GAS EXCHANGE (HUMANS) Flashcards
List what parts are involved in gas exchange
Trachea
Bronchus
Bronchiole
Alveoli
External and internal Intercostal muscles
Ribs
Diaphragm
Give the adaptions for rapid gas exchange in the lungs
–> Branched system increases surface area to volume which shortens diffusion pathway ratio
–> Alveoli create a very large surface area
–> Surrounding every alveolus is a network of capillaries
–> The walls of the alveoli (epithelial cells) and the capillaries (endothelial cells) are very thin (both one cell layer thick) - shorter diffusion pathway
–> The capillaries are so narrow - the red blood cells are flattened against the capillary walls to squeeze through - this slows them down allowing time for diffusion AND reduces diffusion pathways even more
Concentration gradients maintained by:
1. Breathing - ventilates the lungs - constant movement of oxygen in and carbon dioxide out
2. Heart constantly circulates the blood - moving the blood through the capillaries
The diaphragm is a….
Muscle
Describe the process of inspiration (breathing in)
Inspiration:
External intercosastal muscles contract, intercoastal muscles relax
Diapragm contracts
Ribcage moves up and out
Diaphragm flattens
Volume of thoracic cavity increases, lung pressure decreases below atmospheric pressure
Air is forced into the lungs
Describe the process of expiration (breathing out)
Expiration:
External intercostal muscles relax, internal intercostal muscles contract
Diaphragm relaxes
Ribcage moves downwards and up
Diaphragm curves
Volume of thoracic cavity decreases, lung pressure increases above atmospheric pressure
Air is forced out of the lungs
Give the equation for pulmonary ventilation
Pulmonary ventilation = total volume of air moved into and out of the lungs per minute
Pulmonary ventilation rate (dm3 min-1) = tidal volume (dm3) x breathing rate (min -1)
tidal volume - volume of air taken in at each breath
breathing rate - number of breaths taken in 1 minute
