Gas Exchange Humans 2 Flashcards
How is diffusion maintained in the alveoli?
• Air is constantly moved out in and out of the lungs ( breathing )
What is inspiration?
• When the air pressure of the atmosphere is greater than the air pressure inside the lungs air will be forced into the lungs
What is expiration?
• When the air pressure inside the lungs is greater than the air pressure of the atmosphere, air is forced out of the lungs.
What is the pressure change within the lungs dependent on?
Movement of three sets of muscles • Diaphragm • Intercostal Muscles: • Internal Intercostal Muscles • External Intercostal Muscles
What is present between the alveoli?
Collagen and Elastic Fibres
Where are the intercostal muscles present?
They lie between the ribs
What are the two sets of intercostal muscle?
- Internal Intercostal muscles
* External Intercostal Muscle
What is the diaphragm?
Sheet of muscle that separates the thorax from the abdomen
What are the internal costal muscles involved in?
Contractions lead to expiration
What are the external intercostal muscles involved in?
Contraction leads to inspiration
What type of process is inspiration?
- Active
* This uses energy
What type of process is expiration?
- Passive
* Does not require energy
What is the process of inspiration?
- External Intercostal Muscles Contract
- Internal Intercostal Muscles Relax
- Ribs are pulled upwards and outwards increasing the volume of the thorax
- Increased volume of thorax results in reduction of pressure in the lungs
- Atmospheric pressure is now greater than pulmonary pressure, and therefore air is forced into the lungs.
What happens to the external intercostal muscles during inspiration?
Contract
What happens to internal intercostal muscles during inspiration?
Relax
What happens to the ribs during inspiration?
- Pulled upwards and outwards
* This increases the volume of the thorax
What happens if the volume of the thorax is increased?
Reduces pressure in the lungs
What does the diaphragm do during inspiration?
- Contracts, flattening
* Increasing the volume of the thorax
What is the process of expiration?
- Internal Intercostal muscles contract
- External Intercostal muscles relax
- Ribs move downwards and inwards, decreasing the volume of the thorax
- Diaphragm muscles relax, so it is pushed up by the contents of the abdomen that were compressed during inspiration
- Volume of thorax is further decreased
- Decreased volume of the thorax increases the pressure inside the lungs
- Pulmonary pressure is now greater than that of the atmosphere, so air is forced out of the lungs
- Air is forced down the pressure gradient and out of the lungs
What occurs to the ribs during expiration?
- Move downwards and inwards
* Decreasing the volume of the thorax
What happens to the intercostal muscles during expiration?
- Internal Intercostal muscles contract
* External Intercostal muscles relax
What happens to the diaphragm during expiration?
- Diaphragm muscles relax
* It is pushed up by the contents of the abdomen that were compressed during inspiration
What is pulmonary ventilation rate?
Total volume of air that is moved into the lungs during 1 minute
What is the tidal volume?
Volume of air normally taken in at each breath when the body is rest
