Podcast
Questions and Answers
What does Dalton's Law state about the relationship between concentration and partial pressure of a gas in a mixture?
What does Dalton's Law state about the relationship between concentration and partial pressure of a gas in a mixture?
Which factor does NOT affect the rate of diffusion of O2 into the blood?
Which factor does NOT affect the rate of diffusion of O2 into the blood?
What effect does high altitude have on alveolar PO2?
What effect does high altitude have on alveolar PO2?
How can certain pharmaceuticals affect pulmonary gas exchange?
How can certain pharmaceuticals affect pulmonary gas exchange?
Signup and view all the answers
Why do alveolar PO2 and PCO2 remain relatively constant?
Why do alveolar PO2 and PCO2 remain relatively constant?
Signup and view all the answers
What occurs when intraalveolar pressure is less than atmospheric pressure during ventilation?
What occurs when intraalveolar pressure is less than atmospheric pressure during ventilation?
Signup and view all the answers
Which statement correctly describes the movement of gases in the respiratory system?
Which statement correctly describes the movement of gases in the respiratory system?
Signup and view all the answers
Which muscle primarily assists with quiet inspiration?
Which muscle primarily assists with quiet inspiration?
Signup and view all the answers
What usually happens during quiet expiration?
What usually happens during quiet expiration?
Signup and view all the answers
Which of these muscles is NOT typically involved in accessory ventilation during forced inspiration?
Which of these muscles is NOT typically involved in accessory ventilation during forced inspiration?
Signup and view all the answers
What is the normal atmospheric pressure at sea level?
What is the normal atmospheric pressure at sea level?
Signup and view all the answers
What role does the pleural membrane play during ventilation?
What role does the pleural membrane play during ventilation?
Signup and view all the answers
Which type of respiration involves gas exchange at body tissues?
Which type of respiration involves gas exchange at body tissues?
Signup and view all the answers
What does the residual volume (RV) represent in lung volumes?
What does the residual volume (RV) represent in lung volumes?
Signup and view all the answers
Which pulmonary capacity equals the total lung capacity (TLC)?
Which pulmonary capacity equals the total lung capacity (TLC)?
Signup and view all the answers
What is the primary component of anatomical dead space in the lungs?
What is the primary component of anatomical dead space in the lungs?
Signup and view all the answers
What does physiological dead space include?
What does physiological dead space include?
Signup and view all the answers
What is the tidal volume (TV) during normal breathing?
What is the tidal volume (TV) during normal breathing?
Signup and view all the answers
How is vital capacity (VC) calculated?
How is vital capacity (VC) calculated?
Signup and view all the answers
What represents the inspiratory capacity (IC)?
What represents the inspiratory capacity (IC)?
Signup and view all the answers
What is the functional residual capacity (FRC)?
What is the functional residual capacity (FRC)?
Signup and view all the answers
Study Notes
Respiratory Physiology Overview
- Respiratory physiology encompasses specific processes like ventilation (mechanical), gas exchange (external and internal respiration), gas transport in the blood (circulatory), and regulation of respiratory function (autonomic and somatic).
Ventilation Mechanics
- Air, as a fluid, follows physical principles, moving from high to low pressure.
- Normal atmospheric pressure is 760 mmHg.
- Inspiration occurs when alveolar pressure is lower than atmospheric pressure.
- Expiration occurs when alveolar pressure is higher than atmospheric pressure.
- The diaphragm and external intercostal muscles expand the thoracic cavity during inspiration, reducing intra-alveolar pressure.
- Forced inspiration involves additional muscles (e.g., sternocleidomastoid, pectorals, serratus anterior).
- Expiration is primarily passive due to the elastic recoil of the lungs and chest wall.
- Forced expiration utilizes accessory muscles (e.g., abdominal and internal intercostals).
Lung Volumes
- Tidal volume (TV): Air exhaled after a normal inspiration (approximately 500 mL).
- Inspiratory reserve volume (IRV): Additional air that can be inspired after a normal inspiration (approximately 3300 mL).
