types
• Type I alveolar cells
• Simple squamous. Sites of exchange
• Type II alveolar cells
• Produce surfactant
• Also contain alveolar macrophages (dust cells)

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Role of Capillaries and Elastic Fibers
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Emphysema
What effect does the reduced number of alveoli
have?
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Showing Capillary Alveoli An RBC in the
capillary
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Pressure Relationships in the Thoracic Cavity

• Respiratory pressure is always described relative
  to atmospheric pressure
• Atmospheric pressure (Patm)
• Intrapulmonary pressure (Ppul) pressure within
  the alveoli -
• Intrapleural pressure (Pip) pressure within the
  pleural cavity - -2 to -8 relative to
  atmosphere.

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Pressure Relationships

• Two forces act to pull the lungs away from the
  thoracic wall, promoting lung collapse
• Elasticity of lungs causes them to assume
  smallest possible size
• Surface tension of alveolar fluid draws alveoli
  to their smallest possible size
• Opposing force elasticity of the chest wall
  pulls the thorax outward to enlarge the lungs

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Pressure Relationships
Figure 22.12
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Lung Collapse

• Caused by equalization of the intrapleural
  pressure with the intrapulmonary pressure
• Transpulmonary pressure keeps the airways open
• Transpulmonary pressure difference between the
  intrapulmonary and intrapleural pressures (Ppul
  Pip)

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Pneumothorax
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Pulmonary Ventilation

• A mechanical process that depends on volume
  changes in the thoracic cavity
• Volume changes lead to pressure changes, which
  lead to the flow of gases to equalize pressure

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Boyles Law

• Boyles law the relationship between the
  pressure and volume of gases
• P1V1 P2V2
• P pressure of a gas in mm Hg
• V volume of a gas in cubic millimeters
• Subscripts 1 and 2 represent the initial and
  resulting conditions, respectively

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Boyles Law

• Pressure and volume move in opposite directions

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Mechanics of Breathing
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Inspiration
Figure 22.13.1
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Inspiratory Muscles
Diaphragm
External Intercostals
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Diaphragm
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Factors That Diminish Lung Compliance

• Scar tissue or fibrosis that reduces the natural
  resilience of the lungs
• Blockage of the smaller respiratory passages with
  mucus or fluid
• Reduced production of surfactant
• Decreased flexibility of the thoracic cage or its
  decreased ability to expand

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Expiration
Figure 22.13.2
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Pulmonary Pressures
Figure 22.14
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Clinical Applications

• Atelectasis lung collapse air entering
  pleural cavity, or from plugged bronchioles.
• Pneumothorax penetration wound
• Tension pneumothorax worsening of simple
  pneumothorax
• Hemothorax blood in pleural cavity
• IRDS Infant Respiratory Distress Syndrome

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Respiratory volumes

• (See figure 22.16)
• Tidal volume (TV) air that moves into and out
  of the lungs with each breath (approximately 500
  ml)
• Inspiratory reserve volume (IRV) air that can
  be inspired forcibly beyond the tidal volume
  (21003200 ml)
• Expiratory reserve volume (ERV) air that can be
  evacuated from the lungs after a tidal expiration
  (10001200 ml)
• Residual volume (RV) air left in the lungs
  after strenuous expiration (1200 ml)

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Respiratory Capacities

• Vital capacity (VC) the total amount of
  exchangeable air (TV IRV ERV)
• Total lung capacity (TLC) sum of all lung
  volumes (approximately 6000 ml in males)
• Dead Space The amount of air inhaled into the
  airways that does not reach the alveoli. (Hose
  illustration diving).

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Respiratory Capacities

• FVC Forced vital capacity measures amount of
  gas expelled from a deep breath spirometry
• FEV1 Amount expelled in first second. Low FEV1
  indicates obstructive pulmonary disease. Should
  be about 80 of FVC.

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Application of volumes

• Increases of TLC (Total Lung capacity),
  RV(Residual Volume) indicate Obstructive
  disease.
• Decreases indicate restrictive diseases, which
  limit lung expansion.

