Physiology 1 Flashcards
What is meant by “internal respiration?”
The intracellular mechanisms, which consume oxygen and produce carbon dioxide.
What is meant by “external respiration?”
The sequence of events that lead to exchange of oxygen and carbon dioxide between the external atmosphere and the body cells.
What are the four steps of external respiration?
- Ventilation
- Exchange of O2 and CO2 between air in the alveoli and blood
- Transport
- Exchange of O2 and CO2 between blood and tissues
What is meant by ventilation?
The process of moving gas in and out of the lungs
Which three body systems are involved with external respiration?
- Respiratory
- Cardiovascular
- Haematological
What does Boyle’s law state?
At any constant temperature the pressure exerted by a gas varies inversely with the volume of a gas
i.e. as volume increases pressure decreases
Which two forces hold the thoracic wall and the lungs together?
- Intrapleural fluid cohesiveness
- Negative intrapleural pressure
What is “intrapleural fluid cohesiveness?”
Water molecules in the intrapleural fluid are attracted to each other and resist being pulled apart, hence the pleural membranes tend to stick together.
What is meant by “negative intrapleural pressure?”
The sub-atmospheric intrapleural pressure creates transmural pressure gradient across lung wall and chest wall. The lungs are forced to expand and the chest is forced inwards.
Which three pressures are important in ventilation?
- Atmospheric pressure
- Intra-alveolar pressure
- Intrapleural pressure
Is inspiration and active or passive process?
Why?
Active- It depends on muscle contraction
Which muscle causes the thorax volume to increase vertically?
Diaphragm
Which direction does the diaphragm move during contraction?
Inferiorly
Which nerves supply the diaphragm?
C3, C4 and C5 phrenic nerves
Where do the nerves which supply the diaphragm originate?
C3, C4 and C5 vertebrae
