BIO 265 – Human A&P
Chapter 22
Respiratory System
Functions
• What are the functions?
– Pulmonary ventilation (breathing)
– Gas Exchange
Anatomy Overview
• Figure 22.1
Respiratory System
• The respiratory system is completely lined with
mucous membranes
– We produce about 1 liter of mucus each day!!!
– This forms a barrier and trap system
– Respiratory filtering and cilia
• Runny noses and sluggish cilia
– The folds and hairs in the nasal cavity cause turbulence
in the air we breath
• They also heat and humidify inspired air
• They get some of the heat and water back from expired air
– Figure 22.1
Respiratory System
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Sneezing reflex
Rhinitis and sinusitis
Tonsils
Figure 22.3
Respiratory System
• The epiglottis and pop! (Figure 22.3)
Respiratory System
• The coughing reflex can help expel
anything in the trachea
– Air speed can reach 100 mph during a cough!
• What is the Heimlich maneuver?
– Figure 22.1
Respiratory System
• The larynx and vocal cords are involved in
voice production
– The vocal cords vibrate as air passes over them
– Saxophone reed analogy
– Laryngitis
• Figures 22.3 and 22.5
Respiratory System
• The pleural membranes line the lungs and
thoracic cavity
– The pleural cavity is filled with lubricating
pleural fluid
– Figure 22.12
Respiratory System
• Pleurisy is an inflammation of the pleural
membranes and causes painful breathing
• Collapsed lungs and pneumothorax (air in
the pleural cavity)
– Figure 22.12
Respiratory System
• Gas exchange occurs in the alveoli
– Figures 22.8 and 22.9
Respiratory System
• Cell types in the alveolus
– Type I cells make up the wall of the alveoli
– Type II cells secrete surfactant to reduce the
surface tension of the water lining the alveolus
• Infant respiratory distress syndrome
– Alveolar macrophages
– Figure 22.9
Respiratory System
• Oxygen and carbon dioxide must pass
through the respiratory membrane to get in
and out of the blood
– Surface area of the respiratory membrane is
about 40 times larger than the surface of the
skin
– Figure 22.9
Gas Exchange
• What drives gas exchange in the lungs and
the tissues?
– Concentration gradients of O2 and CO2
– Figure 22.17
O2 Transport
• How is O2 transported?
– 98.5% bound to hemoglobin (Hb)
– Each Hb can bind 4 O2 molecules in a
reversible reaction
• Percent saturation changes with PO2
– Hb-O2 Dissociation Curve – Figure 22.20
O2 Transport
• CD Demo
O2 Transport
• Other factors affecting Hb
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pH decrease lowers O2 binding
PCO2 increase lowers O2 binding
Temperature increase lowers O2 binding
Why?
• Carbon monoxide poisoning – CO binds to
Hb 200 times better than O2
CO2 Transport
• How is CO2 transported?
– 7-10% dissolved in plasma
– ~20% bound to hemoglobin
– ~70% as bicarbonate ions
• Reaction on board with carbonic anhdrase
• Figure 22.22
Regulation of Respiration
• Respiration rate is determined by the
respiratory center in the medulla oblongata
– No one knows for sure how rhythmic
ventilation results
• Predict the effect of O2, pH, and CO2 on
respiration rate
– CO2 is the major regulator of respiration rate
– Figure 22.25
Regulation of Respiration
– Hyperventilation can cause a major reduction in
blood CO2 levels
• This can cause vasoconstriction to the point that the
brain does not receive enough oxygen
• Breathing into a paper bag
– Fun activity
Respiratory Problems
• Mountain sickness – at high elevations not enough oxygen
enters the blood
– This leads to headaches, shortness of breath, nausea, and dizziness
• Chronic obstructive pulmonary disease (COPD) –
smoking, dyspnea (difficulty breathing), coughing
• Asthma – allergic response causing constriction of
bronchial passages
• Tuberculosis – bacterial lung infection
• Cystic fibrosis – leads to thick mucus in the respiratory
system
– Cl- ions are not pumped outside the cell, so water stays in the cells