Mammalian Gaseous Exchange System Flashcards
Starting at mouth and nasal passages describe what route air takes into the body.
Mouth and nose Trachea Bronchi Bronchioles Alveoli
What is the trachea made of?
Rings of cartilage
Why must the lungs maintain a steep concentration gradient?
In order to ensure that diffusion can continue
How big are alveoli?
100-300 micrometers
Why must the alveoli produce a surfactant?
To reduce the cohesive forces between water molecules as these tend to cause the lungs to collapse
What are the adaptations to reduce the distance that the gases diffuse?
Alveolus wall one cell thick
Capillary wall one cell thick
Both walls consist of squamous cells
Capillaries in close contact with alveoli
Capillaries are so narrow that RBC are squeezed against capillary wall
What does squamous cells mean?
This means flattened or very thin cells
What does a good blood supply do?
Helps to maintain a steep concentration gradient so that the gases continue to diffuse.
What does ventilation ensure?
Concentration of O2 in air of alveolus higher than in blood.
Concentration of CO2 in air of alveoli lower than in blood.
What are the five key stages of inspiration?
Diaphragm contracts moving organs
External intercostal muscles contract raising rib cage
Volume of chest cavity increases
Pressure in chest cavity drops below atmospheric pressure
Air moves into lungs
What happens after the external intercostal muscles relax during expiration?
The volume of the chest cavity decreases