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Minute Ventilation

• At rest, about 6 L/ minute (12 breaths times 500
  ml)
• With exercise, up to 200 L/Min

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Basic Properties of Gases Daltons Law of
Partial Pressures

• Total pressure exerted by a mixture of gases is
  the sum of the pressures exerted independently by
  each gas in the mixture
• The partial pressure of each gas is directly
  proportional to its percentage in the mixture
• Atmospheric Air
• Oxygen
• Carbon Dioxide
• Nitrogen

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Table 22.4
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Basic Properties of Gases Henrys Law

• When a mixture of gases is in contact with a
  liquid, each gas will dissolve in the liquid in
  proportion to its partial pressure
• The amount of gas that will dissolve in a liquid
  also depends upon its solubility
• Carbon dioxide is the most soluble
• Oxygen is 1/20th as soluble as carbon dioxide
• Nitrogen is practically insoluble in plasma

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Respiratory Membrane
Figure 22.9.c, d
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External Respiration Pulmonary Gas Exchange

• Factors influencing the movement of oxygen and
  carbon dioxide across the respiratory membrane
• Partial pressure gradients and gas solubilities
• Matching of alveolar ventilation and pulmonary
  blood perfusion
• Structural characteristics of the respiratory
  membrane

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Ventilation-Perfusion Coupling

• Ventilation the amount of gas reaching the
  alveoli
• Perfusion the blood flow reaching the alveoli
• Ventilation and perfusion must be tightly
  regulated for efficient gas exchange
• Changes in PCO2 in the alveoli cause changes in
  the diameters of the bronchioles
• Passageways servicing areas where alveolar carbon
  dioxide is high dilate
• Those serving areas where alveolar carbon dioxide
  is low constrict

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Ventilation-Perfusion Coupling
PO2
PCO2
in alveoli
Reduced alveolar ventilation excessive perfusion
Reduced alveolar ventilation reduced perfusion
Pulmonary arterioles serving these
alveoli constrict
PO2
PCO2
in alveoli
Enhanced alveolar ventilation inadequate
perfusion
Enhanced alveolar ventilation enhanced perfusion
Pulmonary arterioles serving these alveoli dilate
Figure 22.19
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Internal Respiration

• The factors promoting gas exchange between
  systemic capillaries and tissue cells are the
  same as those acting in the lungs
• The partial pressures and diffusion gradients are
  reversed
• PO2 in tissue is always lower than in systemic
  arterial blood
• PO2 of venous blood draining tissues is 40 mm Hg
  and PCO2 is 45 mm Hg

PLAY
InterActive Physiology Respiratory System
Gas Exchange, page 317
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Figure 22.17
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Oxygen Transport

• Molecular oxygen is carried in the blood
• Bound to hemoglobin (Hb) within red blood cells
• Dissolved in plasma
• Each Hb molecule binds four oxygen atoms in a
  rapid and reversible process
• The hemoglobin-oxygen combination is called
  oxyhemoglobin (HbO2)
• Hemoglobin that has released oxygen is called
  reduced hemoglobin (HHb)

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Hemoglobin (Hb)

• Saturated hemoglobin when all four hemes of the
  molecule are bound to oxygen
• Partially saturated hemoglobin when one to
  three hemes are bound to oxygen
• The rate that hemoglobin binds and releases
  oxygen is regulated by
• PO2, temperature, blood pH, and PCO2
• These factors ensure adequate delivery of oxygen
  to tissue cells

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Carbon Monoxide Poisoning

• CO competes with O2
• Hemoglobin has higher affinity for CO
• Treatment 100 O2
• Cyanosis
• Skin has bluish color due to increased
  concentration of deoxyhemoglobin (HHb)

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Carbon Dioxide Transport

• Carbon dioxide is transported in the blood in
  three forms
• Dissolved in plasma 7 to 10
• Chemically bound to hemoglobin (the globin, not
  the heme) 20 is carried in RBCs as
  carbaminohemoglobin
• Bicarbonate ion in plasma 70 is transported as
  bicarbonate (HCO3)

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Haldane Effect

• The amount of carbon dioxide transported is
  markedly affected by the PO2
• Haldane effect the lower the PO2 and hemoglobin
  saturation with oxygen, the more carbon dioxide
  can be carried in the blood
• At the tissues, as more carbon dioxide enters the
  blood
• More oxygen dissociates from hemoglobin (Bohr
  effect)
• More carbon dioxide combines with hemoglobin, and
  more bicarbonate ions are formed
• This situation is reversed in pulmonary
  circulation

