EXAM 4 – PHYSIOLOGY 2160
CHAPTER 22 – RESPIRATORY PHYSIOLOGY
Gas Exchange & Transport
Explain how respiration contributes to regulation of blood pH
o Respiration regulates blood pH by controlling the levels of carbon dioxide (CO₂) in the blood.
o CO₂ combines with water to form carbonic acid, which dissociates into hydrogen ions (H⁺)
and bicarbonate ions.
o An increase in CO₂ increases hydrogen ion concentration and lowers pH, making the blood
more acidic.
o A decrease in CO₂ reduces hydrogen ions and raises pH, making the blood more basic.
o Ventilation adjusts CO₂ levels to maintain acid-base balance.
Explain factors that affect gas exchange
o Concentration gradients of gases
o Gas solubility
o Membrane thickness
o Membrane surface area
o Ventilation-perfusion coupling
Explain oxygen transport
o Arterial blood carries about 20 mL of O₂ per deciliter.
o 95% is bound to hemoglobin in RBCs.
o 1.5% is dissolved in plasma.
o Hemoglobin has four heme groups, each binds one O₂.
Explain carbon dioxide transport
o CO₂ is transported in three forms:
Carbonic acid
Carbamino compounds
Dissolved in plasma
o 90% of CO₂ is hydrated to form carbonic acid.
o CO₂ + H₂O → H₂CO₃ → HCO₃⁻ + H⁺
Explain how carbon dioxide production leads to hydrogen ion formation in
red blood cells
o Carbon dioxide produced during cellular respiration diffuses into red blood cells.
o Inside the red blood cells, CO₂ reacts with water to form carbonic acid.
o Carbonic acid then dissociates into hydrogen ions (H⁺) and bicarbonate ions (HCO₃⁻).
o This process increases hydrogen ion concentration and influences blood pH
Describe the role of carbonic anhydrase in red blood cells
o Carbonic anhydrase is an enzyme found in red blood cells that catalyzes the rapid
conversion of carbon dioxide & water into carbonic acid.
o This greatly speeds up the formation of hydrogen ions and bicarbonate, allowing efficient
transport of CO₂ & regulation of blood pH
Explain how hemoglobin transports oxygen and how many oxygen
molecules it can bind
o Hemoglobin transports oxygen by reversibly binding oxygen molecules to its heme groups.
1
, o Each hemoglobin molecule has four heme groups and can bind up to four oxygen molecules.
o This allows efficient transport of oxygen from the lungs to body tissues.
Differentiate hypoxia, anoxia, cyanosis, and eupnea.
o Hypoxia → a condition in which tissues receive insufficient oxygen.
o Anoxia → the complete absence of oxygen supply to tissues.
o Cyanosis → a bluish discoloration of the skin caused by oxygen deficiency in the blood.
o Eupnea → normal, quiet, and unlabored breathing.
Pulmonary Ventilation
Define pulmonary compliance and explain factors that affect it.
o Pulmonary ventilation – goal is to provide oxygen to the tissues and remove carbon dioxide
o Mechanics of Pulmonary Ventilation → down movement of the diaphragm; elevation of the
ribs to increase the diameter of the chest cavity.
o Pulmonary compliance → is the extent to which the lungs can expand when pressure
changes; it reflects how easily the lungs inflate.
o Compliance is affected by elasticity of lung tissue and surface tension within the alveoli.
o A thin film of water creates surface tension within the alveoli.
o Law of Laplace force drawing alveoli inward is directly proportional to surface tension and
inversely proportional to radius.
o Type II alveolar epithelial cells produce pulmonary surfactant, which disrupts hydrogen bonds and
decreases surface tension.
o Increased surface tension decreases compliance, while surfactant decreases surface
tension improves compliance.
Explain how bronchiole diameter influences resistance to airflow.
o Bronchiolar diameter is the primary control over resistance to airflow.
o Bronchoconstriction (bronchioles constrict) resistance & airflow ; triggered by airborne irritants,
cold air, parasympathetic stimulation & histamine.
o Bronchodilation (bronchioles dilate) is stimulated by sympathetic nerves & epinephrine; resistance
& airflow
Explain factors that slow diffusion across the respiratory membrane.
o Diffusion across the respiratory membrane is slowed when the efficiency of gas exchange is
reduced.
o This can occur when the membrane thickness increases, when surface area decreases, or
when pressure gradients are reduced, all of which decrease the rate at which gases move
between alveoli and blood.
