Lecture 1 Flashcards
What is external respiration?
Gas exchange where air is drawn into body and air expelled from lungs to external environment
What is internal respiration?
Intracellualr mechanisms where O2 is used and CO2 is produced
What are the four steps in external respiration?
Ventilation- gas exchange between atmosphere and air sacs in lungs
Gas exchange of O2 and CO2 between air in alveoli and blood in pulmonary capillaries
Binding and transport of O2 and CO2 in blood
Exchange of O2 and CO2 between systemic capillaries and body cells
Explain ventilation
Air moving between atmosphere and alveolar sacs
Air flows down pressure gradient from h to l
Intra alveolar pressure less than atmospheric pressure during inspiration
Thorax and lungs expand
Contraction of inspiration muscles
What is bottles law?
At constant volime the pressure is inversely proportional
How do the lungs adhere to thorax?
Intrapleural fluid cohesiveness- water in intrapleural fluid attracted to each other this pleural membranes stick together.
Negative pleural pressure- pressure gradient across whole lung wall and chest wall. Lungs expand outwards whilst chest squeezed inwards
What does pneumothorax do?
Abolishes transmittal pressure gradient needed for lung expansion
Is inspiration active or passive?
Active
What is resting expiration, active or passive
Passive
What are the inspiration muscles used during normal resting breathing?
Intercostal muscles
Diaphragm
What nerves control the diaphragm?
Sphrenic- 345
How do you make the intra alveolar pressure fall?
Increased size in lungs
Air molecules contained in large space
why does recoil occur?
Due to its elastic properties
How does recoil of lungs make the intra alveolar pressure rise?
Elastic connective tissue in lungs and alveolar surface tension- this resists stretching if lungs
What is pneumothorax?
A puncture in the chest wall results in collapsed lung
