RESPIRATORY SYSTEM
Breathing & Respiration
Respiration = energy release from food. Inhalation = diaphragm contracts, chest
Breathing = inhalation + exhalation. volume ↑.
Cellular respiration = mitochondria. Exhalation = diaphragm relaxes, chest
Normal breathing = 16 times/min. volume ↓
Negative pressure breathing in humans.
Respiratory Organs & Structures
Nasal cavity = warms, moistens, filters Right bronchus = shorter, wider; foreign
air. objects lodge here.
Nasal hairs = filter dust. Bronchioles = small branches of bronchi.
Pharynx = common passage for air & Alveoli = thin-walled sacs, diameter
food. ~0.2–0.3 mm.
Larynx = voice box with vocal cords. Surrounded by capillaries for gas
Trachea = tube with C-shaped cartilage, exchange.
length ~12 cm in adults. Surfactant prevents alveolar collapse.
Lung Volumes & Capacities
Volume / Capacity ml L Notes
Tidal Volume (TV) 500 0.5 Normal breath
Inspiratory Reserve (IRV) 3000 3 Extra inhale
Expiratory Reserve (ERV) 1100 1.1 Extra exhale
Residual Volume (RV) 1200 1.2 Cannot exhale
Vital Capacity (VC) 4600 4.6 TV+IRV+ERV
Total Lung Capacity (TLC) 5800 5.8 VC+RV
Functional Residual Capacity (FRC) 2300 2.3 ERV+RV
Oxygen Transport
97% bound to hemoglobin,
3% dissolved in plasma.
1 g Hb binds 1.34 ml O₂.
100 ml blood → ~20 ml O₂ ( at sea level).
Carbon Dioxide Transport
70% bicarbonate, 20% carbaminohemoglobin, 10% dissolved
.Respiratory Quotient (RQ)
RQ = CO₂ produced ÷ O₂ consumed. Carbs → 1.0, Fats → 0.7, Protein → 0.8.
Breathing & Respiration
Respiration = energy release from food. Inhalation = diaphragm contracts, chest
Breathing = inhalation + exhalation. volume ↑.
Cellular respiration = mitochondria. Exhalation = diaphragm relaxes, chest
Normal breathing = 16 times/min. volume ↓
Negative pressure breathing in humans.
Respiratory Organs & Structures
Nasal cavity = warms, moistens, filters Right bronchus = shorter, wider; foreign
air. objects lodge here.
Nasal hairs = filter dust. Bronchioles = small branches of bronchi.
Pharynx = common passage for air & Alveoli = thin-walled sacs, diameter
food. ~0.2–0.3 mm.
Larynx = voice box with vocal cords. Surrounded by capillaries for gas
Trachea = tube with C-shaped cartilage, exchange.
length ~12 cm in adults. Surfactant prevents alveolar collapse.
Lung Volumes & Capacities
Volume / Capacity ml L Notes
Tidal Volume (TV) 500 0.5 Normal breath
Inspiratory Reserve (IRV) 3000 3 Extra inhale
Expiratory Reserve (ERV) 1100 1.1 Extra exhale
Residual Volume (RV) 1200 1.2 Cannot exhale
Vital Capacity (VC) 4600 4.6 TV+IRV+ERV
Total Lung Capacity (TLC) 5800 5.8 VC+RV
Functional Residual Capacity (FRC) 2300 2.3 ERV+RV
Oxygen Transport
97% bound to hemoglobin,
3% dissolved in plasma.
1 g Hb binds 1.34 ml O₂.
100 ml blood → ~20 ml O₂ ( at sea level).
Carbon Dioxide Transport
70% bicarbonate, 20% carbaminohemoglobin, 10% dissolved
.Respiratory Quotient (RQ)
RQ = CO₂ produced ÷ O₂ consumed. Carbs → 1.0, Fats → 0.7, Protein → 0.8.
