Week 9 Study Guide
Four Main Components of Respiratory Physiology
1. Ventilation:
- Definition: movement of air between the atmosphere and the alveoli of the lungs.
- Mechanism:
- Driven by pressure differences created by the respiratory muscles.
- Inspiration: active process – diaphragm contracts, thoracic cavity expands, pressure
drops, air flows in.
- Expiration: usually passive – diaphragm relaxes, thoracic volume decreases, pressure
rises, air flows out.
- Dependence:
- Functional respiratory muscles
- Patent airways
- Compliance of the lungs and chest wall
2. Gas Exchange:
- Definition: diffusion of gases across the alveolar-capillary membrane.
- Occurs in: alveoli of lungs and pulmonary capillaries
- Depends upon:
- 1. Alveolar gas composition – adequate oxygen in the alveoli.
- 2. Perfusion of capillaries – sufficient blood flow to alveoli
- 3. Blood’s gas-carrying capacity – determined by RBCs and hemoglobin concentration.
- Driving force: partial pressure gradients
3. Gas Transport:
- Definition: movement of oxygen and carbon dioxide through blood and body fluids to
and from tissues.
- Mechanisms and Dependencies:
- Cardiovascular function: effective circulation is essential for gas delivery and removal.
- Hemoglobin: binds oxygen in the lungs and releases it to tissues; carries carbon dioxide
in reverse direction.
- Tissue exchange: tissues must be able to take up oxygen and release carbon dioxide
effectively.
- Forms of transport:
- Oxygen: 98% bound to hemoglobin, 2% dissolved in plasma
- Carbon Dioxide: transported as bicarbonate, carbaminohemoglobin, and dissolved gas.
4. Regulation of Ventilation:
- Definition: control of breathing rate and depth by central nervous system to maintain
homeostasis.
- Primary Control Center:
- Medulla oblongata and pons – generate and adjust respiratory rhythm
, - Main regulatory stimulus:
- Carbon dioxide -> monitored by central chemoreceptors in medulla.
- Secondary influence: oxygen levels, sensed by peripheral chemoreceptors.
- Outcome:
- High CO2 -> increased respiratory rate and depth.
- Low CO2 -> decreased respiratory drive.
Key Terms Associated with Breathing
1. Tidal Volume:
- Definition: volume of air moved in or out of the lungs with each breath under resting
conditions.
- Normal Value: -500 mL in adults.
- Represents: basic unit of ventilation
2. Respiratory Frequency:
- Definition: number of breaths taken per minute
- Normal Resting rate: -12-20 breaths per minute in adults.
- Abbreviation: RR or f
3. Minute Ventilation:
- Definition: total volume of air ventilated per minute.
- Formula: VE = VT x RR
- Also referred as ventilatory equivalent
4. Eupnea:
- Definition: normal, quiet breathing at rest
- Characteristics: normal rate and depth, matching metabolic demand
- Represents: health, balanced ventilatory pattern
5. Hyperpnea:
- Definition: increased rate and depth of breathing that meets metabolic demand.
- Key Point: normal physiological response, not pathology.
- Example: During exercise, ventilation increases proportionally to oxygen need and CO2
production.
- Effect: maintains acid-base balance because CO2 removal matches production.
6. Hyperventilation:
- Definition: increased rate and depth of breathing that exceeds metabolic demand.
- Effect: excess CO2 is exhaled -> low CO2 -> respiratory alkalosis.
- Common Cause: panic attack or anxiety-induced over breathing.
- Clinical consequence: lightheadedness, tingling, or dizziness due to altered pH.
7. Tachypnea:
- Definition: increased respiratory rate w/o a proportional increase in tidal volume.
- Typically involves shallow, rapid breathing.
- Mechanism: decrease in tidal volume while rate increases.
- Examples: pain, restrictive lung disease, fever.
