Physiology Flashcards
What is internal respiration?
The intracellular mechanisms through which oxygen is consumed, and CO2 is produced.
What is external respiration?
The sequence of events that lead to the exchange of oxygen and CO2 between the external environment and the cells of the body.
Has four phases:
Ventilation
Exchange of O2 and CO2 between alveoli and blood in capillaries
Transport in the blood between lung and tissues
Exchange of O2 and CO2 between blood and tissues
What is Boyle’s Law?
For any constant temperature, the pressure exerted by a gas varies inversely with the volume of the gas.
Is atmospheric or alveolar pressure higher?
They are the same - intrapleural pressure is less.
Is inspiration active or passive?
Active - as contraction of the diaphragm is necessary.
Is expiration active or passive?
Passive - muscles relax only.
What is alveolar surface tension?
This is the attraction between water molecules at the liquid-air interface.
The presence of this causes a force which resists the stretching of the lungs - allows for recoil in expiration phase.
Which cells produce surfactant?
Type 2 pneumocytes.
Which forces keep the alveoli open?
Transmural pressure gradient
Pulmonary surfactant
Alveolar interdependence
What is the role of pulmonary surfactant?
Intersperses water molecules in the alveoli - reducing alveolar surface tension - preventing collapse.
Which forces promote alveolar collapse?
Elasticity of stretched lung connective tissue
Alveolar surface tension
What are the major inspiratory muscles?
Diaphragm
External intercostal muscles
What are the accessory muscles of inspiration (those only used in forceful inspiration)?
Sternocleidomastoid
Scalenus
Pectoral
What are the muscles fo active expiration?
Abdominal muscles
Internal intercostal muscles
What is the tidal volume?
The volume of air that enters and leaves with each breath, during normal quiet inspiration/expiration.
Approximately 500ml of air.
What is the inspiratory reserve volume?
The amount of air that can be forcibly inhaled above that in the tidal volume. This depends on muscle strength and lung compliance.
Approximately 3.1L of air.
What is the expiratory reserve volume?
The volume of air that can be forcibly exhaled of a normal tidal volume. Relies on muscle strength and low airway resistance.
What is residual volume?
The volume of air remaining in the lungs after maximal expiration. Increases with age, and some conditions such as emphysema.
What is the vital capacity?
The volume of air that can be exhaled after a maximal inspiration.
VC = IRV + TV + ERV
What is the inspiratory capacity?
Volume of air remaining after quiet expiration.
IC = IRV + TV
What is the functional residual capacity?
Volume of air in lungs at the end of normal passive expiration
FRC = ERV + RV
What is the total lung capacity?
Volume of air in lungs after maximum inspiration - it is the sum of all volumes.
What is FVC?
Forced vital capacity - the maximum air volume that can be expelled in a maximal expiration, following a maximal inspiration.
What is FEV1?
The maximal volume of air that can be expelled in one second following maximal inspiration.
How does parasympathetic stimulation affect the airway?
Bronchoconstriction
How does sympathetic stimulation affect the airway?
Bronchodilation
What is the difference between ventilation and perfusion?
Ventilation refers to gas passing through lungs, however perfusion relates to blood passing through lungs. Breathing is limited by the rate of blood flow.