Explain the physiological purpose of the Valsalva maneuver.
o Take a deep breath, hold it, & contract abnormal muscles.
o Increases pressure in the abdominal cavity.
o Used to expel urine, feces, & aid in childbirth.
2
, Control of Breathing
Compare the roles of the DRG, VRG, and PRG.
o The ventral respiratory group (VRG) in the medulla oblongata is the primary generator of the
basic respiratory rhythm and produces a normal breathing pattern of about 12 breaths per
minute.
o The dorsal respiratory group (DRG) modifies the rate and depth of breathing and receives
input from external sources.
o The pontine respiratory group (PRG) in the pons modifies the rhythm generated by the VRG
and adapts breathing to special circumstances such as sleep, exercise, vocalization, and
emotional responses.
Identify which center generates the basic respiratory rhythm.
o The ventral respiratory group (VRG) generates the basic respiratory rhythm.
Most potent stimulus to breathing
o Most potent stimulus is pH
o Followed by CO₂
o Least significant is O₂
Explain how central chemoreceptors monitor cerebrospinal fluid pH.
o Central chemoreceptors are located in the brainstem and respond to changes in the pH of
cerebrospinal fluid.
o The pH of cerebrospinal fluid reflects the carbon dioxide level in the blood.
o When CO₂ levels increase, pH decreases, and the chemoreceptors stimulate an increase in
ventilation to remove excess CO₂.
Predict how hypocapnia affects ventilation rate.
o Hypocapnia occurs when carbon dioxide levels in the blood are low.
o This causes an increase in pH (more basic), which reduces stimulation of the respiratory
centers.
o As a result, ventilation rate decreases.
CHAPTER 23 URINARY SYSTEM & CHAPTER 24 FLUID BALANCE
Urinary System Overview
List the organs of the urinary system.
o Urinary system → principal means of waste removal; consists of the 2 kidneys, 2 ureters, a
urinary bladder, and the urethra.
o Kidney functions → regulates blood volume & pressure, erythrocyte count, blood gases,
blood pH, electrolyte & acid base balance.
o These organs work together to remove wastes and regulate internal conditions.
Identify which organ systems excrete wastes and the types of wastes
removed.
o The respiratory system excretes carbon dioxide (CO₂), small amounts of other gases, and
water.
o The integumentary system excretes water, inorganic salts, lactic acid, and urea in sweat.
3
CHAPTER 22 – RESPIRATORY PHYSIOLOGY
Gas Exchange & Transport
Explain how respiration contributes to regulation of blood pH
o Respiration regulates blood pH by controlling the levels of carbon dioxide (CO₂) in the blood.
o CO₂ combines with water to form carbonic acid, which dissociates into hydrogen ions (H⁺)
and bicarbonate ions.
o An increase in CO₂ increases hydrogen ion concentration and lowers pH, making the blood
more acidic.
o A decrease in CO₂ reduces hydrogen ions and raises pH, making the blood more basic.
o Ventilation adjusts CO₂ levels to maintain acid-base balance.
Explain factors that affect gas exchange
o Concentration gradients of gases
o Gas solubility
o Membrane thickness
o Membrane surface area
o Ventilation-perfusion coupling
Explain oxygen transport
o Arterial blood carries about 20 mL of O₂ per deciliter.
o 95% is bound to hemoglobin in RBCs.
o 1.5% is dissolved in plasma.
o Hemoglobin has four heme groups, each binds one O₂.
Explain carbon dioxide transport
o CO₂ is transported in three forms:
Carbonic acid
Carbamino compounds
Dissolved in plasma
o 90% of CO₂ is hydrated to form carbonic acid.
o CO₂ + H₂O → H₂CO₃ → HCO₃⁻ + H⁺
Explain how carbon dioxide production leads to hydrogen ion formation in
red blood cells
o Carbon dioxide produced during cellular respiration diffuses into red blood cells.
o Inside the red blood cells, CO₂ reacts with water to form carbonic acid.
o Carbonic acid then dissociates into hydrogen ions (H⁺) and bicarbonate ions (HCO₃⁻).
o This process increases hydrogen ion concentration and influences blood pH
Describe the role of carbonic anhydrase in red blood cells
o Carbonic anhydrase is an enzyme found in red blood cells that catalyzes the rapid
conversion of carbon dioxide & water into carbonic acid.
o This greatly speeds up the formation of hydrogen ions and bicarbonate, allowing efficient
transport of CO₂ & regulation of blood pH
Explain how hemoglobin transports oxygen and how many oxygen
molecules it can bind
o Hemoglobin transports oxygen by reversibly binding oxygen molecules to its heme groups.