- Expiratory reserve volume (ERV): Air that can be forcefully exhaled after a normal expiration (approximately 1200 mL).
- Residual volume (RV): Air remaining in the lungs after maximum exhalation (approximately 1200 mL).
- Pulmonary volumes are measured with a spirometer.
Pulmonary Capacities
- Vital capacity (VC): Maximum volume of air that can be moved in and out of the lungs (approximately 4500-5000 mL).
- Inspiratory capacity (IC): Maximum inspiratory volume following normal exhalation (approximately 3500-3800 mL).
- Functional residual capacity (FRC): Air remaining in the lungs after normal exhalation (approximately 2200-2400 mL).
- Total lung capacity (TLC): Total volume held by the lungs (approximately 5700-6200 mL).
Dead Space
- Only air entering the respiratory zone participates in gas exchange.
- Anatomical dead space is the air in the conducting airways not available for gas exchange.
- Physiological dead space considers both anatomical dead space and alveolar dead space (alveoli not perfused).
Partial Pressures
- Dalton's Law: Partial pressures of gases in a mixture are directly related to their concentrations.
- Normal atmospheric PO2 is 159.6 mmHg.
- Alveolar PO2 is approximately 100 mmHg.
- Arterial PO2 is approximately 100 mmHg.
- Venous PO2 is approximately 37 mmHg.
Pulmonary Gas Exchange
- Gases (O2 and CO2) move down their pressure gradients across the respiratory membrane.
- Rate of O2 diffusion is influenced by the PO2 gradient, surface area of the respiratory membrane, respiratory minute volume, and alveolar ventilation.
Oxygen Transport
- Most oxygen is transported bound to hemoglobin (Hb) in red blood cells as oxyhemoglobin (HbO2).
- Small amounts of oxygen are dissolved in plasma.
Oxygen-Hemoglobin Dissociation Curve
- The sigmoid shape reflects the cooperative binding of oxygen to hemoglobin, where increasing PO2 leads to more complete binding.
- Small changes in PO2 affect oxygen content significantly at lower PO2 values compared to higher PO2 values.
Carbon Dioxide Transport
- Some carbon dioxide is dissolved in plasma.
- A significant amount is transported as carbaminohemoglobin (bound to hemoglobin).
- A substantial portion is transported as bicarbonate ions (HCO3−).
Control of Breathing
- Breathing control is primarily regulated by alterations in blood gas homeostasis, mediated by central and peripheral chemoreceptors located in the medulla and peripheral organs (carotid bodies, aortic bodies).
- Inspiratory and expiratory centres are located in the brainstem, with additional centres in the pons that regulate breathing rhythms.
Chemical Control of Breathing
- Chemoreceptors, sensitive to blood chemistry changes, play a crucial role.
- Peripheral chemoreceptors are in carotid bodies and aortic bodies, detecting changes in partial pressure of oxygen (P02), partial pressure of carbon dioxide (PCO2), and pH, responding with increased firing rates and thus increased ventilation.
Hypoxic Drive
- Hypoxic drive is the reduced sensitivity of the breathing centers to changes in blood oxygen levels at normal Po2 values, which become more prominent when PaO2 is significantly decreased.
Vascular Resistance and Flow
- Decreased alveolar oxygen tension causes vasoconstriction in blood vessels supplying poorly ventilated areas, directing blood flow to better-ventilated alveoli (hypoxic pulmonary vasoconstriction, HPV).
Other Factors
- Other factors, such as voluntary control from the cerebral cortex, sudden pain or cold, or irritation of the larynx/pharynx (choking reflex), can also influence breathing patterns.
- Reflexive acute apneic episodes may occur in response to these stimuli (opposite effect of maintaining such stimulation).
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Related Documents
Description
This quiz covers the fundamental concepts of respiratory physiology, including ventilation mechanics, gas exchange processes, and the regulation of respiratory function. It explores how air moves in accordance with physical principles and the roles of various muscles during inspiration and expiration.
