BIO 163 FINAL PAPER 2025/2026 QUESTIONS AND
SOLUTIONS RANKED A+
✔✔pleural cavity - ✔✔space between visceral and parietal pleura; contain small amount
of fluid
✔✔mechanical coupling - ✔✔elastic connective tissue allows lungs to pull on parietal
pleura after exhalation; allows the lungs to expand as the thoracic cavity expands; relies
on pressure gradients
✔✔pressure gradients - ✔✔cause air movement in and out of the lungs
✔✔Boyle's Law - ✔✔pressure and volume are inversely proportional; gases move from
high to low pressure
✔✔atmospheric pressure - ✔✔air pressure outside the body; constant 760 mmHg;
prevents lungs from collapsing
✔✔intrapleural pressure - ✔✔pressure in the pleural cavity; changes with breathing but
is usually negative; prevents lungs from collapsing with help of surfactant; helps change
size of lungs
✔✔intrapulmonary pressure - ✔✔pressure within the lungs; constant 760 mmHg
✔✔changes in thoracic cavity volume controlled by intrapleural pressure - ✔✔What
causes changes in lung volume?
✔✔inspiration (inhalation) - ✔✔breathing air into the lungs; diaphragm and intercostal
muscles contracts; thoracic volume increases and pressure decreases; outside
pressure is greater than inside; inspiratory neurons
✔✔expiration (exhalation) - ✔✔breathing out; diaphragm and intercostal muscles relax;
thoracic volume decreases and pressure increases; inside pressure is greater than
outside; expiratory neurons
✔✔pneumothorax - ✔✔collapsed lung; intrapleural pressure becomes equal to
atmospheric pressure
✔✔respiratory rate - ✔✔number of breaths per minute (avg. 15)
✔✔Tidal Volume (TV) - ✔✔amount of air inhaled with one breath (avg. 500mL)
✔✔respiratory minute volume - ✔✔volume inhaled in one minute = respiratory rate*tidal
volume
, ✔✔alveolar ventilation - ✔✔amount of air that reaches the respiratory membrane per
minute = respiratory rate*(tidal volume-dead space)
✔✔dead space - ✔✔the portion of the tidal volume that does not reach the alveoli and
thus does not participate in gas exchange
✔✔Dalton's Law - ✔✔each gas contributes a partial pressure to overall pressure of
atmosphere
✔✔Henry's Law - ✔✔gases dissolve in liquid based on their partial pressures and
solubility
✔✔partial pressures of dissolved gases - ✔✔What determines direction of diffusion at
capillary beds within our body?
✔✔Oxygen transportation - ✔✔2% dissolved in plasma and 98% bound to hemoglobin
✔✔Carbon Dioxide transportation - ✔✔5% dissolved in plasma, 10% bound to
hemoglobin, and 85% converted to bicarbonate ions
✔✔partial pressures of external respiration - ✔✔equilibrium between alveoli and blood
✔✔partial pressures of internal respiration - ✔✔equilibrium between target tissues and
blood
✔✔red blood cells - ✔✔carry oxygen; no nuclei or mitochondria; shape promotes travel
through capillaries
✔✔Hematopoiesis - ✔✔formation of blood cells in red bone marrow; blood stem cells
differentiate to produce "formed elements"; stimulated by erythropoietin
✔✔- RBC levels drops and become oxygen deficient (hypoxia)
- sensed by liver and kidney
- erythropoietin stimulates RBC production
- negative feedback loop - ✔✔What triggers hematopoiesis?
✔✔hemoglobin - ✔✔protein found in red blood cells that carries O2; has 4 subunits that
can each hold 1 O2; unload oxygen down a concentration gradient
✔✔oxygen dissociation curve - ✔✔
✔✔equilibrium within blood
SOLUTIONS RANKED A+
✔✔pleural cavity - ✔✔space between visceral and parietal pleura; contain small amount
of fluid
✔✔mechanical coupling - ✔✔elastic connective tissue allows lungs to pull on parietal
pleura after exhalation; allows the lungs to expand as the thoracic cavity expands; relies
on pressure gradients
✔✔pressure gradients - ✔✔cause air movement in and out of the lungs
✔✔Boyle's Law - ✔✔pressure and volume are inversely proportional; gases move from
high to low pressure
✔✔atmospheric pressure - ✔✔air pressure outside the body; constant 760 mmHg;
prevents lungs from collapsing
✔✔intrapleural pressure - ✔✔pressure in the pleural cavity; changes with breathing but
is usually negative; prevents lungs from collapsing with help of surfactant; helps change
size of lungs
✔✔intrapulmonary pressure - ✔✔pressure within the lungs; constant 760 mmHg
✔✔changes in thoracic cavity volume controlled by intrapleural pressure - ✔✔What
causes changes in lung volume?
✔✔inspiration (inhalation) - ✔✔breathing air into the lungs; diaphragm and intercostal
muscles contracts; thoracic volume increases and pressure decreases; outside
pressure is greater than inside; inspiratory neurons
✔✔expiration (exhalation) - ✔✔breathing out; diaphragm and intercostal muscles relax;
thoracic volume decreases and pressure increases; inside pressure is greater than
outside; expiratory neurons
✔✔pneumothorax - ✔✔collapsed lung; intrapleural pressure becomes equal to
atmospheric pressure
✔✔respiratory rate - ✔✔number of breaths per minute (avg. 15)
✔✔Tidal Volume (TV) - ✔✔amount of air inhaled with one breath (avg. 500mL)
✔✔respiratory minute volume - ✔✔volume inhaled in one minute = respiratory rate*tidal
volume
, ✔✔alveolar ventilation - ✔✔amount of air that reaches the respiratory membrane per
minute = respiratory rate*(tidal volume-dead space)
✔✔dead space - ✔✔the portion of the tidal volume that does not reach the alveoli and
thus does not participate in gas exchange
✔✔Dalton's Law - ✔✔each gas contributes a partial pressure to overall pressure of
atmosphere
✔✔Henry's Law - ✔✔gases dissolve in liquid based on their partial pressures and
solubility
✔✔partial pressures of dissolved gases - ✔✔What determines direction of diffusion at
capillary beds within our body?
✔✔Oxygen transportation - ✔✔2% dissolved in plasma and 98% bound to hemoglobin
✔✔Carbon Dioxide transportation - ✔✔5% dissolved in plasma, 10% bound to
hemoglobin, and 85% converted to bicarbonate ions
✔✔partial pressures of external respiration - ✔✔equilibrium between alveoli and blood
✔✔partial pressures of internal respiration - ✔✔equilibrium between target tissues and
blood
✔✔red blood cells - ✔✔carry oxygen; no nuclei or mitochondria; shape promotes travel
through capillaries
✔✔Hematopoiesis - ✔✔formation of blood cells in red bone marrow; blood stem cells
differentiate to produce "formed elements"; stimulated by erythropoietin
✔✔- RBC levels drops and become oxygen deficient (hypoxia)
- sensed by liver and kidney
- erythropoietin stimulates RBC production
- negative feedback loop - ✔✔What triggers hematopoiesis?
✔✔hemoglobin - ✔✔protein found in red blood cells that carries O2; has 4 subunits that
can each hold 1 O2; unload oxygen down a concentration gradient
✔✔oxygen dissociation curve - ✔✔
✔✔equilibrium within blood