1
, o Each hemoglobin molecule has four heme groups and can bind up to four oxygen molecules.
o This allows efficient transport of oxygen from the lungs to body tissues.
Differentiate hypoxia, anoxia, cyanosis, and eupnea.
o Hypoxia → a condition in which tissues receive insufficient oxygen.
o Anoxia → the complete absence of oxygen supply to tissues.
o Cyanosis → a bluish discoloration of the skin caused by oxygen deficiency in the blood.
o Eupnea → normal, quiet, and unlabored breathing.
Pulmonary Ventilation
Define pulmonary compliance and explain factors that affect it.
o Pulmonary ventilation – goal is to provide oxygen to the tissues and remove carbon dioxide
o Mechanics of Pulmonary Ventilation → down movement of the diaphragm; elevation of the
ribs to increase the diameter of the chest cavity.
o Pulmonary compliance → is the extent to which the lungs can expand when pressure
changes; it reflects how easily the lungs inflate.
o Compliance is affected by elasticity of lung tissue and surface tension within the alveoli.
o A thin film of water creates surface tension within the alveoli.
o Law of Laplace force drawing alveoli inward is directly proportional to surface tension and
inversely proportional to radius.
o Type II alveolar epithelial cells produce pulmonary surfactant, which disrupts hydrogen bonds and
decreases surface tension.
o Increased surface tension decreases compliance, while surfactant decreases surface
tension improves compliance.
Explain how bronchiole diameter influences resistance to airflow.
o Bronchiolar diameter is the primary control over resistance to airflow.
o Bronchoconstriction (bronchioles constrict) resistance & airflow ; triggered by airborne irritants,
cold air, parasympathetic stimulation & histamine.
o Bronchodilation (bronchioles dilate) is stimulated by sympathetic nerves & epinephrine; resistance
& airflow
Explain factors that slow diffusion across the respiratory membrane.
o Diffusion across the respiratory membrane is slowed when the efficiency of gas exchange is
reduced.
o This can occur when the membrane thickness increases, when surface area decreases, or
when pressure gradients are reduced, all of which decrease the rate at which gases move
between alveoli and blood.
Explain the physiological purpose of the Valsalva maneuver.
o Take a deep breath, hold it, & contract abnormal muscles.
o Increases pressure in the abdominal cavity.
o Used to expel urine, feces, & aid in childbirth.
2
, Control of Breathing
Compare the roles of the DRG, VRG, and PRG.
o The ventral respiratory group (VRG) in the medulla oblongata is the primary generator of the
basic respiratory rhythm and produces a normal breathing pattern of about 12 breaths per
minute.
o The dorsal respiratory group (DRG) modifies the rate and depth of breathing and receives
input from external sources.
o The pontine respiratory group (PRG) in the pons modifies the rhythm generated by the VRG
and adapts breathing to special circumstances such as sleep, exercise, vocalization, and
emotional responses.
Identify which center generates the basic respiratory rhythm.
o The ventral respiratory group (VRG) generates the basic respiratory rhythm.
Most potent stimulus to breathing
o Most potent stimulus is pH
o Followed by CO₂
o Least significant is O₂
Explain how central chemoreceptors monitor cerebrospinal fluid pH.
o Central chemoreceptors are located in the brainstem and respond to changes in the pH of
cerebrospinal fluid.
o The pH of cerebrospinal fluid reflects the carbon dioxide level in the blood.
o When CO₂ levels increase, pH decreases, and the chemoreceptors stimulate an increase in
ventilation to remove excess CO₂.
Predict how hypocapnia affects ventilation rate.
o Hypocapnia occurs when carbon dioxide levels in the blood are low.
o This causes an increase in pH (more basic), which reduces stimulation of the respiratory
centers.
o As a result, ventilation rate decreases.
CHAPTER 23 URINARY SYSTEM & CHAPTER 24 FLUID BALANCE
Urinary System Overview
List the organs of the urinary system.
o Urinary system → principal means of waste removal; consists of the 2 kidneys, 2 ureters, a
urinary bladder, and the urethra.
o Kidney functions → regulates blood volume & pressure, erythrocyte count, blood gases,
blood pH, electrolyte & acid base balance.
o These organs work together to remove wastes and regulate internal conditions.
Identify which organ systems excrete wastes and the types of wastes
removed.
o The respiratory system excretes carbon dioxide (CO₂), small amounts of other gases, and
water.
o The integumentary system excretes water, inorganic salts, lactic acid, and urea in sweat.
3
