Respiratory System

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Respiratory System
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Structure of Respiratory System

• 2 Lungs light, soft, spongy organs located in
  thoracic region R lung larger than L b/c heart
  takes up space on L.

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• 2 regions
• Conduction Zone - anatomical structures through
  which air travels before reaching (upside-down
  tree)
• Respiratory Zone - region where gas exchange
  occurs (alveoli)

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Pathway of Air

• Nose/mouth
• trachea (windpipe)
• R L bronchi lungs
• bronchioles
• terminal bronchioles
• alveoli

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Alveoli

• functional units of system 300 million tiny air
  sacs in which gas exchange occurs (little bubbles
  that are clustered like grapes)
• Each alveolus is surrounded by network of
  pulmonary capillaries gas diffusion (movement of
  molecules from high concentration to low
  concentration) occurs b/c of difference in
  concentration between O2 (alveoli) and CO2
  (capillaries). O2 heart CO2 exhaled

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3 Phases of Human Respiration

• 1.  Ventilation/breathing inspiration
  expiration
• 2.  Gas exchange
• 3.  Oxygen utilization by tissue for cellular
  respiration
• Changes in thoracic cavity during ventilation
  occur due to activity of diaphragm external
  intercostals muscles

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Lung Volume

• Many factors influence the amount of air that
  moves in/out of the lungs
•        - Body activities (sleeping vs. exercise)
•         -Individual differences (sex, height,
  age, weight)
• -State of the lungs/respiratory organs (health)

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Measurements of Air Volume

• Tidal volume (TV) amount of air moved in/out of
  lungs with 1 breath (avg. 500mL)
• Inspiratory reserve volume (IRV) amount of air
  that can be inhaled forcibly over the TV (avg.
  3100mL) 
• Expiratory reserve volume (ERV) maximum amount
  of air that can be forcibly exhaled after a tidal
  expiration (avg. 1200mL)
• Residual volume (RV) volume of air that remains
  in the lungs after a forced expiration (avg.
  1200mL)

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Measurements of Air Volume

• Vital capacity total amount of exchangeable
  air TV IRV ERV (avg. 4800mL) 
• Total lung capacity sum of vital capacity
  residual volume (avg. 6000mL)
• Anatomic dead space a portion of air that
  enters the respiratory tract never reaches the
  alveoli remains in the air passageways (avg.
  150mL)
• Avg. volume reaching alveoli in 1 breath 350mL

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Breathing

• rhythmic, involuntary process controlled by
  respiratory centre of brain.

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Factors that Effect Breathing

• Chemical changes in blood chemoreceptors
  monitor O2 CO2 levels (hyperventilation results
  during emergency situations when CO2 levels have
  risen beyond normal)
• Degree of stretch of lungs stretch receptors in
  bronchi bronchioles activated during
  inspiration cause expiration prevent lungs
  from over-inflating
• Persons mental state stress, fear, or pain can
  ? rate of breathing automatically some voluntary
  control over breathing but cannot stop breathing
  to the point of death (youd pass out first)

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Mechanics of Breathing

• Brief demonstration of breathing mechanics
• Respiration Lecture