Gas Exchange Flashcards
What is equation for rate of diffusion?
(surface area x difference in concentration) / thickness of surface
What is the path oxygen takes in the lungs?
Trachea -> bronchi -> bronchioles -> alveoli -> across alveolar epithelium -> capillary/blood
How does inhalation occur?
- Internal intercostal muscles relax
- Ribcage moves outwards
- Diaphragm contracts and moves down
- Lung volume increases
- Pressure decreases and air moves into the lungs down the pressure gradient
How does exhalation occur?
- Internal intercostal muscles contract
- Ribcage moves inwards
- Diaphragm relaxes and moves up
- Lung volume decreases
- Pressure increases and air moves out the lungs down the pressure gradient
Why is alveoli a good exchange surface?
- Single cell thick epithelium -> short diffusion pathway
- Constant blood supply -> concentration gradient always maintained
- Many alveoli -> large surface area for diffusion
- Moist walls -> dissolves gases and facilitates diffusion
How do you calculate pulmonary ventilation?
PVR = tidal volume x breathing rate
What is pulmonary ventilation?
The amount of air exchanged in one breathing cycle
Why do larger organisms need to have specialised gas a change systems?
Their surface area to volume ratio is too great for them to exchange gases with their environment
What are the adaptations of exchange surface?
- Large surface area
- Large concentration gradient
- Thin exchange surface
- Partially permeable
- Movement of environmental medium e.g air and internal mediums e.g blood
What is the diaphragm?
Contracts and flattens to increase lung volume.
What are the alveoli?
They are air sacs where gas exchange occurs
What is the trachea?
A tube that allows the air to move in and out of the lungs and mouth
What is the role of the rings of cartilage on the bronco and trachea?
To prevent them from collapsing
What is the definition of tidal volume?
It is the volume of air normally taken in at each breath when the body is at rest
What is the definition of ventilation rate?
It is the number of breaths taken in one minute