The Respiratory System

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The Respiratory System

• Involves the exchange of gases between cells,
  blood and the atmosphere

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Types of Respiration

• Pulmonary ventilation
• inspiration
• expiration
• External respiration
• occurs in the lungs
• Internal respiration
• occurs in the tissues

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Organs of Respiration

• Nose, Pharynx,Larynx,Trachea, Bronchial Tree,
  Lungs

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NOSE

• Moistens, warms, and filters air
• Houses olfactory receptors
• Serves as resonating chamber for speech
• Nasal septum divides nasal cavity

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PALATE

• Serves to separate the nasal cavity from the oral
  cavity
• Hard palate
• Soft palate
• Uvula

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PHARYNX

• Nasopharynx - upper portion, region above the
  soft palate
• Oropharynx - middle portion, area behind the oral
  cavity
• Laryngopharynx - lower portion, area below the
  epiglottis

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LARYNX

• Functions to prevent food or fluid from entering
  the respiratory system during swallowing and
  allows air flow during breathing
• Production of sound is secondary function

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Larynx

• Unpaired cartilages - thyroid, cricoid,
  epiglottis
• Paired cartilage - arytenoid, corniculate,
  cuneiform
• Vocal folds
• Glottis

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TRACHEA

• Tubelike structure leading from the larynx to
  bronchial tree
• Consists of smooth muscle and C shaped hyaline
  cartilage rings
• Lined with psuedostratified ciliated columnar
  epithelium
• Mucociliary escalator

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BRONCHIAL TREE

• Includes a right and left primary bronchus which
  divides to produce secondary bronchi, tertiary
  bronchi and bronchioles
• Terminal bronchioles branch into respiratory
  bronchioles which divide into alveolar ducts that
  connect to alveoli

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ALVEOLI

• Functional unit of the lungs where gas exchange
  occurs (300 million)
• Thin walls made of simple squamous epithelium
• Type I and type II alveolar cells
• Diffusion of gases takes place across an
  alveolar-capillary respiratory membrane

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LUNGS

• Paired organs in the thoracic cavity
• Right lung 3 lobes
• horizontal/oblique fissure
• Left lung 2 lobes
• oblique fissure
• Apex/Base
• Hilus

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PLEURAL MEMBRANES

• Parietal pleura
• Visceral pleura
• Pleural cavity
• Pleurisy
• Pneumothorax

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Physiology of Respiration
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Pressures

• Atmospheric pressure - 760mm Hg
• Intrapleural pressure - is always less than
  atmospheric and alveolar pressure
• Alveolar (intrapulmonary) pressure - changes with
  phases of breathing
• Pressure changes in lungs are produced by
  variations in lung volume

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BOYLES LAW

• The pressure of a gas is inversely proportional
  to its volume
• More volume-less pressure
• Less volume - more pressure

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Inspiration Expiration

• Alveolar pressure is below atmospheric pressure
  due to increased volume
• Air flows into lungs
• 760 vs 758 mm Hg

• Alveolar pressure is above atmospheric pressure
  due to decreased volume
• Air flows out of lung
• 762 vs 760 mm Hg

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Respiratory Air Volumes

• Tidal volume
• Inspiratory reserve volume
• Expiratory reserve volume
• Vital capacity
• Residual volume
• Spirometer

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Regulation of Respiration

• Medullary rhythmicity center - medulla oblongata
  controls basic rhythm of respiration
• Control centers in the pons
• pneumotaxic center inhibits inspiration
• apneustic area stimulates inspiration

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Gas Transport
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Oxygen Transport

• 98 of oxygen is bound to hemoglobin as
  oxyhemoglobin
• Each hemoglobin molecule has the capacity to bind
  with four oxygen molecules
• Hypoxia

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Factors Affecting Hemoglobin Saturation

• Partial pressure of oxygen
• increase pO2, the greater the saturation
• pH - in an acid environment, O2 splits more
  readily from hemoglobin
• Temperature - the higher the temperature, the
  more oxygen released from hemoglobin

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Carbon dioxide tranport

• 70 of CO2 is transported in the plasma as
  bicarbonate ion
• 23 of CO2 is bound to the globin part of
  hemoglobin as carbominohemoglobin
• 7 is dissolved in the plasma

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RESPIRATORY DISORDERS

• COPD (Chronic Obstructive Pulmonary Disease)
• Asthma
• Bronchitis
• Emphysema
• Lung Cancer
• Tuberculosis

• Cystic Fibrosis
• Cheyne-Stokes Respiration
• Pneumonia
• Sleep Apnea
• SIDS

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