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Transport and Exchange of Carbon Dioxide

• Carbon dioxide diffuses into RBCs and combines
  with water to form carbonic acid (H2CO3), which
  quickly dissociates into hydrogen ions and
  bicarbonate ions
• In RBCs, carbonic anhydrase reversibly catalyzes
  the conversion of carbon dioxide and water to
  carbonic acid

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Transport and Exchange of Carbon Dioxide

• At the tissues
• Bicarbonate quickly diffuses from RBCs into the
  plasma
• The chloride shift to counterbalance the
  outrush of negative bicarbonate ions from the
  RBCs, chloride ions (Cl) move from the plasma
  into the erythrocytes

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Transport and Exchange of Carbon Dioxide
Figure 22.22a
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Transport and Exchange of Carbon Dioxide

• At the lungs, these processes are reversed
• Bicarbonate ions move into the RBCs and bind with
  hydrogen ions to form carbonic acid
• Carbonic acid is then split by carbonic anhydrase
  to release carbon dioxide and water
• Carbon dioxide then diffuses from the blood into
  the alveoli

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Transport and Exchange of Carbon Dioxide
Figure 22.22b
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Influence of Carbon Dioxide on Blood pH

• The carbonic acidbicarbonate buffer system
  resists blood pH changes
• If hydrogen ion concentrations in blood begin to
  rise, excess H is removed by combining with
  HCO3
• If hydrogen ion concentrations begin to drop,
  carbonic acid dissociates, releasing H
• Changes in respiratory rate can also
• Alter blood pH
• Provide a fast-acting system to adjust pH when it
  is disturbed by metabolic factors

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Control of Respiration Medullary Respiratory
Centers

• The dorsal respiratory group (DRG), or
  inspiratory center
• Appears to be the pacesetting respiratory center
• Excites the inspiratory muscles and sets eupnea
  (12-15 breaths/minute)
• Becomes dormant during expiration
• The ventral respiratory group (VRG) is involved
  in forced inspiration and expiration

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Figure 22.24
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Hyperventilation - Compensatory

• Hyperventilation increased depth and rate of
  breathing that
• Quickly flushes carbon dioxide from the blood
• Occurs in response to hypercapnia (high CO2 )
• Though a rise CO2 acts as the original stimulus,
  control of breathing at rest is regulated by the
  hydrogen ion concentration in the brain
• Exercise
• Drugs affecting CNS

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Hyperventilation Non-compensatory

• Rapid or extra deep breathing leads to hypocapnia
  -(low CO2)
• Can lead to alkalosis with cramps and spasms
• Causes acute anxiety or emotional tension
• CO2 is vasodilator low PCO2 results in LOCAL
  vasoconstrictions ischemia/hypoxia
• How do you fix it?

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Hypoventilation Non-compensatory

• Hypoventilation slow and shallow breathing due
  to abnormally low PCO2 levels (initially)
• Apnea (breathing cessation) may occur until PCO2
  levels rise
• Leads to too much CO2which leads to drop in pH
  acidosis

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Depth and Rate of Breathing Higher Brain Centers

• Hypothalamic controls act through the limbic
  system to modify rate and depth of respiration
• Example breath holding that occurs in anger
• A rise in body temperature acts to increase
  respiratory rate
• Cortical controls are direct signals from the
  cerebral motor cortex that bypass medullary
  controls
• Examples voluntary breath holding, taking a deep
  breath

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Depth and Rate of Breathing PCO2

• Changing PCO2 levels are monitored by
  chemoreceptors of the brain stem
• Carbon dioxide in the blood diffuses into the
  cerebrospinal fluid where it is hydrated
• Resulting carbonic acid dissociates, releasing
  hydrogen ions
• PCO2 levels rise (hypercapnia) resulting in
  increased depth and rate of breathing

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Depth and Rate of Breathing PCO2

• Arterial oxygen levels are monitored by the
  aortic and carotid bodies
• Substantial drops in arterial PO2 (to 60 mm Hg)
  are needed before oxygen levels become a major
  stimulus for increased ventilation
• If carbon dioxide is not removed (e.g., as in
  emphysema and chronic bronchitis), chemoreceptors
  become unresponsive to PCO2 chemical stimuli
• In such cases, PO2 levels become the principal
  respiratory stimulus (hypoxic drive)

