Physiology Flashcards
The intracellular mechanisms and processes that consume oxygen and produce carbon dioxide.
Internal respiration
At a constant temperature, the pressure exerted by a gas varies inversely with the volume of the gas.
Boyle’s Law
P=2T/r describes the relationship between alveolar radius and the tendency to collapse. A smaller alveolar radius means a higher tendency to collapse.
Law of LaPlace
The processes that exchange oxygen and carbon dioxide between the external environment and the cells of the body.
External respiration
Comprises ventilation, gas exchange between the alveoli and blood, gas transport, and gas exchange at the tissues.
External respiration
Maintains alveolar patency through the elastic recoil of surrounding alveoli preventing alveolar collapse.
Alveolar interdependence
A product of Type II alveolar cells that opposes alveolar surface tension.
Alveolar surfactant
Keeps the visceral and parietal pleurae closely opposed and can be overcome by a pneumothorax.
Transmural pressure gradient
Keeps the visceral and parietal pleurae closely opposed. Dependent on water molecule polarity.
Intrapleural fluid
Fick’s law of diffusion
Gas diffusion across a surface is inversely proportional to surface thickness and proportional to area
Dalton’s law
The total pressure of a mixture of gases equals the sum of the partial pressures of each component gas
The law of LaPlace
Smaller alveoli have a greater tendency to collapse
The volume of air breathed in and out per minute
Pulmonary ventilation
The volume of air exchanged between the atmosphere and alveoli per minute
Alveolar ventilation
The inspired air that is available for gas exchange
Alveolar ventilation
Those alveoli who are well ventilated but not adequately perfused.
Alveolar dead space
The parts of the bronchial tree not available for airway exchange.
Anatomical dead space
The factor that most increases pulmonary ventilation.
Tidal volume
The myoglobin dissociation curve
A hyperbolic curve
The haemoglobin dissociation curve
A sigmoid curve
The Bohr effect on the haemoglobin dissociation curve
A sigmoid curve, shifted right
The Bohr effect
The oxygen dissocation curve is shifted right due to conditions in the tissues, meaning more oxygen is released
The Haldane effect
As O2 is removed from Hb, Hb’s ability to pick up CO2 and CO2-generated H+ ions is increased
Henry’s Law
The amount of a gas dissolved in a given type and volume of liquid at constant temperature is proportional to the partial pressure of the gas in equilibrium with the liquid
Most O2 is transported…
Bound to haemoglobin
Most CO2 is transported…
As bicarbonate
A small proportion of O2 is transported…
In solution
The volume of air in the lungs after a maximal expiration.
Residual volume
Equals inspiratory reserve volume plus tidal volume plus expiratory reserve volume
Vital capacity
The volume of air in the lungs at the end of a normal, passive expiration
Functional residual capacity
Equals expiratory reserve volume plus residual volume.
Functional residual capacity
Equals inspiratory reserve volume plus tidal volume.
Inspiratory capacity
The maximum total volume of air that can be inspired at the end of a normal, quiet respiration.
Inspiratory capacity
The maximum volume of air that can be expired in a single breath following maximum inspiration.
Vital capacity
The volume of air entering or leaving the lungs in a single breath.
Tidal volume
Equals vital capacity plus residual volume
Total lung capacity
Results in increased pulmonary compliance, produces hyperinflated lungs and will show an obstructive defect on spirometry.
Emphysema
Causes shortness of breath on exertion, a restrictive defect on spirometry and reduced pulmonary compliance but no sign of infection.
Pulmonary fibrosis
Will show a low FVC, a low FEV1 and a low FEV1/FVC% on spirometry.
Combined restrictive-obstructive lung disease
Normal expiration
Is a passive process, controlled by the gaps in firing of dorsal neurons within the medulla
Forceful expiration
Is an active process, controlled by the firing of ventral neurons in the medulla
Normal inspiration
Is an active process, controlled by the firing of dorsal neurons within the medulla
These chemoreceptors detect arterial oxygen partial pressure. When stimulated, they cause hyperventilation and increased cardiac output.
Peripheral chemoreceptors
These chemoreceptors are found in the brainstem. They respond to CSF [H+].
Central chemoreceptors in the medulla
These chemoreceptors, when stimulated, can compensate for metabolic acidosis by triggering increased elimination of CO2.
Peripheral chemoreceptors
Chronic adaptation caused by hypoxia
Increased mitochondria, 2,3-BPG, capillaries and polycythaemia with a metabolic acidosis.
Acute mountain sickness
Fatigue, headache, tachycardia, dizziness and shortness of breath, slipping into unconsciousness.
Diabetic ketoacidosis
Hyperventilation with a severe metabolic acidosis.