- Fast and shallow
8. Apnea:
- Definition: cessation of breathing
2
Four Main Components of Respiratory Physiology
1. Ventilation:
- Definition: movement of air between the atmosphere and the alveoli of the lungs.
- Mechanism:
- Driven by pressure differences created by the respiratory muscles.
- Inspiration: active process – diaphragm contracts, thoracic cavity expands, pressure
drops, air flows in.
- Expiration: usually passive – diaphragm relaxes, thoracic volume decreases, pressure
rises, air flows out.
- Dependence:
- Functional respiratory muscles
- Patent airways
- Compliance of the lungs and chest wall
2. Gas Exchange:
- Definition: diffusion of gases across the alveolar-capillary membrane.
- Occurs in: alveoli of lungs and pulmonary capillaries
- Depends upon:
- 1. Alveolar gas composition – adequate oxygen in the alveoli.
- 2. Perfusion of capillaries – sufficient blood flow to alveoli
- 3. Blood’s gas-carrying capacity – determined by RBCs and hemoglobin concentration.
- Driving force: partial pressure gradients
3. Gas Transport:
- Definition: movement of oxygen and carbon dioxide through blood and body fluids to
and from tissues.
- Mechanisms and Dependencies:
- Cardiovascular function: effective circulation is essential for gas delivery and removal.
- Hemoglobin: binds oxygen in the lungs and releases it to tissues; carries carbon dioxide
in reverse direction.
- Tissue exchange: tissues must be able to take up oxygen and release carbon dioxide
effectively.
- Forms of transport:
- Oxygen: 98% bound to hemoglobin, 2% dissolved in plasma
- Carbon Dioxide: transported as bicarbonate, carbaminohemoglobin, and dissolved gas.
4. Regulation of Ventilation:
- Definition: control of breathing rate and depth by central nervous system to maintain
homeostasis.
- Primary Control Center:
- Medulla oblongata and pons – generate and adjust respiratory rhythm
, - Main regulatory stimulus:
- Carbon dioxide -> monitored by central chemoreceptors in medulla.
- Secondary influence: oxygen levels, sensed by peripheral chemoreceptors.
- Outcome:
- High CO2 -> increased respiratory rate and depth.
- Low CO2 -> decreased respiratory drive.
Key Terms Associated with Breathing
1. Tidal Volume:
- Definition: volume of air moved in or out of the lungs with each breath under resting
conditions.
- Normal Value: -500 mL in adults.
- Represents: basic unit of ventilation
2. Respiratory Frequency:
- Definition: number of breaths taken per minute
- Normal Resting rate: -12-20 breaths per minute in adults.
- Abbreviation: RR or f
3. Minute Ventilation:
- Definition: total volume of air ventilated per minute.
- Formula: VE = VT x RR
- Also referred as ventilatory equivalent
4. Eupnea:
- Definition: normal, quiet breathing at rest
- Characteristics: normal rate and depth, matching metabolic demand
- Represents: health, balanced ventilatory pattern
5. Hyperpnea:
- Definition: increased rate and depth of breathing that meets metabolic demand.
- Key Point: normal physiological response, not pathology.
- Example: During exercise, ventilation increases proportionally to oxygen need and CO2
production.
- Effect: maintains acid-base balance because CO2 removal matches production.
6. Hyperventilation:
- Definition: increased rate and depth of breathing that exceeds metabolic demand.
- Effect: excess CO2 is exhaled -> low CO2 -> respiratory alkalosis.
- Common Cause: panic attack or anxiety-induced over breathing.
- Clinical consequence: lightheadedness, tingling, or dizziness due to altered pH.
7. Tachypnea:
- Definition: increased respiratory rate w/o a proportional increase in tidal volume.
- Typically involves shallow, rapid breathing.
- Mechanism: decrease in tidal volume while rate increases.
- Examples: pain, restrictive lung disease, fever.
- Fast and shallow
8. Apnea:
- Definition: cessation of breathing
2
