Respiration

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Respiration

• Chapter 42

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Respiration

• Gas exchange
• Movement of gas across membrane
• Diffusion (passive)
• To improve gas absorption
• Increase surface area for diffusion
• Decrease distance diffused gas travels
• Respiratory organs

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Fish
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Amphibians

• Lungs
• Cutaneous respiration

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Amphibians
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Birds

• Parabronchi (lungs)
• Air sacs

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Fig. 42-26
Air
Air
Anterior air sacs
Trachea
Posterior air sacs
Lungs
Lungs
Air tubes (parabronchi) in lung
1 mm
EXHALATION Air sacs empty lungs fill
INHALATION Air sacs fill
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Anatomy

• Mouth (nose)
• Pharynx (back of throat)
• Larynx (voice box)
• Trachea

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Anatomy
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Anatomy
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Anatomy

• Bronchi (Bronchus)
• Bronchioles
• Alveoli
• Air sacs
• Gas exchange
• One cell layer thick
• Lung tissue consists of millions

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Anatomy
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Anatomy
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Anatomy

• Lungs
• 3 right lobes
• RUL, RML, RLL
• 2 left lobes
• LUL, LLL

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Anatomy
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Anatomy
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Anatomy

• Lung covered by a double folded membrane
• Visceral pleural membrane
• Covers the lung
• Parietal pleural membrane
• Lines inner wall of thoracic cavity

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Anatomy

• Pleural cavity
• Space between two membranes
• Filled with fluid
• Helps with movement of lungs

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Breathing

• Diaphragm
• Muscle
• Separates thoracic cavity from abdominal cavity
• Intercostal muscles
• Muscles between the ribs

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Inhalation (inspiration)

• Diaphragm contracts flattens
• Intercostal muscles contract
• Raises the ribs
• Increases volume (decreases pressure)
• Air flows into the lungs

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Exhalation (expiration)

• Diaphragm relaxes elevates
• Intercostal muscles relax
• Ribs lower
• Decreased volume
• Forces air out

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Breathing
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Breathing measurements

• Tidal volume
• Amount of air moved into out of lungs at rest
• Vital capacity
• Maximum amount of air that can be expired after
  forceful exhalation

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Breathing measurements
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Control of breathing

• Normal breathing
• Medulla oblongata
• Respiratory control center
• Neurons send impulse for muscles
  (diaphragm/intercostal) to contract
• Inspiration (inhalation)
• Stop sending impulse
• Expiration (exhalation)

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Control of breathing

• Blood O2 CO2 in normal range
• Neurons respond to a change in O2 CO2
• More response to CO2
• Increase CO2
• Increases carbonic acid (H2CO3)
• CO2 H2O ?H2CO3 ? H HCO3
• Lowers pH

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Control of breathing

• Stimulates peripheral chemoreceptors
• Aorta carotids
• Send impulses to respiratory control center
  (medulla oblongata)
• Stimulates increased breathing

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Control of breathing

• Central chemoreceptors
• Located in brain
• Respond to increased amount of CO2
• Peripheral receptors immediate response
• Central receptors maintained response until pH is
  back to normal

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Transport of gas

• Hemoglobin
• Contains four heme groups
• Center of each heme group is an iron
• Oxygen binds the iron (4 O2 molecules)
• Oxygen in blood is mostly bound to Hgb
• Little is dissolved plasma

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Transport of gas
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Transport of gas

• Oxyhemoglobin
• Hemoglobin full of oxygen
• Lungs
• Deoxyhemoglobin
• Hemoglobin releases some oxygen
• Capillaries

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Transport of gas

• Blood that leaves lungs 97 saturated
• Circulates oxygen diffuses into tissues
• 75 saturated
• Allows for reserves of oxygen
• Exercise
• Cardiac arrest

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Transport of gas

• Decreased pH
• Lower affinity of oxygen for hemoglobin
• Releases oxygen
• Increased temperature
• Lower affinity
• Exercise
• Increased CO2, decreased pH, increased
  temperature
• Increased release of O2 to muscles

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Transport of gas

• CO2
• In tissues
• Small amount bound to protein part of Hgb
• Remaining CO2 in RBC
• Forms carbonic acid H2CO3
• Carbonic anhydrase

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Transport of gas

• Carbonic acid separates
• Bicarbonate (HCO3-1) H1
• Buffer
• Blood at alveoli
• Carbonic anhydrase reverses
• Forms water CO2
• CO2 diffuses into lungs

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Abnormalities

• Emphysema
• Lung disease that destroys alveoli sacs
• Decreases vital capacity
• Traps air
• Hypoventilation
• Decreased air movement increased CO2
• Hyperventilation
• Increased air movement decreased CO2

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Emphysema
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