Physiology Flashcards
What is internal respiration?
Intracellular mechanisms that consume O2 and produce CO2
What is external respiration?
Exchange of O2 and CO2 between the external environment and cells
What are the 4 steps of external respiration?
- Ventilation
- Gas exchange between alveoli and blood
- Gas transport in the blood
- Gas exchange at the tissues
What body systems are involved with external respiration?
Respiratory
Cardiovascular
Haematology
Nervous
What is ventilation?
The mechanical process of moving air between the atmosphere and alveolar sacs
Boyle’s Law means…
As the volume of the lungs increases, the pressure of gas inside the lungs decreases
How do the thorax and lungs expand during inspiration?
Contraction of inspiratory muscles
What must the pressure conditions be for air to flow into the lungs?
Intra-alveolar pressure must be lower than the atmospheric pressure
What 2 forces hold the lungs to the thoracic wall?
- Intrapleural fluid cohesiveness
2. Negative intrapleural pressure
What is the average pressure of atmosphere?
760 mmHg
What is the average pressure of intra-alveolar
760 mmHg
How would you describe the relative intrapleural pressure
sub atmospheric
What kind of process is inspiration?
Active
What kind of process is expiration?
Passive
What is the transmural gradient?
difference in pressure between two sides of thoracic wall
Define pneumothorax and list the three main common causes
Accumulation of air in pleural space
- Traumatic
- Spontaneous
- Iatrogenic
How does a pneumothorax effect transmural pressure gradient?
Abolishes transmural pressure gradient- can cause lung collapse.
what are the signs of a pneumothorax?
Hyper-resonant percussion note
Decreased/absent breath sounds
What are the symptoms of a pneumothorax?
Shortness of breath
Chest pain
what causes lungs to recoil?
Elastic CT
Alveolar surface tension
What is surfactant and it’s function?
Surfactant is a complex mix secreted by type II alveoli
It’s function is to lower surface tension by interspersing between the H2O molecules lining the alveoli
What causes respiratory distress syndrome in newborns? especially preterm babies?
Often not sufficient supply of surfactant, as produced late in pregnancy
What alveolar interdependence?
The mechanism of surrounding alveoli helping to open collapsed alveoli (using expanding forces)
What is the order of rhythm of respiration?
Inspiration, expiration