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Depth and Rate of Breathing Arterial pH

• Changes in arterial pH can modify respiratory
  rate even if carbon dioxide and oxygen levels are
  normal
• Increased ventilation in response to falling pH
  is mediated by peripheral chemoreceptors

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Depth and Rate of Breathing Arterial pH

• Acidosis may reflect
• Carbon dioxide retention
• Accumulation of lactic acid
• Excess fatty acids in patients with diabetes
  mellitus
• Respiratory system controls will attempt to raise
  the pH by increasing respiratory rate and depth

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Factors Influencing Rate and Depth
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Respiratory Adjustments Exercise

• Respiratory adjustments are geared to both the
  intensity and duration of exercise
• During vigorous exercise
• Ventilation can increase 20 fold
• Breathing becomes deeper and more vigorous, but
  respiratory rate may not be significantly changed
  (hyperpnea)
• Exercise-enhanced breathing is not prompted by an
  increase in PCO2 or a decrease in PO2 or pH
• These levels remain surprisingly constant during
  exercise

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Respiratory Adjustments Exercise

• As exercise begins
• Ventilation increases abruptly, rises slowly, and
  reaches a steady state
• When exercise stops
• Ventilation declines suddenly, then gradually
  decreases to normal

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Respiratory Adjustments Exercise

• Neural factors bring about the above changes,
  including
• Psychic stimuli
• Cortical motor activation
• Excitatory impulses from proprioceptors in muscles

PLAY
InterActive Physiology Control of
Respiration, pages 315
116
Respiratory Adjustments High Altitude

• The body responds to quick movement to high
  altitude (above 8000 ft) with symptoms of acute
  mountain sickness headache, shortness of
  breath, nausea, and dizziness

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Respiratory Adjustments High Altitude

• Acclimatization respiratory and hematopoietic
  adjustments to altitude include
• Increased ventilation 2-3 L/min higher than at
  sea level
• Chemoreceptors become more responsive to PCO2
• Substantial decline in PO2 stimulates peripheral
  chemoreceptors

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Chronic Obstructive Pulmonary Disease (COPD)

• Includes chronic bronchitis and obstructive
  emphysema
• Patients have a history of
• Smoking
• Dyspnea, where labored breathing occurs and gets
  progressively worse
• Coughing and frequent pulmonary infections
• COPD victims develop respiratory failure
  accompanied by hypoxemia, carbon dioxide
  retention, and respiratory acidosis

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Chronic Bronchitis

• Role of cigarette smoke
• Mucus collection
• Ventilation impared
• Blue bloaters

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Pathogenesis of COPD
Figure 22.28
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Asthma

• Characterized by dyspnea, wheezing, and chest
  tightness
• Active inflammation of the airways precedes
  bronchospasms
• Airway inflammation is an immune response caused
  by release of IL-4 and IL-5, which stimulate IgE
  and recruit inflammatory cells
• Airways thickened with inflammatory exudates
  increase the effect of bronchospasms

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Tuberculosis

• Infectious disease caused by the bacterium
  Mycobacterium tuberculosis
• Symptoms include fever, night sweats, weight
  loss, a racking cough, and splitting headache
• Treatment entails a 12-month course of antibiotics

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Lung Cancer

• Accounts for 1/3 of all cancer deaths in the U.S.
• 90 of all patients with lung cancer were smokers
• The three most common types are
• Squamous cell carcinoma (20-40 of cases) arises
  in bronchial epithelium
• Adenocarcinoma (25-35 of cases) originates in
  peripheral lung area
• Small cell carcinoma (20-25 of cases) contains
  lymphocyte-like cells that originate in the
  primary bronchi and subsequently metastasize

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What if ????

• Alveolar PO2 is 100, alveolar Pco2 is 38 and
  alveolar PCO is 1
• A child eats 20 aspirin tablets (aspirin is
  acetylsalicylic acid. How will respiratory rate
  be affected?
• A few hours after surgery I am experiencing lots
  of pain, so I take a dose of my narcotic pain
  killer 5 minutes later it still hurts so I take
  another .How will RR be affected?